Xin Xin Zhang

Constructing TiO2/Gr with Rapid Electrons Transfer for Efficiency Photocatalysis

TiO2/Gr powders were fabricated by hydrothermal method. Their micro-structure was characterized by transmission electron microscopy (TEM). The results revealed TiO2 particles anchored on the Gr sheets. DRS analysis indicated there was an obvious red shift of the absorption edge of TiO2/Gr compared to that of TiO2. The experiment of photocatalytic degradation of Rhodamine B (RhB) showed that the degradation rate with TiO2/Gr was 2.40 times as much as that with TiO2. The enhanced photocatalytic performance was firstly attribSubscript textuted to the rapid transfer of the photogenerated electrons from TiO2 to Gr, which could increase the charge carrier separation, limit their recombination, and enhance the photocatalytic efficiency. Furthermore, the extended light absorption range may also contribute to the enhanced photocatalytic performance.

Effect of Pypocholoride Pretreatment on the Disintegration of Excess Sludge

This article focuses on the effects of pretreatment on sewage sludge with sodium hypochlorite addition. The solubilization of organic matters of sludge was investigated. It was found that the pypocholoride treatment provided a efficient process to release organics from sludge flocs. When the ClO- dose was about 21mg /g SS with a reaction time of 3 hours, the supernatant soluble chemical oxygen demand (SCOD), total nitrogen (TN), total phosphorus (TP), protein and polysaccharide increased by 400%, 67%, 1791%, 635%, 214%, and 556%, respectively. After hypochlorite pretreatment, the sludge extracelluar polymers (EPS) were disintegrated and the cell walls were broken. Then the intracellular organic matters were released into the supernatant, leading to the increase of organic matters in the supernatant.

Photocatalytic Degradation and Kinetics of Methyl Orange with Bi-Doped TiO2 under Simulated Sunlight

Bi-doped TiO2 was prepared with sol-gel method and was characterized by X-ray photoelectron spectroscopy (XPS). The photocatalytic degradation and kinetics of Methyl orange with Bi-doped TiO2 under xenon lamp irradiation were investigated. The optimum conditions were as follows: the initial concentration of Methyl orange was 20 mg/L, the value of pH was 3.0 and the dosage of Bi-doped TiO2 was 1.0 g/L. Under the optimal conditions, the decolorization rate of Methyl orange was 75.1 % and the kinetic constant was 0.0113 min-1.

Preparation of Hydrophobic Silica Aerogels from Industrial Microsilica and its Oil Adsorption Properties

Hydrophobic silica aerogels were prepared from industrial microsilica via ambient pressure drying. The process consists of two stages, synthesis of sodium silicate solution from microsilica by hydrothermal reaction with sodium hydroxide, and preparation of silica aqueous gel and porous silica aerogels from the obtained sodium silicate solution. The mixed solution of hexane/ethanol/trimethylchlorosilane was used to modify the sol-gel derived silica aqueous gel so as to obtain porous structure by ambient pressure drying. The microstructure, pore properties of the silica aerogels were analyzed by FTIR and N2 adsorption-desorption methods, and the oil adsorption of the synthesized silica aerogels was investigated. The results indicate that the obtained silica aerogels are light-weight and hydrophobic porous materials, with the specific surface area of 767~828 m2•g-1, porosity of 91.5~95.1% and the average pore diameter of 5.22~8.02 nm. The synthesized silica aerogels have good oil adsorption capacity and the highest saturated oil adsorption rate can achieve 1105%.

Hydrothermal Synthesis of ZnO/Zn Composites with Enhanced Photocatalytic Performance

ZnO/Zn composites photocatalysts were prepared by hydrothermal method using Zn powder as raw material, and the morphology, structure, and photocatalytic performance of composites were investigated. The results showed that the ZnO nanoparticles were produced at the surface of Zn metal powder during hydrothermal process. The thickness of ZnO outer layer (internal metal-semiconductor interfaces) can be controlled by varying hydrothermal treatment time. The resulting ZnO/Zn composites exhibit significantly higher photocatalytic activity than that of pure ZnO for degradation of anthraquinone dye (reactive brilliant blue KN-R) aqueous solution under ultraviolet light irradiation. The enhancement of photocatalytic performance of ZnO/Zn composites can be attributed to the formation of internal metal-semiconductor interfaces. The designed fabrication procedure is simple, feasible, and universal for a series of oxide/metal with controlled microstructure and improved performances.

