熔渗温度和时间对 C/C-SiC-ZrC 复合材料性能的影响研究

目的研究熔渗温度和熔渗时间对复合材料密度和弯曲性能的影响。方法采用化学气相渗透法(CVI)和聚合物浸渍裂解法(PIP)制备熔渗用低密度C/C复合材料,以Si0.9-Zr0.1合金为熔渗金属,采用反应熔渗法(RMI)制备C/C-SiC-ZrC复合材料。测试C/C-SiC-ZrC复合材料的开孔率、密度、弯曲强度,分析试样的相组成。结果熔渗温度为1450℃时,复合材料的密度仅有1.97 g/cm3,弯曲强度仅为153 MPa;当熔渗温度升高到1550℃时,密度和弯曲强度分别升高到2.39 g/cm~3和260 MPa;而当熔渗温度升高到1650℃时,密度和弯曲强度又分别降为2.18 g/cm~3和208 MPa。1.5 h熔渗时复合材料的密度值最大,为2.46 g/cm~3,相对0.5 h熔渗的最小值提高了5.1%;1.0 h熔渗时复合材料材料的弯曲强度最高,达到了260 MPa,相对于1.5 h熔渗的最低值仅提高了3.2%。结论复合材料的致密度和弯曲强度随熔渗温度的升高先升高后降低,密度随熔渗时间的延长而增大,而弯曲强度随熔渗时间的延长先升高后降低,但密度和弯曲强度随熔渗时间的延长变化较小。     

镧改性ZnO-TiO_2光催化氧化活性染料的实验研究

采用溶胶-凝胶法制备掺杂Zn O的Ti O2复合半导体,用X射线衍射和电镜扫描对晶体结构进行表征,最优的锌掺杂量、镧掺杂量、煅烧温度分别为3%,0.3%,500℃。以活性染料配水作为目标降解物,考察了对6种不同活性染料的光催化氧化效果。0.3%镧改性Zn O-Ti O2对活性艳蓝X-BR的色度去除率可以达到97.3%,得到最佳脱色率的条件是使用紫外光作为光源,光照时间2 h,初始质量浓度100 mg/L,p H值控制在1左右,氯离子浓度控制在1 mol/L。     

Bisolute Equilibrium Studies for the Sorption of Basic Dyes on a GAC from Almond Shells: A Nonlinear Approach

Aqueous phase adsorption of three textile dyes onto a granular activated carbon produced from acid activation of almond shells is presented. Primarily, the sorption of three basic dyes, methylene blue, rhodamine b, and malachite green oxalate were studied. Four models, the Freundlich, the Langmuir, the Redlich-Peterson, and the Toth isotherms were compared for their quality of fit to the single-solute sorption data. Next, sorption of the three likely binary systems was examined. Four bi-solute models, the extended Langmuir with and without an interaction term, the extended Redlich-Peterson with an interaction term, and the empirical extended Freundlich model were used to predict sorption in the binary systems. Nonlinearly determined constants of the corresponding single-solute isotherms were used in the binary models to compare with experimental binary sorption data. For the single-solute system, the three-parameter models of the Redlich-Peterson and the Toth isotherms outperformed the Langmuir and Freundlich models. The empirical extended Freundlich model produced the closest comparison to the binary data in each system. In general, the nonlinear method provided a simple and computationally effective technique of producing optimal fitting parameters for the bi-solute sorption models.     

不同结构阳离子染料好氧生物脱色性能的研究

采用好氧驯化活性污泥对5种不同结构阳离子染料的生物脱色效果进行了动态观察,并在不同醋酸浓度下对脱色效果的影响进行了研究,结果表明,在好氧条件下,活性污泥对阳离子染料的脱色率较高,阳离子红GTL和阳离子艳蓝2RL(浓度为2 0mg L)的脱色率分别达93%和98% ;提高污泥浓度对染料脱色率的影响不明显;醋酸(2 0 0～12 0 0mg L)和染料(2 0～10 0mg L)浓度的改变对阳离子红2GL、阳离子红GTL、阳离子艳蓝2RL、碱性绿染料的脱色率影响不大,揭示这几种结构阳离子染料的生物脱色是吸附和后续生物降解共同作用的结果;而随醋酸浓度增加,阳离子红6B的脱色率增加,是与醋酸产生共代谢作用的结果。     

Photocatalytic degradation of Chicago Sky Blue 6B and Benzopurpurin 4B using titanium dioxide thin film

Aqueous solutions of azo dyes undergo degradation to form harmless intermediates and colorless products following irradiation by visible light in the presence of titanium dioxide thin films. The dyes that were studied in this work are： Chicago Sky Blue 6B and Benzopurpurin 4B. Results obtained indicated that complete mineralization of the dyes took place under the experimental conditions. There was an increase in conductivity after the complete mineralization experiments possibly indicating the formation of ions such as NO3^- and SO4^2-. Chemical oxygen demand（COD） measurements show a decrease in organic matter for both dyes following complete degradation. The effect of how changing experimental conditions such as pH, temperature and starting concentrations of dyes affected the rate of dye degradation was measured. There was an increase in the rate of disappearance of the dye color at lower pH. High concentrations of dye solutions reauired Iona dearadation time.     

