Structure Control Of Attapulgite Based Heterogeneous Catalyst And Treatment Of Refractory Organic Wastewater

While the rapid development of industrialization brings convenience to our lives,more and more refractory organic substances（ROCs）often appear in industrial wastewater.These organic substances often have more complex components,poor biochemistry,high chroma and carcinogenesis.If they enter the environment without effective degradation treatment,they would pose a great threat to the ecological environment,animals,plants and mankind.In recent years,how to treat such wastewater efficiently has attracted the attention of researchers.In this study,attapulgite J03 produced in Xuyi,Jiangsu Province was selected as the carrier from different attapulgites.Two kinds of supported attapulgite heterogeneous catalysts were prepared by supersonic impregnation,combined with chitosan（CTS）and loaded with monometallic and bimetallic metals.The morphological structure,surface functional groups,elemental morphology,specific surface area and pore size of the catalysts were tested and analyzed.The single factor degradation experiments of MB,CR and CIP were carried out with these two catalysts,respectively.The degradation mechanism of refractory organic matter in this reaction system was given,and the degradation intermediates of MB and CIP as well as the degradation path were studied.The study content mainly includes the following points:（1）Take attapulgite J02 and J03（Xuyi,Jiangsu Province）,attapulgite G03（Linze,Gansu Province）and attapulgite 45,80,102（Australia）as the study objects.Attapulgite G03,J02,J03were characterized,and the adsorption properties of these six attapulgites to methylene blue solution were tested.The rod crystals of attapulgite G03 and J02 are thicker,and there are more lamellar structures,while the rod crystals of J03 are finer,and the lamellar structures are less;The purity of attapulgite J03 is higher than that of attapulgite G03 and J02,and the cation exchange ability of J03 is stronger;The pores in attapulgite G03,J02 and J03 belong to the mesoporous structure;attapulgite J03 showed excellent adsorption properties for MB solution after calcination and acidification,and the removal ratio of 100 mg/L methylene blue solution reached 99.64%after adsorption for 4 hours.（2）The supported heterogeneous catalysts Fe₂O₃/CTS-ATP and CuO-Fe₂O₃/CTS-ATP were prepared by ultrasonic impregnation of activated Jiangsu Xuyi attapulgite J03 blended with chitosan under acidic conditions,and the catalysts were tested and analyzed by XRD,FT-IR,SEM,EDS,BET and XPS.The intrusion of chitosan coated attapulgite rods,but with the loading of monometals and bimetals,many new pore structures composed of micropores and mesopores appeared on the surfaces of Fe₂O₃/CTS-ATP and CuO-Fe₂O₃/CTS-ATP,and the dispersion of copper elements on the surfaces of CuO-Fe₂O₃/CTS-ATP was better than that of iron elements.The crystal diffraction peaks of attapulgite can be detected in both catalysts.（3）The preparation conditions of Fe₂O₃/CTS-ATP and CuO-Fe₂O₃/CTS-ATP and the reaction conditions for refractory organics were optimized respectively.The effects of precursor concentration,ultrasonic impregnation time,catalyst addition,p H,reaction temperature,reaction time,concentration of H₂O₂,and initial concentration of ROCs on the degradation ratio were investigated.Under the optimal conditions,the degradation ratio of MB,CR,and CIP by Fe₂O₃/CTS-ATP were 98.78%,83.59%,84.62%respectively,while the degradation ratio of MB,CR,and CIP by CuO-Fe₂O₃/CTS-ATP reached 99.34%,86.91%,86.20%;the catalytic degradation performance of CuO-Fe₂O₃/CTS-ATP was higher than that of Fe₂O₃/CTS-ATP,showing that when the reaction conditions were optimal,the degradation ratio of ROCs by CuO-Fe₂O₃/CTS-ATP was higher,while the ultrasonic time required for preparation was less,the catalyst addition was less,the p H range of MB and CR reactions was wider and the stability was higher after five cycles.（4）The differences in the degradation ratio of ROCs in five systems of H₂O₂,Fe₂O₃/CTS-ATP,CuO-Fe₂O₃/CTS-ATP,Fe₂O₃/CTS-ATP/H₂O₂ and CuO-Fe₂O₃/CTS-ATP/H₂O₂ were compared;the amount of·OH produced in Fe₂O₃/CTS-ATP/H₂O₂ and CuO-Fe₂O₃/CTS-ATP/H₂O₂ systems was detected;the degradation mechanism of ROCS by CuO-Fe₂O₃/CTS-ATP was given;the degradation process of MB and CIP was analyzed by high performance liquid mass spectrometry.