Enhanced adsorption of 2, 4-dichlorophenoxyacetic acid from aqueous medium by graphene oxide/alginate composites

Abstract

Calcium alginate beads (A), graphene oxide (GO) and GO/alginate beads composites (GA1, GA2 and GA3) as solid adsorbents were prepared and characterized by thermogravimetric curves (TGA), nitrogen adsorption/desorption curves, point of zero charge (pH PZC ), X-ray difffractometer (XRD), transmission electron microscope (TEM) and Fourier-transform infrared spectroscopy (FTIR). Adsorption of 2, 4-dichlorophenoxyacetic acid as one of the most toxic applied herbicide in the fields worldwide was studied considering the effect of different adsorption parameters. Results revealed that the optimum adsorbent dosage and initial pH value were found 2.0 g/L and pH 6, respectively. Freundlich and Langmuir adsorption models were applied and the maximum adsorption capacity was confirmed by GA3 (150.4 mg/g). Kinetic and thermodynamic studies proved that the adsorption follows the pseudo-second order kinetic models (PSO) and the exothermic spontaneous physisorption process.