阳离子絮凝剂P(AM-DMC)的合成及其对活性染料废水的絮凝脱色

以K2S2O8-脲为引发剂,通过自由基聚合法合成了丙烯酰胺-2-甲基丙烯酰氧乙基三甲基氯化铵P（AM—DMC）絮凝剂,并研究了其对4种活性染料模拟废水的脱色效果,考察了P（AM—DMC）加入量、阳离子度、特性粘数、染料溶液pH等因素对脱色效果的影响。实验结果表明：最佳P（AM—DMC）加入量随染料分子中磺酸基数目的增加而增加,随絮凝剂阳离子度的增大而减少;阳离子度大于52％时,最高脱色率基本相同;特性粘数对脱色效果影响很小;在染料溶液为弱酸性及中性条件下,P（AM—DMC）的脱色效果较好。P（AM—DMC）对活性染料废水的脱色机理是,P（AM—DMC）中的-N^＋（CH3）3与染料分子中的-SO3^-结合,生成-N^＋（CH3）3SO3^-,同时也形成了分子间氢键,通过键合作用使染料分子聚集沉降。     

阴离子染料酸性大红GR水溶液的脱色及反应机理

以阴离子染料酸性大红GR为代表,采用十二胺做助剂,硫酸铝做混凝剂对其水溶液进行脱色处理,研究了助剂、混凝剂投加量、pH值及其盐效应等的影响．通过电导率、丁达尔效应和IR谱图分析其脱色机理：阴离子染料在水溶液中与十二胺之间发生化学反应,靠氢键和静电键结合,使染料微粒聚集形成胶体,再与硫酸铝混凝剂作用产生沉淀．     

改性粉煤灰对活性艳兰染料吸附性能的研究

采用添加熟石灰并升温活化的方法对粉煤灰进行改性,研究了粉煤灰改性的适宜条件及其对活性艳兰染料的吸附脱色规律。试验结果表明,活性艳兰染料溶液浓度60mg/L,改性粉煤灰用量40g/L,pH范围5~10,搅拌吸附时间30min,脱色率可达98%以上。改性粉煤灰对活性艳兰染料的脱色吸附符合Freundlich方程。随着吸附温度的升高,改性粉煤灰的吸附能力下降。     

Effect of transition metal ions on photocatalytic activity of ZnO in bleaching of some dyes

The photocatalytic bleaching of some dyes (erythrosin-B, fast green FCF and eosin Y) was carried in the presence of semiconducting zinc oxide and was observed spectrophotometrically. The effects of various operating variables like pH, concentration of dyes, amount of semiconductor and light intensity on the efficiency of the reaction were also observed. Attempts have been made to study the effect of the addition of other metal ions (Fe²⁺, Ni²⁺, Ag⁺, Cu²⁺, Co²⁺, V²⁺ and Mn²⁺). All the added metal ions increase the reaction rate to some extent. It was also observed that Fe²⁺ is most effective in photobleaching of erythrosin-B, whereas V²⁺ is more effective in the cases of fast green FCF and eosin Y. A tentative mechanism has been proposed.     

Cytotoxic effect of fenitrothion and lambda-cyhalothrin mixture on lipid peroxidation and antioxidant defense system in rat kidney

A mixture of pyrethroids plus organophosphates was assessed for their potential effects on lipid peroxidation, the antioxidant defense system and lactate dehydrogenase (LDH) in rat kidney in vitro. Various insecticide concentrations were incubated with kidney homogenate at 37°C for different incubation times. Treatment with fenitothion (FNT) plus lambda-cyhalothrin (LC) caused a significant induction (P < 0.05) in thiobarbituric acid reactive substances (TBARS), which might be associated to decreased levels of reduced glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST) activities and protein content in rat kidney. However, a significant induction of lactate dehydrogenase (LDH) activity was observed. The effect was concentration and time dependent. It can be concluded that depletion of GSH might indicate that reactive oxygen species (ROS) could be involved in the toxic effects of FNT plus LC which lead to marked perturbations in antioxidant defense system.