Nanotechnology in water treatment

GCW University Sialkot
Topic:
Nanotechnology in water treatment
Assignment:
Applied chemistry
Submitted to:
M’am Anmu Noor
Submitted by:
Shahrbano (58) & Aysha Kishwer (83)
Department:
Chemistry

What is Nanotechnology:
Nanoscience and nanotechnology are the study and application of extremely small things and can
be used across all the other scientific fields, such as chemistry, biology, physics, materials
science, and engineering. he ideas and concepts behind nanoscience and nanotechnology started
with a talk entitled “There’s Plenty of Room at the Bottom” by physicist Richard Feynman at an
American Physical Society meeting at the California Institute of Technology on December 29,
1959, long before the term nanotechnology was used. In his talk, Feynman described a process in
which scientists would be able to manipulate and control individual atoms and molecules.
Fundamental concept of Nanoscience:
It’s hard to imagine just how small nanotechnology is. One nanometer is a billionth of a meter,
or 10-9 of a meter. Here are a few illustrative examples:
1. There are 25,400,000 nanometers in an inch
2. A sheet of newspaper is about 100,000 nanometers thick
Nanotechnology and water treatment
(Nanowerk Spotlight) Only 30% of all freshwater on the planet is not locked up in ice caps or
glaciers (not for much longer, though). Of that, some 20% is in areas too remote for humans
to access and of the remaining 80% about three-quarters comes at the wrong time and place -
in monsoons and floods - and is not always captured for use by people. The remainder is less
than 0.08 of 1% of the total water on the planet . Expressed another way, if all the earth's
freshwater were stored in a 5-liter container, available fresh water would not quite fill a
teaspoon. The problem is that we don't manage this teaspoon very well. Currently, 600
million people face water scarcity. Depending on future rates of population growth, between
2.7 billion and 3.2 billion people may be living in either water-scarce or water-stressed
conditions by 2025:
Fig1.1

and renewable freshwater availability. (Source: Environment Canada)We have written about this
in a previous Spotlight (Water, nanotechnology's promises, and economic reality): Freshwater
looks like it will become the oil of the 21st century - scarce, expensive and the reason for armed
conflicts. While in our previous article we have only talked about nanotechnology and water in
general terms, a new paper gives us the opportunity to look in more detail at the role that
nanotechnology could play in resolving issues relating to water shortage and water quality.This
review highlights the uses of nanotechnology to purify water, including separation and reactive
media for water filtration, as well as nanomaterials and nanoparticles for use in water
bioremediation and disinfection."The potential impact areas for nanotechnology in water
applications are divided into three categories, i.e., treatment and remediation, sensing and
detection, and pollution prevention" Prof. Eugene Cloete tells Nanowerk. "Within the category
of treatment and remediation, nanotechnology has the potential to contribute to long-term water
quality, availability, and viability of water resources, such as through the use of advanced
filtration materials that enable greater water reuse, recycling, and desalinization. Within the
category of sensing and detection, of particular interest is the development of new and enhanced
sensors to detect biological and chemical contaminants at very low concentration levels in the
environment, including water."Cloete is Head of the Microbiology Department at the University
of Pretoria in South Africa and Chairperson of the university's School of Biological Sciences.
Together with Associate Professor Jacques Theron and J.A. Walker he published the review
article, titled "Nanotechnology and Water Treatment: Applications and Emerging Opportunities",
in the February 2008 issue of Critical Reviews in Microbiolog.
Nanomaterials and water filtration
Membrane processes are considered key components of advanced water purification and
desalination technologies and nanomaterials such as carbon nanotubes, nanoparticles, and
dendrimers are contributing to the development of more efficient and cost-effective water
filtration processes.There are two types of nanotechnology membranes that could be effective:
nanostructured filters, where either carbon nanotubes or nanocapillary arrays provide the basis
for nanofiltration; and nanoreactive membranes, where functionalized nanoparticles aid the
filtration process.The researchers also note that advances in macromolecular chemistry such as
the synthesis of dendritic polymers have provided opportunities to refine, as well as to develop
effective filtration processes for purification of water contaminated by different organic solutes
and inorganic anions.Nanotechnologies for water remediationMany areas, especially in
developing countries, are seriously contaminated or damaged with consequent impoverishment
of natural resources and serious effects on human health. Remediation of contaminated water –
the process of removing, reducing or neutralizing water contaminants that threaten human health
and/or ecosystem productivity and integrity – is a field of technology that has attracted much
interest recently.In general, remediation technologies can be grouped into categories using
thermal, physico-chemical or biological methods. The various techniques usually work well
when applied to a specific type of water pollution, though no readily available treatments were
discovered that could clean all types of pollutants. Due to the complex nature of many polluted
waters, it is frequently necessary to apply several techniques to soil from a particular location to
reduce the concentrations of pollutants to acceptable levels.

