Efficient decontamination of ciprofloxacin at neutral pH via visible light assisted Fenton-like process mediated by Fe(III)-GLDA complexation.

This work demonstrated a novel N,N-bis(carboxymethyl)glutamic acid (GLDA) modified visible (vis) light assisted Fenton-like system which could effectively removal ciprofloxacin (CIP) at neutral pH. The removal rate of CIP in the GLDA/Fe(III)/H2O2/vis system was 97.9% within 120 min and was approximately twice as high as that in the Fe(III)/H2O2/vis system. GLDA could significantly accelerate the Fe(III)/Fe(II) cycle under visible light irradiation. Radical scavenging experiments demonstrated that 74.2% of the Fe(II) in the GLDA/Fe(III)/H2O2/vis system originated from the ligand-to-metal charge transfer reaction between Fe(III) and GLDA. The hydroxyl radical was the dominant species for CIP degradation. H2O2 utilization kinetic modeling exhibited that 90.1% of H2O2 was used for CIP mineralization. The effects of experimental parameters and coexisting substances on the removal of CIP in the Fe(III)/GLDA/H2O2/vis system were investigated in detail. The intermediate products of CIP were explored via the high-performance liquid chromatography-mass spectrometry.