Abstract— NaOH, H2O2 and NaOH/H2O2 treatment methods were investigated to eliminate the lignin and hemicellulose distributed in the lignocellulosic matrix of rice husk. In order to prevent the decomposition of H2O2 at higher temperatures, a low temperature treatment for 4 hours has been performed. A composition analysis indicated that NaOH/H2O2 may achieve the highest concentration of α-cellulose, but had the lowest overall solid recovery rate. Both FTIR and TGA results confirmed that only the H2O2 treated rice husk contained hemicellulose residue, which could be found at the absorption peak 1740 cm-1. The TGA analysis demonstrated the NaOH/H2O2 modified rice husks presented the most uniform structure. The SEM gave a clear picture of the raw rice husks and modified rice husks.
Rice Husk Ash (RHA), a waste product of the rice industry is rich in silica. A simple method based on alkaline extraction, followed by acid precipitation was developed to produce pure silica xerogels from RHA, with minimal mineral contaminants.
Rice Husk Ash (RHA), a waste product of the rice industry is rich in silica. A simple method based on alkaline extraction, followed by acid precipitation was developed to produce pure silica xerogels from RHA, with minimal mineral contaminants.
Bleaching Process of Cotton Goods in Winch MachineMobin Mithun
Academic Presentation | Shitty 3rd Year (2020-2022)
We got the opportunity to pitch a slide presentation after the longggg... pandemic. But omicron is knocking at our doors :3
Treatment of water for domestic use,Screening,Sedimentation,Co-agulation,Filtration,Disinfection of water,Water softening
Permutit Process,Ion exchange method,Mixed bed Dimneralisation process, Lime- Soda process ,Desalination
RO Method, Electrodialysis
The manufacturing process of Hydrogen Peroxide. This slide will give u all information about the manufacturing process of hydrogen peroxide. First it will describe u about the raw material used for the manufacturing of hydrogen peroxide and then the manufacturing process of hydrogen peroxide and then the utilities and uses of hydrogen peroxide.
Separation of CO2 and Moisture from biogas by Adsorption methodMinza Mumtaz
Group of post graduate students have made a system to remaove carbondioxide and moisture from biogas production. It is reusable. Checkout the presentation to get the idea how to prepare it.
For further information can contact.
Statistical Optimization of Synthetic Soda Ash for Water Softeningijtsrd
Synthesized soda ash was prepared by Solvay process with different molar ratio for application of water softening process. In urban utilization, water supply is very important for safe condition. In this research, Box Behnken experimental design was employed for optimization of soda ash. The maximum yield percent of 19.882 of soda ash was obtained by the reaction salt to ammonium hydroxide to carbon dioxide 1 3 6.8 during the reaction time 90 min. The synthesized soda ash was analyzed by X ray diffraction XRD , Scanning Electron Microscope SEM , Energy Dispersive X ray Fluorescence EDXRF and Fourier Transform Infrared Spectroscopy FTIR . Soda ash obtained from optimum condition was applied in water softening of tap water. According to the experimental results of water softening process, the maximum removal of hardness of water was observed at 3 ml of 10 lime solution with 20 ml of 5 of soda ash solution for 1000 ml of water. After treated the lime soda process, the total hardness of water was reduced to initial condition of 255 ppm to 24 ppm. Su Mon Tun | May Myat Khine | Khin Thidar Cho "Statistical Optimization of Synthetic Soda Ash for Water Softening" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-3 | Issue-5 , August 2019, URL: https://www.ijtsrd.com/papers/ijtsrd27841.pdf Paper URL: https://www.ijtsrd.com/engineering/chemical-engineering/27841/statistical-optimization-of-synthetic-soda-ash-for-water-softening/su-mon-tun
Determination of sulphur and ash content in the sample of coal charcoaMithil Fal Desai
The residue left after the burning of coal is known as ash. It is generally composed of inorganic substances. The total sulphur content of coal can be determined gravimetrically by the Eschka method. In this method, a coal sample is heated with the Eschka mixture (2:1 calcined magnesia and anhydrous sodium carbonate by weight) in an oxidizing atmosphere. This removes majorly all combustible matter and converts all forms of sulphur (pyritic’ and ‘organic, sulphur) to sulphate
Increment of carbohydrate concentration of Chlorella minutissima microalgae f...IJERA Editor
Microalgae, like any other microorganism react to changes in the external environment with changes in their
intracellular environment. Thus, the manipulation of cultivation conditions, especially the presence or absence
of certain nutrients, stimulates the biosynthesis of compounds of interest. Their carbohydrates can be used to
produce bioethanol. The objective of this study was to evaluate the effect of the medium and the concentrations
of nitrogen and phosphate components used in the culture medium of the microalgae Chlorella minutissima in
the carbohydrate concentration of the same. Box-Behnken Planning was used, totaling 15 trials. The cultivations
were carried out until early stationary phase of growth of the microalgae in closed 2 L reactors. At the end of the
cultivation, the carbohydrate concentrations of dry biomass (%) and yield in carbohydrates (g.L-1
.d-1
) were
determined. According to the analysis of effects, the microalgae Chlorella minutissima cultivated in Basal
medium, with the addition of 0.125 gL-1
of the nitrogenized component (KNO3) and without addition of
phosphatized components (K2HPO4 and KH2PO4) had a higher yield in carbohydrates in the cultivation (0,030 ±
0.002 g.L-1
.d-1
).
Bleaching Process of Cotton Goods in Winch MachineMobin Mithun
Academic Presentation | Shitty 3rd Year (2020-2022)
We got the opportunity to pitch a slide presentation after the longggg... pandemic. But omicron is knocking at our doors :3
Treatment of water for domestic use,Screening,Sedimentation,Co-agulation,Filtration,Disinfection of water,Water softening
Permutit Process,Ion exchange method,Mixed bed Dimneralisation process, Lime- Soda process ,Desalination
RO Method, Electrodialysis
The manufacturing process of Hydrogen Peroxide. This slide will give u all information about the manufacturing process of hydrogen peroxide. First it will describe u about the raw material used for the manufacturing of hydrogen peroxide and then the manufacturing process of hydrogen peroxide and then the utilities and uses of hydrogen peroxide.
Separation of CO2 and Moisture from biogas by Adsorption methodMinza Mumtaz
Group of post graduate students have made a system to remaove carbondioxide and moisture from biogas production. It is reusable. Checkout the presentation to get the idea how to prepare it.
For further information can contact.
Statistical Optimization of Synthetic Soda Ash for Water Softeningijtsrd
Synthesized soda ash was prepared by Solvay process with different molar ratio for application of water softening process. In urban utilization, water supply is very important for safe condition. In this research, Box Behnken experimental design was employed for optimization of soda ash. The maximum yield percent of 19.882 of soda ash was obtained by the reaction salt to ammonium hydroxide to carbon dioxide 1 3 6.8 during the reaction time 90 min. The synthesized soda ash was analyzed by X ray diffraction XRD , Scanning Electron Microscope SEM , Energy Dispersive X ray Fluorescence EDXRF and Fourier Transform Infrared Spectroscopy FTIR . Soda ash obtained from optimum condition was applied in water softening of tap water. According to the experimental results of water softening process, the maximum removal of hardness of water was observed at 3 ml of 10 lime solution with 20 ml of 5 of soda ash solution for 1000 ml of water. After treated the lime soda process, the total hardness of water was reduced to initial condition of 255 ppm to 24 ppm. Su Mon Tun | May Myat Khine | Khin Thidar Cho "Statistical Optimization of Synthetic Soda Ash for Water Softening" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-3 | Issue-5 , August 2019, URL: https://www.ijtsrd.com/papers/ijtsrd27841.pdf Paper URL: https://www.ijtsrd.com/engineering/chemical-engineering/27841/statistical-optimization-of-synthetic-soda-ash-for-water-softening/su-mon-tun
Determination of sulphur and ash content in the sample of coal charcoaMithil Fal Desai
The residue left after the burning of coal is known as ash. It is generally composed of inorganic substances. The total sulphur content of coal can be determined gravimetrically by the Eschka method. In this method, a coal sample is heated with the Eschka mixture (2:1 calcined magnesia and anhydrous sodium carbonate by weight) in an oxidizing atmosphere. This removes majorly all combustible matter and converts all forms of sulphur (pyritic’ and ‘organic, sulphur) to sulphate
Increment of carbohydrate concentration of Chlorella minutissima microalgae f...IJERA Editor
Microalgae, like any other microorganism react to changes in the external environment with changes in their
intracellular environment. Thus, the manipulation of cultivation conditions, especially the presence or absence
of certain nutrients, stimulates the biosynthesis of compounds of interest. Their carbohydrates can be used to
produce bioethanol. The objective of this study was to evaluate the effect of the medium and the concentrations
of nitrogen and phosphate components used in the culture medium of the microalgae Chlorella minutissima in
the carbohydrate concentration of the same. Box-Behnken Planning was used, totaling 15 trials. The cultivations
were carried out until early stationary phase of growth of the microalgae in closed 2 L reactors. At the end of the
cultivation, the carbohydrate concentrations of dry biomass (%) and yield in carbohydrates (g.L-1
.d-1
) were
determined. According to the analysis of effects, the microalgae Chlorella minutissima cultivated in Basal
medium, with the addition of 0.125 gL-1
of the nitrogenized component (KNO3) and without addition of
phosphatized components (K2HPO4 and KH2PO4) had a higher yield in carbohydrates in the cultivation (0,030 ±
0.002 g.L-1
.d-1
).