Cloete and his co-authors write that most of the traditional technologies such as solvent
extraction, activated carbon adsorption, and common chemical oxidation, whilst effective, very
often are costly and time-consuming: "Biological degradation is environmentally friendly and
cost-effective; but it is usually time-consuming. Thus, the ability to remove toxic contaminants
from these environments to a safe level and doing so rapidly, efficiently, and within reasonable
costs is important. Nanotechnology could play an important role in this regard. An active
emerging area of research is the development of novel nanomaterials with increased affinity,
capacity, and selectivity for heavy metals and other contaminants. The benefits from use of
nanomaterials may derive from their enhanced reactivity, surface area and sequestration
characteristics. A variety of nanomaterials are in various stages of research and development,
each possessing unique functionalities that is potentially applicable to the remediation of
industrial effluents, groundwater, surface water and drinking water."
The report provides detailed examples of various nanoparticles and nanomaterials that could be
used in water remediation: zeolites, carbon nanotubes, self-assembled monolayer on mesoporous
supports (SAMMS), biopolymers, single-enzyme nanoparticles, zero-valent iron nanoparticles,
bimetallic iron nanoparticles, and nanoscale semiconductor photocatalyst.
Bioactive nanoparticles for water disinfections
There is a growing threat of water-borne infectious diseases, especially in the developing world.
This threat is rapidly being exacerbated by demographic explosion, a global trend towards
urbanization without adequate infrastructure to provide safe drinking water, increased water
demand by agriculture that draws more and more of the potable water supply, and emerging
pollutants and antibiotic-resistant pathogens that contaminate our water resources. No country is
immune. Even in OECD countries, the number of outbreaks reported in the last decade
demonstrates that transmission of pathogens by drinking water remains a significant problem. It
is estimated that water-borne pathogens cause between 10 and 20 million deaths a year
worldwide.According to Cloete, nanotechnology may present a reasonable alternative for
development of new chlorine-free biocides. Among the most promising antimicrobial
nanomaterials are metallic and metal-oxide nanoparticles, especially silver, and titanium dioxide
catalysts for photocatalytic disinfections.
What about toxicity?
As with any other nanotechnology application where there is a possibility that engineered
nanoparticles could eventually appear in various environments, the potential human and
ecological risk factors associated with this are largely unknown and subject to much debate.
Cloete and co-authors discuss various toxicity studies of nanomaterials and also point out several
recent studies of the toxicological impact of nanoparticles on different aquatic organisms.The
bottomline seems to be that it might be advisable to come to some definite conclusions regarding
nanoparticle ecotoxicology before we embark an large-scale use of engineered nanoparticles in
water applications. Nevertheless, there is a growing body of research and development that will
lead to nanomaterials playing a key role in future water and wastewater treatment.

