Bi-phenyl derived hyper-crosslinked polymer as a metal-free adsorbent for the removal of pharmaceuticals from water

Abstract

The global concern of emergent aquatic pollutants, especially pharmaceutical contaminants, emphasizes the necessity for metal-free adsorbents to tackle water contamination issues. In this direction, a biphenyl-derived hyper-crosslinked polymer (poly-biph) was utilized as an adsorbent for the removal of ciprofloxacin (CPX) and doxycycline (DOX) from water. Micro-mesoporous hyper-crosslinked polymeric adsorbent (poly-biph) was synthesized by using bi-phenyl as precursor and formaldehyde dimethyl acetal (FDA) as crosslinker via microwave assisted method. It exhibits specific surface area (SABET) and pore volume of 1088 m2/g and 1.3 cm3/g, respectively. The spectral analysis confirmed the successful crosslinking of biphenyl with the linker FDA. The sorption efficiency of metal-free poly-biph for CPX and DOX was evaluated via batch and continuous flow modes under various operational parameters. poly-biph exhibited swift removal efficiency (>80 %) for CPX and DOX within a min. The batch mode sorption modeling revealed a chemisorption process and remarkable maximum sorption capacity of 470.8 and 425.1 mg/g for CPX and DOX, respectively. The continuous-flow studies of poly-biph revealed the better applicability of the Clark kinetic model with a maximum bed capacity of 313.5 and 372.4 mg/g for CPX and DOX, respectively. Synergistic mechanisms, including π-π interaction, electrostatic interaction, and pore-filling effect, were found to be the main driving forces for the sorptive removal of CPX and DOX onto poly-biph. The findings indicated that poly-biph possesses the ability to effectively eliminate DOX and CPX from the aquatic environment.