— Municipal Solid Waste (MSW), mainly Kitchen Waste
(K) with Cow Dung (C) and Fungi Culture (F) can be used to
generate energy which could save on the fossil fuels conventionally
used as source of energy. In this study, the possibility was
explored to mix Cow Dung with Fungi Culture for anaerobic
digestion, so that energy can be generated as biogas and at the
same time digested sludge can be used as fertilizer for agricultural
applications. Pre-treatment of Kitchen Waste was done by alkali
method. Anaerobic digestion (AD) was carried out in mesophilic
temperature range of 30°C to 37°C with different fermentation
slurries of 8 % total solids. Digestion was carried for a retention
period of 60 days. The gas produced was collected by the
downward displacement of water and was subsequently measured
and analyzed. The overall results showed that blending of Kitchen
waste with cow dung and fungi culture (Aspergillus flavus) had
significant improvement on the biogas yield.
GC-MS and FTIR analysis of bio-oil obtained from freshwater algae (spirogyra)...Agriculture Journal IJOEAR
Abstract— Algae are gaining broad consideration as a substitute renewable source of biomass for the manufacture of bioethanol, due to this reason categorized under the “third generation biofuels” .İn this work, GC-MS analysis and FTIR has been done of bio-oil obtained from fast pyrolysis of Freshwater Algae( Spirogyra ) in this paper we have shown a simple process of converting biomass of fresh water algae to bio-oil through pyrolysis and explained it with the help of graphs and tables. Pyrolysis is a thermal process for converting various biomasses , residues and wastes to produce high-energy-density fuels (bio-oil, biochar). The bio-oil was obtained in two step pyrolysis in which temperature of the system kept 25ºC and then increased up to 650ºC time by time. After pyrolysis these fractions were analyzed by gas chromatography/mass spectrometry (GC-MS) and FTIR which show different peaks and data of different compounds and functional groups present in this bio-oil
Engineering escherichia coli to convert acetic acid to free fatty acidszhenhua82
Fatty acids (FAs) are promising precursors of advanced biofuels. This study investigated conversion of acetic acid (HAc) to FAs by an engineered Escherichia coli strain. We combined established genetic engineering strategies including overexpression of acs and tesA genes, and knockout of fadE in E. coli BL21, resulting in the production of similar to 1 g/L FAs from acetic acid. The microbial conversion of HAc to FAs was achieved with similar to 20% of the theoretical yield. We cultured the engineered strain with HAc-rich liquid wastes, which yielded similar to 0.43 g/L FAs using waste streams from dilute acid hydrolysis of lignocellulosic biomass and similar to 0.17 g/L FAs using effluent from anaerobic-digested sewage sludge. C-13-isotopic experiments showed that the metabolism in our engineered strain had high carbon fluxes toward FAs synthesis and TCA cycle in a complex HAc medium. This proof-of-concept work demonstrates the possibility for coupling the waste treatment with the biosynthesis of advanced biofuel via genetically engineered microbial species.
cellulose, the most abundant natural biopolymer, has long been
investigated as a new green source to replace non-renewable materials and chemicals, but its highly ordered hydrogen bond network
and high crystallinity, which both detract cellulose reactivity and
solubility (Kondo, 1998), have made it difficult to exploit the full
potential of cellulose materials. To overcome these problems, many
new solvent systems have been studied to enable the homogeneous
modification of cellulose (Ramos, Frollini, & Heinze, 2005; Wu
et al., 2004). Many modifications are nevertheless still preferably
conducted heterogeneously in an aqueous medium, particularly
because of the advantages of this approach with regard to toxicity,
volatility and price.
One potential react
Abstract— Biofuel production from microalgae biomass appears as a promising long term alternative. Dunaliella tertiolecta is a microalgae with high tolerance to salinity, temperature, and light, making it relatively easy to grow. The aim of this study was to establish a pilot-scale culture to evaluate the biomass yield and bioethanol production. The cell culture of D. tertiolecta was started in 20 ml tubes and escalated to 20 L containers. The biomass yield was 0.153 g L-1 of dry basis (db) and its characterization showed protein (37% db) as major component followed by carbohydrates (35.6), lipids (13% db) and ash (6.5%). The carbohydrate fraction was composed of starch (27.1% db) and fiber (8.5 %) and its neutral sugar characterization yield glucose (91% molar). The main components of the lipid fraction were linolenic and palmitic acids. The biomass was subjected to an acid pre-treatment for the saccharification of complex carbohydrates, and the hydrolyzed biomass was fermented by Saccharomyces cerevisiae. It was possible to produce 0.615 ml g-1 of ethanol. In conclusion, D. tertiolecta has the potential for bioethanol production, making it a promising option for the biofuels future.
Oleaginous fungal lipid fermentation on combined acid and alkali-pretreated ...zhenhua82
A combined hydrolysis process, which first mixed dilute acid- and alkali-pretreated corn stover at a 1:1 (w/w) ratio, directly followed by enzymatic saccharification without pH adjustment, has been developed in this study in order to minimize the need of neutralization, detoxification, and washing during the process of lignocellulosic biofuel production. The oleaginous fungus Mortierella isabellina was selected and applied to the combined hydrolysate as well as a synthetic medium to compare fungal lipid accumulation and biodiesel production in both shake flask and 7.5 L fermentor. Fungal cultivation on combined hydrolysate exhibited comparable cell mass and lipid yield with those from synthetic medium, indicating that the integration of combined hydrolysis with oleaginous fungal lipid fermentation has great potential to improve performance of advanced lignocellulosic biofuel production
Multiple response optimization analysis for pretreatments of Tequila’s stilla...Roberto Bolaños
The objective of this work was study the effect of three pretreatments (alkalinization, thermical treatment, and sonication) on Tequila’s
stillages hydrolysis process in acidogenesis stage, through the following response variables: soluble chemical oxygen demand (CODs),
total sugar and volatile fatty acids profile and the hydrogen production at the time. The stillages were subject to these pretreatments
(according to a 23 factorial design); afterward they were transferred to a batch reactor at 35 C and inoculated with an anaerobic digestor
sludge. Multiple response optimization (MRO) analysis was done to find the global optimum for the response variables described above.
This optimum is able to maximize simultaneously all these variables. It was found adequate to be useful hydrolyzing the organic matter
present in Tequila’s stillages. Mathematical models were fitted to observe the estimated effects of pretreatments on each response variable,
then the MRO was applied.
2007 Elsevier Ltd. All rights reserved.
Isolation and Screening of Hydrogen Producing Bacterial Strain from Sugarcane...Editor IJCATR
The aim of this study is to isolate a highly competent bacterium with potent cellulose degrading capability and a better
hydrogen producer. Soil sample from sugarcane bagasse yard was isolated, serially diluted and plated on cellulose specific nutrient
agar plate. Four colonies have been isolated in which a single colony has potent cellulose degrading ability and the highest hydrogen
productivity of 275.13 mL H2 L-1. The newly isolated bacterium was morphologically and biochemically characterized. The
molecular characterization of the bacterium was carried out using 16S rDNA sequencing and the organism was identified as
Bacilllus subtilis AuChE413. Proteomic analysis such as MALDI-TOF was carried out to differentiate the isolated Bacillus subtilis
from Bacillus thuringiensis and Bacillus amyloliquefaciens. Phylogenetic tree was constructed to analyze the evolutionary
relationship among different genus and species with the newly isolated strain.
Characterization of Rubber Seed Shell and Kernel (Hevea brasiliensis) as Raw ...CrimsonPublishersACSR
Characterization of Rubber Seed Shell and Kernel
(Hevea brasiliensis) as Raw Materials for Coliquefaction with Low Rank Coal by Mohd Azlan Mohd Ishak*, Siti Nur Ain Mohd Hassan, Ali H Jawad and Khudzir Ismail in Annals of Chemical Science Research
Anaerobic Co-Digestion of Cassava Waste Water and Abdominal Cow Dung under Ch...IJCMESJOURNAL
Anaerobic co-digestion of cassava waste water (CWW) and abdominal cow dung (ACD)in different proportions was studied in five treatments under changing meteorological conditions. The five treatment cases T1: 100% CWW; T2: 100% ACD; T3: 90%CWW +10%ACD; T4:70%CWW+30%ACD; T5: 50%CWW+50%ACD were digested under anaerobic conditions in model batch, metallic bio digesters of same working volume (32.0 liters) for 30 days retention period. Results indicated that T2 system flamed on the 20th day, T5 on the 20th day while T1, T4 and T3 systems didn’t flame. T1 had cumulative gas yield of 12.7 liters; T2 had 28.85 liters; T3 had 12.5 liters,T4 had 11.1 liters while T5 had cumulative gas yield of 15.8 liters per 24kg mass of slurry. T2had 91.20% methane; while T5 produced 92.999% methane. Daily biogas yields were modeled as functions of meteorological parameters. Results indicated that many parameters showed good correlations with ambient temperature.
