COFs Derived Composite Catalysts For Peroxymonosulfate Activation Toward Organic Pollutants Degradation

The organic pollutants such as endocrine-disrupting chemicals（EDCs）,pharmaceuticals and personal care products（PPCPs）and dyes in water poses a significant threat to humans and ecosystems.In recent years,advanced oxidation technology based on peroxymonosulfate（PMS）has been widely used because of its wide p H range,high universality and strong oxidation ability.In this work,the composite catalysts derived from covalent organic framework materials（COFs）were constructed and applied as peroxymonosulfate activator togenerate active species for degrading organic pollutants.The CC@Co3O4 and NOC-Mn3O4 catalysts were derived from COF@ZIF-67（TAPB-DMTP-COF@ZIF-67）and COF@Mn-MOF（TAPB-DMTP-COF@Mn-MOF）,respectively.The physical and chemical properties of the catalysts were investigated by Scanning electron microscopy（SEM）,Transmission electron microscopy（TEM）,X-ray photoelectron spectroscopy（XPS）,X-ray diffraction（XRD）and Fourier transform infrared spectroscopy（FT-IR）.A series of CC@Co3O4 and NOC-Mn3O4 composite catalysts were used to activate PMS to degrade the representative target pollutants of bisphenol A（BPA）and rhodamine B（Rh B）.The effects of catalyst dosage,PMS dosage,target pollutants concentration,reaction temperature,solution p H,inorganic ions and natural organic matter on the performance for activating PMS to degrade target pollutants of the composite catalysts were investigated.And the catalytic performance of composite catalysts on target pollutants in actual water was also investigated.At the same time,the reusability,stability and universality of the catalyst were evaluated.In addition,the degradation mechanism and possible degradation pathways of target pollutants were speculated and the toxicity of target pollutant degradation intermediates was evaluated.Therefore,the following main work has been carried out:（1）The COF@ZIF-67 precursor was synthesized by hydrothermal and in-situ growth method.The derived composite catalyst CC@Co3O4 was prepared and used for the PMS activation to degrade organic pollutants after carbonization.The results showed that CC@Co3O4-0.10 was the best catalyst.By optimizing the dosage of catalyst and PMS,the concentration of BPA and Rh B,the reaction temperature and the solution p H,the removal rates of BPA and Rh B in CC@Co3O4-0.10/PMS system were93.8%within 60 min and 98.2%within 40 min with the catalyst dosage was 0.10 g/L and the PMS dosage was 0.20 g/L without adjusting p H and room temperature.The effects of different inorganic ions and humic acids on the catalytic performance of CC@Co3O4-0.10 were also investigated.The results showed that CC@Co3O4-0.10/PMS system has good anti-interference ability.In addition,the removal rate of Tetracycline（TC）,Crystal violet（CV）,Methyl orange（MO）,Congo red（CR）and Malachite green（MG）in solution by CC@Co3O4-0.10/PMS system could reach more than 77.9%,indicating that CC@Co3O4-0.10/PMS system could remove various of organic pollutants efficiently.The reuse experiment showed that the catalytic activity of CC@Co3O4-0.10 decreased with the increase of reuse times,but the catalytic performance recovered after heat treatment.In addition,Liquid chromatography-mass spectrometry（LC-MS）was used to predict possible target pollutants degradation pathways,and the toxicity of target pollutant degradation intermediates was evaluated by the T.E.S.T.The results showed that CC@Co3O4-0.10/PMS system could reduce the comprehensive toxicity of BPA and Rh B.Combined with radical quenching experiments,electron paramagnetic resonance（EPR）and XPS and electrochemical tests,the mechanism of CC@Co3O4-0.10 activated PMS to degrade target pollutants was studied.The results demonstrated that CC@Co3O4-0.10/PMS system degraded BPA and Rh B by^·OH,SO₄^·-,^·O₂^-,¹O₂ and electron transfer.The^·O₂^-played a major role in the BPA degradation,while ¹O2 played a major role in the Rh B degradation.The removal of BPA and Rh B from Tap water,Yellow River water and Lake water by CC@Co3O4-0.10/PMS system was investigated.The study indicated that CC@Co3O4-0.10/PMS system has potential practical application value.（2）The composite catalyst NOC-Mn3O4 derived from COF@Mn-MOF was prepared by carbonization,which was used to activate PMS to degrade organic pollutants.The results showed that 1NOC-Mn3O4 was the best catalyst.By optimizing the dosage of catalyst and PMS,the concentration of BPA and Rh B,the reaction temperature and the solution p H,the removal rate of BPA in 1NOC-Mn3O4/PMS system was 92.1%within 30 min with the catalyst dosage was 0.20 g/L and the PMS dosage was 0.20 g/L without adjusting p H and room temperature.With 0.20 g/L of 1NOC-Mn3O4 and 0.30 g/L of PMS,the removal rate of Rh B by 1NOC-Mn3O4/PMS system was 96.9%within 30 min.The effects of different inorganic ions and humic acids on the catalytic performance of 1NOC-Mn3O4 were also investigated.The results illustrated that 1NOC-Mn3O4/PMS system had good anti-interference ability.Meanwhile,the removal rate of BPA and Rh B could still maintained more than 87%after 10 reuses,which suggested that the prepared 1NOC-Mn3O4 obtained good reusability and stability.In addition,the possible pollutants degradation pathways were inferred by LC-MS,and the toxicity of target pollutant degradation intermediates was evaluated by the T.E.S.T.The results showed that 1NOC-Mn3O4/PMS system could reduce the comprehensive toxicity of BPA and Rh B.Combined with radical quenching experiments,EPR,XPS and electrochemical tests,the mechanism of 1NOC-Mn3O4activated PMS to degrade target pollutants was studied.The results illustrated that SO4^·-,^·OH,^·O2^-,¹O2 and electron transfer were involved in the degradation of BPA and Rh B in the 1NOC-Mn3O4/PMS system.The^·O2^-and ¹O2 played a major role in the degradation of BPA,and^·OH played a major role in the degradation of Rh B.The1NOC-Mn3O4/PMS system had certain effect on the removal of BPA and Rh B in Tap water,Yellow River water and Lake water,indicating that 1NOC-Mn3O4/PMS system had great application prospect in the removal of organic pollutants in actual water.In conclusion,this paper provided a new idea for the construction of COFs-based PMS catalysts in the field of water pollution remediation.