Chloramphenicol Degradation in Fenton and Photo-Fenton: Formation of Fe2+-Chloramphenicol Chelate and Reaction Pathways

The aim of the present study was to investigate the formation of the Fe2+-chloramphenicol complex (FeCHPLCOM) and to compare the performances of Fenton processes for the degradation of CHPL and the FeCHPLCOM mixture at high concentration. LC-MS spectra evidenced for formation of charge transfer FeCHPLCOM at a 1:1 CHPL-to-Fe2+ ratio. CHPL acted as a bidented ligand coordinated with Fe2+. The IR study uncovered that ligand-to-metal bonding weakened the stretching frequency of both the OH bond and the -C-O group through coordination with Fe2+. The enhanced FeCHPLCOM degradation (13.4% more) was found in a photoassisted Fenton reaction. The asymmetry centers of CHPL with weakly bonded hydrogen atoms of high nucleophilic character were the most preferred sites of HO center dot attack. CHPL was oxidized through segmentation of the aliphatic chain attached to the benzene ring under acidic conditions (pH 3). The toxicity of CHPL to Escherichia coli (E. coli) XL 10GOLD decreased significantly after 45 min of decomposition.