Determination of tetracycline degradation by alkali-catalyzed hydrogen peroxide system:law of action and mechanism analysis
When alkali catalyzes hydrogen peroxide to degrade pollutants,different alkali catalysts have different mechanisms of catalyzing hydrogen peroxide to degrade pollutants.The study selected sodium hydroxide,sodium carbonate,sodium bicarbonate,and disodium hydrogen phosphate as different alkali catalysts,and used tetracycline as the target pollutant to explore the rules and mechanisms of the degradation of tetracycline by alkali-catalyzed hydrogen peroxide systems.The effects of pH,tetracycline concentration,H2 O2 concentration,buffer substance dosage,buffer substance type and pre-reaction time on the degradation of tetracycline were investigated.The results showed that pH had the most significant effect on the degradation effect of tetracycline,with the best effect at pH 10.00-10.50,and the rest of the influencing factors did not produce significant effects within the gradient range studied in this paper.Meanwhile,it was found that the pH of different alkali-catalyzed hydrogen peroxide systems had different trends during the reaction process.In other systems,the pH decreased continuously as the reaction proceeded,while the pH increased continuously during the degradation of tetracycline in the NaHCO3-H2 O2 system,and it was speculated that this phenomenon was caused by the process of HCO-4 production after the analysis of the carbon conversion mechanism.The degradation of tetracycline was divided into two processes,decolorization and mineralization:free radical quenching experiments proved that free radicals did not contribute much to the decolorization process of tetracycline.CO2 flux experiments confirmed that HCO-4 does not oxidize tetracycline and that the main acting substance in tetracycline decolorization is HO-2.By comparing the TOC test results of NaOH-H2 O2 system and NaHCO3-H2 O2 system,it was found that the mineralization degree of NaOH-H2 O2 system was higher than that of NaHCO3-H2 O2 system,and EPR electron paramagnetic resonance experiments revealed that the signals of HO·and O·-2 in the NaOH-H2 O2 system were higher than that of the NaHCO3-H2 O2 system,and that mineralization process of free radicals are the main oxides.
tetracyclinebicarbonatehydrogen peroxidealkaline catalyticmechanism of action
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