Phosphorus-Containing Polybutadiene Rubber–Bentonite Hybrid Composite for the Removal of Rhodamine 6G from Water

Abstract

ABSTRACTHere is reported the adsorption of rhodamine 6G from aqueous solution using a phosphorus-containing polybutadiene rubber–bentonite hybrid composite. The polybutadiene rubber–bentonite hybrid composite was synthesized via oxidative chlorophosphorylation of polybutadiene rubber and bentonite with subsequent hydrolysis. The static exchange capacity of the polybutadiene rubber–bentonite hybrid composite and the concentration of phosphorus were evaluated. The functional groups present in the polybutadiene rubber–bentonite hybrid composite were characterized by infrared spectroscopy. The adsorption of rhodamine 6G on the polybutadiene rubber–bentonite hybrid composite was investigated on the basis of initial rhodamine 6G concentration, contact time, and temperature. The equilibrium isotherm was analyzed using Langmuir, Freundlich, and Dubinin–Radushkevich models. The adsorption equilibrium measurements of rhodamine 6G in solution correlated well with the Langmuir isotherm equation. This model revealed that the maximum monolayer adsorption capacity of polybutadiene rubber–bentonite hybrid composite was 32.2 mg g−1. Pseudo first-order, pseudo second-order, and intraparticle diffusion models were used to characterize the adsorption kinetics of rhodamine 6G. The dynamic data fitted well with the pseudo second-order kinetic model. The Gibbs free energy, enthalpy, and entropy changes indicated that the rhodamine 6G adsorption on polybutadiene rubber–bentonite hybrid composite was spontaneous and endothermic. The results were compared with corresponding data in the literature. This study demonstrates that the polybutadiene rubber–bentonite hybrid composite is an effective adsorbent for rhodamine 6G.