Fast and effective hydroquinone adsorption by poly (2-dimethylaminoethyl methacrylate)/zinc oxide nanocomposite hydrogel in textile wastewater treatment

Abstract

ABSTRACT Hydroquinone, a widely used phenolic compound, poses significant health and environmental risk and must be removed from wastewater. In this study, a novel adsorbent was developed for the removal of hydroquinone from aqueous solutions through the in-situ polymerisation of 2-(dimethylamino)ethyl methacrylate (DMAEMA) in the presence of zinc oxide nanoparticles (ZnO NPs). The kinetics of equilibrium swelling in deionised water (DI) and the effect of pH on the swelling behaviour were investigated. The structure of the nanocomposite hydrogel was analysed using FTIR, XRD, FESEM, EDX, TEM, and BET analysis. Various factors affecting the adsorption process, such as solution pH (2–12), initial concentration (25–200 mg/L), adsorbent dosage (4.0–80 mg/100 mL), NaCl concentration (0.1–1.0 mol/L), and temperature, were also investigated. The adsorption capacity of hydroquinone and the removal efficiency of PDMAEMA@ZnO reached 455 mg/g and 91%, respectively, at pH 11 within 15 minutes. Furthermore, PDMAEMA@ZnO showed a high removal efficiency of 99.47% in tests with real wastewater. Reusability studies showed that the adsorbent retained its ability to remove hydroquinone after four regeneration cycles. The adsorption data were well described by the pseudo-second order and Langmuir models. The thermodynamic parameters indicated that the adsorption process is spontaneous and endothermic. Therefore, the adsorbent, has considerable industrial potential as it quickly and efficiently adsorbs phenolic impurities such as hydroquinone from real textile wastewater.