Synthesis and Characterization of High Electrocatalytic Active Nanosized RuO2 Powder with Narrow Distribution by Ultrasonic Precipitation

In this paper, synthesis of RuO2 with uniform nanosized sphere-like morphologies by ultrasonic precipitation using ammonia is presented. The structures, properties and electrocatalytic performance of materials were characterized by XRD, FE-SEM, CV and polarization curve. FE-SEM photographs showed that the sample prepared by ultrasonic precipitation has a relatively narrow size distribution compared with the sample prepared by conventional precipitation with magnetic stirring. The CV and polarization curve for OER (oxygen evolution reaction) confirmed that electrochemical active surface area and OER activity of sample by ultrasonic precipitation are higher than that of sample by conventional precipitation under magnetic stirring.

Preparation of SiO2 Aerogel Supported Nano-TiO2 Photocatalysts for Removing Rhodamine B in the Waste Water

Using the as-prepared SiO2 aerogels as carriers, SiO2 aerogel supported nano-TiO2 (TiO2/SiO2 aerogel) photocatalysts were prepared by sol-gel and adsorption loading process. The microstructure, morphology and properties of the obtained TiO2/SiO2 aerogel were studied by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and Brunauer-Emmett-Teller (BET) N2 adsorption-desorption analysis. The adsorption/photocatalytic degradation for Rhodamine B of TiO2/SiO2 aerogel composite photocatalysts was investigated. The results indicate that TiO2 sol concentration is the main factor influencing the microstructure and properties of TiO2/SiO2 aerogel composite photocatalysts. With the increasing of TiO2 sol concentration, the amount of loaded TiO2 increased, but the specific surface area, pore volume and pore size gradually decreased. The specific surface area, pore volume and pore diameter of TiO2/SiO2 aerogel photocatalysts after annealed at 550oC are 444.76～750.34 m2/g, 0.08～0.70 m3/g and 2.46～4.58nm, respectively. The TiO2/SiO2 aerogel prepared with 0.75 mol/L TiO2 sol concentration has best adsorption/photocatalytic degradation for Rhdamine B.

Preparation of TiO2/AC and Investigation of its Photocatalytic Activity

TiO2/AC composite was prepared by sol-gel method. The effect of annealed temperature and loading (or doping) ratio of AC on photocatalytic performances of TiO2/AC composite was explored. The optimum preparation conditions were 400 °C (annealed temperatur) and 2% (loading (or doping) ratio of AC). The experimental results of MB removal showed that the photocatalytic ability of TiO2/AC composite prepared under optimum conditions was higher than that of TiO2, which could be attributed to strong adsorption capacity, efficient photoproduced electron-hole separation, and higher light response.

Degradation of Reactive Brilliant Blue KN-R by Zero-Valent Iron/Activated Carbon Combined with Ultrasound

The treatment of Reactive Brilliant Blue KN-R in wastewater was conducted by using the zero-valent iron/activated carbon (Fe0/AC) combined with ultrasound (US). Although ultrasound alone had a little effect on the KN-R degradation and Fe0/AC had some disadvantages when it acted on the KN-R, the efficiency of the degradation was dramatically enhanced which used the combination of Fe0/AC /U.S. that also could eliminate the shortcomings. The decolorization percentage was nearly up to 100% and the COD removal rate has approached to 87.38%.

Oxidative Degradation of Azo Dye Reactive Red 2BF by Potassium Ferrate

The oxidative degradation of azo dye Reactive Red 2BF in aqueous solution by using potassium ferrate (Ⅵ) was studied. The initial concentration of wastewater 100 mg/L, pH 4.0, reaction time 20 min, and the dosage of potassium ferrate was 0.9 g/L. Under the optimal conditions, the decolorizing rate of Reactive Red 2BF and the COD removal rate were 99.9% and 73.3%.