Trisodium phosphate, TSP was utilized to valorize abundant glycerol to fine chemicals (Glycerol carbonate). The catalyst displayed superior stability and activity over nine times reuse. Hence, its strongly recommended for potential industrial application.
UNDERSTANDING WHAT GREEN WASHING IS!.pdfJulietMogola
Many companies today use green washing to lure the public into thinking they are conserving the environment but in real sense they are doing more harm. There have been such several cases from very big companies here in Kenya and also globally. This ranges from various sectors from manufacturing and goes to consumer products. Educating people on greenwashing will enable people to make better choices based on their analysis and not on what they see on marketing sites.
Characterization and the Kinetics of drying at the drying oven and with micro...Open Access Research Paper
The objective of this work is to contribute to valorization de Nephelium lappaceum by the characterization of kinetics of drying of seeds of Nephelium lappaceum. The seeds were dehydrated until a constant mass respectively in a drying oven and a microwawe oven. The temperatures and the powers of drying are respectively: 50, 60 and 70°C and 140, 280 and 420 W. The results show that the curves of drying of seeds of Nephelium lappaceum do not present a phase of constant kinetics. The coefficients of diffusion vary between 2.09.10-8 to 2.98. 10-8m-2/s in the interval of 50°C at 70°C and between 4.83×10-07 at 9.04×10-07 m-8/s for the powers going of 140 W with 420 W the relation between Arrhenius and a value of energy of activation of 16.49 kJ. mol-1 expressed the effect of the temperature on effective diffusivity.
Artificial Reefs by Kuddle Life Foundation - May 2024punit537210
Situated in Pondicherry, India, Kuddle Life Foundation is a charitable, non-profit and non-governmental organization (NGO) dedicated to improving the living standards of coastal communities and simultaneously placing a strong emphasis on the protection of marine ecosystems.
One of the key areas we work in is Artificial Reefs. This presentation captures our journey so far and our learnings. We hope you get as excited about marine conservation and artificial reefs as we are.
Please visit our website: https://kuddlelife.org
Our Instagram channel:
@kuddlelifefoundation
Our Linkedin Page:
https://www.linkedin.com/company/kuddlelifefoundation/
and write to us if you have any questions:
info@kuddlelife.org
"Understanding the Carbon Cycle: Processes, Human Impacts, and Strategies for...MMariSelvam4
The carbon cycle is a critical component of Earth's environmental system, governing the movement and transformation of carbon through various reservoirs, including the atmosphere, oceans, soil, and living organisms. This complex cycle involves several key processes such as photosynthesis, respiration, decomposition, and carbon sequestration, each contributing to the regulation of carbon levels on the planet.
Human activities, particularly fossil fuel combustion and deforestation, have significantly altered the natural carbon cycle, leading to increased atmospheric carbon dioxide concentrations and driving climate change. Understanding the intricacies of the carbon cycle is essential for assessing the impacts of these changes and developing effective mitigation strategies.
By studying the carbon cycle, scientists can identify carbon sources and sinks, measure carbon fluxes, and predict future trends. This knowledge is crucial for crafting policies aimed at reducing carbon emissions, enhancing carbon storage, and promoting sustainable practices. The carbon cycle's interplay with climate systems, ecosystems, and human activities underscores its importance in maintaining a stable and healthy planet.
In-depth exploration of the carbon cycle reveals the delicate balance required to sustain life and the urgent need to address anthropogenic influences. Through research, education, and policy, we can work towards restoring equilibrium in the carbon cycle and ensuring a sustainable future for generations to come.
Willie Nelson Net Worth: A Journey Through Music, Movies, and Business Venturesgreendigital
Willie Nelson is a name that resonates within the world of music and entertainment. Known for his unique voice, and masterful guitar skills. and an extraordinary career spanning several decades. Nelson has become a legend in the country music scene. But, his influence extends far beyond the realm of music. with ventures in acting, writing, activism, and business. This comprehensive article delves into Willie Nelson net worth. exploring the various facets of his career that have contributed to his large fortune.
Follow us on: Pinterest
Introduction
Willie Nelson net worth is a testament to his enduring influence and success in many fields. Born on April 29, 1933, in Abbott, Texas. Nelson's journey from a humble beginning to becoming one of the most iconic figures in American music is nothing short of inspirational. His net worth, which estimated to be around $25 million as of 2024. reflects a career that is as diverse as it is prolific.
Early Life and Musical Beginnings
Humble Origins
Willie Hugh Nelson was born during the Great Depression. a time of significant economic hardship in the United States. Raised by his grandparents. Nelson found solace and inspiration in music from an early age. His grandmother taught him to play the guitar. setting the stage for what would become an illustrious career.
First Steps in Music
Nelson's initial foray into the music industry was fraught with challenges. He moved to Nashville, Tennessee, to pursue his dreams, but success did not come . Working as a songwriter, Nelson penned hits for other artists. which helped him gain a foothold in the competitive music scene. His songwriting skills contributed to his early earnings. laying the foundation for his net worth.
Rise to Stardom
Breakthrough Albums
The 1970s marked a turning point in Willie Nelson's career. His albums "Shotgun Willie" (1973), "Red Headed Stranger" (1975). and "Stardust" (1978) received critical acclaim and commercial success. These albums not only solidified his position in the country music genre. but also introduced his music to a broader audience. The success of these albums played a crucial role in boosting Willie Nelson net worth.
Iconic Songs
Willie Nelson net worth is also attributed to his extensive catalog of hit songs. Tracks like "Blue Eyes Crying in the Rain," "On the Road Again," and "Always on My Mind" have become timeless classics. These songs have not only earned Nelson large royalties but have also ensured his continued relevance in the music industry.
Acting and Film Career
Hollywood Ventures
In addition to his music career, Willie Nelson has also made a mark in Hollywood. His distinctive personality and on-screen presence have landed him roles in several films and television shows. Notable appearances include roles in "The Electric Horseman" (1979), "Honeysuckle Rose" (1980), and "Barbarosa" (1982). These acting gigs have added a significant amount to Willie Nelson net worth.
Television Appearances
Nelson's char
WRI’s brand new “Food Service Playbook for Promoting Sustainable Food Choices” gives food service operators the very latest strategies for creating dining environments that empower consumers to choose sustainable, plant-rich dishes. This research builds off our first guide for food service, now with industry experience and insights from nearly 350 academic trials.
Prevalence of Toxoplasma gondii infection in domestic animals in District Ban...Open Access Research Paper
Toxoplasma gondii is an intracellular zoonotic protozoan parasite, infect both humans and animals population worldwide. It can also cause abortion and inborn disease in humans and livestock population. In the present study total of 313 domestic animals were screened for Toxoplasma gondii infection. Of which 45 cows, 55 buffalos, 68 goats, 60 sheep and 85 shaver chicken were tested. Among these 40 (88.88%) cows were negative and 05 (11.12%) were positive. Similarly 55 (92.72%) buffalos were negative and 04 (07.28%) were positive. In goats 68 (98.52%) were negative and 01 (01.48%) was recorded positive. In sheep and shaver chicken the infection were not recorded.
Climate Change All over the World .pptxsairaanwer024
Climate change refers to significant and lasting changes in the average weather patterns over periods ranging from decades to millions of years. It encompasses both global warming driven by human emissions of greenhouse gases and the resulting large-scale shifts in weather patterns. While climate change is a natural phenomenon, human activities, particularly since the Industrial Revolution, have accelerated its pace and intensity
A comparison of chemical treatment methods for the preparation of rice husk cellulosic fibers
1. International Journal of Environmental & Agriculture Research (IJOEAR) ISSN [2454-1850] [Vol-2, Issue-1, January- 2016]
Page | 67
A comparison of chemical treatment methods for the preparation
of rice husk cellulosic fibers
Zhixuan Wang1
, Jiaying Li2
, John P. Barford3
, Klaus Hellgradt4
, Gordon McKay5*
1,4
Department of Chemical Engineering, Imperial College London, South Kensington Campus, London, UK.
2 ,3,5
Department of Chemical and Biomolecular Engineering, Hong Kong University of Science and Technology, Clear
Water Bay, Hong Kong.
5
Division of Sustainability, College of Science, Engineering and Technology, Hamad Bin Khalifa University, Education
City, Qatar Foundation, Qatar.
