Equilibrium Study of Cadmium Ions Adsorption on Sericin/Alginate Particles

Abstract

Cadmium is a pollutant widely found in industrial effluents and its toxicity affects the ecosystem and presents human health risk. The adsorption can be used to remove toxic metals in dilute solutions. Industrial waste, such as sericin, can efficiently replace conventional bioadsorbent materials. Sericin is a protein present in silkworm cocoon and is usually discarded in effluent of spinning processes. Alginate is a polysaccharide used to improve the characteristics of the blend. The objective of this study was to investigate the use ofsericin/alginate particles as bioadsorbent to remove cadmium ions (Cd2+) in waste water through adsorptionequilibrium study. Equilibrium experiments were conducted to evaluate the influence of adsorption temperature (10 °C, 20 °C, 40 °C and 60 °C), which indicated that the cadmium adsorption capacity increased with decreasing temperature. Adsorption isotherm models, Langmuir, Freundlich, Dubinin-Radushkevich and Temkin were used to analyse the equilibrium data. Cadmium adsorption equilibrium could be described by the Freundlich adsorption model at all the temperatures essayed. The values of the n parameter, which aregreater than unity, indicate that Cd2+ ions are favourably adsorbed by sericin/alginate particles at thetemperature range studied.