Microwave-Enhanced Photolysis of Norfloxacin: Kinetics, Matrix Effects, and Degradation Pathways

Abstract

Degradation of norfloxacin (NOR) was studied using a combination of microwave and UV irradiation methods (MW/UV process). Remarkable synergistic effect was found between MW and UV light. The removal rate with the MW/UV process was much faster than that with UV light irradiation only. Degradation of NOR followed second-order kinetics and ~72% of NOR could be removed in the first 5 min of MW/UV reaction. Influence of inorganic ions (cations (K+, Mg2+, Ca2+, Cu2+) and anions (Cl−, SO42−, NO3−, CO32−)), humic acid (HA) and surfactants (cation, anion, and non-ionic) on the degradation of NOR by the MW/UV process was investigated. Among the ions, Cu2+ and NO3− ions inhibited the degradation of NOR. The presence of HA and surfactants in water showed a slight inhibition on the NOR removal. Furthermore, the NOR degradation in the MW/UV process was primarily caused by the ·OH-photosensitization steps. Seven intermediates formed by the oxidation of NOR were identified and three reaction pathways were proposed. Removals of NOR in tap water (TW), synthetic wastewater (WW), river water (RW), and seawater (SW) were also studied, which demonstrated that the MW/UV process was an effective oxidation technology for degrading fluoroquinolone antibiotics in different water matrices.

A review of the adsorption method for norfloxacin reduction from aqueous media

“…The efficacy of the oxidant determines how well AOPs perform [45] . AOPs investigated for NRFX removal include photocatalysis [ 27 , [46] , [47] , [48] ], photolysis [ 49 , 50 ], chlorine processes [51] , [52] , [53] , ozonolysis [54] , [55] , [56] , sonolysis [57] , sonocatalysis [ 28 , 58 ], Fenton (sono-Fenton, electro-Fenton, and photo-Fenton, etc.) [ 25 , [59] , [60] , [61] , [62] ].…”

“…[ 25 , [59] , [60] , [61] , [62] ]. The degradation of NRFX photolysis enhanced by microwave has been demonstrated by Liao, Sharma [49] . Within five minutes of the MW/UV reaction, approximately 75% of NRFX was removed.…”

Microwave-assisted high-efficiency degradation of methyl orange by using CuFe2O4/CNT catalysts and insight into degradation mechanism

“…Studies have shown that an increase in the density of cations on the surface of mineral particles is beneficial to the microwave degradation of nitrosodiphenylamine, and the lower the free energy of cation hydration, the higher the degradation rate. This is due to the fact that hot spots can be formed by the selective heating of polar substances in mineral particles, including surface cations, hydroxide radicals, adsorbed water molecules and organic molecules (Liao et al 2017). Overall, all ions had little effects on MO degradation.…”

Efficient microwave degradation of humic acids in water using persulfate and activated carbon

“…Microwave irradiation has been tested to determine its efficacy for degrading pollutants because of its short reaction time, high effi and lack of secondary pollutant generation (Kim and Ahn 2017;Liao et al 2017a;Remya and Lin 2011a;Wang and Wang 2016). Additionally, the heating that occurs with microwave irradiation accelerates the reaction rates more than conventional heating, thereby saving energy and shortening the treatment process time (Liao et al 2017b).…”