Abstract— NaOH, H2O2 and NaOH/H2O2 treatment methods were investigated to eliminate the lignin and hemicellulose
distributed in the lignocellulosic matrix of rice husk. In order to prevent the decomposition of H2O2 at higher temperatures, a
low temperature treatment for 4 hours has been performed. A composition analysis indicated that NaOH/H2O2 may achieve
the highest concentration of α-cellulose, but had the lowest overall solid recovery rate. Both FTIR and TGA results
confirmed that only the H2O2 treated rice husk contained hemicellulose residue, which could be found at the absorption peak
1740 cm-1
. The TGA analysis demonstrated the NaOH/H2O2 modified rice husks presented the most uniform structure. The
SEM gave a clear picture of the raw rice husks and modified rice husks.
Keywords— cellulose, delignification, H2O2, kinetics, NaOH.
I. INTRODUCTION
Due to its properties of weightless, inexpensive, tractable, renewable, biodegradable and biocompatible, cellulose has
attracted the attention of many researchers in recent years. As one of the most abundant natural polymers, cellulosic materials
are easily accessible, especially from agricultural wastes, like rice husks [1,2]. Globally, up to 120 million tons of rice husks
are produced annually. Although some are used as animal feed or burned for energy generation, huge quantities of rice husk
are still burnt or dumped as a waste [3-4].
Previous studies demonstrated that rice husks contains cellulose (25 to 35%), hemicellulose (18 to 21%), lignin( 26 to 31%),
silica (15 to 17%), solubles (2 to 5%), and moisture ca (7.5%) [4]. In the rice husks cell wall, cellulose exists in a complex
lignocellulosic matrix, surrounded by hemicellulose and lignin [5]. Linking together by both intermolecular and
intramolecular hydrogen bonds, the cellulose polymers present a microfibrils structure in the nature [6]. The crystalline
structure is formed by combined hydrogen bond energy that makes it insoluble and nonundegradable. In association with
cellulose, hemicellulose is mainly made up of arabinose, galactose, glucose, mannose and xylose. Different from cellulose,
hemicellulose presents a branched and amorphous form and tends to be hydrolyzed by chemical solvents. Consisting of
coniferyl alcohol, sinapyl alcohol and coumaryl alcohol, lignin is a large three-dimensional polymer, which stiffens and
coheres the cell wall fibers together [7].
In order to selectively separate cellulose from the lignocellulosic matrix, alkaline and peroxide treatments were applied to the
rice husks. As one of the most wildly used alkali treated agents, sodium hydroxide (NaOH) can perform a saponification
effect on the intermolecular ester bonds linked between xylan hemicellulose and lignin. This may decrease the degree of
polymerization and crystallization and hence break the crosslinks exiting in the lignin structure [8]. Using the hydrogen
peroxide treatment (H2O2), the H2O2 can decompose into hydroxyl radicals (OH) and superoxide anions (O2-
) under heat,
promote lignin degradation. Since H2O2 treatment is costly, lower H2O2 concentrations in alkaline hydrogen peroxide (AHP)
treatment could be selected and adjusted to overcome the economic drawbacks. After AHP treatment, the three-dimensional
structure of the lignicellulosic matrix become more open and fragile and the cellulosic crystallinity remain the same [9].
In the present work, rice husks were pretreated by NaOH, H2O2 and NaOH combined with H2O2. High Performance Liquid
Chromatography (HPLC) and Fourier Transform Infrared (FT-IR) analysis were undertaken as the basis to investigate the
reaction. Thermogravimetric analysis (TGA) was carried out to study the thermal behavior of modified rice husks.
2. International Journal of Environmental & Agriculture Research (IJOEAR) ISSN [2454-1850] [Vol-2, Issue-1, January- 2016]
Page | 68
II. MATERIAL AND METHOD
2.1 Reagents and material preparation
Sodium hydroxide (NaOH) pellets (Catalog No.: AC20606), and H2O2 (50wt% solution, Catalog No.: H341-500) were
obtained from Fisher-scientific (Waltham, MA). The rice husks used for the present study were obtained from Hunan
province in China. The rice husks were first washed with DI water at 50°C for 2h and dried at 60°C in an oven for 24h. The
dry rice husks were extracted with toluene-ethanol (2:1, v/v) in a Soxhlet for 6 hours due to the presence of fatty acids, free
alcohols and other extractives present. The dewaxed rice husks were then treated with water at 50°C for 2h. The rice husks
were maintained at 60°C in an oven for at least 24 hours for further use.
2.2 Sodium hydroxide (NaOH) and hydrogen peroxide (H2O2) treatment
NaOH or H2O2 at concentrations of 2, 4, 6, and 8% (w/v) was used to pretreat 1 g rice husks samples at a solid loading of 2%
(w/v). Treatments were performed at 40°C, 60°C, and 80°C with continuous stirring. Sodium hydroxide (NaOH) at
concentrations of 2, 4, 6, and 8% (w/v) in 5% hydrogen peroxide (H2O2) solution was also used to treat 1 g rice husks
samples at a solid loading of 2% (w/v). Treatments were performed by four different step-changes: 40°C for the first 4h and
60°C for the next 20h; 40°C for the first 4h and 80°C for the next 20h; 60°C for the first 4h and 80°C for the next 20h. The
last one is heated at 80°C for 24h without any change. The collected solids were washed with 500 mL of hot deionized water
5 times and soaked for 24 hours. Then the modified rice husks were transferred into the oven at 60°C for 24 hours. The
treatments were performed in triplicate and the residue solids were used for determining the concentration of lignin,
holocellulose and carbohydrate.
2.3 Analysis methods
The lignin concentration is composed of acid soluble lignin and acid insoluble lignin, which may be calculated according to
the National Renewable Energy Laboratory (NREL) analytical procedure [10,11]. All the analysis were conducted in
duplicate. The holocellulose concentrations (combination of hemicellulose and cellulose) were measured by gravimetric
methods [12]. The composition of carbohydrate was determined by using a high performance liquid chromatography system
(HPLC) equipped with Accuflow Series Ⅲ Pump, degasser (ERC 3215 ALPHA, ERC Inc.), RI detertor (Shodex RI-71;
Tokyo, Japan) and Bio-Rad Aminex HPX-87P column, according to the standard National Renewable Energy Laboratory
(NREL) methods [13].
2.4 Fourier Transform Infrared Spectroscopy(FTIR) and Thermogravimetric Analysis(TGA)
The modified rice husk samples were analyzed by ATR-FTIR (Vertex 70 Hyperion 1000 (Bruker)) at the Materials
Characterization and Preparation Facility(MCPF), Hong Kong University of Science and Technology. The tests were
conducted with the use of 128 scans, 4cm-1
resolution, and an interval of 1 cm-1
. The thermogravimetric experiments were
conducted by applying a Thermo-gravimetric analyzer (Model Q5000, Thermal Analysis instruments) also at MCPF.
Nitrogen gas was used as carrier gas. Experiments were carried out using a thermobalance at a linear heating rate of 10 °C
/min, with the temperature range from 30 to 750°C, at a steady nitrogen flow of 100 mL/min.
III. RESULTS AND DISCUSSION
3.1 Characterization of rice husk
According to a previous study, the chemical composition of rice husks is cellulose (25 to 35%), hemicellulose(18 to 20%),
lignin(26 to 31%), silica(15 to 17%), solubles (2 to 5%), and moisture ca. 7.5%. Factors affecting the concentration of
different components varied among harvesting methods, growing area and season, and testing procedures. The composition
of the rice husks in this study is shown in Table 1.
3. International Journal of Environmental & Agriculture Research (IJOEAR) ISSN [2454-1850] [Vol-2, Issue-1, January- 2016]
Page | 69
TABLE 1
THE COMPOSITION OF RAW RICE HUSKS
Component Percentage (%)
(a) Solid composition
Holocellulose 49.72
α-cellulose 31.13
Acid-insoluble lignin 24.89
Acid-soluble lignin 3.36
Extractives 5.01
Ash 16.50
(b) Carbohydrate composition Glucan 32.61
Xylan 17.25
Galactan 1.28
Araban 1.52
Based on the analysis procedure of Han and Rowell (1997), the holocellulose concentration was 49.72% of the dry biomass.
By comparing the concentration of holocellulose and carbohydrate, the difference in percentage could be explained by the
sugar degradation caused by the hydrolysis effect of 72% sulfuric acid during the total sugar analysis experiments [14]. The
α-cellulose content of 31.13% was nearly in the middle of the 25.89% to 35.50% range that has been reported for other
lignocellulosic materials in rice husks [15]. The 28.25% lignin concentration, the total amount of acid soluble lignin and acid
insoluble lignin, is also in the middle range comparing with the previously reported values. Although acid insoluble parts
always considered as lignin, other possible parts like rice grain also resist the acid treatment and effect the actually lignin
content. Because the protein portion of the rice grain would condense and become insoluble when treated by a high
concentration sulfuric acid. However, by comparing with the lignin percentage, rice grain only comprise a tiny part of the
totally acid insoluble material [16].
