Performance Evaluation Of Supported Biochar Catalytic Materials For Purifying Water Pollutants

In this paper,supported biochar catalytic materials were synthesized by simple impregnation and pyrolysis method with biomass waste as carbon carrier.The typical toxic organic pollutants（Orange II）and heavy metal hexavalent chromium(Cr^VI)were used as target pollutants to construct a novel Fenton-like oxidation reaction system based on peroxymonosulfate（PMS）and a novel chemical catalytic reduction reaction system based on formic acid（FA）.The formation,evolution and control steps of the structure of the composite catalytic materials were revealed.The relationship among the structure and activity of the composition,microstructure and catalytic performance of the biomass carbon-based materials was investigated,and the mechanism of active components and active free radicals in catalytic reaction system was clarified.The main study contents and conclusions of this paper are as follows:（1）A series of nitrogen-doped iron-based biochar catalysts were synthesized by simple impregnation pyrolysis using pomelo peel as nitrogen and carbon sources,and phthalocyanine and iron phthalocyanine as nitrogen and iron sources,which denoted as Fe-N@BC.The catalytic reaction efficiency of activated PMS to degrade organic pollutants and activated FA to remove heavy metal Cr^VI was investigated.Besides,the composition and structure of the composite materials were analyzed by various characterization techniques.The results clearly showed that the Fe and N atoms are uniformly distributed in the three-dimensional hierarchical porous biochar carrier.The synergistic catalytic removal of organic pollutants and heavy metal ions by metallic iron nanoparticles and nitrogen-doped carbon layers.The effects of reaction temperature,p H value of solution,PMS/FA dosage and other reaction factors on the catalytic efficiency were investigated systematically.The cycle experiment showed that the catalyst had good reusability.In addition,it was proved that ¹O₂ and₂^·O^-are the main reactive oxygen species for mineralization of Orange II in Fe-N@BC-600/PMS reaction system by free radical inhibition experiment and electron paramagnetic resonance（ESR）technique.Finally,the catalytic reaction mechanism of Fe-N@BC-600/PMS and Fe-N@BC-800/FA system was proposed.（2）A series of nitrogen-doped Fe and Mo supported biochar catalytic materials were synthesized by simple impregnation pyrolysis,which denoted as Fe-Mo@N-BC.The catalytic reaction efficiency of activated PMS to degrade organic pollutants was investigated.Besides,the composition and structure of the composite materials were analyzed by XRD,XPS,Raman,FESEM,FETEM,BET and other modern characterization techniques.The results clearly showed that the Fe and Mo atoms are uniformly distributed in the nitrogen doped porous biochar carrier.The synergistic effect between Fe and Mo promoted the activation of PMS and degradation of organic pollutants.N doped porous biochar can improve the metal loading capacity and electrical conductivity,and accelerate the electron transfer in the catalytic process.The cycle experiment showed that Fe-Mo@N-BC had good reusability.In addition,it was proved that HO·,SO₄^·-1O2 and₂^·O^-are the main reactive oxygen species for mineralization of Orange II in Fe-Mo@N-BC/PMS reaction system by free radical inhibition experiment and electron paramagnetic resonance（ESR）technique.