Egg-shaped core/shell α-Mn2O3@α-MnO2 as heterogeneous catalysts for decomposition of phenolics in aqueous solutions.
Novel uniform ellipsoid α-Mn2O3@α-MnO2 core/shell (McMs) nanocomposites were prepared via a hydrothermal process with a shape-control protocol followed by calcination at different temperatures. The properties of the composites were characterized by a number of techniques such as thermogravimetric analysis (TGA), X-ray diffraction (XRD), N2 adsorption, and scanning electron microscopy (SEM). The core/shell materials were much effective in heterogeneous oxone(®) activation to generate sulfate and hydroxyl radicals for degradation of aqueous phenol. The McMs composites demonstrated catalytic activity for 100% phenol decomposition in short duration varying between 20 and 120 min, much higher than that of homogeneous Mn(2+) system with 95% phenol degradation in 120 min. They also showed a higher activity than single-phase α-Mn2O3 or α-MnO2. The catalytic activity of phenol degradation depends on temperature, oxone(®) concentration, phenol concentration, and catalyst loading. The catalysts also showed a stable activity in several cycles. Kinetic study demonstrated that phenol degradation reactions follow a first order reaction on McMs catalysts giving activation energies at 32.1-68.8 kJ/mol. With the detection of radicals by electron paramagnetic resonance (EPR), the generation mechanism was proposed.
Department of Chemical Engineering and CRC for Contamination Assessment and Remediation of the Environment (CRC-CARE), Curtin University, GPO Box U1987, Perth, WA 6845, Australia; Department of Chemical Engineering, Riau University, Pekanbaru 28293, Indonesia.
Edy
E
Saputra
Department of Chemical Engineering and CRC for Contamination Assessment and Remediation of the Environment (CRC-CARE), Curtin University, GPO Box U1987, Perth, WA 6845, Australia.
Huayang
H
Zhang
Department of Chemical Engineering and CRC for Contamination Assessment and Remediation of the Environment (CRC-CARE), Curtin University, GPO Box U1987, Perth, WA 6845, Australia.
Qiaoran
Q
Liu
Department of Chemical Engineering and CRC for Contamination Assessment and Remediation of the Environment (CRC-CARE), Curtin University, GPO Box U1987, Perth, WA 6845, Australia; School of Engineering, Edith Cowan University, 270 Joondalup Drive, Joondalup, Perth, WA 6027, Australia.
Hongqi
H
Sun
Department of Chemical Engineering and CRC for Contamination Assessment and Remediation of the Environment (CRC-CARE), Curtin University, GPO Box U1987, Perth, WA 6845, Australia. Electronic address: shaobin.wang@curtin.edu.au.
Shaobin
S
Wang
D000327:Adsorption; D002384:Catalysis; D017895:Manganese Compounds / Q000737:chemistry*; D053758:Nanoparticles / Q000737:chemistry*; D010084:Oxidation-Reduction; D010087:Oxides / Q000737:chemistry*; D019800:Phenol / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D018508:Water Purification / Q000295:instrumentation / Q000379:methods*; D014961:X-Ray Diffraction
D017895:Manganese Compounds; D010087:Oxides; D014874:Water Pollutants, Chemical; D019800:Phenol; C027424:manganese oxide; C016552:manganese dioxide
Core/shell structure; Manganese oxides; Phenol removal; Sulfate radical; Water treatment