1. Nanotechnology and Water Treatment: Applications and Emerging
Opportunities
Nanotechnology, the engineering and art of manipulating matter at the nanoscale (1-100 nm),
offers the potential of novel nanomaterials for treatment of surface water, groundwater and
wastewater contaminated by toxic metal ions, organic and inorganic solutes, and
microorganisms. Due to their unique activity toward recalcitrant contaminants and application
flexibility, many nanomaterials are under active research and development. Accordingly,
literature about current research on different nanomaterials (nanostructured catalytic membranes,
nanosorbents, nanocatalysts and bioactive nanoparticles) and their application in water treatment,
purification and disinfection is reviewed. Moreover, knowledge regarding toxicological effects
of engineered nanomaterials on humans and the environment is presented.
2. Current Molecular and Emerging Nanobiotechnology Approaches for the
Detection of Microbial Pathogens
An adequate supply of safe drinking water is one of the major prerequisites for a healthy life, but
waterborne diseases is still a major cause of death in many parts of the world, particularly in
young children, the elderly, or those with compromised immune systems. As the epidemiology
of waterborne diseases is changing, there is a growing global public health concern about new
and reemerging infectious diseases that are occurring through a complex interaction of social,
economic, evolutionary, and ecological factors. An important challenge is therefore the rapid,
specific and sensitive detection of waterborne pathogens. Presently, microbial tests are based
essentially on time-consuming culture methods. However, newer enzymatic, immunological and
genetic methods are being developed to replace and/or support classical approaches to microbial
detection. Moreover, innovations in nanotechnology and nanosciences are having a significant
impact in biodiagnostics, where a number of nanoparticle-based assays and nanodevices have
been introduced for biomolecular detection. Accordingly, current and emerging molecular
approaches for the detection of microbial pathogens as well as nanobiotechnologies that that will
extend the limits of current molecular diagnostics are discussed.
3. The Potential of Nanofibers and Nanobiocides in Water Purification
Electrospun nanofibers and nanobiocides show potential in the improvement of water filtration
membranes. Biofouling of membranes caused by the bacterial load in water reduces the quality
of drinking water and has become a major problem. Several studies showed inhibition of these
bacteria after exposure to nanofibers with functionalized surfaces. Nanobiocides such as metal
nanoparticles and engineered nanomaterials are successfully incorporated into nanofibers
showing high antimicrobial activity and stability in water. Research on the applications of
nanofibers and nanobiocides in water purification, the fabrication thereof and recently published
patents are reviewed in this article.
4. Nanozymes for Biofilm Removal
Sessile communities of bacteria encased in extracellular polymeric substances (EPS) are known
as biofilms and causes serious problems in various areas, amongst other, the medical industry,
industrial water settings, paper industry and food processing industry. Although various methods
of biofilm control exist, these methods are not without limitations and often fail to remove
biofilms from surfaces. Biofilms often show reduced susceptibility to antimicrobials or

chemicals and chemical by-products may be toxic to the environment, whereas mechanical
methods may be labour intensive and expensive due to down-time required to clean the system.
This has led to a great interest in the enzymatic degradation of biofilms. Enzymes are highly
selective and disrupt the structural stability of the biofilm EPS matrix. Various studies have
focused on the enzymatic degradation of polysaccharides and proteins for biofilm detachment
since these are the two dominant components of the EPS. Due to the structural role of proteins
and polysaccharides in the EPS matrix, a combination of various proteases and polysaccharases
may be successful in biofilm removal. The biodegradability and low toxicity of enzymes also
make them attractive biofilm control agents. Regardless of all the advantages associated with
enzymes, they also suffer from various drawbacks given that they are relatively expensive, show
insufficient stability or activity under certain conditions, and cannot be reused. Various
approaches are being used to increase the stability of enzymes, including enzyme modification,
enzyme immobilization, protein engineering and medium engineering. Although these
conventional methods have been used frequently to improve the stability of enzymes, various
new techniques, such as self-immobilization of enzymes, the immobilization of enzymes on
nano-scale structures and the production of single-enzyme nanoparticles, have been developed.
Self-immobilization of enzymes entails the cross-linking of enzyme molecules with each other
and yields final preparations consisting of essentially pure proteins and high concentrations of
enzyme per unit volume. The activity, stability and efficiency of immobilized enzymes can be
improved by reducing the size of the enzyme-carrier. Nano-scale carrier materials allow for high
enzyme loading per unit mass, catalytic recycling and a reduced loss of enzyme activity.
Furthermore, enzymes can be stabilized by producing single-enzyme nanoparticles consisting of
single-enzyme molecules surrounded by a porous organic-inorganic network of less than a few
nanometers thick. All these new technologies of enzyme stabilization make enzymes even more
attractive alternatives to other biofilm removal and control agents.
5. Nanofiltration for Water and Wastewater Treatment
Nanofiltration (NF) is a new type of pressure driven membrane process and used between
reverse osmosis and ultrafiltration membranes. The most different specialty of NF membranes is
the higher rejection of multivalent ions than monovalent ions. NF membranes are used in
softening water, brackish water treatment, industrial wastewater treatment and reuse, product
separation in the industry, salt recovery and recently desalination as to pass NF system. In this
chapter, a general overview of nanofiltration membranes, membrane materials and
manufacturing techniques, principles such as performance and modelling, module types,
membrane characterization and applications on water and wastewater treatment were given
6. Reverse Osmosis:Membranes, Materials, Applications and Nanotechnology
This chapter provides a review about the membrane separation technologies, focusing on reverse
osmosis (hyperfiltration) and nanofiltration. The first one is based on the basic principle of
osmotic pressure, while the latter makes use of molecule size for separation. Recent advances on
nanotechnology are opening a range of possibilities in membrane technologies. This chapter also
reviews some of these aspects: new membrane preparation and cleaning methods, new surface
and interior modification possibilities, the use of new nanostructured materials, and new
characterization techniques.
7. Electrospinning Nanofibers for Water Treatment Applications

