Advanced Materials Research Vols. 343-344

Abstract: In this study, removal of Cr(Ⅵ) from synthetic groundwater by adsorption onto commercial activated carbon (CAC) made up of coconut shell is investigated in batch studies. Surface modification of CAC with sulfuric acid is also conducted to evaluate its removal performance. It is evident that CAC chemically modified with sulfuric acid (sulfuric-treated CAC) demonstrates higher Cr(Ⅵ) removal efficiency than non-treated CAC in dealing with contaminated groundwater with the pH is about 7.0, suggesting that sulfuric-treated CAC is suitable for the in-situ remediation of Cr(Ⅵ) contaminated groundwater. Adsorption of Cr(Ⅵ) is strongly affected by pH, the granular sulfuric-treated CAC exhibits the highest Cr(Ⅵ) adsorption capacity at pH 1.5 and the maximum Cr(Ⅵ) adsorption capacity of which estimated with the Langmuir model was 8.24mg/g.

Abstract: α-Fe₂O₃ hollow microspheres and nanorods were synthesized via a hydrothermal method using glucose and ethylenediaminetetraacetic acid (EDTA) as morphology controlled agents, followed by calcination at 500 °C for 4 h in air. The crystal structures of products were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The results show that the hollow microspheres with diameters of 1-2 μm are consist of nanoparticles (80-100 nm), and the nanorods have a structure in the diameter of 80-100 nm and length about 1 μm. Furthermore, the α-Fe₂O₃ hollow microspheres show higher gas response to ethanol than that of nanorods and nanoparticles.

Abstract: The CdTe thin film solar cells with the structure of ITO/ZnO/CdS/CdTe/Au were irradiated by 1.6MeV high-energy electrons with the fluences from 5×10¹³/cm² to 1×10¹⁶/cm². The characteristics of devices before and after irradiation were studied using dark current-voltage (I-V), capacitance-voltage (C-V) and admittance spectroscopy (AS) measurements in the temperature range from 303K to 353K. The results are shown that the diode ideal factor and dark saturation current for irradiated devices first decrease and then increase significantly with fluences from 5×10¹³/cm² to 1×10¹⁶/cm², meantime the effective carrier concentration at room temperature of CdTe absorbing layer increases first and then decreases. The carrier transport mechanisms in CdTe solar cells are analyzed before and after irradiation. The non-irradiated devices and irradiated devices with fluences less than 5×10¹⁴/cm² are dominated by the recombination current of electron-hole pairs in the depletion layer. However, it is dominated by the recombination current of tunneling at the interface after the irradiation of higher fluences. The changes of types and amount of defects caused by electron irradiation are the major reasons for the above mentioned variations.

Abstract: Anchoring metal on TiO₂ by photoreduction process characterized as adsorbent and photocatalyst is the target in this study. Metal anchored TiO₂ is expected to remove acid-odors well at room temperature. Besides the adsorption and absorption mechanism, the material could also decompose the acid-odors by photocatalysis process under UV irradiation. Thus the removal efficiency of acid-odors processed via metal anchored TiO₂ could be better than those of the common adsorbent and photocatalyst no matter with or without UV irradiation, the service life of the decontamination via metal anchored TiO₂ is also extended more than common adsorbent. According to the comparisons between TiO₂ and various porous materials during acid-odors adsorption, Beta type zeolite shows the best efficiency due to the maximum silica-alumina ratio and excellent specific surface area. However, Ag anchored TiO₂(Ag-TiO₂) via photoreduction process can improve the photocatalysis efficiency of acid-odors; at the same time, Ag on TiO₂ surface also reacts with acetic acid in the chemical absorption mechanism with or without UV illumination. The regeneration activation procedure can carry away and desorb the acetic acid from Ag-TiO₂. With UV irradiation, the Ag on oxidation state will attract the electrons excited from TiO₂, and reduce itself to Ag on metal state, which is reactive to acetic acid; hence, the adsorption and photocatalysis efficiency of acid-odors via the regenerated Ag-TiO₂ is similar to brand new ones.

