The improvement of levofloxacin and tetracycline removal from simulated water by thermosensitive flocculant: Mechanisms and simulation

Abstract

Antibiotics were detected in worldwide natural water especially in COVID-19 period. The common flocculants rarely removed the dissolved antibiotics from natural water and wastewater. The flocculation improvement of organic polymer flocculants might solve the issue of antibiotic pollution or promote the removal efficiencies of antibiotics in water/wastewater treatment plants. Herein, a thermosensitive flocculant, P(DAC-NIPAM), was prepared via one-step method. It was investigated that the relationship between the various functional groups of P(DAC-NIPAM) and its flocculation performances in the treatment of simulated water containing levofloxacin, tetracycline, colloidal particles and natural organic matters. The removal mechanisms were discussed. The results indicated that the rich cationic, hydrophilic and hydrophobic groups of P(DAC-NIPAM) enhanced the interaction between flocculants and pollutants. The bridging of P(DAC-NIPAM) among micelles, charge neutralization, hydrogen bond between P(DAC-NIPAM) and two antibiotics, the shrinkage of P(DAC-NIPAM) molecule and enhancement of hydrophobicity when water temperature was above low critical solution temperature (LCST), co-flocculation and co-settlement of multiple pollutants all contributed to the efficient removal of levofloxacin and tetracycline from water. Flocculation simulation further confirmed that thermosensitive flocculant combined with heating plates was a potential candidate for antibiotic treatment in actual water treatment plants.