Chinese Journal of Catalysis,2018年39(3):542-548 ISSN：0253-9837
Ma, Jing-Jun;Li, Shiyou
[Liu, Bing-Rui; Liu, Qi-Feng; Zhang, Qian; Ma, Jing-Jun] Agr Univ Hebei, Coll Sci & Technol, Huanghua 061100, Hebei, Peoples R China.;[Li, Shiyou] Univ South China, Hunan Prov Key Lab Pollut Control & Resources Tec, Hengyang 421001, Hunan, Peoples R China.;[Ma, Jing-Jun] Hebei Agr Prod Proc Engn Technol Res Ctr, Baoding 071001, Hebei, Peoples R China.
[Ma, Jing-Jun] Agr Univ Hebei, Coll Sci & Technol, Huanghua 061100, Hebei, Peoples R China.;[Li, Shiyou] Univ South China, Hunan Prov Key Lab Pollut Control & Resources Tec, Hengyang 421001, Hunan, Peoples R China.;[Ma, Jing-Jun] Hebei Agr Prod Proc Engn Technol Res Ctr, Baoding 071001, Hebei, Peoples R China.
Construction of surface defects;Ultrafine TiO_2;Low-cost transition metal;Surface doping;Photocatalytic H_2 production
Inefficient charge separation and limited light absorption are two critical issues associated with high-efficiency photocatalytic H_2 production using TiO_2. Surface defects within a certain concentration range in photocatalyst materials are beneficial for photocatalytic activity. In this study, surface defects (oxygen vacancies and metal cation replacement defects) were induced with a facile and effective approach by surface doping with low-cost transition metals (Co, Ni, Cu, and Mn) on ultrafine TiO_2. The obtained surface-defective TiO_2 exhibited a 3-4-fold improved activity compared to that of the original ultrafine TiO_2. In addition, a H_2 production rate of 3.4 µmol/h was obtained using visible light (λ > 420 nm) irradiation. The apparent quantum yield (AQY) at 365 nm reached 36.9% over TiO_2-Cu, significantly more than the commercial P25 TiO_2. The enhancement of photocatalytic H_2 production activity can be attributed to improved rapid charge separation efficiency and expanded light absorption window. This hydrothermal treatment with transition metal was proven to be a very facile and effective method for obtaining surface defects.
Anthraquinone-2-sulfonate (AQS) was employed in humus substitutes to evaluate the effects and influencing factors of U(VI) reduction-by Shewanella oneidensis MR-1 (S. oneidensis MR-1) under anaerobic-condition. The removal rate of U(VI) at 30 ℃ reaches 99.0% afterd 96 h with the pH value of 7.0 and AQS concentration of 1.0 mmol/L. The effective concentrations of AQS as the accelerator for U(VI) bioreduction are approximately 0.5-1.0 mmol/L. The bioreduction of U(VI) is inhibited when the concentration of AQS exceeds 2.0 mmol/L. The coexistence of ions, such as Cu~(2+), Cr~(6+), Mn~(2+), shows a remarkable negative effect on the U(VI) reduction, and Zn~(2+) shows less influence on the process compared with other tested ions. The U(VI) reduction is remarkably inhibited when the concentration of nitrate ion exceeds 1.0-mmol/L. Otherwise, no difference is found when the nitrate ion concentration is less than 0.5 mmol/L. Sulfate ion (<5.0 mmol/L) slightly promotes the U(VI) reduction. Zero-valent iron (ZVI) promotes the U(VI) reduction by S. oneidensis, and the reduction rate improves with increasing the amount of ZVI in the range of 0-2.0 g/L. The XPS result indicates that uranium deposits on the cell surface are in U(VI) and U(IV) forms, and the majority of uranium in the solution is stable UO_2.
To enhance the impact strength of polyamide 6, hydrolytic polymerization modification by the polyaminoamide-g-poly(ethylene glycol) (PAAEG) derivatives with poly(ethylene glycol) (PEG) molecular weight of 400-10000 was studied. Amide groups of polyaminoamide segments were postulated to form hydrogen bonding with polyamide 6, and hydroxy groups of PAAEG units were expected to react with carboxylic acid groups of polyamide 6 forming copolymers during the polymerization. The improved compatibility in amorphous regions of blends has been confirmed by differential scanning calorimetry (DSC) and scanning electron microscopy (SEM) of fracture surfaces. The effects of PAAEG on the water absorption and notch sensitivity of blends were investigated, using water uptake measurement and mechanical testings, respectively. For comparison, pure polyamide 6 and the blend of PEG/polyamide 6 were also investigated. The addition of PAAEG retarded the crystallization of polyamide 6, but did not make remarkable influences on its crystalline structure. As a consequence of the strong interactions between the dispersed phases and polyamide 6 matrices, PAAEG was a more suitable additive for improving the notched impact strength of polyamide 6 than PEG.
[邵小平; 石平五] College of Resource and Energy, Xi'an University of Science and Technology, Xi'an 710054, China;[贺桂成] College of Architectural and Environment Engineering, Nanhua University, Hengyang 421001, China
College of Resource and Energy, Xi'an University of Science and Technology, China
[董辉; 杨珺博] College of Civil Engineering and Mechanics, Xiangtan University, Hunan Xiangtan 411105, China;[傅鹤林; 聂春龙] School of Civil and Architectural Engineering, Central South University, Changsha 410075, China;[聂春龙] College of Urban Construction, South China University, Hunan Hengyang 421001, China
College of Civil Engineering and Mechanics, Xiangtan University, China