Advanced Oxidation Removal Of Diethyl Phthalate,Glyphosate And Tetracycline

The increasing presence of plasticizers,herbicides and pharmaceuticals in environmental media is threatening farmland ecosystem and food safety due to the extensive use of plastic film,pesticides and manure.It has become one of the environmental problems that restrict the sustainable development of modern agriculture.The photochemical reaction system composed of goethite and oxalic acid（α-FeOOH/Ox/VIS）exists widely in the natural environment and can significantly affect the migration and transformation of organic pollutants in water,soil and other environmental media.However,pollutants with different properties may affect their degradation process in this system.Therefore,we useα-FeOOH/Ox/VIS to explore the degradation of diethyl terephthalate（DEP）,glyphosate（PMG）and tetracycline（TC）.Besides,calcium peroxide（CaO₂）is a kind of environmental friendly material with the advantages of low price,easy transportation and good stability.Therefore,we explore its effect on single or combined pollution soils caused by the DEP,PMG and TC.The main research results are as follows:（1）Theα-FeOOH/Ox/VIS system could effectively remove three organic compounds and reached 87.1%for DEP,99.7%for TC,and 83.3%for PMG.Through the analysis of solid phase residual,it was further found that whereas DEP and TC were well degraded,some PMG was adsorbed onα-FeOOH rather than degradation.（2）Inα-FeOOH/Ox/VIS system,DEP was mainly transformed in two ways,the reaction between·OH and a precursor to give a hydroxylated product and hydrolysis and oxidation of an ester group;PMG was mainly attacked by·OH at the C-N bonds;The conversion of TC occurred mainly on two enol hydroxyl groups,both of which are double bonds opened and added to one hydroxyl group and hydroxyl group oxidized to C=O bond.（3）In view of the shortcomings of the above photochemical reaction system,the advanced oxidation system with CaO₂ could effectively remove the three pollutants in soil.DEP and PMG were degraded over by 60.0%and 91.7%respectively,while TC was completely degraded when 25mg·g^-1 CaO₂ was applied to remediate single or combined pollution soils caused by the DEP,PMG and TC.（4）The products of DEP,PMG,and TC by CaO₂ led us to propose their degradation pathways.The degradation of DEP was mainly the cleavage and oxidation of two ester groups;PMG was mainly attacked by·OH at the C-N bonds.TC is mainly converted in two ways under the action of·OH.One is that double bonds of two enol hydroxyl groups are opened successively to form one hydroxyl group and simultaneously the hydroxyl group oxidized to C=O bond;The other is that deamidation and ring-opening reactions may occur further.