Removal of copper and zinc from wastewater using chitosan

Abstract

Heavy metals are one of the most toxic materials to the environment. Adsorption is the process which is used for the removal of heavy metals from wastewater. Many researches have been conducted to remove heavy metals using different materials. Various adsorbents have been used to remove different type of heavy metal ions from wastewater especially those that are harmful to mankind. Activated carbons, plant or lignocellulosic wastes, clays and biopolymers are the most common adsorbents used. For this research, chitosan was used as a adsorbent to remove copper and zinc from wastewater. Chitosan, a type of biopolymer, is a good adsorbent to remove the heavy metal ions from wastewater. The synthetic wastewater was prepared in the laboratory to conduct the experiments. Batch experiments were conducted to obtain the optimum conditions for copper and zinc. Effect of parameter like pH, adsorbent dose, contact time, temperature and initial metal ion concentration were also determined. The optimum conditions obtained were 360 min contact time, 200 mg adsorbent dose and pH 5 for copper and 180 min contact time, 200 mg adsorbent dose and pH 7 for zinc. Adsorption behavior could be described using the Langmuir, Freundlich and Temkin isotherm model. Adsorption data was well fitted in Langmuir isotherm model for both metals. The maximum adsorption capacity was found to be 89% for copper and 96.97% for zinc. The kinetics of adsorption could describe using pseudo first order and pseudo second order kinetic model. In all cases the kinetics follows the pseudo second order rate equation. The negative values of ∆G0 and ∆H0 indicate that the process was thermodynamically spontaneous and exothermic in nature.