Metal ion adsorption by carbonized and surface-modified cation exchange resin

Abstract

Sulfonated polystyrene-divinylbenzene cation exchange resin waste was carbonized at various temperatures (300-500℃) and the products were characterized by TGA and FT-IR. The cation exchange resin carbonized at 300℃ or CCR300 was used to extract cations such as Cu(II), Cd(II), Ni(II), Zn(II) and Pb(II) in aqueous solution. The cation exchange resin carbonized at 500℃ was surface-modified by cetyl trimethylammonium bromide, namely CTAB-CCR500 and used to extract chromate ions. The concentrations of heavy metal ions were measured by Flame Atomic Absorption Spectrometry (FAAS). For batch extraction, the optimal contact time for the cations and chromate ions were 30 and 90 min, respectively. The optimum pH for the adsorption of cations and chromate were 2 and 3, respectively. The maximum sorption capacities of CCR300 for Cu(II), Cd(II), Ni(II), Zn(II) and Pb(II) were found to be 34.7, 28.9, 31.9, 39.4 and 89.6 mg g-1, respectively, while the maximum capacity of CTAB-CCR500 for chromate was 4.3 mg g⁻¹. The adsorption isotherm and adsorption kinetics for metal ions followed Langmuir isotherm and pseudo-second order kinetics model, respectively. In case of column extraction, the extraction percentage of heavy metal ions decreased with increasing the solution flow rate. The highest percentage of extraction was nearly 80% for cations and 50% for chromate. The proposed method could be applied to remove Ni(II) present in wastewater from a nickel alloy industry. It was found the removal efficiency by batch method (~99% extraction) was greater than that obtained by column method (~70% extraction).