A study on biosorption of copper ions by fungal chitosan: an alternative to shrimp chitosan

Abstract

Introduction : One of the main applications of chitosan is for heavy metals removal from waste waters. Industrially, chitosan is produced through deacetylation of chitin present in shellfish waste. Another source of chitosan is the cell wall of zygomycetes fungi with several advantages over shellfish wastes . Materials and method s: Fungal chitosan purified from biomass of Mucor indicus and shrimp chitosan were applied and compared for removal of copper ions from aqueous solution. The effects of pH (3 to 5.5), copper ion concentration (5 to 52 mg l-1), the amount of chitosan (200 to 3000 mg l-1), adsorption time, temperature, and presence of other metal ions on the biosorption of Cu2+ were investigated . Results : Maximum adsorption capacities for fungal and shrimp chitosans were 58.5 and 60.7 mg g-1, respectively. T he rate of copper adsorption by the fungal chitosan was significantly higher than that by the shrimp chitosan. Among p seudo-first order, pseudo-second order, intra-particle diffusion, and Elovich models, Ho’s pseudo-second order model was the best model for fitting the kinetic data. The adsorption capacity increased for both types of chitosans by increasing the solution pH. However, temperature and presence of other ions did not show significant effects on the biosorption capacity of copper. The isotherm data were very well described by Langmuir, Freundlich, and Redlich-Peterson models . Discussion and conclusion : Both fungal and shrimp chitosans can effectively be used for removal of copper ions from aqueous solutions. Adsorption process for fungal chitosan is fast, while the process is slower for the shrimp chitosan. Therefore, from the kinetics point of view, the fungal chitosan is preferable compared with the shrimp chitosan . Key words: Biosorption, Copper, Fungal chitosan, Shrimp chitosan, Water treatment .