Promotional effect of transition metal doping on the properties of KF/CaO catalyst for biodiesel synthesis

A series of heterogeneous KF/CaO catalysts modified with transition metals (lanthanum, cerium, and zirconium) were prepared via wet impregnation method and applied to the trsansesterification process of waste cooking oil (WCO) as feedstock with methanol to biodiesel production. The structure, performance of the solid catalysts was characterized by X-ray diffraction (XRD), temperature programmed desorption of CO₂ (CO₂-TPD), scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDS). The effect of methanol/oil molar ratio, ¹reaction time, reaction temperature, catalyst amount, and stability was investigated. The results showed that 10 wt% of lanthanum, cerium, and zirconium improved the catalytic activity of KF/CaO catalyst. The maximum catalytic activity using the lanthanum doping of 10wt% on KF/CaO catalyst was reached 98.7% under the optimal reaction condition of methanol/oil molar ratio of 12:1, reaction for 1 h at reaction temperature of 65°C, and 4% (wt/wt oil) catalyst amount. In addition, the FAME yield of KF/CaO/La catalyst remained higher than 95% after 10 cycles. The promotional effect of lanthanum doping could be attributed to the enhancement of the basicity strength of KF/CaO catalyst and block the leach of Ca²⁺ in the transesterification reaction.     

用微电极测定曝气量对SBR系统中硝化作用的影响

为了研究曝气量对硝化作用的影响,实验采用3个相同的SBR装置,分别在曝气量为4、10和16 L/h的条件下处理人工污水,并采用自制的溶解氧、NO3-、NH4+和pH微电极测定了活性污泥絮体内部微元环境中相应基质的浓度。结果表明,曝气量为4 L/h时,活性污泥絮体内存在厌氧微区,NO3--N浓度减小了,发生了反硝化作用;而曝气量为10 L/h和16 L/h时,活性污泥絮体内发生的都是硝化反应,且NH4+-N浓度的减小量、NO3--N浓度的增大量都随着曝气量的增大而增大,pH随着曝气量的增大而减小。     

腐蚀性工业废气治理技术的研发及应用

这些年工业快速发展带动了我国经济快速发展,但是在工业生产过程中产生了大量的废气废液,有效处理这些工业有毒物质是工业发展需要面临的重要问题。本文在此基础上就腐蚀性工业废气治理技术的相关问题作了一定研究,以更好地促进我国经济的协调发展。     

臭氧氧化预处理难降解农药废水的研究

采用臭氧氧化技术预处理脲类农药生产废水,调节废水pH至弱碱,在此基础上考察废水臭氧氧化预处理的影响因素,得出最佳预处理条件：COD为200 mg/L,初始pH为11.3,臭氧投加量为14.2 mg/L。连续预处理180 min后,可生化性从0.12提高到0.58,说明该项技术可大大提高脲类农药废水的可生化性。     

上泉拱坝稳定分析及加固设计

上泉水库坝体为浆砌石连拱坝,现被定为病险水库,通过对拱坝结构强度、支墩抗滑稳定的计算分析,采用右坝肩基础、支墩防渗处理、坝体加固处理等措施进行除险加固,并对大坝稳定进行了验算。     

厌氧氨氧化在生物转盘系统中的实现

厌氧生物转盘系统中接种来自ASBR的厌氧污泥,在温度40～41℃、pH值为8.25～8.50和HRT为1.3d条件下连续运行142d,先后经历了以出水氨氮浓度略高于进水氨氮浓度为特征的污泥适应阶段、以氨氮小幅度去除为特征的厌氧氨氧化菌活性表现阶段及以氨氨和亚硝酸盐氮成比例并大幅度去除为特征的厌氧氨氧化菌活性提高阶段后,成功培养了厌氧氨氧化菌种,启动了反应.在进水氨氮和亚硝酸盐氮负荷均为0.051 kg·m-3·d-1情况下,对二者的去除率分别达到了98.15%和99.56%.污泥的颜色也发生了由黑色→黄白色→棕红色→棕褐色等一系列的变化,通过显微镜镜检发现污泥中细菌主要是革兰氏阴性菌,有短杆状和球状,扫描电镜镜检发现颗粒污泥表面有球状菌的聚集体.     

