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Zhonglin Chen - One of the best experts on this subject based on the ideXlab platform.
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cobalt modified red mud catalytic ozonation for the degradation of bezafibrate in water catalyst Surface properties characterization and reaction mechanism
Chemical Engineering Journal, 2016Co-Authors: Bingbing Xu, Didier Robert, Jizhou Zhang, Huanan Li, Fei Qi, Zhonglin ChenAbstract:Abstract A systematic investigation of the catalytic reaction mechanism of Surface cobalt-loaded red mud (RM) was carried out using the reaction kinetics analysis and catalyst Surface property characterization. First, multiple characterization methods (XRD, FT-IR and XPS) were used to investigate the variation of Surface texture and chemical properties of the catalyst after Surface cobalt loading. Second, the contributions of molecular ozone (39.22%), Hydroxyl radicals (45.20%), and Surface adsorption (15.57%) for bezafibrate (BZF) degradation by Co/RM were identified by the reaction kinetic analysis using the tertiary butanol used as an organic quencher, confirming that Surface cobalt loading promoted the role of the Hydroxyl radical reaction. The phosphate was used as an inorganic probe to study the role of the solution and Surface reactions in catalytic ozonation. The presence of phosphate inhibited 17.5%, 25.1%, and 27.2% efficient when phosphate concentration was 0.0104, 0.0208, and 0.0416 mM, respectively. The kinetics analysis showed that the inhibiting effect of phosphate on BZF degradation was due to quenching of HO in solution, and not the Surface chelation reaction. However, Surface cobalt loading enhanced this Surface interface reaction. Finally, the relationship between Surface texture/chemical properties and catalytic activity was established, confirming that Surface cobalt loading developed mesopores leading to an increase of the specific Surface area. This was favorable for the catalytic activity. Co3O4 covered over the mesopore Surface of RM and developed the Surface Hydroxyl Group by the chemical water deduced from the cobalt Surface loading. This is the main catalytic reaction site.
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Mechanism investigation of catalyzed ozonation of 2-methylisoborneol in drinking water over aluminum (Hydroxyl) oxides: Role of Surface Hydroxyl Group
Chemical Engineering Journal, 2010Co-Authors: Zhonglin Chen, Liqiu Zhang, Panyue Zhang, Dezhi SunAbstract:Abstract In this investigation, the mechanism of catalyzed ozonation of MIB by aluminum oxides (γ-AlOOH and γ-Al 2 O 3 ) was studied. It was concluded that the roles of Surface Hydroxyl Groups in adsorption and catalyzed ozonation determined catalyzed ozonation mechanism. The removal efficiency of MIB in catalyzed ozonation by γ-Al 2 O 3 or γ-AlOOH was 98.4% and 27.5%, respectively. Effect of water pH on catalyzed ozonation indicated that Surface Hydroxyl Group, of which Surface net charge was zero, was the active site of catalysts. Radical scavenger experiments results indicated that catalyzed ozonation by γ-Al 2 O 3 followed a Hydroxyl radical ( OH) reaction-pathway and the reaction-pathway of catalyzed ozonation by γ-AlOOH followed solid Surface mechanism. However, both γ-AlOOH and γ-Al 2 O 3 can enhance ozone decomposition to generate Hydroxyl radical in catalytic ozone decomposition (without MIB). The inconsistent results between radical scavengers and catalytic ozone decomposition were mainly due to the interaction between MIB and Surface Hydroxyl Groups. According to MIB adsorption on γ-AlOOH or γ-Al 2 O 3 , MIB interacted with Surface Hydroxyl Group by chemical adsorption, and Surface Hydroxyl Group was the main adsorption site. The adsorption capability of γ-AlOOH was higher than that of γ-Al 2 O 3 . The participation of Surface Hydroxyl Group in adsorption restrained its capability of catalyzed ozone decomposition to generating OH. γ-AlOOH that was covered with more Surface Hydroxyl Groups, adsorbed MIB more stronger and inhibited generation of OH in catalyzed ozonation of MIB, resulting in lower removal efficiency of MIB in catalyzed ozonation. In addition, the Surface texture and chemical properties of catalyst that can help to understand the catalyzed mechanism.
Michio Komatsu - One of the best experts on this subject based on the ideXlab platform.
