Degradation of Ofloxacin Using the UV/ZnO/Iodide Process in an Integrated Photocatalytic-Biological Reactor Containing Baffles

Abstract

The goal of this study is to achieve zero waste with a UV/ Iodide/ZnO (UIZ)-based integrated photocatalytic-biological reactor (IPBR) containing baffles that has been devised to degrade ofloxacin (OFX) completely. The efficiency of the photoreactor was determined by first investigating the removal of OFX through the UIZ, UV/Iodide, UV/ ZnO, and UV-only treatments, which resulted in the degradation of 97−100, 57.9−71.4, 47.8−67.5, and 37.9−42.5%, of the OFX molecules, respectively. The optimization result obtained 0.87:1:50 as the optimal molar ratio of Iodide/ZnO/OFX. Information about the liquid chromatography-mass spectroscopy on the effluents obtained from the UIZ process revealed that the OFX molecules degrade into ring-shaped compounds and then into linear molecules within 15 min. The application of the pseudo-first-order kinetics model indicated that the observed rate constant (k obs ) of the photochemical process and the associated rate (r obs ), respectively, increase from 0.4109 to 0.1371 min −1 and from 4.109 to 27.42 mg L −1 min −1 when the OFX concentration increases from 10 to 200 mg L −1 . The proposed integrated reactor was found to be a promising technology for the complete removal of OFX from wastewaters. The carbon oxidation state (COS) level increases sharply from −1.29 to 0.52 after 10 min of treatment in the UIZ reactor and also increases from 0.52 to 1.29 at 30 min and from 2.37 to 3.04 at 480 min of the biological process. The average oxidation state (AOS) level was found to be around 3.58.

Mechanism insight into the photocatalytic degradation of fluoroquinolone antibiotics by the ZIF-8@Bi2MoO6 heterojunction

“…In particular, the product M 17 ( m / z = 161) can be formed from M 12 , M 16 , and M 20 by the removal of the carboxyl group, F atom and carbonyl groups, and amine group, respectively. 96…”

“…In particular, the product M 17 (m/z = 161) can be formed from M 12 , M 16 , and M 20 by the removal of the carboxyl group, F atom and carbonyl groups, and amine group, respectively. 96 In the second stage, the breakdown of heterocyclic rings forms simple aromatic products M 21 (m/z = 165), M 22 (m/z = 137), M 23 (m/z = 110), and M 24 (m/z = 93). The third stage is the ring-opening reaction to form aldehyde and short-chain organic acids such as M 25 (m/z = 116), M 26 (m/z = 90), M 27 (m/ z = 86), M 28 (m/z = 84), M 29 (m/z = 70), M 30 (m/z = 68), and M 31 (m/z = 56).…”

“…The third stage is the ring-opening reaction to form aldehyde and short-chain organic acids such as M 25 (m/z = 116), M 26 (m/z = 90), M 27 (m/ z = 86), M 28 (m/z = 84), M 29 (m/z = 70), M 30 (m/z = 68), and M 31 (m/z = 56). 96,97 In the last stage, the mineralization of intermediates occurs to form CO 2 , H 2 O, ammonium, nitrate, and nitrite. 96 The mineralization of OFX (at 10 mg L −1 , pH 6.4) was confirmed via the COD value of its solution before and after the reaction.…”

“…96,97 In the last stage, the mineralization of intermediates occurs to form CO 2 , H 2 O, ammonium, nitrate, and nitrite. 96 The mineralization of OFX (at 10 mg L −1 , pH 6.4) was confirmed via the COD value of its solution before and after the reaction. After 25 min of LED visible light irradiation using the BIZ/Na 2 S 2 O 8 /OFX system, 65.9% of COD was removed, confirming the complete oxidation of OFX to mineralized products.…”