药剂抑制铜绿微囊藻生长的试验研究

研究用从芦苇中提取的2-甲基乙酰乙酸乙酯和大麦秸浸出液两种化感物质以及十六烷基溴化铵和异噻唑啉酮等四种药剂对不同生长期的铜绿微囊藻进行了对比抑制试验,结果显示在铜绿微囊藻生长的迟缓期投加试验药剂效果比在对数期投加效果都好,在迟缓期投加四种药剂,都有很好的抑藻效果;在铜绿微囊藻生长的对数期投加化感物质,虽然有一定的抑藻率,但效果较差,而在藻对数期投加10mg/L以下的CTAB和异噻唑啉酮能达到很好的水华抑制效果。同时发现,化感物质在某些浓度时还对铜绿微囊藻有刺激生长的作用。     

Temperature and nutrients are significant drivers of seasonal shift in phytoplankton community from a drinking water reservoir,subtropical China

Reservoirs are an important source of water supply in many densely populated areas in southeast China. Phytoplankton plays an important role in maintaining the structure and function of these reservoir ecosystems. Understanding of seasonal succession in phytoplankton communities and its driving factors is essential for effective water quality management in drinking-water reservoirs. In this study, water samples were collected monthly at the surface layers of riverine, transitional, and lacustrine zones from May 2010 to April 2011 in Tingxi Reservoir, southeast China. The phytoplankton showed distinct seasonal shifts in community structure at both taxonomic and functional levels. Cyanophyta was the dominant group in summer, especially species of Raphidiopsis in May and Aphanizomenon in June, and cyanobacterial dominance was promoted by both warmer conditions and excessive nutrients loading. Cyanophyta was gradually replaced by Cryptophyta (e.g., Chroomonas caudata) in abundance and by Bacillariophyta (Fragilaria sp. or Synedra sp. and Melosira sp.) in biomass with decreasing temperature. It appeared that seasonal shifts in phytoplankton composition were closely related to climate, nutrient status, and hydrology in this reservoir. Our partial RDA results clearly showed that water temperature and nutrients (TN and TP) were the most critical factors driving phytoplankton community shift in the abundance and biomass data, respectively. Further, with the global warming, cyanobacterial blooms may increase in distribution, duration, and intensity. In our study, the abundance and biomass of cyanobacteria had significant and positive correlations with temperature and phosphorus. Therefore, a stricter limit on nutrient input should be a priority in watershed management to protect drinking water from the effects of cyanobacterial blooms, especially in high-temperature period.     

Methyl-triclosan binding to human serum albumin: Multi-spectroscopic study and visualized molecular simulation

Methyl-triclosan (MTCS), a transformation product and metabolite of triclosan, has been widely spread in environment through the daily use of triclosan which is a commonly used anti-bacterial and anti-fungal substance in consumer products. Once entering human body, MTCS could affect the conformation of human serum albumin (HSA) by forming MTCS–HSA complex and alter function of protein and endocrine in human body. To evaluate the potential toxicity of MTCS, the binding mechanism of HSA with MTCS was investigated by UV–vis absorption, circular dichroism and Fourier transform infrared spectroscopy. Binding constants, thermodynamic parameters, the binding forces and the specific binding site were studied in detail. Binding constant at room tempreture (T = 298 K) is 6.32 × 10³ L mol⁻¹; ΔH⁰, ΔS⁰ and ΔG⁰ were 22.48 kJ mol⁻¹, 148.16 J mol⁻¹ K⁻¹ and −21.68 kJ mol⁻¹, respectively. The results showed that the interactions between MTCS and HSA are mainly hydrophobic forces. The effects of MTCS on HSA conformation were also discussed. The binding distance (r = 1.2 nm) for MTCS–HSA system was calculated by the efficiency of fluorescence resonance energy transfer. The visualized binding details were also exhibited by molecular modeling method and the results could agree well with that from the experimental study.     

Removal of <Emphasis Type="Italic">Anabaena spiroides</Emphasis> by potassium permanganate pre-oxidation: effect on photosynthetic capacity and molecular weight distribution

Bench scale tests were conducted to investigate the effect of potassium permanganate pre-oxidation on the photosynthetic activity and molecular weight distribution of Anabaena spiroides. Different concentrations of potassium permanganate were added into the suspension of Anabaena spiroides, one of the dominant algae in water bloom, and after pre-oxidation of permanganate for 1 h, the results show that the removal rate significantly increases by 33.99~36.35% compared to direct coagulation. Then, the algal characteristics, including photosynthetic ability, the changes in extracellular organic matter three-dimensional fluorescence, and the distribution of molecular weight were conducted and the results show that along with increasing concentration of potassium permanganate, the photosynthetic ability of algae decreases, more extracellular organic matter is secreted, and large molecular weight matter (humic-like and fulvic-like substances) are generated. Therefore, this study demonstrates that potassium permanganate could be used in addressing the algae-rich water.