3.2 Sodium hydroxide (NaOH) treatment
The effects of NaOH treatment on the delignification of rice husks are shown in Table 2. The lignin, after NaOH treatment,
varied from 14.71% (24 h, 40°C) to 6.5% (24 h, 80°C). Concentration had a significant effect on delignification for
treatments at 40°C for 24h and 60°C for 24h. Increasing the temperature from 40°C to 80°C sharply increased the
delignification results. The lignin concentration was analyzed based on acid soluble and acid insoluble lignin. As one of the
major portions of the rice husk cell wall, the lignin concentration stands for the major indicator of the delignification
effectiveness of alkaline treatment. By performing experiments in tirplicate, similar results were achieved, which confirmed
the validity of the experimental data and minimised the potential of experimental error. In addition, when the temperature
rose from 40°C to 60°C and 60°C to 80°C, the delignification results from 2% NaOH always had a better performance than
that from the 8% NaOH in the lower temperature stage. A reasonable explanation for this would be that the 20°C temperature
variation had a significant effect on rice husk lignin degradation results.
Contrary to the lignin result, the holocellulose concentration, which stands for cellulose and hemicellulose concentration,
varied from 71.66% (24h, 40°C) to 84.7% (24 h, 80°C). The changes in the NaOH concentration lead to a continuous
increase in the holocellulose contents. The NaOH concentration had a more obvious effect on the holocellullose
concentration at a relatively lower temperature (40°C) than the higher ones, which implied the NaOH concentration effect
was less significant when temperature rose. The solids from holocellulose analysis were used for α-cellulose analysis. The α-
cellulose, which makes up the largest portion of cellulose, was considered as the most important indicator for evaluating the
effectiveness of different treatments for the further oil sorption studies. The amount of α-cellulose after NaOH treatment
ranged from 58.26% (24 h, 40°C) for 2% NaOH to 81.40% (24 h, 80°C) for 8% NaOH, with changes in concentration
causing the most continuous increase in the α-cellulose contents. In addition, when the temperature rose from 40°C to 60°C
and 60°C to 80°C, the increase of α-cellulose concentration did not appear in the same trend like the lignin concentration
trend. A reasonable explanation for this would be that the lignin and hemicellulose are more unstable a the cellulose when
treated with alkaline reagents. Thus when the α-cellulose concentration increases quickly, the rise in the lignin concentration
is not as fast.
4. International Journal of Environmental & Agriculture Research (IJOEAR) ISSN [2454-1850] [Vol-2, Issue-1, January- 2016]
Page | 70
Based on HPLC analysis, xylan constituted between 13.40% (2%, 40°C, 24h) and 3.30% (8%, 80°C, 24h) of the modified
solids. The percentage of xylan during NaOH treatment decreased with increasing concentration and still remained in the
modified rice husks after NaOH treatment. At lower temperatures the NaOH concentration had no obvious effect. However,
after a rising the temperature to 40°C in this study, the reduction of xylan dramatically increased. A possible explanation to
this phenomenon would be that the high temperature was a good support for the xylan hydrolysis.
TABLE 2
PERCENTAGE OF LIGNIN FOR SODIUM HYDROXIDE TREATMENT
Concentration (%)
Temperature°C
Lignin % Holocellulose % α-cellulose % Xylan% Solids
Recovered %
2% NaOH, 40°C 14.71±2.07 71.66±1.41 58.26±2.31 13.40±1.75 68.16±1.54
4% NaOH, 40°C 13.39±1.35 74.40±1.18 61.45±2.59 12.95±0.96 64.94±1.21
6% NaOH, 40°C 11.94±1.52 74.64±1.74 62.64±1.42 12.00±1.02 61.31±2.06
8% NaOH, 40°C 10.87±1.23 77.79±1.21 67.20±2.11 10.59±0.45 56.29±1.77
2% NaOH, 60°C 11.12±1.61 77.39±1.45 67.72±2.29 9.67±0.67 60.52±1.49
4% NaOH, 60°C 10.64±1.04 78.15±1.76 69.39±1.81 8.76±0.81 57.01±3.37
6% NaOH, 60°C 9.45±0.75 79.97±1.62 71.98±1.77 7.99±1.32 53.98±1.18
8% NaOH, 60°C 8.84±0.95 81.00±1.29 74.87±1.02 6.13±0.27 49.24±2.40
2% NaOH, 80°C 8.92±0.36 80.55±2.75 75.52±1.33 5.03±0.39 50.47±1.73
4% NaOH, 80°C 7.43±0.72 83.23±2.98 78.29±1.46 4.94±0.64 47.86±1.65
6% NaOH, 80°C 6.71±1.51 84.37±2.22 80.10±2.27 4.27±0.25 45.92±1.92
8%NaOH, 80°C 6.50±0.37 84.7±1.83 81.40±1.94 3.30±0.41 42.37±1.41
3.3 Hydrogen peroxide treatment
Hydrogen peroxide treatment utilized oxidative delignification to detach and solubilize the lignin and loosen the
lignocellulosic matrix. The extent by which lignin degradation occurred in this study was not as high as expected. The lignin
after hydrogen peroxide pretreatment varied from 27.32% (24 h, 40°C) to 20.98% (24 h, 80°C). A summary of these results,
as well as those for the amount of holocellulose in the hydrogen peroxide treatment, is presented in Table 3. Temperature and
concentration had a continuous effect on the percent lignin reduction during hydrogen peroxide pretreatment. Hydrogen
peroxide concentration had a significant effect on delignification for the treatment at 8% H2O2 for 24h. Increasing the
temperature from 40°C to 60°C also increased delignification for 24h at 2%, 4%, 6%, 8% H2O2.
By analyzing acid soluble and acid insoluble lignin, when the temperature went from 40°C to 60 °C, the delignification
results had a better performance than these from the 60°C to 80 °C NaOH treatment. A reasonable explanation is that when
the hydrogen peroxide is exposed to heat, it undergoes the following decomposition reaction 2H2O2 ==> 2H2O + O2 where
the hydrogen peroxide decomposes to water. However, with the rising delignification results, it is possible that although
hydrogen peroxide decomposition may happen, the higher concentration and reaction time of hydrogen peroxide can still
have a slight rising trend in the delignification treatment.
The amount of holocellulose after H2O2 treatment ranged from 53.44% (24 h, 8% H2O2, 60°C) to 50.18% (24h, 2% H2O2,
40°C). When the temperature went from 60°C to 80 °C, the holocellulose percent production showed a little decrease, which
was different from the lignin reduction percent when the highest temperature presented an increase. A reasonable explanation
is the hydrogen peroxide decomposition at higher temperature may affected the holocellulose concentration, the other
components of rice husks like silica, may not be affected strongly by hydrogen peroxide. Comparing with the NaOH
treatment, in the same situation (concentration, time and temperature) the delignification effect and cellulose production
percentage of hydrogen peroxide treatment is not as high as that of the sodium hydroxide treatment. In other words, without
any other condition changes, sodium hydroxide treatment has the priority for delignification.
5. International Journal of Environmental & Agriculture Research (IJOEAR) ISSN [2454-1850] [Vol-2, Issue-1, January- 2016]
Page | 71
The amount of α-cellulose after H2O2 treatment ranged from 32.12% (24 h, 40°C) for 2% H2O2 to 37.02% (24 h, 80°C) for
8% H2O2, with changes in temperature causing a continuous increase in the α-cellulose content. However, when the
temperature increased from 40°C to 60 °C, the α-cellulose percent production percent showed no significant rise, which was
different from the lignin percent reduction when the temperature rise presented a sharp increase. A reasonable explanation for
this would be that the effect belongs to the other components of rice husks like silica, which may not be affected strongly by
hydrogen peroxide. The remaining percentage of xylan ranged from 18.06% (2%, 40°C, 24h) and 15.10% (8%, 80°C, 24h) of
the modified rice husk. The major effect of temperature and concentration were mild for hemicellulose reduction during
hydrogen peroxide pretreatment. Also the total recovered solids were higher than that of NaOH treatment.