Electrospinning is a highly versatile technique that can be used to create ultrafine fibers of
various polymers and other materials, with diameters ranging from a few micrometers down to
tens of nanometers. The nonwoven webs of fibers formed through this process typically have
high specific surface areas, nano-scale pore sizes, high and controllable porosity and extreme
flexibility with regard to the materials used and modification of the surface chemistry of the
fibers. This chapter describes the combination of these features in the application of electrospun
nanofibres in a variety of water treatment applications, including filtration, solid phase extraction
and reactive membranes.
8. Potential Risks of Using Nanotechnology in Water Treatment on Human
Health
The risk assessment of nanoparticles and nanomaterials is of key importance for the continuous
development in the already striving new field of nanotechnology. Humans are increasingly being
exposed to nanoparticles and nanomaterials, placing stress on the development and validation of
reproducible toxicity tests. The tests currently used include genotoxicity and cytotoxicity tests,
and in vivo toxicity models. The unique characteristics of nanoparticles and nanomaterials are
responsible for their toxicity and interaction with biological macromolecules within the human
body. This may lead to the development of diseases and clinical disorders. A loss in cell viability
and structure can also occur in exposed tissues as well as inflammation and granuloma
formation. The future of nanotechnology depends on the responsible assessment of nanoparticles
and nanomaterials.
Figures Facts
3.4 Millions In developing countries people dies from water-related diseases every year
63 Millions In developing countries like Bangladesh, India and Nepal people suffers with Arsenic pollution
6 Km Women’s from Africa and Asian continent walk to fetch water
80 % Water related deaths in children between age 0-14 years
40 % Water related deaths are due to Diarrhoea
Table 1: Water related facts of developing countries
Significance of Nanotechnology in Wastewater Treatment
Modern advances imply that several issues relating water quality could be determined or
significantly increased the usage of nanomaterials and related stuff which resulted the growth
of nanotechnology. Novel routes in the development of new nanomaterials to desalinate
water are among the most thrilling and gifted technologies. Different materials science
research teams in the world are exploiting specific nanomaterials targeting the analyte and
making the entire system effective, economical and rapid for the treatment of waste waters.
On the other hand treatment of industrial wastewater with newly synthesized nanomaterials is
another potentially useful application. Most of the remediation technologies available today,
while effective, very often are costly and time consuming, particularly pump-and-treat
methods. The capability to remove toxic compounds from surface and sub-surface and other
environments are very difficult to access in situ, and doing so rapidly, efficiently and within
reasonable costs is the ultimate goal. Hence, nanotechnology based waste water treatment

