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)/H 2 O 2 /vis system was 97.9% within 120 min and was approximately twice as high as that in the Fe(III)/H 2 O 2 /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)/H 2 O 2 /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. H 2 O 2 utilization kinetic modeling exhibited that 90.1% of H 2 O 2 was used for CIP mineralization. The effects of experimental parameters and coexisting substances on the removal of CIP in the Fe(III)/GLDA/H 2 O 2 /vis system were investigated in detail. The intermediate products of CIP were explored via the high–performance liquid chromatography-mass spectrometry.