TABLE 3
PERCENTAGE OF LIGNIN FOR HYDROGEN PEROXIDE TREATMENT
Concentration (%)
Temperature°C
Lignin % α-cellulose % Holocellulose % Xylan% Solids
Recovered %
2% H2O2, 40°C 27.32±1.31 32.12±1.92 50.18±2.22 18.06±1.07 92.27±1.01
4% H2O2, 40°C 26.94±2.29 33.20±0.86 51.15±1.46 17.95±1.54 90.52±1.25
6% H2O2, 40°C 26.51±1.48 34.66±2.11 52.05±1.52 17.43±0.68 89.46±0.57
8% H2O2, 40°C 25.77±1.63 34.75±1.06 51.92±1.37 17.17±0.92 88.35±1.33
2% H2O2, 60°C 23.92±1.73 34.29±1.63 51.78±1.98 17.49±1.11 88.61±1.96
4% H2O2, 60°C 23.13±1.91 35.60±1.77 52.62±1.49 17.02±0.71 87.11±1.28
6% H2O2, 60°C 22.77±1.88 36.42±1.22 53.32±2.03 16.90±0.32 85.85±1.68
8% H2O2, 60°C 22.17±1.89 36.63±1.34 53.44±1.92 16.81±0.95 83.70±1.64
2% H2O2, 80°C 22.09±1.03 35.70±1.56 51.91±1.25 16.21±0.23 83.00±1.03
4% H2O2, 80°C 21.92±0.96 36.31±1.81 52.08±3.08 15.77±0.46 81.43±1.85
6% H2O2, 80°C 21.49±1.21 36.63±2.75 52.31±1.62 15.68±0.81 79.14±2.43
8% H2O2, 80°C 20.98±1.47 37.02±1.64 52.12±2.35 15.10±0.47 78.09±1.96
3.4 Sodium hydroxide/ hydrogen peroxide (NaOH/H2O2) pretreatment
Sodium hydroxide pretreatment supplemented by 5% H2O2 caused a significant lignin degradation varying from 84.27% (24
h, 40°C) to 92.21% (24 h, 80°C). A summary of these results is presented in Table 4, which presented the amount of lignin
and holocellulose concentration after the NaOH/H2O2 pretreatment. Temperature, concentration and time had significant
effects on the percent lignin reduction during sodium hydroxide pretreatment. The amount of lignin after NaOH pretreatment
ranged from 6.54% (24 h, 40°C-60°C) for 2% NaOH/5% H2O2 to 3.27% (24 h, 80°C) for 8% NaOH/5% H2O2, with changes
in concentration causing the most significant decrease in the lignin contents compared with the previous two treatment
methods. When H2O2 was supplemented to the NaOH pretreatment, the extent of delignification increased. A reasonable
explanation for this would be that H2O2 promotes delignification by its oxidative action [17]. When there is an increase of
temperature, the effectiveness of H2O2 decreases because of its unstable nature especially at high temperature. Because of the
unstable property of H2O2, different temperature strategies were considered in order to maximize the efficiency of H2O2 and
delignification in sodium hydroxide pretreatment with H2O2. Among the temperature policies attempted, a step-change of
temperature has proven to be effective [18].
The amount of holocellulose after NaOH/H2O2 treatment ranged from 83.46% (24 h, 40°C-60°C) for 2% NaOH/5% H2O2 to
94.32% (24 h, 80°C) for 8% NaOH/5% H2O2, with change in temperature causing a continuous increasing trend. In addition,
comparing with the step-change temperature (60°C to 80°C) with 80°C, such a change did not cause too much difference on
the increasing trend of holocellulose concentration. A reasonable explanation for this would be that although high
temperature might cause a certain degree of H2O2 decomposition, the temperature might not be high enough to cause a total
decomposition of H2O2, making the NaOH/H2O2 treatment produce a better yield of holocellulose. Meanwhile, the amount of
α-cellulose after NaOH/H2O2 pretreatment ranged from 74.42% (24 h, 40°C-60°C) for 2% NaOH/5% H2O2 to 88.71% (24 h,
6. International Journal of Environmental & Agriculture Research (IJOEAR) ISSN [2454-1850] [Vol-2, Issue-1, January- 2016]
Page | 72
80°C) for 8% NaOH/5% H2O2, with changes in temperature causing a continuous increase in the α-cellulose content. Also,
like holocellulose, the concentration of α-cellulose was not affected too much by the decomposition of holocellulose.
Another possibility, since holocellulose contains both cellulose and hemicellulose, is that the H2O2 concentration might not
have too much effect on hemicellulose degradation as discussed before. However, the total results were still enhanced in the
NaOH/H2O2 system [19]. The xylan concentration varied between 9.04% (2%, 40°C, 24h) and 5.52% (8%, 80°C, 24h) after
modified by NaOH/H2O2. The temperature step-change in xylan degradation did have a slight effect to eliminate more xylan,
compared with the no step change at 80°C. Although according to the previous results, the hydrolysis effect of H2O2 on xylan
was limited; in the NaOH/H2O2 system the hydrolysis effect of xylan was enhanced.
TABLE 4
COMPOSITION OF SODIUM HYDROXIDE/ HYDROGEN PEROXIDE PRETREATED RICE HUSKS
Concentration (%)
Temperature °C
Lignin % α-cellulose % Holocellulose % Xylan% Solids
Recovered %
2% NaOH + 5% H2O2,
40°C(4h)-60°C(20h)
6.54±1.21 74.42±1.99 83.46±2.32 9.04±0.46 56.23±1.46
4% NaOH + 5% H2O2,
40°C(4h)-60°C(20h)
5.97±0.36 75.66±2.05 84.53±2.05 8.87±0.52 53.84±1.35
6% NaOH + 5% H2O2,
40°C(4h)-60°C(20h)
5.62±0.79 76.99±1.03 85.38±2.26 8.39±0.97 50.07±1.59
8% NaOH + 5% H2O2,
40°C(4h)-60°C(20h)
4.88±0.98 78.91±1.29 86.62±3.71 7.71±0.31 49.97±3.47
2% NaOH + 5% H2O2,
40°C(4h)-80°C(20h)
5.03±1.03 78.41±1.73 86.97±1.09 8.56±0.12 50.02±1.92
4% NaOH + 5% H2O2,
40°C(4h)-80°C(20h)
4.71±0.65 80.52±1.47 87.79±1.96 7.27±0.64 47.11±2.18
6% NaOH + 5% H2O2,
40°C(4h)-80°C(20h)
4.42±0.67 81.72±2.23 88.58±2.58 6.86±0.25 45.83±1.42
8% NaOH + 5% H2O2,
40°C(4h)-80°C(20h)
3.94±0.32 83.22±1.59 89.56±2.94 6.34±0.18 42.68±1.76
2% NaOH + 5% H2O2,
60°C(4h)-80°C(20h)
4.49±0.77 82.46±1.76 89.51±1.72 7.05±0.71 43.91±1.81
4% NaOH + 5% H2O2,
60°C(4h)-80°C(20h)
4.23±0.54 83.70±2.07 90.27±3.37 6.57±0.22 41.72±2.24
6% NaOH + 5% H2O2,
60°C(4h)-80°C(20h)
3.71±0.49 85.52±3.11 91.61±3.44 6.09±0.69 39.98±1.82
8% NaOH + 5% H2O2,
60°C(4h)-80°C(20h)
3.50±0.82 86.02±2.17 92.00±2.17 5.98±0.33 37.52±1.53
2% NaOH + 5% H2O2,
80°C(24h)
4.38±0.21 85.17±1.94 91.62±3.36 6.45±0.46 38.74±1.80
4% NaOH + 5% H2O2,
80°C(24h)
3.86±0.33 86.47±2.58 92.64±2.56 6.17±0.52 37.12±1.39
6% NaOH + 5% H2O2,
80°C(24h)
3.41±0.22 87.75±1.12 93.59±2.54 5.84±0.21 35.91±2.44
8% NaOH + 5% H2O2,
80°C(24h)
3.27±0.27 88.71±2.37 94.23±3.15 5.52±0.67 34.07±1.07
In all the treatment methods in Table 4, considerable amounts of lignin were dissolved. The residue lignin concentrations
were dependent upon the types of chemicals and conditions. In NaOH treatment, better delignification performance was
achieved than that with H2O2 pretreatment. Although H2O2 was not very effective on lignin degradation, the addition of H2O2
7. International Journal of Environmental & Agriculture Research (IJOEAR) ISSN [2454-1850] [Vol-2, Issue-1, January- 2016]
Page | 73
in NaOH treatment was effective for delignification, and also caused sugar degradation especially at high temperature.
Meanwhile high temperature was considered as a drawback for the hydrolysis of H2O2, according to the experimental results.
By increasing the temperature, the delignification effect in both H2O2 and NaOH/H2O2 pretreatments was enhanced.
However, the total solid recovered after H2O2/NaOH was extremely low when compared with the other methods, and hence
affected the productivity.
3.5 Scanning electron microscope (SEM) analysis
SEM technology was used to study the morphology of both raw rice husk and modified rice husk, in order to give a
visualized insight. SEM micrographs of outer and inner surfaces of raw rice husk are shown Fig.1.
FIGURE 1. SEM MICROGRAPHS OF RAW RICE HUSK OUTER (A) AND INNER (B) SURFACES AND RICE HUSK
TREATED BY 8%NaOH/5%H2O2 AT 80°C (c).
Comparing with the smooth inter surface of raw rice husk in Fig. 1(b), the outer epidermis was highly asperous and presented
a linear ridged conformation with bright dome-like structures, due to a more concentrated distribution of silica. However, a
previous study [20] applying field-emission SEM (FE-SEM) and energy dispersive X-ray micro-analysis (EDXA)
technology proved that silica also appeared in other parts of rice husk with a relatively low concentration. Such silica
throughout structure enhanced the strength of the rice husk epidermis [21].
