Egg-shaped core/shell α-Mn2O3@α-MnO2 as heterogeneous catalysts for decomposition of phenolics in aqueous solutions. (September 2016)

• Record Type: Journal Article
• Authors: Saputra, Edy; Zhang, Huayang; Liu, Qiaoran; Sun, Hongqi; Wang, Shaobin
• Is Part Of: Chemosphere. Volume 159(2016)
• Page Start: 351
• Page End: 358
• Publication Date: 2016-09
• Subjects: Core/shell structure -- Manganese oxides -- Phenol removal -- Sulfate radical -- Water treatment; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2016.06.021
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: Novel uniform ellipsoid α-Mn2 O3 @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-Mn2 O3 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. Highlights: Egg-shaped core/shell α-Mn2 O3 @α-MnO2 materials were synthesized. The materials were effective in generation of reactive radicals from oxone. The materials presented high activity and stability for phenol degradation.