TiO_2薄膜光催化降解甲基橙反应动力学研究

以甲基橙为模型污染物、TiO2薄膜为光催化剂,在自制的光催化反应器上进行了光催化降解反应实验,主要研究了甲基橙初始浓度(c0)和紫外光光照强度(I)对其光催化降解反应的影响。结果表明,该降解反应可用一级反应动力学方程进行描述,反应速率常数(k)与c0及光强I的关系分别为:k∝c0-1 4和k∝I0.65。     

Flow-induced degradation of hydrolyzed polyacrylamide in porous media

Summary In this work we present an experimental study of flow-induced degradation of hydrolyzed polyacrylamide in aqueous solutions flowing through porous media. The degradation is analyzed by passing the solution repeatedly through the medium at a constant flow velocity and the degraded solution is then characterized by porous media and opposed jets flows. When the polyacrylamide is dissolved in deionized water, it exhibits a gradual extension thickening in the flow through porous media and opposed jets. In this case, the polymer degrades as it passes through the porous medium even at relatively low flow rates. When the polyacrylamide is dissolved in an NaCl solution, it exhibits critical extension thickening in porous media flows, and it only degrades at Reynolds numbers that are higher than the onset of the extension thickening behavior. Chain degradation is therefore only encountered when extension thickening is produced. The results also show that the extent of degradation decreases as the pore size decreases.     

纳米TiO_2改性苯丙乳液内墙涂料的研究

采用物理掺和法,在苯丙乳液中加入锐钛型纳米TiO2,制成内墙涂料,进行抑菌试验和甲醛降解实验研究,分析了纳米TiO2的光催化原理和抗菌机理。结果表明,随着TiO2含量增加,甲醛降解能力和抗菌性能增强,当TiO2含量为4%时效果最好。     

Syntheses of TiO2 photocatalysts by the molten salts method: Application to the photocatalytic degradation of Prosulfuron

Titania photocatalysts were synthesised by the molten salts method by reaction of a titanium precursor with three different alkali metal nitrates (LiNO₃, NaNO₃, KNO₃). The titania powders obtained have been characterised using TEM, XRD, BET and UV-Vis absorption spectroscopy. Their photoactivities were evaluated by degrading a commercial sulfonylurea herbicide, Prosulfuron^®. It has been found that the rate constants increased in the following order: Li2 prepared in KNO₃, with a rate constant 1.4 times smaller than that of P25. The effect of calcination was also studied, especially for the sample prepared in NaNO₃ (TiO₂[Na]). An improvement in photocatalytic activity was observed when TiO₂[Na] was calcined in the region of 700–800 °C. Even though the photocatalytic activities obtained did not exceed or even equal to that of Degussa P25, nevertheless, this study constitutes the first attempt to synthesise titania photocatalysts by the molten salts method.     

生态型高吸水性树脂的研究

从高吸水性树脂的化学结构出发，论述了树脂的降解机理和降解方法，归纳和评述了近期我国在可降解天然聚合物、丙烯酸接枝共混和丙烯酸（盐）合成聚合物方向的研究，并对未来作出展望。     

SIS-g-AN热降解性能的研究

采用热重分析法和差示热重分析法研究丙烯腈(AN)接枝热塑性弹性体SIS(SIS g AN)的热降解性能。结果得出,SIS g AN的平衡起始降解温度、平衡最大降解速率温度和平衡终止降解温度分别为659. 17, 713. 94 和740.05 K;热降解反应活化能为195.2 kJ·mol-1;热降解机理是Deceleration中的D3 降解机理;不同质量损失率下的热寿命与温度呈线性关系。     

分子生物技术在石油降解微生物研究中的应用

总结了生物法治理石油污染的局限性,介绍了几种在石油降解微生物研究中广泛应用的分子生物技术,并对该研究领域未来的发展趋势进行了预测。     

Polymer waste recycling over “used” catalysts

Catalytic degradation of high-density polyethylene (HDPE) was carried out under nitrogen using a laboratory fluidised bed reactor operating at 360 °C with catalyst to polymer feed ratio of 2:1 and at 450 °C with catalyst to polymer feed ratio of 6:1 under atmospheric pressure. The catalysts used in this study were ZSM-5, US-Y, ASA, fresh FCC (fluid catalytic cracking) commercial catalyst (Cat-A) and equilibrium FCC catalysts with different levels of metal poisoning were studied. The initial results for polymer degradation at 360 °C (catalyst to polymer ratio of 2:1) in a fluidised bed reactor in terms of the yield of volatile hydrocarbon products were: model catalysts>commercial FCC catalyst>E-Cats. However, when the process conditions more closely resembled to FCC conditions, the fresh commercial FCC catalyst was more favourable in terms of the yield of volatile hydrocarbon products. The degradation of HDPE over E-Cats although reduced was similar to ASA in product selectivity and yield, and the level of metal contamination did not affect the product stream generated. A simple economic evaluation of polymer recycling process is reported showing that a catalytic system based on E-Cats appears comparable in costs to a commercial thermal cracking plant.     

微生物脱砷预处理难冶含砷金矿提金的研究

用化能自养的氧化铁硫杆菌和氧化硫硫杆菌，对河北半壁山含砷金精矿进行了公斤级的预处理氧化脱砷实验．在细菌预处理反应器中的连续和批式脱砷实验表明，目前选育的菌种是有效的．严格控制工艺条件，可以在4天左右便脱砷率高于80％．后续氰化提金实验证实，金的总回收率可达90％以上．用微生物脱砷预处理难冶含砷金矿有金浸出率高、便于固定浸出的砷、免除对环境污染的优点，是有很好应用前景的处理难冶含砷金矿的技术路线．     

Ion‐exchange resins. II. Acrylamide crosslinked copolymers as precursors for some ion exchangers

Crosslinked copolymers of acrylamide (AA) and ethylacrylate and some ion exchangers derived from them containing either primary amine groups, obtained by the Hofmann degradation of the amide groups, or carboxylic groups, obtained by the alkaline hydrolysis of the ester groups, were studied. Divinylbenzene and N,N′‐methylenebisacrylamide were used as crosslinkers. The starting copolymers and the corresponding ion exchangers were characterized by IR spectroscopy, swelling behavior, and thermogravimetric analysis. The ion‐exchanger properties were correlated with the crosslinker nature and the chemical reactions performed on the AA copolymers. The average molecular weight between two crosslinks, determined from the swelling data in water, was compared with that calculated on the basis of the copolymerization stoichiometry only for the carboxylic cation exchangers. In this way, the preservation of the crosslink density after the hydrolysis was revealed. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2701–2707, 2003