Ultrahigh selective adsorption of zwitterionic PPCPs both in the absence and presence of humic acid: Performance and mechanism

Abstract

Since zwitterionic PPCPs could be combined with humic acid (HA) leading to certain contaminants residue in aqueous solution, adsorbents with much stronger binding with zwitterionic PPCPs were needed to avoid this phenomenon. Through comparison of serial magnetic carboxyl modified hypercrosslinked resins including MA10, MA30, MA40 and MA70, MA50 was found to exhibit ultrahigh selective adsorption of zwitterionic PPCPs including tetracycline and quinolone antibiotics due to the remarkable synergistic effects generated from cation exchange interaction and non-ion exchange interaction. To figure out the effect of HA, other five adsorbents including hypercrosslinked resin Q100, aminated hypercrosslinked resin GMA50, anion exchange resin MIEX, wood-based activated carbon F400D and coal-based activated carbon Norit were chosen as comparison to MA50 in adsorption performance of tetracycline (TC) and ciprofloxacin (CPX). It turned out that the percentage of CPX or TC combined with HA in aqueous solution varied greatly for studied adsorbents. There existed serious false-positive adsorption during the adsorption process by some commercial adsorbents such as MIEX and F400D, while MA50 exhibited relatively lower false-positive adsorption, ensuring the maximum safety of effluents. Breakthrough tests showed that MA50 had significant advantages in PPCPs removal at environment concentration, indicating its potential in application for real water.

Keywords: Activated carbon; False-positive adsorption; Magnetic resin; Synergistic effects; Zwitterionic antibiotics.