Abstract: The batch removal of dye from textile dyeing wastewater by using nanooxides decorated multiwalled carbon nanotubes was studied under electron beam conditions. The effect of different nanooxides decorated multiwalled carbon nanotubes content and irradiation dosage was also investigated. The color removal efficiency was 94.9% in dose of 17.5kGy. The colour removal efficiency with Fe2O3 decorated multiwalled carbon nanotubes was similar to with TiO2 decorated multiwalled carbon nanotubues. The COD removal efficiency was 52.5% in the dose of 14.0kGy. When the irradiation dose of 17.5kGy, the COD removal efficiency was 98.2% with TiO2 decorated multiwalled carbon nanotubes.Overall, the study demonstrated that nanooxides decorated multiwalled carbon nanotubes can effectively remove color and COD from aqueous solution under irradiation.

Abstract: A new type of poly-crystalline amorphous thin film photovoltaic module with high visible light transmittance was developed for use in a building. The method of PECVD (Plasma-enhanced chemical vapor deposition) was applied to produce satisfactory high color rendering index (HCRI) BIPV module of good quality with visible light transmittance as high as 26.9%, solar radiation absorptance below 60% and shading coefficient equal to 54%. The thermal and optical properties of HCRI BIPV module are studied in some detail and the results reported. The thermal conductivity and diffusivity of HCRI BIPV module are less than that of Si-based BIPV. The HCRI-BIPV module appeared to be effective in improving the visible transmittance and reducing the absorptance, but the value of SC of HCRI-BIPV module was higher than that of Si-based BIPV. This indicates that there is still a trade-off between day lighting and thermal insulation for designing an optimal BIPV module. Further thermal performance work conducted by a small-sized hot-box with a solar simulator lamp revealed that heat is mostly absorbed by the HCRI-BIPV and a small amount of heat is conducted into building. The surface temperature on both sides of Si-based BIPV reached a steady state is faster than that of HCRI-BIPV due to the higher thermal diffusivity. This can have important practical implications on the fabrication of low-cost, high visible light transmittance of BIPV module.

Abstract: Hydrophobic and elastic aerogels derived from methyltrimethoxysilane (MTMS) precursor were prepared by ambient pressure drying under various processing conditions, and their morphology and physical and mechanical properties were characterised and evaluated. The results of this study demonstrated that for inherently hydrophobic gels like MTMS based gels, high temperature ageing is a practical and effective means to reduce volume shrinkage and produce low bulk density monolithic aerogels at ambient pressure, without the need of any solvent exchange and surface modification. By using this simple method, we were able to produce an aerogel with a bulk density as low as 0.064g/cm³. The results also revealed a significant difference from that previously reported in the literature.

Abstract: In this paper, five different energy of cross price elasticity were calculated, the substitutional relation between different energy sources in China were discussed. The status of natural gas in energy market was analysed. The results show that only LNG take a role of complements to natural gas, while electricity, gasoline, diesel oil and coal have alternative relations with natural gas. Besides,electricity has the strongest ability to substitute natural gas. Conversely, if it is possible for natural gas to replace other energy sources , LNG will be the best substitute and be followed by gasoline,diesel oil,and power. And the natural gas has the weakest ability to substitute coal in China.

Abstract: Nitrogen doped titanium dioxide nanoparticals (N-TiO2) were prepared by the sol-hydrothermal method using urea as N sources. SEM showed the sphericity of as-prepared nanoparticals. XRD indicated that N-TiO2 was anatase crystal after thermal treatment. While Na-chlorophyllin copper (Na-chl-Cu) was used as to sensitize the N-TiO2, the photocurrent of Na-chl-Cu/N-TiO2 was 50 ìA double than that of N-TiO2 under visible light illumination. Thus, the visible light photoelectrocatalytic degradation properties of Na-chl-Cu/N-TiO2 were investigated using methyl orange (MO) as the objective pollution. When 1.8 V anodic bias potential and visible light were simultaneously applied, the highest degradation efficiency of MO over the Na-chl-Cu/N-TiO2 was obtained.

Abstract: The preparation and production technology of biodiesel was explained in this paper. The transesterification mechanism was discussed from the synthesis reaction of biodiesel. Then the synthetic effects on the reaction were investigated such as water of the raw material oil, free fatty acids, temperature, pressure, catalyst, reaction time, alcohol-oil ratios, the mixing degree of raw materials and other aspects. The best synthetic technology was obtained.