Management of Thiocyanate Pollution Using a Novel Low Cost Natural Waste Biomass

Environmental pollution caused due to the release of toxic and hazardous (T&H) chemical wastes from industrial processes is an issue of major environmental concern. ‘Thiocyanate', one such T&H chemical, is encountered in several industrial effluents. Owing to its toxicity, its proper management by removal from liquid wastes using suitable cost-effective and efficient technology is the key. Management/removal by sorption using biomass is one such technology. Waste biomass (powdered dried leaves) of various photosynthetic plants (consisting of big trees and weeds) were screened for the removal of thiocyanate from the aqueous solutions. Among the tested biomaterials, Mangifera indica (Mango) biomass was found to be highly efficient biosorbent of thiocyanate. Biosorption of thiocyanate from solutions took place optimally in the pH range of 4 to 6 and biosorbent quantity of 3% (w/v). Loading capacity of Mangifera indica biomass (10.5 mg/g) was comparable with that of activated charcoal (11 mg/g), which was used as a reference material. Kinetic study showed that the process of biosorption was rapid and for maximum thiocyanate sorption the contact time required was 60 minutes. The experimental data showed that thiocyanate uptake values could well be fitted to the Langmuir and Freundlich adsorption isotherms models. When the process of biosorption was carried out under standardised conditions, a 10-17 fold concentration of thiocyanate could be achieved using sodium hydroxide as an eluting agent. Laboratory experiments thus, clearly indicate that thiocyanate could effectively be managed by its removal from aqueous solutions using low-cost natural waste biomass