Research On Ozonation Catalyzed By Activated Carbon And Iron/manganese Supported On Activated Carbon For Treatment Of Phenol

Phenol pollution is a serious environmental problem.It has attracted wide attention in recent years because of its low biodegradability,high toxicity,and cumulative effect.Among many treatment technologies,heterogeneous catalytic ozonation has become an excellent technology for the treatment of phenol wastewater due to its advantages of high efficiency,low cost,and easy application.In this study,phenol was used as the target pollutant,and activated carbon and its supported iron and/or manganese materials were used as catalysts to evaluate the catalytic ozonation of phenol by changing ozone concentration and catalyst dosage.The physical and chemical properties of the catalysts were characterized by XRD,FTIR,XPS and CV,and the degradation products and pathways of phenol were determined by HPLC and GC-MS.The products were analyzed;the active substances were identified by capturing the free radicals in the reaction system.The reaction mechanism and degradation pathway of phenol oxidation by ozone catalyzed by activated carbon and its supported iron and/or manganese materials were obtained by combining the above experimental results.The main results are as follows:AC/O₃ system can greatly enhance the degradation and mineralization of phenol.It was found that the removal efficiency of phenol and TOC can be improved by increasing ozone concentration and activated carbon dosage appropriately.AC/O₃system produced almost no active substances at pH 3.0.It mainly relied on activated carbon adsorption and ozone attack to remove phenol.At pH 11.0,more active substances(·OH?O₂^·-and H₂O₂)can be produced to degrade phenol.Phenol degradation was carried out by hydroxylation of benzene ring,ring opening,formation of small molecule acids,and mineralization of CO₂ and H₂O.Oxalic acid was accumulated at the later stage of the reaction under different conditions of solution pH=3.0 and 11.0.AC/O₃ system had good effect in treating phenol wastewater,and the treatment effect of secondary effluent of chemical industry was general.In the process of treating phenol with Fe/Mn/GAC/O₃ system,the effect of mineralizing phenol with Mn/GAC?0.10?/O₃ system is the most remarkable.The removal rate is 70.7%,which is 23.7%higher than that of GAC/O₃ system,and the system has excellent stability.The catalytic mechanism of Fe/Mn/GAC mainly depended on the oxidation and redox cycles of Fe²⁺-Fe³⁺and Mn²⁺-Mn³⁺-Mn⁴⁺on its surface to transform ozone to·OH,thereby enhancing the degradation of phenol.There was corrosion between Fe₃O₄ and MnO₂ on the surface of Fe-Mn/GAC catalyst,and it reduced its catalytic site.Compared with AC/O₃ system,resorcinol,hydroquinone and succinic acid were added to phenol degradation products of Fe/Mn/GAC/O₃ system,and some degradation pathways were also changed.Mn/GAC?0.10?/O₃ system can rapidly reduce phenol,COD,TOC and other indexes in secondary effluent of petrochemical industry.It is an efficient advanced treatment process.The results showed that the developed ozone catalyst based on activated carbon can be used for the treatment of phenol wastewater,which provided technical support for the treatment of complex phenol wastewater.