8. International Journal of Environmental & Agriculture Research (IJOEAR) ISSN [2454-1850] [Vol-2, Issue-1, January- 2016]
Page | 74
Considering the effect of cellulosic concentration, the micrographs of 8%NaOH/5%H2O2 at 80°C treated rice husks was
observed by SEM and illustrate the original structure of rice husks were almost destroyed and the inorganic fraction (mainly
silica) present as the conical protrusions on the raw rice husks was removed(Fig. 1(c)). The removal of the outer surface and
the disappearance of the inner surface also implied the elimination of theorganic part. Meanwhile, after preferential
degradation of the cementing lignin and hemicellulose among the lignocellulosic matrix, the light color of the sample seemed
to show that the resultant modified rice husks could mostly be cellulose. This was due to the lignin concentration of raw rice
husks always presenting a really dark color.
The SEM analysis proved that the rice husk morphology was significatnly changed in both inner and outer surface after being
treated in alkaline conditions, which confirmed the elimination of inorganic components (like silica), organic components
(like hemicellulose and lignin) and the decrease in cellulosic crystallization. The resultant rice husk presented a bright color
and a more uniform fiber distribution.
3.6 Fourier transform infrared (FTIR) spectra of modified rice husk
The FTIR spectra comparison among raw rice husks, NaOH treated rice husks, H2O2 treated rice husks and NaOH/H2O2
treated rice husks were compared in Fig. 2. A broad band, ranged from 3800 to 3040 cm-1
and centered around 3350 cm-1
,
was associated with the –OH stretching from the hydrogen bonds of cellulose [22-25]. The FTIR spectra of raw rice husks,
NaOH treated rice husks, H2O2 treated rice husks and NaOH/H2O2 treated rice husks presented a similar absorption peak.
However, the intensity of those four spectra showed an increasing trend and the broad region became centered and sharper,
which implied that the treatment methods did not disrupt the crystallinity of cellulose, but even enhanced such a structure.
Meanwhile, the absorption band around 2900 cm-1
was related to the symmetric methyl and methylene stretching bonds [26].
The CH2 scissoring motion located at 1414 cm-1
was related to the cellulose. The C-H bending at 1362 cm-1
indicated both
cellulose and hemicellulose [27-29]. The cellulose and hemicellulose related bonds also ranged from 1200 to 1000 cm-1
. The
peak around 1126 cm-1
was assigned to the C-O-C ring skeletal vibration. The C=O stretching was located at 1029 cm-1
[30].
After delignification, the intensity of the peaks was enhanced dealing to the increase of the cellulosic concentration. For the
hemicellulose, the peak located at 1740 cm-1
was associated with the C=O stretching of acetyl groups from the raw rice husk,
and also considered as the linkage of hemicellulose and lignin. According to the experimental results, both NaOH and
NaOH/H2O2 treatments were effective in the elimination of hemicellulose and the decrease of xylan, which was connected
with the disappearance of the 1740 cm-1
peak in their FTIR spectra.
FIGURE 2. FTIR SPECTRA OF RAW RICE HUSK AND MODIFIED RICE HUSKS SAMPLES PRETREATED WITH
8%H2O2, 8%NaOH AND 8%NaOH+5%H2O2 at 80°C.
9. International Journal of Environmental & Agriculture Research (IJOEAR) ISSN [2454-1850] [Vol-2, Issue-1, January- 2016]
Page | 75
The lignin associated groups could be found at 1640, 1606, 1506, 1460, 1425, 1305 and 1240 cm-1
[31]. The C=O group at
1640 cm-1
was suggested to conjugated with the aromatic structure from aldehydes and ketones from the lignin. The C=C
aromatic skeletal stretching was located at 1600 and 1506 cm-1
. The peaks at 1460 and 1425 cm-1
were associated to the CH3
deformation with the methoxyl groups of lignin [32]. Also the C-O stretching in the syringyl ring of lignin could be found at
1305 and 1240 cm-1
. Although the intensities of some lignin peaks still could be found and even presented a higher trend,
such a trap trend could be concluded to the hydrolysis of the lignin. Groups like C=O could generate after different
treatments. When the lignin matrix was destroyed, the degradation of ester-associated bonds lead to the smaller lignin
fragments.
3.7 Thermo-gravimetric analysis (TGA)
The presence or absence of cellulose, hemicellulose and lignin of both raw rice husk and modified rice husks were
determined by thermogravimetric analysis (TG). The TG/DTG curves (in nitrogen atmospheres) of raw rice husk are shown
in Fig. 3.
The TG curves presented several continuous decomposition steps related to the complex thermal decomposition of the
lignocellulosic matrix. The heating program may cause different physical and chemical decomposition steps. At the very
beginning, the absorbed moisture and primary volatile substances evaporate with increasing temperature and mostly
volatalise before 130°C. The first very small peak of the DTG curve can be observed around 300°C, and was associated with
the thermal decomposition of hemicellulose and glycosidic links of cellulose. Previous studies also proved such
decomposition patterns by analysis raw rice husk and a variety of other plants [33]. By continuous heating, when the
temperature went up to 360°C, a thermal decomposition peak of cellulose could be found in the DTG curve [34, 35]. The
different decomposition temperatures were due to the different structures between hemicellulose and amorphous cellulose
and crystalline cellulose. With the crystallization structure, cellulose was more resistant to the heating process and became
more difficulty to be degraded. The broad range from 200°C to 500°C and centered around 350°C indicated the thermal
decomposition of lignin. This wide range is superimposed by the peaks of hemicellulose and cellulose coordinated with the
complex structure of lignin. The residue found after heating consisted of carbonaceous products and silica, which occupied
44% of the total weight of the raw rice husk sample. Such high percentage residue may due to the high silica concentration
and probably the incomplete lignin decomposition [36]. After the H2O2 pretreatment, the thermal decomposition temperature
of cellulose as decreased by 10°C according to the DTG curve, since parts of the cementing materials were removed. As
verified by the FTIR peaks, the residue color was still dark, and was associated to the existence of lignin.
FIGURE 3. TG(A) AND DTG(B) CURVES OF RAW RICE HUSK, 8% H2O2 AT 80°C PRETREATED RICE HUSK, 8% NaOH AT 80
°C PRETREATED RICE HUSK AND 8%NaOH/5%H2O2 at 80 °C PRETREATED RICE HUSK IN NITROGEN.
The NaOH sample in Fig. 3(b) presented only one shoulder a with very smooth shape, which indicating the majority
decomposition of hemicellulose was achieved. Following the first step of volatile substances evaporation between 60 and
135°C, the second decomposition of volatile material like hemicellulose started at 250 °C. The DTG curve became
centralized around 340°C and its shape became sharper after NaOH treatment, which implied a more uniformed
concentration, an increase of crystalized cellulosic percentage and a correspondingly lower lignin concentration. For the
NaOH/H2O2 treatment, the single peak around 340°C became sharper than that of the NaOH treatment, which implied the
10. International Journal of Environmental & Agriculture Research (IJOEAR) ISSN [2454-1850] [Vol-2, Issue-1, January- 2016]
Page | 76
components like hemicellulose were almost gone. In the TGA analysis of raw rice husks, the hemicellulose decomposition
temperature around 340°C could also be the potential decomposition temperature for the evaporation of volatile substances
or the aliphatic chain and carbon bond of the lignin aromatic ring. After NaOH and NaOH/H2O2 treatment, the wax, natural
fats, hemicellulose as well as lignin from raw rice husks were removed with the heating process. Comparing the cellulose and
lignin degradation in the arrange from 350°C and 380°C with the raw rice husk, the largest weight loss after NaOH and
NaOH/H2O2 treatment shifted to a lower range from 230 to 350°C, according to the decomposition of cementing
components, such as lignin, hemicellulose and wax [37]. Such a phenomenon could also be found when comparing the H2O2
treated samples with raw rice husks.
IV. CONCLUSION
The rice husks treated by NaOH/H2O2 were a superior on eliminating hemicellulose and lignin, with a correspondingly
higher α-cellulose concentration. However, with higher α-cellulose, the total solid recovery percentage showed a reverse
trend. The highest recovery rate was achieved by H2O2 methods, followed by NaOH and NaOH/H2O2 treatments. According
to the FTIR and TGA results, H2O2 treatment was considered to be less effective. Hence, from the aspect of both increasing
the cellulosic concentration and total solid recovery rate, the NaOH treatment assisted by a lower percentage of H2O2 in a
mild temperature were suggested.
ACKNOWLEDGEMENTS
We thank the Materials Characterization and Preparation Facility of the Hong Kong University of Science and Technology
for FTIR analyses. One of the authors (ZXW) extends thanks to the Hong Kong Research Grants Council for the provision of
a postgraduate studentship.
REFERENCES
[1] G.Deschamps, H.Caruel, M.E.Borredon, C.Bonnin, C.Vignoles, “Oil Removal from water by selective sorption on hydrophobic
cotton fibers. 1. Study of sorption properties and comparison with other cotton fiber-based sorbents.” Environ. Sci. Technol, vol.37,
pp.1013–1015, 2003.
[2] S.F.S.Draman, R.Daik, F.A.Latif, S.M.El-Sheikh, “Characterization and thermal decomposition kinetics of kapok (Ceiba pentandra
L.)-Based Cellulose,” Bioresources. vol.9, pp.8-23, 2014.
