Removal of chromium
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Chromium exists in various oxidation states and is essential for maintaining blood glucose levels but poses health risks, particularly hexavalent chromium, which is a potential carcinogen linked to lung cancer. The document discusses methods for chromium removal from solutions, including precipitation and biosorption, noting their effectiveness is influenced by pH and other ions. It highlights serious health hazards associated with excessive chromium exposure, particularly in industries like tanning, where products often exceed safe chromium levels.
Removal of chromium
- 2. .
- 3. Chromium is a metal that exists in several oxidation:
- 4. • 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 levels. • Exist in food, fruit, fishes and underground water.
- 6. • Aircraft Painting • Leather tanning • Electroplating • Textile manufacturing • dyeing, cement industry • metal finishing
- 8. 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 accomplished by: 1. the addition of ferrous sulphate and lime. Ferrous ion 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.
- 9. 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.
- 10. • Defined as accumulation of liquid or gas phase on the surface of a solid phase. • 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.
- 11. •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.
- 12. • Ingestion Hazards –Erosive to stomach, Hemorrhaging and death • Eyes –Direct eye contact with chromic acid or chromate dusts can cause permanent eye damage. • 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 cancer. 2. Insoluble forms such as zinc chromate are the most potent 20 year cancer latency
- 13. 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 with chromium-6 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 0.00003% kg 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.
- 15. http://water.epa.gov/drink/info/chromium/ http://water.epa.gov/drink/contaminants/basicinformation/chromium.cfm http://www.slideshare.net/ArvindGupta9/methods-for-removal-of-chromium http://www.elwatannews.com/news/details/585685 http://digital.ahram.org.eg/articles.aspx?Serial=325739&eid=3041 http://water.epa.gov/drink/contaminants/basicinformation/chromium.cfm http://gilgamish.org/printarticle.php?id=983 .http://www.atsdr.cdc.gov/toxfaqs/index.asp 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