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Title Studies on removal of toxic heavy metal residues from process water
 
Names Das, S.S.
Lakshmanan, P.T.
Mukundan, M.K.
Date Issued 2003 (iso8601)
Abstract A study was carried out for the purification of water to remove toxic heavy metals for conformity to standards stipulated by EU (80/778/EEC) by using chitosan made from shrimp shell waste. The capacity of chitosan for chelation of heavy metals was estimated and was compared with that of chitin, chitosan from squilla shell waste and activated granular carbon. The effect of different physico-chemical parameters such as temperature, pH, time of contact, concentration of residues, in presence of other metallic residues, etc., on the chelation were studied. The longevity of the chitosan column was also studied. It was observed that the adsorptive capacity of chitin was less than that of all other adsorbents used in the study. Among the metals tested the maximum adsorption was seen for mercury and minimum for cadmium towards all the adsorbents used. The study revealed a linear relationship between temperature and adsorption capacity of all the metallic elements for all the adsorbents tested. But there was no significant difference between 30"C and 45°C. The role of pH was found to be insignificant in chelation towards all the heavy metals used. The rate of chelation was maximum in the case of mercury, followed by cadmium during contact time of 15 to 30 minutes. In the case of lead the chelation rate was slow that it required about one hour to reach higher degree of chelation. But 2 hours of contact time was required to reach near saturation for all the metals tested. A linear relationship was observed between the capacity and concentration of residues in the solution. The capacity of chelation of all the metallic elements tested was considerably reduced in presence of other metallic ions. Again, the percentage of reduction was minimum for mercury followed by lead and cadmium. The chitosan was also tested for the purification of water containing low but above maximum admissible concentration of mercury, cadmium and lead and found satisfactory. Finally, it is concluded that chitosan is an excellent chelating polymer and can be used for purification of water intended for handling and processing of food products.
Genre Article
Topic Heavy metals
Identifier Proceedings of the Symposium on Seafood Safety - Status and Strategies, 28-30 May 2002, Cochin, India ed. by Surendran, P.K. et. al, 277-289