Study On The Degradation Of DMP In Tail Water By Combined Magnetic Field And Catalytic Ozonation Treatment System

Phthalic Acid Esters (PAEs) compounds are a class of environmental endocrinedisruptors which easily enrich but are not readily biodegradable. conventional watertreatment processes can not effectively remove PAEs. Because of its strong oxidation,ozonation water treatment technology has a certain removal effect on PAEs in waterbut the efficiency still needs improvement. The objective of this study was to treat tailwater with low concentration of dimethyl phthalate(DMP) and the evaluationindicators chosen were DMP and TOC removal rate. The study examines how relatedfactors of initial pH of the solution, initial concentration of DMP and ozone dosageaffect ozonation. In the optimization of parameters, Mn-Cu/zeolite catalyst wasprepared as the optimum bimetallic catalyst. The degradation pathway mechanism ofDMP in simulated wastewater and tail water using ozonation system, catalyticozonation system, magnetic/ozonation system and magnetic/catalytic ozonationsystem were also studied. The results are as follows:(1) For DMP removal from simulated wastewater adding magnetic field for30min (magnetic field strength of195mT, initial solution pH of7.5, DMPconcentration of50mg/L), DMP and TOC removal rates were61%and42.5%in theozonation system. This shows an increase by18%and11%compared to the systemwithout magnetic field.(2) In the optimization of parameters, Mn-Cu/zeolite catalyst was prepared as theoptimum bimetallic catalyst. According to XRD and XPS results, the oxides loadedon the catalyst were mainly MnO2and CuO. The stability of the catalyst made itpossible to reuse it a certain number of times.(3) After30min ozonation combined with Mn-Cu/zeolite catalyst system, theremoval rates of DMP and TOC reached81.8%and60.9%. This compared withozonation system without catalyst indicates an improvement by22%and33%respectively. In the catalytic ozonation system with magnetic field the DMP and TOCremoval rates reached92.3%and62.8%. This shows an increase by2%and3%whencompared to the catalytic system without the magnetic field.(4) For the removal of the DMP in actual tail water, adding magnetic reaction for50min (magnetic field strength of195mT, initial solution pH=7.5), the removal ratesof DMP and TOC reached59.9%and33%, showing an increase by11%and8% compared with the system without magnetic field; while in catalytic ozonation system,the removal rates of DMP and TOC were68%and37%, consistent with the results ofthe system which did not have magnetic field.(5) According to the result of GC-MS analysis, in catalytic ozonation system andmagnetic/ozonation system, the main intermediates of DMP were salicylic acid,methyl benzoate, and benzofuran.(6) The variation of concentration of hydroxyl radical in the reaction systemshowed that, the addition of catalyst and magnetic field promoted the productionof·OH produced, thereby significantly improving the efficiency of the degradation ofthe DMP.