Synthesis of poly(2-acrylamido-2-methylpropane sulphonic acid/ 2-hydroxyethyl methacrylate)/TiO2/ZnO hydrogel nanocomposite by γ-irradiation for remediation of dyes in wastewater

Abstract

ABSTRACT This study aimed to synthesise a novel adsorbent of poly(AMPS/HEMA)/TiO2/ZnO hydrogel nanocomposite by γ-irradiation polymerisation of 2-acrylamido-2-methylpropane sulphonic acid (AMPS) solution and 2-hydroxyethyl methacrylate (HEMA) monomer incorporated with TiO2/ZnO nanoparticles for potential use in the uptake of methylene blue (MB) and crystal violet (CV) dyes from wastewater. The effect of irradiation dose and AMPS/HEMA composition ratio on gel content (%) and swelling (%) were studied. From the results of the gel content (%) and swelling (%), the composition ratio AMPS/HEMA (80/20) and the dose of 15 kGy were selected for the preparation of the hydrogel nanocomposite. The properties of prepared materials were characterised by different analytical techniques. FTIR results proved the successful interaction of TiO2/ZnO nanoparticles within AMPS and HEMA chains. The SEM/EDS results proved the peaks corresponding to C, O, S, Zn, and Ti. XRD of nanocomposite indicated the peaks of TiO2 and ZnO nanoparticles. The factors affecting the uptake of MB and CV dyes were evaluated according to the impact of reaction time, pH, dye concentration, dosage, and temperature. The adsorption amount of MB and CV onto poly(AMPS/HEMA)/TiO2/ZnO hydrogel nanocomposite was fast time and effective for highly concentrated dye-bearing effluents. The uptake characteristics of the two dyes were similar. The ideal adsorption capacity of nanocomposite towards MB and CV dyes were 257.6 and 215.9 (mg/g) with a removal rate of 89.7% and 81.8%, respectively. The optimal conditions were pH 9 and 7, a reaction time of 70 min, dye concentration of 300 mg/L, and 0.3 g nanocomposite dosage. The adsorption process was chemisorption, endothermic and spontaneous. It is fitted with Langmuir isotherm and Pseudo-second-order models. Furthermore, the poly(AMPS/HEMA)/TiO2/ZnO nanocomposite supports the high capability for adsorption of binary MB/CV dyes mixture. The prepared hydrogel nanocomposite is a novel adsorbent for the uptake of dyes from wastewater with good recyclability.