Enhancement of the photocatalytic performance of Ag-modified TiO2 photocatalyst under visible light

A highly visible-light photocatalytic active Ag-modified TiO₂ (Ag–TiO₂) was prepared by a simple sol–gel process using TiOSO₄ as the starting material, AgNO₃ as a silver doping source, and hydrazine as a reducing agent. The prepared Ag–TiO₂ samples were characterized by several techniques such as X-ray powder diffraction (XRD), BET surface area measurement, scanning electron microscopy (SEM), transmission electron microscopy (TEM), inductively coupled plasma optical emission spectroscopy (ICP-OES), energy dispersive X-ray spectrometry (EDX), X-ray absorption spectroscopy (XAS) and UV–vis diffuse reflectance spectroscopy (DRS). The Ag–TiO₂ photocatalyst, a mixture of amorphous and anatase phases, has a high surface area. The silver contents in the Ag–TiO₂ samples were determined by ICP measurements. The diffused reflectance UV–vis spectra indicated that the Ag–TiO₂ samples exhibited higher red shifts compared with the undoped TiO₂ sample. Indigo carmine degradation under visible irradiation indicated that the Ag–TiO₂ catalyst gave higher photocatalytic efficiency than those of commercial P25-TiO₂ and undoped-TiO₂ samples. The Ag–TiO₂ catalyst can be reused many times without any additional treatment.     

Simultaneous analysis of main catechins contents in green tea (Camellia sinensis (L.)) by Fourier transform near infrared reflectance (FT-NIR) spectroscopy

This paper reported the results of simultaneous analysis of main catechins (i.e., EGC, EC, EGCG and ECG) contents in green tea by the Fourier transform near infrared reflectance (FT-NIR) spectroscopy and the multivariate calibration. Partial least squares (PLS) algorithm was conducted on the calibration of regression model. The number of PLS factors and the spectral preprocessing methods were optimised simultaneously by cross-validation in the model calibration. The performance of the final model was evaluated according to root mean square error of cross-validation (RMSECV), root mean square error of prediction (RMSEP) and correlation coefficient (R). The correlations coefficients (R) in the prediction set were achieved as follows: R = 0.9852 for EGC model, R = 0.9596 for EC model, R = 0.9760 for EGCG model and R = 0.9763 for ECG model. This work demonstrated that NIR spectroscopy with PLS algorithm could be used to analyse main catechins contents in green tea.     

Wind power potential and characteristic analysis of Chiang Mai,Thailand

An investigation of wind characteristics and wind energy potential at Chiang Mai Province, Thailand was studied. Wind data taken from the weather station at Chiang Mai International Airport between 2001–2006 was analyzed in order to obtain the potential energy generated by a Vertical Axis Wind Turbine (VAWT). It was found that the yearly average wind velocity was 5.7 meters per second with a standard deviation value of 2.2 meters per second. The analysis assumed that wind blew in the S.W. to N.E. direction. Two parameters for the local wind, the shape parameter (k) and scale parameter (c) were obtained at 2.928 and 6.381 meters per second, respectively. The estimated power that could be generated by a Vertical Axis Wind Turbine was 183.09 W/m² at 30 meters above ground level. This particular site corresponds to class 1 wind power. This level of power density may be adequate for non-connected electrical and mechanical applications, such as battery charging and water pumping.     

Biodiesel production from crude rice bran oil and properties as fuel

This research reported on the successfully production of biodiesel by transesterification of crude rice bran oil (RBO). The process included three-steps. Firstly, the acid value of RBO was reduced to below 1 mg KOH/g by two-steps pretreatment process in the presence of sulfuric acid catalyst. Secondly, the product prepared from the first process was carried out esterification with an alkaline catalyst. The influence of four variables on conversion efficiency to methyl ester, i.e., methanol/RBO molar ratio, catalyst amount, reaction temperature and reaction time, was studied at this stage. The content of methyl ester was analyzed by chromatographic analysis. Through orthogonal analysis of parameters in a four-factor and three-level test, the optimum reaction conditions for the transesterification were obtained: methanol/RBO molar ratio 6:1, usage amount of KOH 0.9% w/w, reaction temperature 60 °C and reaction time 60 min. In the third step, methyl ester prepared from the second processing step was refined to become biodiesel. Fuel properties of RBO biodiesel were studied and compared according to ASTM D6751-02 and DIN V51606 standards for biodiesel. Most fuel properties complied with the limits prescribed in the aforementioned standards. The consequent engine test showed a similar power output compared with regular diesel but consumption rate was slightly higher. Emission tests showed a marked decrease in CO, HC and PM, however, with a slight increase in NO_X.     

连续茶叶筛选和揉捻装置的评估(英文)

研究茶叶连续筛选、揉捻装置的设计、制造,并对其性能进行测试。在200℃条件下,分别将茶叶筛选装置和揉捻装置的转速设定在7～14r／min和34～68r／min范围内进行试验。结果显示最佳的试验条件是筛选装置转速10．8r／min,揉捻装置转速51r／min．当筛选量45kg／h和揉捻量18kg／g时,揉捻茶叶的产率最高,可以达到81％。