Photocatalytic degradation of methyl tert‐butyl ether (MTBE) in contaminated water by ZnO nanoparticles

BACKGROUND: Over the past several decades methyl tert‐butyl ether (MTBE) as additive to gasoline, intended to either boost ratings of fuel or to reduce air pollution, has been accepted worldwide. Since MTBE has high water solubility, the occurrence of fuel spills or leaks from underground storage tanks or transferring pipeline has led to the contamination of natural waters. In this study the degradation of aqueous MTBE at relatively high concentrations was investigated by a UV‐visible/ZnO/H₂O₂ photocatalytic process. The effects of important operational parameters such as pH, amount of H₂O₂, catalyst loading and irradiation time were also investigated. Concentration of MTBE and intermediates such as tert‐butyl formate and tert‐butyl alcohol were measured. RESULTS: Time required for complete degradation increased from 20 to 150 min when the initial concentration was increased from 10 to 500 mg L^?1. The first‐order rate constants for degradation of MTBE were estimated to be 0.183–0.022 min^?1 as the concentration increased from 10 to 500 mg L^?1. Study of the overall mineralization monitored by total organic carbon analysis showed that at an initial concentration of 100 mg L^?1 MTBE complete mineralization was obtained after 100 min under UV‐visible/ZnO/H₂O₂ photocatalysis. CONCLUSION: The data presented in this paper clearly indicated that UV‐visible/ZnO/O₂ as an advanced oxidation process provides an efficient treatment alternative for the remediation of MTBE‐contaminated waters. Copyright © 2008 Society of Chemical Industry     

最大重迭对称性分子轨道和分子几何参数计算

建立了AMl级别的最大重迭对称性分子轨道计算方案(MOSMO)。采用通常的半经验分子轨道方法AMl级别中完全相同的参数，计算了各种分子的几何参数等。所得计算结果与实验值及HF／6-31G*从头算方法计算结果相符，说明提出的计算方案是可行的。同时，由于提出的计算方案过程简单，更易推广使用到从头算方法难以解决的大分子体系和超分子体系的结构和性质研究。     

Nonaqueous Phase Liquid Pool Dissolution as a Function of Average Pore Water Velocity

Bench-scale reactor experiments were performed to study the dissolution of a binary naphthalene-in-nonane mixture nonaqueous phase liquid (NAPL) pool over a wide range of average pore water velocities, vx (≈0.1–60 m/day). Experimental NAPL pool dissolution flux values were determined using a steady-state mass balance approach. The experimental flux data were compared to model predictions made assuming either local equilibrium or mass-transfer limited conditions. The local equilibrium model could describe the trends in the average effluent concentration and dissolution flux with 0.110?m/day. Data determined to be under mass-transfer limited conditions were fit to the nonequilibrium model to estimate values for an overall mass-transfer coefficient. The calculated overall mass-transfer coefficients had an average value of 0.407 m/day and showed no correlation with vx, probably due to mass-transfer resistance becoming dominated by the diffusional resistance in the NAPL. These results suggest that the nonequilibrium approach is better suited for describing high velocity (vx>10?m/day) dissolution of multicomponent NAPL pools, and that flushing of groundwater at very high velocities may not be an effective approach for enhancing NAPL-pool dissolution flux.     

Determination of the total concentration and speciation of Al(III) in tea infusions

The aluminium species in different tea infusions were investigated, by determining their stability constants and concentration. This was done for some particular samples using a simple experimental method based on the sorption of aluminium on the strongly sorbing resin Chelex 100, by a batch procedure. From the thermodynamic information obtained it is possible to calculate the concentration of the different species, and in particular that of the free metal ion, which is very important for evaluating the adsorption of aluminium on biological membranes. It was found that aluminium in the tea infusions here considered is present at high total concentration, approximately 0.1 mM, but mainly linked to strong complexes, for instance with side reaction coefficient higher than 10(5.11) at pH 3.95 in one case (tea 1). This could be the reason for the low toxicity of aluminium in tea. These strong complexes were not dissociated even in the presence of Chelex 100. In this case only a limiting value of the reaction coefficient could be evaluated. The presence of the very strong complexes was found in all the tea sample here considered. In two of the considered samples (one black and one green tea) a part of Al(III) was linked to less strong complexes, for example with a reaction coefficient 10(4.14) (tea 2, pH 4.20). The presence in the considered tea infusions of other substances able to complex aluminium was also detected, by the well known ligand titration procedure, at concentration ranging from 0.65 to 3.37 mM in three tea infusions, and at somewhat higher concentration in the case of the ready drink, which was also considered for comparison.     

厦门市气源转换的技术分析

分析了气源转换时原有输配系统的管道、调压设备、计量设备、用气设备与天然气系统相适应的问题，提出了相应的措施。     

用常规电阻率测井资料确定水淹层的剩余油饱和度

油田综合含水越来越高，利用电阻率测井资料确定地层的剩余油饱和度变得非常困难。针对这一问题，提出了确定地层水民阻率和含油饱和度的方法。（１）利用已知的地怪水分析资料，采用井下自然电位刻度，井间对经和双自然电位一方法来示准地层水混合电阻率，然后利用相邻井相同地层的电阻率对比方法求含水饱和度。（２）利用电阻率的横向探测特性，避开阿尔奇公式中ｍ、ａ选择上的困难，采用横向法计算水淹层目前的含水饱和度。利用以     

隆德县大水沟饮水工程建设与管理措施分析

隆德县在大水沟农村饮水工程建设管理中，科学规划，优化设计方案，完善政策措施，创新管理体制和运行机制，尤其是用水户全过程参与工程建设管理、实行“两部制”水价、实施工程定期检查养护制度、建立工程管理单位目标责任考核制度、执行水费统一管理和提留统筹费等一系列做法．确保了国家投资效益的充分发挥和工程的可持续利用．     

DFMC在水利机械产品开发中的应用研究

分析了DFMC(大规模定制设计)关键技术及相关技术,提出了运用该项技术开发产品企业应作好的前期准备,研究了水利机械产品"大型移动启闭机"的定制开发。     

Precise rendering method for exact anti-aliasing and highlighting

This paper introduces the Precise Rendering Method, which generates accurately anti-aliased and highlighted images from tessellated polygons. The Precise Rendering Method first solves the aliasing problems of hidden surface removal by using the Cross Scanline Algorithm. This algorithm can exactly calculate polygon areas projected onto each pixel by using horizontal and vertical scanlines. Aliasing artifacts in shading are then prevented by the Reflection Intergration Method, which analytically integrates the intensity of reflection in the solid angle defined by surface normals at vertices of the projected area. Several synthesized images are created to show the efficiency of the Precise Rendering Method.     

高炉冲渣水在采暖工程中的应用

随着我国经济的迅速发展,能源消耗不断增加,节约能源、降低能源消耗势在必行,余热利用是节约能源的一个重要环节,冶金行业高炉冲渣水作为采暖热媒可以节约大量能源。