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

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 freezedrying 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.

Automated summary

This study developed a low-cost adsorbent by preparing hydrogels with porous carbon and polyvinyl alcohol. The hydrogels showed excellent mechanical properties and demonstrated good adsorption capacity for organic pollutants in wastewater. The adsorption mechanism was found to be mainly multilayer physical adsorption. Therefore, this method has potential application value in water purification.