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a convenient determination of Surface Hydroxyl Group on silica gel by conversion of silanol hydrogen to dimethylsilyl Group with diffuse reflectance ftir spectroscopy
Journal of Colloid and Interface Science, 1992Co-Authors: Kohji Yoshinaga, Yukiko Yamamoto, Hiroshi Yoshida, Kazuaki Takakura, Michio KomatsuAbstract:Abstract A new and convenient determination method of silanol Groups on silica gels is proposed. The dimethylsilyl(Si(CH 3 ) 2 H) substitution of Hydroxyl hydrogen on Surfaces successfully led to silanol quantitation by diffuse reflectance FTIR spectroscopy. This procedure was compared with a typical accepted method utilizing the reaction of silanol Group with LiAlH 4 , and found to be available as one of the simple silanol analytical methods. The method is also shown to be applicable for residual silanol Group determination of organic compound-modified silica gels.
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A Convenient Determination of Surface Hydroxyl Group on Silica Gel by FT-IR Spectroscopy.
Chemistry Letters, 1991Co-Authors: Kohji Yoshinaga, Masaru Rikitake, Taketoshi Kito, Yukiko Yamamoto, Hiroshi Eguchi, Michio KomatsuAbstract:The dimethylsilyl(–Si(CH3)2H) substitution of Hydroxyl hydrogen led to a convenient determination of Surface silanol Group on silica gels by Si-H bond stretching vibrational absorption analysis. The proposed procedure can be freed from influences of adsorbed water and moisture through the measurement process.
Karthik Krishnamurthy - One of the best experts on this subject based on the ideXlab platform.
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Computational study on the structural and Surface properties of amorphous Hydroxylated TiO_2 spherical nanoparticles
Journal of Nanoparticle Research, 2017Co-Authors: Naveen Kumar Kaliannan, Karthik KrishnamurthyAbstract:Monte Carlo simulations were carried out on amorphous titanium dioxide (TiO_2) for both bulk and Hydroxylated nanoparticles with particle sizes ranging from 1 to 10 nm. The potential developed by the Matsui and Akaogi (MA) was used to model the interatomic interactions of TiO_2 in both cases (bulk and nanoparticles). Besides, Angular and Morse potentials proposed by the Tether, Cormack, Du et. al. (TCD) were introduced to model the interactions of Hydroxyl Groups on the TiO_2 Surfaces, i.e., the Ti-O-H Groups with an experimental and theoretical angles of 125^ o . The bulk system was developed using periodic boundary conditions. The TiO_2 nanoparticles were extracted by applying a spherical cut section in the bulk TiO_2 melt structure to obtain the required size. Free valences on the nanoparticle Surfaces were saturated via additional Hydroxyl Groups and then quenched to 300 K under free boundary conditions. The bulk and Surface properties of the nanoparticles were calculated at 300 K and zero pressure and characterized via radial distribution functions, bond angle distributions, bond distances, coordination numbers, OH Group concentrations and radial density profiles. In addition, to understand the difference in properties of amorphous Hydroxylated TiO_2 nanoparticles and bulk amorphous TiO_2, a comparative study was done at the same thermodynamic conditions. The study shows that the bulk properties of amorphous Hydroxylated TiO_2 nanoparticles are strongly size-dependent and different from those of the bulk TiO_2. As expected, increasing the particle size leads to an approach of the particle’s bulk properties to the bulk properties of the (quasi) infinite system. The size effects show that decreasing the particle size results in increasing the Surface effects and Surface OH Group concentrations. Accordingly, small-sized TiO_2 nanoparticles have higher Surface OH Group concentrations and larger Surface effects than large-sized TiO_2 nanoparticles. Larger Surface effects result significant changes in their bond angles, bond distances, and coordination numbers. The simulation results of the Surface properties reveal that the Surface titanium atoms in the TiO2 nanoparticles have the capability of accommodating up to 5 Hydroxyl Groups. The mean Surface Hydroxyl Group density of the amorphous TiO_2 spherical nanoparticles is estimated to be around 8.1/nm ^2, which lies in the range of 8–16/nm ^2, found by experimental and other simulation studies. Details of the modelling, simulations results and the study are presented in this paper.
Jingwei Guo - One of the best experts on this subject based on the ideXlab platform.