effectively eliminates the contaminants and helps in the recycling process to get purified
water, which leads to reduction in labour, time and expenditure to industry and solves the
various environmental issues.
Nanomaterials are mainly categorised into various groups based on their physical and surface
properties. Nanomaterials include carbon nano-adsorbents (CNTs), metal nano-adsorbents
(Al2O3 NPs, ZNO NPs, TiO2 NPs and CeO2 NPs), metallic nanoparticles (Au & Ag NPs),
mixed oxide nanoparticle (Fe-Ti NPs), polymer nano-adsorbents, nanofibers, nanoclays.
Additionally, it also utilizes the existence of nanoscopic pores in zeolite filtration
membranes, as well as nanocatalysts. Metallic/metal oxide nanoparticles such as Titanium
oxide nanoparticles and palladium nanoparticles are used as Nanosensors for the analysis of
organic and inorganic pollutants in the water systems.
Wastewater treatment processes are designed to achieve improvements in the quality of the
wastewater. The various treatment processes may reduce: (i) Suspended solids (ii)
Biodegradable organics (iii) Pathogenic bacteria (iv) Nitrates and phosphates. Wastewater
treatment is classified into three types: (a) Primary (b) Secondary and (c) Tertiary treatments.
Based on the type of treatment and stage of purification, nanomaterials are selected for the
effective removal of contaminants from the water systems. Nanotechnology can also be
adopted for the removal of sediments, chemical effluents and charged particles.
Nanofiltration is a new type of pressure driven membrane process and used between reverse
osmosis and ultrafiltration membranes. The most different speciality of nanofiltration
membranes is the higher rejection of multivalent ions than monovalent ions.
Nanofiltration
Membranes are used in softening water, brackish water treatment, industrial wastewater
treatment and reuse, product separation in the industry, salt recovery and recently
desalination as two pass nanofiltration systems. Carbon nanotubes are unique nanomaterials
which can eliminates wide range of contaminants including organic, inorganic, oil, turbidity,
bacteria and viruses. Although their pores are significantly smaller carbon nanotubes have
shown to have an equal or a faster flow rate as compared to larger pores, possibly because of
the smooth interior of the nanotubes. Nanofibrous alumina filters and other nanofiber
materials also remove negatively charged contaminants such as viruses, bacteria, and organic
and inorganic colloids at a faster rate than conventional filters.
Singlewalled carbon nanotubes (SWCNTs) are distinguished from multiwalled carbon
nanotubes (MWCNTs) by their number of layers, and many researchers are focusing due to
its unique structure, excellent properties and variety of potential applications. Van der Waals
force of attraction makes CNTs to form aggregation due to entanglement of hundreds of
individual CNTs [1,2] which provides large external surface area for the adsorption of
analytes [3-6]. TiO2 NPs is using as a photo degradator of organic pollutants. In fact,
TiO2 NPs have been successfully used in environmental technology for the treatment of
waste water and ground water, for the removal of organic wastes. Ceria NPs has distinct
properties of strong size dependent and would be show significant quantum size effect [7].
However, the synthesis of CeO2 NPs [8] below 10 nm is a challenging task for the scientist in
the field of material science. ZNO NPs have attracted the interest of several scientists in
recent years due to its remarkable properties. ZNO NPs offer a great benefits applied to a
catalytic reaction process because of their large surface area and high catalytic activity.