[3] M.R.Giddel, A.P.Jivan, “Waste to wealth, potential of rice husk in India a literature review,” International Conference on Clear
Technologies and Environmental Management PEC, Pondicherry, India, 2007.
[4] L.Ludueña, D.Fasce, V.A.Alvarez, P.M.Stefani, “Nanocellulose from rice husk following alkaline treatment to remove silica,”
Bioresources. vol.6, pp.1440-1454. 2011.
[5] S.I.Mussatto, J.A.Teixeira, “Lignocellulose as raw material in fermentation Processes,” in: Current Research, Technology and
Education, Topics in Applied Microbiology and Microbial Biotechnology, A.Mendez-Vilas, Eds. Formatex Research Center, Badajoz,
pp. 897–907. 2010.
[6] N.Carpita, M.McCann, “The cell wall,” in: Biochemistry & Molecular Biology of Plants, B.B.Buchanan, W.Gruissem, R.L.Jones,
Eds. American Society of Plant Physiologists, Rockville, MD, 2000, pp.61.
[7] Z.Wang, J.P.Barford, C.W.Hui, G. McKay, “Kinetic and equilibrium studies of hydrophilic and hydrophobic rice husk cellulosic
fibers used as oil spill sorbents,” Chem. Eng. J. vol.281, pp.961-969,2015.
[8] H.Tarkow, W.C.Feist, “A mechanism for improving the digestibility of lignocellulosic materials with dilute alkali and liquid NH3,”
in: “Cellulases and Their Applications,” G.J.Hajny, E.T.Reeses, Eds, Advance Chemistry Series 95, American Chemical Society,
Washington, DC, 1969, pp. 197-218.
[9] P.S.Nigam, N.Gupta, A.Anthwal, “Pre-treatment of agro-industrial residues,” in Biothechnology for agro-industrial residues
utilization, P.S.Nigam, A.Pandey, Eds. Netherlands. Springer Netherlands, 2009, pp. 13-33.
[10] T.Ehrman, “Method for determination of acid-soluble lignin in biomass,” in: Laboratory Analytical Procedures No.004. Golden, CO,
National Renewable Energy Laboratory, 1996.
[11] D.Templetion, T.Ehrman, “Determiantion of acid-insoluble lignin in biomass,” in: Laboratory Analytical Procedures No.003. Golden,
CO, National Renewable Energy Laboratory, 1994.
[12] J.Han, J.Rowell, “Chemical composition of fibers,” in: R.Rowell, R.Young, J.Rowell, Eds. Paper Composites from Agro-Based
Resources. CRC Lewis Publisher, New York, 1997, pp.83-134.
[13] A.Sluiter, R.Hames, Ruiz, C.Scarlata, J.Sluiter, D.Templetion, D.Crocker, “Determination of structural carbohydrates and lignin in
biomass,” NREL/TP-510-42618, National Renewable Energy Laboratory, Golden, CO, 2005.
[14] P.C.Badger, “Ethanol from cellulose: a general review,” in: Trends in New Crops and New Uses, J.Janick and A.Whipkey, Eds.
ASHS Press, Alexandria, VA, 2002, pp.17-21.
11. International Journal of Environmental & Agriculture Research (IJOEAR) ISSN [2454-1850] [Vol-2, Issue-1, January- 2016]
Page | 77
[15] K.G.Mansaray, A.E.Ghaly, “Thermal degradation of rice husks in nitrogen atmosphere,” Bioresource Technol. vol.65, pp.13-20,
1998.
[16] F.A.Agblevor, R.J.Evans, K.D.Johnson, “Molecular-beam mass-spectrometric analysis of lignocellulosic materials. I. Herbaceous
biomass,” J. Anal. Appl. Pyrol. vol.30, pp.125-144, 1994.
[17] Y.Z.Lai, “Chemical degradation,” in: Hon, N.-S.David, Shiraishi, Nobuo, Wood and Cellulosic Chemistry. Marcel Dekker Inc., New
York, Basel, pp. 443–512, 2001.
[18] R.Gupta, Y.Y.Lee, “Pretreatment of hybrid poplar by aqueous ammonia,” Biotechnol. Progr. vol.25, pp.357–364. 2009.
[19] R.Gupta, Y.Y.Lee, “Investigation of biomass degradation mechanism in pretreatment of switchgrass by aqueous ammonia and sodium
hydroxide,” Bioresource Technol. vol.101, pp.8185-8191, 2010.
[20] B.D.Park, S.G.Wi, K.H.Lee, A.P.Singh, T.-H.Yoon, Y.S. Kim, “Characterization of anatomical features and silica distribution in rice
husk using microscopic and micro-analytical techniques,” Biomass Bioenergy. vol.25, pp.319-327, 2003.
[21] R.A.Ruseckaite, E.M.Ciannamea, P.Leiva, P.M.Stefani, “Particleboards based on rice husk,” in: “Polymer and Biopolymer Analysis
and Characterization,” G.E. Zaikov, A.Jimenez, Eds. Nova Science Publishing Inc., New York, 2007, pp. 1-12.
[22] T.C.Hsu, G.L.Guo, W.H.Chen, W.S.Hwang, “Effect of dilute acid pretreatment of rice straw on structural properties and enzymatic
hydrolysis,” Bioresource Technol. vol.101, pp.4907-4913. 2010.
[23] S.Marx, I.Chiyanzu, N.Piyo, “Influence of reaction atmosphere and solvent on biochar yield and characteristics,” Bioresource
Technol. vol.164, pp.177-183. 2014.
[24] I.M.De Rosa, J.M.Kenny, D.Puglia, C.Santulli, F.Sarasini, “Morphological, thermal and mechanical characterization of okra
(Abelmoschus esculentus) fibres as potential reinforcement in polymer composites,” Compos. Sci. Technol. vol.70, pp.116-122, 2010.
[25] G.Sócrates, “Infrared and Raman Characteristic Group Frequencies: Tables and Charts”, 3rd Edition, John Wiley and Sons, New
York. 2004.
[26] E.Rosales, L.Ferreira, M. A.Sanromán, T.Tavares, M.Pazos, “Enhanced selective metal adsorption on optimized agroforestry waste
mixtures,” Bioresource Technol. vol.182, pp.41-49, 2015.
[27] R.T.O’Connor, E.F.DuPré, D.Mitcham, “Applications of infrared absorption spectroscopy to investigations of cotton and modified
cottons. Part I. Physical and crystalline modifications and oxidations,” Text. Res. J. vol.28, pp.382-392. 1958.
[28] C.Y.Liang, R.H.Marchessault, “Infrared spectra of crystalline polysaccharides. I. Hydrogen bonds in native celluloses,” J. Polym. Sci.
vol.37, pp.385-395. 1959.
[29] R.Zuluaga, J. L.Putaux, J.Cruz, J.Vélez, I.Mondragon, P.Gañán, “Cellulose microfibrils from banana rachis: Effect of alkaline
treatments on structural and morphological features,” Carbohyd. Polym. vol.76, pp.51-59, 2009.
[30] A. B.Diaz, M.M.Moretti, C.Bezerra-Bussoli, C.D.Carreira Nunes, A.Blandino, R.da Silva, E.Gomes, “Evaluation of microwave-
assisted pretreatment of lignocellulosic biomass immersed in alkaline glycerol for fermentable sugars production.” Bioresource
Technol. vol.185, pp.316-323, 2015.
[31] A.Sakakibara, Y.Sano, “Chemistry of lignin,” in: Wood and Cellulosic Chemistry, Hon, N.-S.David, Shiraishi, Nobuo, Eds. Marcel
Dekker Inc., New York, Basel, 2001, pp. 109–173.
[32] G.L.Guo, D.C.Hsu, W.H.Chen, W.H.Chen, W.S.Hwang, “Characterization of enzymatic saccharification for acid-pretreated
lignocellulosic materials with different lignin composition,” Enzyme Microb. Technol, vol.45, pp.80–87, 2009.
[33] V.A.Alvarez, A.Vázquez, “Thermal degradation of cellulose derivatives/starch blends and sisal fibre biocomposites,” Polym. Degrad.
Stabil. vol.84, pp.13-21, 2004.
[34] P.M.Stefani, D.Garcia, J.Lopez, A.Jimenez, “Thermogravimetric analysis of composites obtained from sintering of rice husk–scrap
tire mixtures,” J. Therm. Anal. Calorim. vol.81, pp.315-320, 2005.
[35] B.S.Ndazi, C.Nyahumwa, J.Tesha, “Chemical and thermal stability of rice husks against alkali treatment,” BioResources. vol.3,
pp.1267-1277, 2008.
[36] E.M.Ciannamea, P.M.Stefani, R.A.Ruseckaite, “Medium-density particlesboards from modified rice husks and soybean protein
concentrated-based adhesives,” Bioresource Technol. vol.101, pp.818-825, 2010.
[37] H.M.Choi, “Needle punched cotton nonwovens and other natural fibers as oil cleanup Sorbents,” J. Environ. Sci. Health A. vol.31,
pp.1441-1457, 1996.