Preparation And Performance Of Fenton-like Photocatalysts Based On ·OH And ·SO₄^-

With the rapid development of pharmaceutical industry,the wastewater from pharmaceutical industry must be treated because of its complex composition,high concentration of refractory pollutants and poor biodegradability.Fenton/Fenton-like technology,a kind of advanced oxidation technology,has been widely studied for its excellent catalytic performance because it can release many kinds of reactive oxygen species.The purpose of this paper is to design and prepare Fenton-like photocatalyst which can produce reactive oxygen species（·OH and·SO₄^-）.In combination with the manganese compounds with good performance and simplicity in preparation,g-C₃N₄and CuFe₂O₄were modified to improve their catalytic performance respectively.And the composition,micro-morphology,performance status,mechanism and practical application of the obtained materials were explored.The details are as follows:（1）The MnO₂/CNK-OH-Mn_xFenton-like photocatalyst was synthesized by calcination-impregnaization based on g-C₃N₄.The optimal MnO₂/CNK-OH-Mn_15%showed the highest activity with 96.7%removal and 74.9%TOC removal efficiency of TC.And the formation of NO₃^-further revealed deep mineralization of TC to inorganic substance during the photocatalytic degradation.Moreover,MnO₂/CNK-OH-Mn_15%has the highest COD removal rate（77.1%）for pharmaceutical wastewater.All the above excellent properties are attributed to the highest·OH yield of MnO₂/CNK-OH-Mn_15%by synergism of surface grafted hydroxyl groups,Z-scheme charge transfer and H₂O₂activation via redox cycles of Mn（IV）/Mn（III）/Mn（II）during the catalytic degradation process.（2）CFO/Mn-x Fenton-like&Photo bifunctional catalysts with different surface areas were synthesized by hydrothermal method at different temperatures.“bifunctional”means CFO/Mn-x can initiate Fenton-like reaction via stimulated PMS to product·SO₄^-in the dark（PMS&CFO/Mn-x）and can be exited by light without PMS（CFO/Mn-x&Photo）as a photocatalytic catalyst.When light,CFO/Mn-x,PMS were all present,Fenton-like catalysis and photocatalysis were performed synergistically（PMS&CFO/Mn-x&Photo）.The 3D spherical structure CFO/Mn-100 with the largest surface area exhibited the best catalytic performance,and it could degrade and mineralize some organic pollutants（The degradation efficiencies of TC,2NP and ceftriaxone sodium were 99.03%,98.16%and 85.09%,respectively）under the visible light（xenon lamp）.And the degradation rate was satisfactory in the dark（98.74%,95.38%and 79.51%,respectively）,which greatly facilitates resource saving and cost control.In addition,CFO/Mn-100 has the highest COD removal rate for real pharmaceutical wastewater and has excellent application prospects.Moreover,CFO/Mn-100 nanocomposite has high stability and magnetic properties,which can realize its rapid separation from solution and facilitate recycling.