| With the development of industry,the problem of water pollution is constantly emerging,and the problem of bio-refractory wastewater has become an urgent technical problem in today’s society.Since the traditional technology cannot deal with the pollution problem of bio-refractory wastewater,it is urgent to find a new technology to solve this problem.Manganese oxide is a kind of green and environmentally friendly material due to its abundant reserves in the earth’s crust,various valence states and different morphologies.Therefore,it is of great significance to develop manganese oxide catalytic materials for the removal of refractory organic pollutants in water.However,manganese oxide materials are easy to agglomerate and have poor sedimentation properties,so it is worth studying that how this problem will be solved.In this research,through the innovation of preparation process,four kinds of silica mesoporous materials loaded with manganese oxide were developed,and the advanced oxidation technology of activated persulfate to remove bio-refractory wastewater was constructed.The effect of different crystalline manganese oxides loaded silica mesoporous materials on the degradation effect was studied.The main conclusions of this paper are as follows:（1）Mesoporous silica containing manganese oxides with multivalent states,high oxidation and strong catalytic performance was prepared by in-situ oxidation of divalent manganese salts with sodium hypochlorite.By adjusting the p H value of the preparation system to about 7,the prepared mesoporous silica material loaded with manganese oxide has the best activation effect on persulfate（PMS）.By adjusting the molar ratio of manganese sulfate to sodium hypochlorite(n Mn SO4/n Na Cl O)and the mass ratio of manganese sulfate to liquid sodium silicate(m Mn SO4/m LSS),the optimum preparation conditions were obtained as follows:n Mn SO4/n Na Cl Owas 1:2 and m Mn SO4/m LSSwas 1:5.SEM,XRD,BET,XPS and FT-IR were used to characterize and analyze the morphology,structure and composition of the as-prepared Mn Ox@Si O2.In addition,the persulfate advanced oxidation technology was used to explore the removal effect of p-chlorophenol,and the catalytic activity of Mn Ox@Si O2 mesoporous material was further analyzed.The effects of p H value,amount of catalyst,amount of PMS and different reaction systems on the degradation of p-chlorophenol were studied.It was found that with Mn Ox@Si O2/PMS system and under acidic condition,the degradation effect of p-chlorophenol was the best.（2）Three kinds of mesoporous silica materials loaded with Mn O2of different crystal forms（α-Mn O2@Si O2,β-Mn O2@Si O2,γ-Mn O2@Si O2）were successfully prepared by hydrothermal method and SEM,XRD,XPS,and FT-IR were used to analyze the morphology,structure and composition of these mesoporous silica materials.Then,these mesoporous silica materials loaded with manganese dioxide were used to activate persulfate to degrade phenol,the representative pollutant of phenolic wastewater.The effects of p H value of phenol wastewater,addition amount of PMS,and initial concentration of phenol on pollutant degradation were studied.We found that all of Mn O2@Si O2/PMS systems with three kinds of crystal forms showed excellent degradation effect in the treatment of phenol wastewater with concentration of 200mg/L and the p H value of wastewater had no obvious effect on the degradation effect.The results of liquid chromatography showed that when 50 mg of Mn O2@Si O2（α-Mn O2@Si O2,β-Mn O2@Si O2,γ-Mn O2@Si O2）and 30 mg of PMS were added to 100 m L of the phenol wastewater with concentration of 200 mg/L,phenol was completely degraded after stirred at room temperature for 3 h and COD value of wastewater decreased from initial 428.20 mg/L to 8.64 mg/L,43.20 mg/L,and27.00 mg/L forα-Mn O2@Si O2,β-Mn O2@Si O2,andγ-Mn O2@Si O2,respectively,which fully met the first national discharge standard according to wastewater discharge standard GB8978-1996[COD≤100（mg/L）].These results fully demonstrate that the as-prepared Mn O2@Si O2 mesoporous materials with three different crystal forms of Mn O2developed in this paper have potential application value in the degradation of bio-refractory organic wastewater by persulfate advanced oxidation technology. |
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