Removal of copper and lead from aqueous solution by carboxylic acid functionalized deacetylated konjac glucomannan

Carboxylic acid functionalized deacetylated konjac glucomannan was synthesized by free radical graft copolymerization of methyl acrylate (MA) and methyl methacrylate (MMA) onto the backbone of deacetylated konjac glucomannan with subsequent chemical activation of the ester groups in the side chains of the resulting graft copolymer by sodium hydroxide. Effects of sodium hydroxide concentration and hydrolyzed time on the conversion of ester groups into carboxylic acid groups were studied. A comprehensive adsorption study of Cu(2+) and Pb(2+) ions from aqueous solution was also conducted regarding the effects of initial pH, adsorbent dosage, time, and initial concentration. The new konjac glucomannan adsorbent offered high removal efficiency, fast adsorption rate and high uptake capacity for Cu(2+) and Pb(2+) ions. The maximum removal efficiency at pH 5.0 was found to 98% for Cu(2+) and 99% for Pb(2+) ions. The kinetic data were fitted well to pseudo-second-order model. The maximum uptake capacity of Cu(2+) and Pb(2+) ions onto carboxylic acid functionalized deacetylated konjac glucomannan was found to 64.5 mg g(-1) and 191.3 mg g(-1), respectively. The isotherm adsorption data was well described by the Langmuir isotherm model.