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Chromium is a metal that exists in several oxidation
• Chromium is a metal that exists in several oxidation or valence states, ranging from chromium (-II) to chromium (+VI).
• Chromium compounds are very stable in the trivalent state and occur naturally in this state in ores such as ferrochromite, or chromite ore.
• Chrome III is an essential nutrient for maintaining blood glucose levels
• The hexavalent, Cr(VI) or chromate, is the second most stable state. It rarely occurs naturally.
Chromium is a metal that exists in several
• Chromium (trivalent) is a basic food item helps the body use sugar,
protein, and fat.
• Chrome III is an essential nutrient for maintaining blood glucose
• Exist in food, fruit, fishes and underground water.
• Aircraft Painting
• Leather tanning
• Textile manufacturing
• dyeing, cement industry
• metal finishing
Formation of a separable solid substance from a solution, either by
converting the substance into an insoluble form or by changing the
composition of the solvent to diminish the solubility of the substance in it.
The removal of chromium can be
1. the addition of ferrous sulphate and lime.
2. first reduces hexavalent chromium to
trivalent chromium by simultaneous
oxidation of ferrous ion to ferric.
3. The resulting forms can be precipitated as
hydroxides by lime.
Cr3++ (OH)-→ Cr (OH)3.
Chromium is precipitated as hydroxide:
• finally leads to the generation of a
high water content sludge .
• its efficiency is affected by low pH
and the presence of other salts (ions).
• and is ineffective in removal of the
metal ions at low concentration.
• Defined as accumulation of liquid or gas phase on the surface of a solid
• The material that adsorbs is called adsorbent and the substance
getting adsorbed is called adsorbate.
• Adsorption may be physical adsorption or Chemical adsorption or a
combination of both.
•If we have to remove soluble material from the solution phase, but the material is neither
volatile nor biodegradable, we often employ adsorption processes.
•Biosorptions a property of certain types of inactive, dead, microbial biomass to bind and
concentrate heavy metals from even very dilute aqueous solutions.
• The advantages of biosorption process are that these are cost effective, technically
feasible and eco-friendly.
• Ingestion Hazards
–Erosive to stomach, Hemorrhaging and
–Direct eye contact with chromic acid or
chromate dusts can cause permanent eye
• Hexavalent chromium is considered
a potential lung carcinogen.
1. Studies of workers in the chromate
production, plating, and pigment industries
consistently show increase rates of lung
2. Insoluble forms such as zinc chromate are
the most potent 20 year cancer latency
In a research that have done by AL-Watan news paper that took samples
from the local stores and they’ve found that all of the samples contain
chromuim-6 that is dangerous for the skin :
1. About 60,000 employees work in 500 Tannery contact directly
2. Most of the tannery use a cheap materials in the tanning process
3. The products of these tanneries (bag, shoes, jacket, leather)
Standard Egyptian provide that the chromium ratio should be
But the products have a ratio of 13% kg which is very dangerous for
the humans and effect on the health and cause a skin problems and in the
long-term skin cancer.
Agency for Toxic Substances and Disease Registry Division of Toxicology and
Human Health Sciences,
الكرومToxFAQs™ رقم3-47- CAS 7440
Health Effects of Hexavalent Chromium-OSHA Fact sheet