It has been generally unclear over the mechanism of inhibitory influence of silicate on structural rearrangement or solely physical adsorption onto manganese dioxide(MnO_2) about the decomposition of hydrogen peroxide...It has been generally unclear over the mechanism of inhibitory influence of silicate on structural rearrangement or solely physical adsorption onto manganese dioxide(MnO_2) about the decomposition of hydrogen peroxide(H_2O_2). Consequently,several experiments were carried out by using MnO_2 as a catalyst for the decomposition of H_2O_2 in a concentration series under certain concentrations of silicates. The silicates were analyzed by using a molybdenum blue colorimetric method. The results showed that the determination of silicates was inhibited by H_2O_2, whose inhibitory effect was greatly increased by increasing its concentration, but not limited by p H. SEM-EDX(scanning electron microscopy-energy dispersive x-ray spectrometry) results showed that the adsorption of silicates onto the surface of MnO_2 was not purely via a structural rearrangement, with increasing Mn atoms protruding on the outer surface by covering oxygen and silicon atoms. XRD(X-ray diffraction) and FTIR(Fourier transform infrared) spectra results further revealed no significant total crystal structural changes in MnO_2 after the adsorption of silicates, but only a small shift of 0.21° at 2θ from 56.36° to 56.15°, and a FTIR vibration showed at around 1 050 cm-1. The results, therefore, showed that silicate adsorption onto MnO_2 took place via both surface adsorption and structural rearrangement by interfacial reaction.展开更多
基金Supported by the Provincial Basic Research Program of Hebei Education Department(ZD2015110)the National Special Project on Key Technologies and Demonstration of Wetland Ecological Restoration in the Haihe River Basin(2014ZX07203008)
文摘It has been generally unclear over the mechanism of inhibitory influence of silicate on structural rearrangement or solely physical adsorption onto manganese dioxide(MnO_2) about the decomposition of hydrogen peroxide(H_2O_2). Consequently,several experiments were carried out by using MnO_2 as a catalyst for the decomposition of H_2O_2 in a concentration series under certain concentrations of silicates. The silicates were analyzed by using a molybdenum blue colorimetric method. The results showed that the determination of silicates was inhibited by H_2O_2, whose inhibitory effect was greatly increased by increasing its concentration, but not limited by p H. SEM-EDX(scanning electron microscopy-energy dispersive x-ray spectrometry) results showed that the adsorption of silicates onto the surface of MnO_2 was not purely via a structural rearrangement, with increasing Mn atoms protruding on the outer surface by covering oxygen and silicon atoms. XRD(X-ray diffraction) and FTIR(Fourier transform infrared) spectra results further revealed no significant total crystal structural changes in MnO_2 after the adsorption of silicates, but only a small shift of 0.21° at 2θ from 56.36° to 56.15°, and a FTIR vibration showed at around 1 050 cm-1. The results, therefore, showed that silicate adsorption onto MnO_2 took place via both surface adsorption and structural rearrangement by interfacial reaction.
