Ethylenediamine grafted poly(glycidylmethacrylate-co-methylmethacrylate) adsorbent for removal of chromate anions

The removal of chromate anions (CrO42−) from aqueous solutions under different experimental conditions using cross-linked poly(glycidylmethacrylate-co-methylmethacrylate), poly(GMA-co-MMA), adsorbent was investigated in this study. The epoxy group containing adsorbent in the beads form was prepared from glycidylmethacrylate and methylmethacrylate via suspension polymerization. The epoxy groups of the poly(GMA-co-MMA) beads were used for grafting with ethylenediamine to prepare specific adsorbent (poly(GMA-co-MMA)-ED) for CrO42− anions removal from aqueous solutions. Adsorption equilibrium was achieved in approximately 120 min. The removal was favored at low pH, with a maximum adsorption at pH 2.0. Isotherm studies showed that CrO42− anions could be effectively removed by poly(GMA-co-MMA)-ED beads. The maximum adsorption capacities of the poly(GMA-co-MMA) and poly(GMA-co-MMA)-ED beads were 0.044 and 0.441 mmol CrO42− anions/g of dry adsorbents, respectively. The experimental data of the adsorption equilibrium from CrO42− anions aqueous solution correlated well with the Langmuir-Freundlich isotherm model. The experimental data were analyzed using the first- and the second-order kinetic models. The rate constants of adsorption for both kinetics models have been calculated. The second-order model provides the best correlation of the data. Desorption experiments show that the process of adsorption of CrO42− anions was reversible and the adsorbent was easily regenerated with 0.1 M NaOH up to 96% recovery.