Poly(4-styrene sulfonic acid) resin for heavy metal ions adsorption: characterization, adsorption properties, thermodynamic and reusability studies

ABSTRACT A novel poly(4-styrene sulfonic acid)-graft resin (PSS-g-PS) with high adsorption capacity was prepared by grafting poly(4-styrene sulfonic acid) (PSS) onto chloromethylated styrene resin via surface-initiated atom transfer radical polymerization. The surface composition of the poly(4-styrene sulfonic acid)-grafted resin were characterized by Fourier-transform infrared spectrometry, scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy. It was found that the grafting amount of 4-styrenesulfonic acid increased linearly with the polymerization time. Effect of parameters such as pH, initial concentration and temperature on the removal of heavy metal ions was studied. The maximum adsorption capacities of the resin were up to 275 mg·g –1 for Pb(II), 169 mg·g –1 for Cu(II), 115 mg·g –1 for Cd(II), 90.8 mg·g –1 for Cr(III) and 75 mg·g –1 for Ni(II) at pH 5.0. The adsorption isotherms of the five metal ions were best described by the Langmuir model, and their adsorption kinetics followed the pseudo-second-order kinetic equation. Thermodynamic studies showed that the adsorption was spontaneous. Furthermore, the resins still maintained good adsorption capacity after 10 cycles of adsorption–regeneration. All the results suggested that the resin could be potentially applied to the efficient removal of heavy metal ions from wastewater.