Research On Degradation Of Persistent Organic Pollutants In Water Based On Sulfate Radicals

Advanced oxidation technology based on sulfate radicals（AOPs）could oxidize the refractory persistent organic pollutants into CO₂ and H₂O directly.In recent years,it has attracted extensive attention,and the development of highly efficient and easy to recycle heterogeneous catalysts has become a research hotspot.In this paper,two heterogeneous catalysts,metal organic framework MIL-101（Cr）and copper mesh supported reduction graphene（rGO/BM）,were prepared by hydrothermal method.The microstructures were characterized by SEM,XRD and FT-IR.And the ability of the two kinds of catalysts for activating peroxymonosulfate（PMS）to produce·SO₄^-was evaluating by degradating Rhodamine B（RhB）.The result of studies had shown that MIL-101（Cr）prepared by hydrothermal method exhibited very good catalytic performance in activating PMS to degrade RhB.In this work,we found that when the molar ratio of H₂BDC to Cr（NO₃）₃ reach1:1,the catalyst MIL-101（Cr）got the best catalytic performance.Then the dosage of catalyst and oxidant,the initial pH,the anion species in water and the reaction temperature all had a great influence on the catalytic activation.First,the degradation rate of RhB increased with the increase of catalyst dosage and reaction temperature.Second,when the dosage of oxidant was0.114 mM,the degradation rate of RhB was better.Third,it was better of that when the degradation of RhB was under acidic conditions.However,when the pH was of the range of alkaline pH=9-11,the catalyst also got good catalytic activity,and the degradation rate of RhB was still about 90%.Fourth,the inhibition of different anion in water followed the order of CO₃^2—>HCO₃^—>Cl^—>NO₃^—>H₂PO₄^—>SO₄^2—.Finally,the catalyst MIL-101（Cr）had a certain stability.During the oxidative degradation process,the catalyst had a small amount of chromium dissolved,but its morphology and metal-organic framework structure had no obvious changes.For the prepared rGO/BM catalyst,it was characterized by SEM,XRD and EDS.The results showed that the inner rGO loaded on the brass mesh was evenly distributed in a single layer or a small layer structure,and was closely combined with the brass mesh.The catalyst exhibited good catalytic activity for the degradation of RhB by activating PMS.When the concentration of GO was 1 mg/mL and the hydrothermal synthesis temperature was 160°C,the degradation of RhB by synthetic rGO/BM was better.When the dosage of oxidant and the initial pH value of water were 0.104 mM and 3,respectively,the degradation rate of RhB was faster.And the degradation rate of RhB increased with the increase of reaction temperature.After 10times of rGO/BM recycling,the degradation rate of RhB can be kept at 73.5%.There was no loss of rGO during use,and it could be recycled and reused without any special separation means.Therefore,it had a good application prospect.