Adsorption of mercuric chloride and phenyl mercuric acetate from aqueous solution using chitosan beads

Abstract

Removal of mercury compounds from aqueous solution by adsorption was investigated in this study. Chitosan gel and dry beads are used as adsorbents. Both types of beads were prepared using chitosan solution having 2, 3, and 4 percent by weight of chitosan in 1 M acetic acid solution. The experiments were conducted at atmospheric pressure and at temperatures of 30 ํC, 40 ํC, and 50 ํC. Initial pH of solutions were 5, 7, and 9. Mercuric chloride and phenylmercuric acetate were selected as model mercury compounds to represent inorganic and organic forms. Mercury compounds were dissolved in demineralized water to obtain feedstock solutions containing 10 ppm of mercury. The results showed that chitosan beads adsorbents can be used effectively in the removal of mercury compounds in aqueous solution. Removal of mercury compounds depended on type of mercury compounds, initial pH of solution, temperature, concentration of chitosan solution, and type of chitosan. Adsorption ability of chitosan beads on mercuric chloride and phenylmercuric acetate decreased with increasing initial pH of solution. Mercuric chloride can be adsorbed better with increasing operating temperature but phenylmercuric acetate showed an opposite result. It is also found that chitosan gel beads can be used to remove mercury compounds more effectively than chitosan dry beads. Concentration of chitosan solution does not affect adsorption ability of mercury compounds but adsorption ability of chitosan dry beads decreased with increasing concentration of chitosan solution.