Thermodynamic quantities for the oxidation of ranitidine by diperiodatocuprate(III) in aqueous alkaline medium

Copper oxide/peroxydisulfate system for urban wastewater disinfection: Performances, reactive species, and antibiotic resistance genes removal

In this study, copper oxide (CuO) catalyzed peroxydisulfate (PDS) system was investigated for the inactivation of a broad range of pathogenic microorganisms from urban wastewater. Complete inactivation of Escherichia coli, Enterococcus, F-specific RNA bacteriophages from secondary treated wastewater was achieved after a short time (15-30 min) treatment with CuO (10 g/L)/PDS (1 mM) system, but spores of sulfite-reducing bacteria took 120 min. No bacterial regrowth occurred during storage after treatment. Significant reduction of the pathogens was explained by the generation of the highly selective Cu(III) oxidant, as the predominant reactive species, which could quickly oxidize guanine through a one-electron oxidation pathway. Additionally, the potential of the CuO (10 g/L)/PDS (1 mM) system to inactivate antibiotic-resistant bacteria and antibiotic resistance genes (ARB&Gs) was explored. Sulfamethoxazole-resistant E. coli was used as the model ARB and a 3.2 log of reduction was observed after 10 min of treatment. A considerable reduction (0.7-2.3 log) of selected ARGs including blaTEM, qnrS, emrB, sul1, and genes related to the dissemination of antibiotic resistance, including the Class 1 integron-integrase (intI1), and the insertion sequence (IS613) was achieved after 60 min treatment. All these findings indicated the promising applicability of the CuO/PDS system as a disinfection technology for wastewater reuse in agriculture.

Kinetic and Mechanistic Investigation of S-Oxidation of Ranitidine Hydrochloride with Chloramine-t in Acid and Alkaline Media

Ranitidine hydrochloride (RNH), chemically known as A-dimethyl-5-[2-(l- methylamino-2-nitro-vinyl)-ethylthiomethyl]furfuryl amine hydrochloride, is an antiulcer drug and its oxidation-kinetic study is of much significant in understanding its mechanistic chemistry in redox reactions. Consequently, the kinetics of oxidation of RNH by sodium N-chloro-p-toluenesulfonamide (chloramine-T or CAT) have been examined in HC104 and NaOH media at 298 K. The stoichiometry and oxidation products of RNH - CAT reaction are the same in both media, however, their kinetic patterns were found to be different. The reaction rate exhibits first-order kinetics with respect to [CAT]O and [RNH]O in both media. The rate of reaction increases with increase in [H+], but it decreases with respect to [OH -] with a slope of unity in both the cases. Decrease of the dielectric constant of the medium decreases the reaction rate in both media. Variation of the ionic strength of the medium, and addition of /7-tolucncsul foil amide or NaCl, have no significant effect on the rate. The reaction was studied at different temperatures and activation parameters have been deduced. Ranitidine-S'-oxide was identified as the oxidation product of RNH by GC-MS in both media. The conjugate free acid CH3C6H4S02NHC1 of CAT is postulated as the reactive oxidizing species in both cases. The observed results have been explained by plausible mechanisms and related rate laws have been deduced.