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uv induced photoactive adsorption mechanism of arsenite by anatase tio2 with high Surface Hydroxyl Group density
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2014Co-Authors: Xiaojiao Cai, Jingwei GuoAbstract:Abstract Adsorption and photo-oxidation using anatase TiO2 is a promising technique for arsenite removal from aqueous solution. However, adsorption and photo-oxidation at the solid/liquid interface of TiO2 in aqueous suspensions is a complex reaction process. In this study, we use a simple and inexpensive synthesis method for this type of TiO2 and assess its arsenite adsorption and photo-oxidation performance. The prepared anatase TiO2 is rich in Hydroxyl Groups, with a Hydroxyl concentration of approximately 12.84 nm−2. Under irradiation with UV light, the adsorption capacity increases and the residual concentration of arsenic in the solution is lower than 10 μg L−1. According to zeta potential, FTIR, and XPS analyses, the Hydroxyl Groups on the anatase TiO2 Surface are responsible for arsenic adsorption. The effect of Hydroxyl radicals is investigated through scavenger experiments, the results of which indicate that Hydroxyl radicals play a key role in the oxidation of arsenite on anatase TiO2 under UV irradiation. The number of Hydroxyl Groups on the anatase TiO2 increases upon UV illumination, indicating that these are the photoactive species for arsenic adsorption.
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the preparation and characterization of a three dimensional titanium dioxide nanostructure with high Surface Hydroxyl Group density and high performance in water treatment
Chemical Engineering Journal, 2013Co-Authors: Jingwei Guo, Xiaojiao Cai, Ruiguo Zhai, Shimin ZhouAbstract:Abstract A three-dimensional (3D) titanium dioxide nanostructure consisting of a nanoparticle core and needlelike Surface was fabricated. The effects of Ti 4+ concentration, stirring methods and stirring time for TiO 2 preparation were discussed with results from transmission and scanning electron microscopy; meanwhile, the TiO 2 growth mechanism was illustrated by morphology evolution and crystallization of titanium dioxide spheres. The spherical diameter could be easily controlled by altering the concentration of precursor using a mechanical stirring method. X-ray photoelectron spectroscopy, Fourier transform infrared spectrometry and thermogravimetric analysis were used to confirm the composition of titanium dioxide spheres rich with Hydroxyl Groups. The product showed excellent ability for arsenic(V) and chromium(VI) removal and could be separated using sedimentation. Most of the ions could be removed in less than 1 h, and TiO 2 had maximum adsorption capacities of 59.7 mg g −1 for arsenic(V) and 21.92 mg g −1 for chromium(VI). The high performance of self-assembled 3D titanium dioxide in water treatment was due to (1) its large Hydroxyl Group density and high specific Surface area and (2) its 3D nanostructure consisting of a nanoparticle core and needlelike Surface.
Ching-cheng Chen - One of the best experts on this subject based on the ideXlab platform.
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Effects of Surface Hydroxyl Group density on the photocatalytic activity of Fe3+-doped TiO2
Journal of Alloys and Compounds, 2015Co-Authors: Ching-cheng ChenAbstract:Abstract The aim of the work is to study the effects of oxygen vacancy and Surface Hydroxyl Group density on the photocatalytic activity of Fe3+-doped TiO2, and to investigate how the titanium dioxide doped with different levels of the Fe3+ influenced their physical and chemical characterizations. The photocatalysts were characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), electron spin resonance (ESR), X-ray photoelectron spectroscope (XPS) and Fourier transform infrared (FTIR) spectra. The results revealed that adsorbed Hydroxyl Group density significantly influenced the photocatalytic activity, and a small amount of Fe3+ can act as a photo-generated hole and a photo-generated electron trap and inhibit the electron–hole recombination. The 0.10%-Fe3+-TiO2 with the highest Surface Hydroxyl Group density revealed the maximum rate constant of 0.716 and the optimal photocatalytic degradation of MB. As Fe3+ doping levels are larger than 0.10%, the cluster of Fe Ti ′ – V ¨ O – Fe Ti ′ generated gradually. This implied that an excessive amount of Fe3+ doped into TiO2 is detrimental to the photocatalytic activity due to the formation of Fe Ti ′ – V ¨ O – Fe Ti ′ clusters and enhances the recombination of photogenerated electrons and holes.
