Study On Degradation Efficiency And Mechanism Of Ibuprofen By Fe(Ⅲ)-S(Ⅳ)-PDS In Homogeneous System

Pharmaceuticals and personal care products（PPCPs）,mainly including contrast agents,cosmetics,artificial fragrances,antibiotic drugs,hormone drugs,etc.,are environmental hazards that have been continuously detected in the natural environment in recent years.Due to their stable nature,difficult to natural degradation,and generally have a certain degree of toxicity,poses a certain potential threat to humans and nature;ibuprofen（IBP）is a common non-steroidal anti-inflammatory drugs,as medical supplies,its own although the environmental residue is small,but due to the large number of use and the difficulty of natural degradation,the formation of pseudo-persistent phenomenon in the environment,through the bioaccumulation in the biosphere The use of these drugs may eventually cause greater harm to plants and animals.Therefore,a green and efficient treatment method is urgently needed to completely remove PPCPs.Sulfate radical advanced oxidation technology（SR-AOPs）has been widely used in water treatment research because of its strong oxidation capacity and green and efficient treatment of PPCPs in water.In this study,peroxynitrite（PDS）was used as the oxidant,and five relatively effective systems were compared with known effective systems to remove 50μM of IBP at a PDS content of 100μM,and the treatment effect could reach more than 50%in all cases.After increasing the dosage of these five systems,it was found that after the oxidant dosage was raised to 10 times that of IBP,the removal efficiency of the trivalent iron（Fe（III））-thiosulfate（TS）-peroxysulfate（PDS）combination system reached a removal efficiency of 96.44%,which was significantly better than the other systems,thus establishing the system of this study.In the subsequent experiments,the number of reaction stages was determined by the initial rate method.pH,the effect of the initial temperature of the reaction system,the effect of inorganic anions in the system,the effect of natural organic matter（FA）on the system,the effect of the dosing sequence in the Fe（III）-TS-PDS system,the effect of the initial concentration of IBP,and the application of the Fe（III）-TS-PDS system in real water bodies.It was hypothesized and proved that the Fe in the system could be recycled.The quenching test initially determined the active species of the system and showed by EPR test that the system contains various radicals such as·OH,·SO₄-,¹O₂,·O₂^-.The degradation products of IBP molecules were identified by gas chromatography-mass spectrometry,and the degradation pathways and degradation mechanisms of the molecules were proposed,mainly including hydroxylation,dehydroxylation,oxygen substitution,demethylation,methylation,carboxyl substitution and benzene ring breakage reactions.Finally,the intermediate products of IBP molecules treated by Fe（III）-TS-PDS system were determined by fitting,and their biological toxicity was substantially reduced compared with that before treatment,which confirmed the practical application potential of Fe（III）-TS-PDS system.The removal of IBP and the decrease of TOC in multiple batches after increasing the initial concentration of IBP demonstrated that the Fe（III）-TS-PDS system can recycle iron ions by continuously adding thiosulfate and persulfate to the initial reaction system;the presence of multiple reactive substances（ROSs）in the system was demonstrated by quenching tests and electron paramagnetic resonance（EPR）experiments and the minimal effect of dissolved oxygen in the solution was demonstrated by aeration.The degradation pathway and degradation mechanism of IBP molecules in Fe（III）-TS-PDS system were determined by chromatography-mass spectrometry,which mainly included hydroxylation,dehydroxylation,oxygen substitution,demethylation,methylation,carboxyl substitution,benzene ring breakage,etc.to finally reach the mineralization of IBP molecules.Finally,based on the quantitative structure-activity relationship（QSAR）,the developmental toxicity of the original IBP sample and the reaction intermediates before and after the reaction were fitted by T.E.S.T.evaluation software,and it was confirmed that the biological toxicity of the reaction intermediates was significantly decreased compared with the IBP molecules before the reaction.this study investigated the effectiveness and mechanism of the Fe（III）-TS-PDS system to degrade IBP,and determined that the Fe（III）-TS-PDS system can recycle the initially added Fe and can also be applied well in actual water bodies,which is a homogeneous water treatment system with excellent oxidation capacity and good application prospects.