title: Performance of magnetic activated carbon composite as peroxymonosulfate activator and regenerable adsorbent via sulfate radical-mediated oxidation processes.
abstract: Magnetic activated carbon composite (CuFe2O4/AC, MACC) was prepared by a co-precipitation-calcination method. The MACC consisted of porous micro-particle morphology with homogeneously distributed CuFe2O4 and possessed high magnetic saturation moment (8.1 emu g(-1)). The performance of MACC was evaluated as catalyst and regenerable adsorbent via peroxymonosulfate (PMS, Oxone(®)) activation for methylene blue (MB) removal. Optimum CuFe2O4/AC w/w ratio was 1:1.5 giving excellent performance and can be reused for at least 3 cycles. The presence of common inorganic ions, namely Cl(-) and NO3(-) did not exert significant influence on MB degradation but humic acid decreased the MB degradation rate. As a regenerable adsorbent, negligible difference in regeneration efficiency was observed when a higher Oxone(®) dosage was employed but a better efficiency was obtained at a lower MACC loading. The factors hindering complete MACC regeneration are MB adsorption irreversibility and AC surface modification by PMS making it less favorable for subsequent MB adsorption. With an additional mild heat treatment (150 °C) after regeneration, 82% of the active sites were successfully regenerated. A kinetic model incorporating simultaneous first-order desorption, second-order adsorption and pseudo-first order degradation processes was numerically-solved to describe the rate of regeneration. The regeneration rate increased linearly with increasing Oxone(®):MACC ratio. The MACC could potentially serve as a catalyst for PMS activation and regenerable adsorbent.
authors.affiliation: Nanyang Environment and Water Research Institute (NEWRI), Interdisciplinary Graduate School, Nanyang Technological University, 1 Cleantech Loop, CleanTech One Singapore, 637141, Singapore; Division of Environmental and Water Resources Engineering, School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore.
authors.forename: Wen-Da
authors.initials: WD
authors.lastname: Oh
authors.affiliation: Nanyang Environment and Water Research Institute (NEWRI), Interdisciplinary Graduate School, Nanyang Technological University, 1 Cleantech Loop, CleanTech One Singapore, 637141, Singapore; School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore.
authors.forename: Shun-Kuang
authors.initials: SK
authors.lastname: Lua
authors.affiliation: Nanyang Environment and Water Research Institute (NEWRI), Interdisciplinary Graduate School, Nanyang Technological University, 1 Cleantech Loop, CleanTech One Singapore, 637141, Singapore; School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore.
authors.forename: Zhili
authors.initials: Z
authors.lastname: Dong
authors.affiliation: Nanyang Environment and Water Research Institute (NEWRI), Interdisciplinary Graduate School, Nanyang Technological University, 1 Cleantech Loop, CleanTech One Singapore, 637141, Singapore; Division of Environmental and Water Resources Engineering, School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore. Electronic address: cttlim@ntu.edu.sg.
authors.forename: Teik-Thye
authors.initials: TT
authors.lastname: Lim
mesh_terms: D000327:Adsorption; D002244:Carbon / Q000737:chemistry*; D002606:Charcoal / Q000737:chemistry*; D003460:Crystallization; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D060328:Magnetic Phenomena; D008280:Magnetics; D008422:Materials Testing; D008751:Methylene Blue / Q000737:chemistry*; D010100:Oxygen / Q000737:chemistry; D010545:Peroxides / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013431:Sulfates / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis; D018508:Water Purification / Q000379:methods; D014961:X-Ray Diffraction
chemical_list: D010545:Peroxides; D013431:Sulfates; D014874:Water Pollutants, Chemical; C069025:sulfate radical; D002606:Charcoal; C038288:peroxymonosulfate; D002244:Carbon; D010100:Oxygen; D008751:Methylene Blue
keywords: Activated carbon regeneration; Magnetic activated carbon composite; Peroxymonosulfate; Sulfate radical; Surface chemistry