Dextrin‐graft‐poly(2‐dimethylamino ethyl acrylate‐co‐2‐acrylamido‐2‐methyl propane sulfonic acid) polymer: A potential adsorbent for the fast removal of nitrophenols from aqueous medium

Abstract

AbstractA graft copolymer is synthesized by grafting a mixture of 2‐(dimethylamino) ethyl acrylate (DMAEA) and 2‐acrylamido‐2‐methyl propane sulfonic acid (AMPS) monomers onto the dextrin, polysaccharide backbone via free radical polymerization process using potassium peroxydisulfate (KPS) as radical initiator in aqueous phase. Various characterization techniques like 1H and 13C NMR, FT‐IR, SEM, EDAX, and XRD analysis are used to characterize the copolymer. The polymer is used as an adsorbent for the removal of nitrophenols namely ortho‐nitrophenol (ONP), para‐nitrophenol (PNP), and 2,4‐ dinitrophenol (DNP) from their water solutions. Adsorption dynamics, kinetics, isotherms, and thermodynamics are studied. The maximum nitrophenol adsorption occurs at time 80 min, temperature 45°C, pH 3.5 (DNP), and 4.5 (ONP and PNP), polymer dose 30 mg/L. The nitrophenol adsorption data are well‐fitted with the Langmuir isotherm model with maximum adsorption capacity () 215.26 mg g−1 for ONP, 223.60 mg g−1 for PNP, and 288.24 mg g−1 for DNP. The equilibrium kinetics follow pseudo‐second‐order kinetic model. Thermodynamic values unfold that the following nitrophenol adsorption onto the polymer surface is spontaneous and endothermic in nature. The value of Gibb's free energy for the nitrophenol adsorption is in the range of −6.5 to −9.5 kJ mol−1. The preferential nitrophenol adsorption by the copolymer is followed in the order ONP<PNP<DNP.