Al2O3 NPs are high in surface area, more reactivity and greater adsorption capacity hence; it
has been employed successfully for the separation and determination of toxic metals of
environmental importance [9]. Nanotechnology has spurred efforts to design and produce
nanoscale components for incorporation into devices. Magnetic nanoparticles are an
important class of functional materials, possessing unique magnetic properties due to their
reduced size (below 100 nm) with potential for use in devices with reduced dimensions.
Polymer adsorbents are gaining more attention in sample pre-treatment step. Organic
polymers are the system into which inorganic nanosized particles can be incorporated to
enhance their physical, chemical, mechanical and sorption properties. Nanopolymer sphere,
for example Dendrimers are tailored adsorbents that are capable to eliminate organic and
inorganic species. The interior walls of dendrimers are hydrophobic in nature and useful for
sorption of organic compounds while the exterior branches can be tailored (e.g., hydroxyl-
oramine-terminated) for adsorption of heavy metals. Nanoclays are the naturally occurring
particles with nanometer scale, and considered as a nanomaterials of geological origin.
Nanoclays exhibits different structures which include tetrahedral silicates and octahedral
aluminium layers, and the variety of the clays depends on the arrangement and composition
of these layers [10].
Instrument based Wastewater Analysis with Nanomaterials
Recently several advancements came into light on applications of nanomaterials in analytical
chemistry for detection of organic and inorganic pollutants using different instruments as
depicted in Figure 1. For instance two examples were discussed in this paper. A new
synthesized Schiff base, 3- (4-methoxybenzylideneamino)-2- thioxothiazolodin-4-one was
synthesized for the development of Carbon Paste Electrode (CPE) on the Multi-Walled
Carbon Nanotubes (MWCNTs) for the concurrent detection of mercury(II) and lead(II) by
Square Wave Anodic Stripping Voltammetry (SWASV). This fabricated electrode showed
fair sensitivity and selectivity due to easy and fast electron transfer rate between the electrode
surface and the metal ions. To improve the selectivity, stability of the complex and detection
limits, different experimental parameters such as pH, deposition potential and deposition
time were optimized. Under optimal conditions the limits of detection, were found to be 9.0 ×
10-4 and 6.0 ×10-4 μ mol L-1 for mercury (II) and lead (II) respectively with a 90 as a
preconcentration factor. In addition, the modified electrode displayed excellent
reproducibility and selectivity, making it appropriate for the simultaneous analysis of
mercury (II) and lead (II) in different wastewater systems [11]. Palladium-graphene
nanocomposite and ions liquid was fabricated and tested as a sensor for chlorophenols. The
Pd-graphene nanocomposite was prepared via a sonoelectrochemical route, and the possible
formation mechanism was proposed. TEM, SEM, XRD and Raman spectrum were used for
the characterization of structure and morphology of the nanocomposite. The experimental
results showed that Pd nanospheres comprised of small Pd NPs were uniformly attached on
graphene sheets. The EC properties were investigated by CV and Differential Pulse
Voltammetry (DPV), which indicated that the Pd-graphene nanocomposite had high activity
for chlorophenol oxidation. Herein, 2-chlorophenol was selected as the model molecules. The
results showed that graphene played an important role in the fabrication of the chlorophenols
sensor. The nanocomposite with large electrochemical active surface led to the excellent
electrocatalytic activity, and ionic liquid further enhanced the catalytic activity of

Pdgraphene for chlorophenols in several secondary effluent samples from a wastewater
treatment plant.
 References
1. Donaldson K, Aitken R, Tran L, Stone V, Duffin R, et al. (2006) Carbon nanotubes: a
review of their properties in relation to pulmonary toxicology and workplace safety.
ToxicolSci 92: 5-22.
2. Yan J, Estevez MC, Smith JE, Wang K, He X, et al. (2007) Dye-doped nanoparticles for
bioanalysis. Nano Today 2: 44-50
3. Chen W, Duan L, Zhu D (2007) Adsorption of polar and nonpolar organic chemicals to
carbon nanotubes. Environ SciTechnol 41: 8295-8300.
4. Li YH, Ding J, Luan Z, Di Z, Zhu Y, et al. (2003) Competitive adsorption of Pb2+, Cu2+
and Cd2+ ions from aqueous solutions by multiwalled carbon nanotubes. Carbon 41:
2787-2792.
5. Liu G, Lin Y (2007) Nanomaterial labels in electrochemical immunosensors and
immunoassays. Talanta 74: 308-317.
6. Yang K, Wu W, Jing Q, Zhu L (2008) Aqueous adsorption of aniline, phenol, and their
substitutes by multi-walled carbon nanotubes. Environ SciTechnol 42: 7931-7936.
7. Xu H, Li G, Li L (2008) CeO2 nanocrystals: seed-mediated synthesis and size control.
Mater Res Bull 43: 990–995.
8. Tok AIY, Boey FYC, Dong Z, Sun XL (2007) Hydrothermal synthesis of CeO2 nano-
particles. J. Mater. Process. Technol. 190: 217–222.
9. Manzoori JL, Amjadi M, Darvishnejad M (2012) Separation and preconcentration of
trace quantities of copper ion using modified alumina nanoparticles, and its determination
by flame atomic absorption spectrometry. Microchim. Acta 176: 437-443.

Nanotechnology in water treatment

Nanotechnology in water treatment

Recomendados

Recomendados

Mais conteúdo relacionado

Mais procurados

Mais procurados (20)

Semelhante a Nanotechnology in water treatment

Semelhante a Nanotechnology in water treatment (20)

Mais de Shahrbano Awan

Mais de Shahrbano Awan (12)

Último

Último (20)

Nanotechnology in water treatment