焦化污泥基生物炭在氯介质下催化降解间甲酚的性能

Catalytic degradation of m-cresol by coking sludge based biochar in chloride medium

以焦化污泥制备生物炭,并在硝酸溶液中低温条件下进行改性,研究其在氯介质下对间甲酚降解的效率与机理.焦化污泥(CSS)具有较大的比表面积和丰富的官能团,其吸附作用较强,对间甲酚的吸附去除率为27.1%.而通过炭化和改性的焦化污泥炭的比表面积显著降低,官能团数量减少,吸附作用极弱.在催化降解过程中,改性焦化污泥炭(CSSC-N)对间甲酚和总有机碳(TOC)的去除率分别为98.1%和80.1%,远高于未改性的焦化污泥炭(CSSC-0),主要归因于CSSC-N中具有多种含铁物质,有利于铁循环,且表面铁含量高达60.10%,能提供丰富的催化活性组分.Cl-对间甲酚和TOC的去除率有抑制作用,随着Cl-浓度的升高,去除率降低.当废水中的NaCl为5%wt时,在催化重复实验中间甲酚的去除率均高于70%.CSSC-N具有一定的抗氯性能,在氯介质下具有较高的催化活性和稳定性.三维荧光光谱分析和中间产物鉴定结果表明Cl-的存在影响了间甲酚的降解过程,生成了难降解的氯代副产物.

A biochar was prepared from coking sludge and modified with nitric acid at low temperature.Afterwards,the degradation efficiency and mechanism of m-cresol in chloride medium was studied.Coking sludge(CSS)had a large specific surface area and was rich in functional groups,so its adsorption effect was strong.The adsorption removal rate of m-cresol with CSS was 27.1%.However,the adsorption effect of the coking sludge carbon through carbonization and modification was very weak,because the specific surface area and the number of functional groups were significantly reduced.In the catalytic degradation process,the removal rates of m-cresol and Total organic carbon(TOC)with the modified coking sludge carbon(CSSC-N)were 98.1%and 80.1%,respectively,which were much higher than those with the unmodified coking sludge carbon(CSSC-0).That was mainly because there were a variety of iron-containing substances in CSSC-N which was conducive to iron circulation,and the surface iron content was as high as 60.10%,providing catalytic active components.The removal rate of m-cresol and TOC was inhibited by Cl-,which was deceased with an increase of Cl-concentration.When the concentration of NaCl in wastewater was 5%wt,the removal rates of m-cresol during the catalytic repeat experiment were all above 70%.Therefore,CSSC-N with the chorine-resistant property had a high catalytic activity and stability in chlorine medium.Based on the results of three-dimensional fluorescence spectrometry analysis and intermediate products identification,the presence of Cl-affected the degradation process of m-cresol and chlorine-containing intermediates were produced.