Adsorptive behaviors and mechanisms for removing three organic pollutants from aqueous solutions by polyvinyl alcohol/porous carbon composite hydrogels

Abstract

Confronted with severe water contamination induced by organic pollutants, developing low-cost adsorbents with high removal efficiency is a crucial approach to addressing the issue of residual organic pollutants in wastewater. This study prepared polyvinyl alcohol/porous carbon (PVA/C) hydrogels using freeze-thaw cycles and freeze-drying processes. And the adsorption behaviors were investigated with organic pollutants including congo red (CR), ibuprofen and doxycycline hydrochloride (DOX). Compared with pure PVA hydrogels, tensile test showed that PVA/coconut shell carbon hydrogel with a mass ratio of 10:2 (PCS2) had an increase of 285.78% in tensile stress. Through the adsorption experiment, PCS2 hydrogel demonstrated a good adsorption capacity for CR (27.39 mg/g), ibuprofen (15.48 mg/g), and DOX (17.07 mg/g). Furthermore, the adsorption mechanism of three organic pollutants by PCS2 hydrogel consistent with quasi-first-order kinetic and Freundlich adsorption isotherm model, indicating its adsorption process was dominated by multilayer physical adsorption. Therefore, this paper built a green, convenient, and economic method to prepare environmentally friendly and multifunctional PVA hydrogels for water purification.