酸溶粉煤灰制备混凝剂及其处理污水效果

为了提高粉煤灰的利用价值,采用酸溶法提取其中的铝、铁元素,制备粉煤灰基混凝剂.以硫酸为酸浸液,固定酸灰比为3:1,考查不同酸溶方式的溶出效果,并利用制得的混凝剂处理生活污水.实验结果表明:硫酸浓度或反应温度的提高有助于粉煤灰中铝、铁的溶出.添加NH4F为助溶剂,铝、铁的总溶出率可达63.42%,但存在F-的二次污染.经过高温焙烧后粉煤灰中铝、铁酸溶性降低,但添加碳酸钠且配比达到0.06以上时,熟料中铝酸溶性提高;由此制得的混凝剂处理污水时,适宜投量为1.2 mL/L,效果优于市售混凝剂,COD、TP的去除率分别为69%、95%,剩余SS低于20 mg/L.     

Photocatalytic oxidation of methylene blue dye under visible light by Ni doped Ag2S nanoparticles

Ag₂S nanoparticles were prepared using a hydrothermal method, and Ni was doped via a photo-assisted deposition method. The samples produced were characterized using different tools. Furthermore, the catalytic performance of the Ag₂S and Ni/Ag₂S samples was examined in the degradation of methylene blue dye under visible light. The UV–vis spectral analysis detected a red shift after loading of Ni. The maximum degradation efficiency achieved was 100% with 3 wt% Ni/Ag₂S as the photocatalyst after a 40-min reaction time. The catalyst could be reused without any loss in activity for the first five cycles.     

Alkalibacillus halophilus subsp. hitensis subsp. nov.:A new subspecies of moderately halophilic bacterium isolated from a chemical plant in China

In order to develop halophilic microorganism resources to improve environment,a Gram-positive,strictly aerobic and moderately halophilic bacterial strain JSA1 was obtained from the waste water sample collected from Jinhong Chemical Plant at Weihai city,by the methods of quick isolation and screening of halophilic bacteria. Systematic studies on it were carried out. Results show that the strain JSA1 is bacillus. The temperature range most suitable for its growth is 29-35 ℃ and the most suitable pH is 6.5-9.0. It can grow well at the salt mass concentration of 30-150 g/L. The C+G mole fraction of its DNA is 37.5%. The analytical result of 16S rRNA gene sequence reveals that this strain has the closest relationship with Alkalibacillus halophilus (DQ359731) of Alkalibacillus. Their similarities are as high as 99%. However,they have obvious differences in aspects of whole-cell main fatty acid components,cell size,cell morphology,motility,oxidase,gelatine liquefication,NaCl tolerance range,pH tolerance range,G+C mole fraction,sole carbon source,sole nitrogen source,antibiotic sensitivity and strain source. Comparing with other species of the same genus,differences of this strain are even more obvious. In view of multiple identification results,we believe this strain is a new subspecies of Alkalibacillus halophilus and name it Alkalibacillus halophilus subsp. hitensis subsp. nov.     

Electronic and optical proeprties of neon-doped rutile TiO<Subscript>2</Subscript> from ab inito calculations

The electronic-structure and optical properties of neon-doped rutile TiO₂ have been investigated using density functional theory with Slater type orbitals basis set and correlation. This was done using the PBE method as implemented within the Hyper Chem 7.52 software package with Ne concentration approaching the low level may present in industrial samples of rutile TiO₂. Defect states involving substitution of an oxygen atom for a neon atom were studied along with the more stable configuration of one neon substitution. Neon change the band structure and lead to a reduce in the band gap in rutile. This make that neon doping brings the absorption edge into the visible range and therefore increase the photocatalytic activity.     

膜生物反应器净化微污染引黄水库水效能

为考察膜组合工艺处理微污染原水的可行性,研究膜生物反应器（MBR）与膜粉末活性炭生物反应器（PAC-MBR）对低温低浊微污染引黄水库水的处理效果及膜污染状况.两者对浑浊度均能保证稳定的去除效果,去除率保持在97%以上;对有机物去除能力依次为PAC-MBR〉MBR〉常规处理工艺〉单独的超滤膜（UF）;单独的超滤膜对氨氮几...     

PDAB比色法直接测定液相中的常量尿素

为提供一种快速、简单的液相中尿素浓度测定方法,对二甲氨基苯甲醛(PDAB)比色法进行了研究.分别对该法的测定条件、特点、范围和盐浓度以及氨氮浓度的影响进行了试验,结果表明,在波长422 nm,显色10 min,显色剂配比为4:4:96的条件下该法具有较高的精确度和准确度,在此条件下的测定范围为8.8~107 mg/L;在氨氮浓度小于300 mg/L,氯化钠浓度在400~8000 mg/L的条件下仍具有较好的测定效果.因此PDAB比色法可用于含有较高氨氮和盐浓度的溶液中尿素浓度的测定,且具有快速、稳定、操作简单等优点.     

Probing plasmonic Ag nanoparticles on TiO2 nanotube arrays electrode for efficient solar water splitting

Decoration of semiconductors with plasmonic nanoparticles provides a new direction for efficient solar water splitting for hydrogen production. Herein, Ag nanoparticles as the plasmonic metal were electrodeposited on a TiO₂ nanotube arrays (TNTA) photoelectrode by controlling deposition-charge density. The resulting Ag/TNTA electrode with 10–50 nm diameter Ag nanoparticles exhibited a higher photocurrent density and hydrogen production rate than a bare TNTA electrode under AM 1.5 irradiation. The origins of this enhancement were explored by analyzing the photoelectrochemical behaviors with the relevant optical properties. The absorption of these Ag/TNTA electrodes in the visible light region increased owing to the surface plasmon resonance (SPR) effect of the Ag nanoparticles, and only low photocurrent densities under visible light irradiation were observed. The overall enhancement is owing to the greater incident photon-to-electron conversion efficiency in the 300–400 nm range that is more dependent on the interfacial charge transfer from TNTA to Ag nanoparticles. The localized electronic field of the SPR also reduces the electron transport time in the Ag/TNTA electrodes.     

Study on mechanism of enhanced photocatalytic performance of N-doped TiO2/Ti photoelectrodes by theoretical and experimental methods

Several kinds of N-doped/undoped TiO₂ photoelectrodes with different nanostructures have been successfully prepared by anodization method and plasma-based ion implantation (PBII) technique. The morphology and structure of as-prepared photoelectrodes were studied by scanning electron microscopy, X-ray diffraction, and ultra violet/visible light diffuse reflectance spectra. Electronic structure and optical properties were calculated by means of first-principle. Photocatalytic (PC) and photoelectrocatalytic (PEC) performance were measured by the decomposition of terephthalic acid (TA) and Rhodamine B under xenon light illumination. Theoretical calculation results demonstrated that crystal phases have great influence on the electric and optical properties, and N-doped TiO₂ photoelectrodes have isolated N_2P impurity states nearby the top of the valence band. The optical properties and UV/Vis analysis confirmed that the absorption edge of N–TiO₂ emerged red-shift and high photosensitivity. The discrepancy of PC and PEC performance of as-prepared TiO₂ photoelectrodes were ascribed to band gap narrowing, N_2p impurity states, self-semiconductor coupling effect, and long-range ordered orientation of photogenerated carries originated from applied electric field.