title: Catalyzing the oxidation of sulfamethoxazole by permanganate using molecular sieves supported ruthenium nanoparticles.
abstract: This study developed a heterogeneous catalytic permanganate oxidation system with three molecular sieves, i.e., nanosized ZSM-5 (ZSM-5A), microsized ZSM-5 (ZSM-5B) and MCM-41, supported ruthenium nanoparticles as catalyst, denoted as Ru/ZSM-5A, Ru/ZSM-5B and Ru/MCM-41, respectively. The presence of 0.5gL(-1) Ru/ZSM-5A, Ru/ZSM-5B and Ru/MCM-41 increased the oxidation rate of sulfamethoxazole (SMX) by permanganate at pH 7.0 by 27-1144 times. The catalytic performance of Ru catalysts toward SMX oxidation by permanganate was strongly dependent on Ru loading on the catalysts. The X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) analyses confirmed that Ru catalyst acted as an electron shuttle in catalytic permanganate oxidation process. Ru(III) deposited on the surface of catalysts was oxidized by permanganate to its higher oxidation state Ru(VII), which could work as a co-oxidant with permanganate to decompose SMX and was then reduced to its initial tri-valence. During the successive runs, Ru/ZSM-5A could not maintain its catalytic activity due to the deposition of MnO2, which was the reductive product of permanganate, onto the surface of Ru/ZSM-5A. Thus, the regeneration of partially deactivated Ru catalysts by reductant NH2OH⋅HCl or ascorbic acid was proposed. Ru/ZSM-5A regenerated by NH2OH⋅HCl displayed comparable catalytic ability to its virgin counterpart, while ascorbic acid could not completely remove the deposited MnO2. A trace amount of leaching of Ru into the reaction solution was also observed, which would be ameliorated by improving the preparation conditions in the future study.
authors.affiliation: State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, PR China; Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing, PR China.
authors.forename: Jing
authors.initials: J
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, PR China.
authors.forename: Bo
authors.initials: B
authors.lastname: Sun
authors.affiliation: Shanghai Synchrotron Radiation Facility, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai, PR China.
authors.forename: Yuying
authors.initials: Y
authors.lastname: Huang
authors.affiliation: State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, PR China. Electronic address: guanxh@tongji.edu.cn.
authors.forename: Xiaohong
authors.initials: X
authors.lastname: Guan
mesh_terms: D002384:Catalysis; D017895:Manganese Compounds / Q000737:chemistry*; D053758:Nanoparticles / Q000737:chemistry*; D010084:Oxidation-Reduction; D010087:Oxides / Q000737:chemistry*; D012428:Ruthenium / Q000737:chemistry*; D013420:Sulfamethoxazole / Q000032:analysis* / Q000737:chemistry; D013499:Surface Properties; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000737:chemistry; D018508:Water Purification / Q000379:methods*; D056928:X-Ray Absorption Spectroscopy
chemical_list: D017895:Manganese Compounds; D010087:Oxides; D014874:Water Pollutants, Chemical; C048856:permanganic acid; D012428:Ruthenium; D013420:Sulfamethoxazole
keywords: Catalyst regeneration; Emerging contaminants; MCM-41; ZSM-5