Lead removal from battery wastewater using synthesized poly(ethyleneglycol dimethacrylate-methacrylic acid) gel bead and poly(methacrylic acid) hydrogel

Abstract

This study presents the synthesis and characterization of two new polymers with the aim of Pb2+ ion removal from the wastewater of a battery factory. Poly(ethyleneglycol dimethacrylate-methacrylic acid) (poly(EGDMA-MAA)) gel bead and polymetacrylic acid (polyMAA) hydrogel were prepared and characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), environmental scanning electron microscopy (ESEM), swelling capacity analysis and zeta potential measurements. Both polymers showed greater negative zeta potential values in the range of pH 3–8. Poly(EGDMA-MAA) had a relatively lower swelling capacity of 0.9 gwater/gpolymer than polyMAA because of the crosslinking degree. The FTIR spectrum of the virgin poly(EGDMA-MAA) showed that the polymer has carboxylic groups to sorb the Pb2+ ions. The FTIR spectrum of poly(EGDMA-MAA) after sorption showed that interactions between the Pb2+ ions and carboxyl groups caused a decrease in the intensity of the C=O peak. The sorption experiments carried out under different conditions yielded optimal conditions of contact time and polymer amount. The Pb2+ adsorption capacities were found to be 1.995 and 2.047 mg g−1 for poly(EGDMA-MAA) and polyMAA, respectively. Moreover, the sorption mechanism was studied using kinetic and thermodynamic models. The higher R2 (0.9997 and 0.9999), lower e% (1.3 and 0.8) and closer values of qexp and qcal show that the data fit well with the type (I) pseudo-second-order model. The higher positive ΔS° value indicated that greater structural changes occurred in polyMAA than in poly(EGDMA-MAA).