Solvent-free synthesis of the cellulose-based hybrid beads for adsorption of lead ions in aqueous solutions

Abstract

In this work, the adsorption of Pb²⁺ onto maleic anhydride modified cellulose/diatomite beads (MCDBs) was investigated. Instead of the general process for esterifying the cellulose beads, a solvent free synthesis which needs no catalyst or solvent was used. An appropriate amount of calcium carbonate was added during the formation of MCDBs to increase pore structure after being removed under an acidic condition. The synthesized adsorbent was characterized by FTIR, SEM, and BET. The degree of the carboxyl group of MCDBs was found to be 0.450 mmol g⁻¹ based on colloid titration. The effects of pH, temperature, contact time, and the concentration of Pb²⁺ on adsorption were studied in batch mode. The results indicated that the MCDBs had a good adsorption capacity toward Pb²⁺ with the maximum adsorption at 44 mg g⁻¹. The experimental kinetic data fit the pseudo-second order model very well. Moreover, the adsorption process for Pb²⁺ was better described by the Langmuir isotherm model. The regeneration of the MCDBs could be readily accomplished using an HCl (1 M) treatment without lowering the adsorption capacity significantly.