Adsorption of lead ions from aqueous solution by using carboxymethyl cellulose-g-poly (acrylic acid)/attapulgite hydrogel composites

A series of carboxymethyl cellulose-g-poly (acrylic acid)/attapulgite (CMC-g-PAA/APT) hydrogel composites was prepared and used for Pb(II) adsorption from aqueous solution. The effects of APT content, pH value, contact time, initial concentration and ionic strength on adsorption were investigated. Results from kinetic experiments showed that adsorption rate of Pb(II) ions onto the composite was quite fast. Adsorption equilibrium may be reached within 60 min and more than 90% of the equilibrium adsorption was achieved within the initial 10 min and 30 min for the composites with 5 wt.% and 20 wt.% APT, respectively. The adsorption process can be well described by the pseudo-second-order kinetic model, and the equilibrium adsorption isotherm was closely fitted with the Langmuir model. FTIR spectra before and after adsorption of Pb(II) on the composite revealed that complexation was considered as the main adsorption mechanism.