Ecological Behavior of Linear Alkylbenzene Sulfonate (LAS) in Soil-Plant Systems

More and more linear alkylbenzene sulfonate (LAS) has contaminated the water and soil ma pollution discharge, making it important to identify the ecological behavior and toxicity of LAS so as to carry out measures that will reduce its negative effects on the ecosystem. The ecological behavior of LAS. including degradation, migration, and plant uptake, in both soil-paddy rice and soil-soybean systems was studied. Reduction of LAS in pot and field plots followed the first order reaction kinetics with degradation half-lives of 35-50 days with LAS decreasing to very low concentrations after a season of crop growth. Strong migration ability for LAS was found and the breakthrough time in a 1.5 in soil monolith was significantly shortened to 23 days by preferential flow. Leachate volumes of soil-paddy and soil-soybean systems at preferential breakthrough were much different, while the leachate volumes at equilibrium governed by soil adsorption/desorption processes were very similar. Significant uptake of LAS in both paddy rice and sovbeans was observed in pot and field experiments (P < 0.05). In aquatic culture, 20 μg mL-1 and above of LAS significantly inhibited the growth of paddy seedlings (P < 0.05). The critical concentration for LAS in soil inhibiting the growth and yield of paddy was 160 μg g-1; when higher, there was a strong negative influence, with decreases in height, spike length, and production, when lower than 80 μg g-1, paddy growth was stimulated. There was little effect of LAS on soybeans.

Effect of Dermal Exposure to Paraphenylenediamine and Linear Alkylbenzene Sulphonate in Guinea Pigs

To study the effects of paraphenylenediamine （PPD） and linear alkylbenzene sulphonate （LAS） alone and in combination on the skin. Methods Forty-eight guinea pigs were divided equally into 4 groups and exposed to PPD （4 mg/kg）, LAS （12 mg/kg） and PPD （4 mg/kg） plus LAS （12 mg/kg） for 30 days. The biochemical parameters such as acid phosphatase, gtutathione-s-transferase, glutathione peroxidase, glutathione, lipid peroxidafion and histamine contents in exposed skin were estimated. The histopathological examination of the exposed skin was also carried out. Results The skin enzymes, lipid peroxidation, and histamine increased while glutathione decreased in skin. The simultaneously exposed group showed additive toxic effects. The histopathological examination showed severe hyperkeratosis, thickening of collagen fibres and vacuolisation of epidermal cells in PPD plus LAS exposed skin. Conclusion The findings of the present study suggest that simultaneous exposure to PPD and LAS has additive toxic effects.

Simulation of Suspension Catalytic Distillation for Synthesis of Linear Alkylbenzene

Suspension catalytic distillation (SCD) has been developed recently as an innovative technology in catalytic distillation. In this paper, a brief introduction to SCD is given and an equilibrium stage (EQ) modei is developed to simulate this new process for synthesis of linear alkylbenzene (LAB) from benzene and 1-dodecene. Since non-ideality of this reaction systern is not strong, EQ modei developed could be applied to it successfully. Simulation results agree well with experimental data, and indicate some characteristics of SCD process as an advanced technology for the production of LAB: 100% conversion of olefins, low temperature (90-100℃) and low benzene/olefin mole ratio.

Surfactant Linear Alkylbenzene Sulfonate Effect on Soil Cd Fractions and Cd Distribution in Soybean Plants in a Pot Experiment

A pot experiment was conducted to study the effect of an anionic surfactant linear alkylbenzene sulfonate(LAS) application on cadmium(Cd)fractions in soils and Cd distribution in different tissues of soybean(Glycine max)plants as well as soil pH.Soil samples were treated with three levels of Cd(0,5,and 10 mg kg^(-1))and five levels of LAS(0,5, 15,50,and 100 mg L^(-1)).Results indicated that compared to the control soils(no Cd and no LAS treatment),soil pH increased and available Cd decreased in the soil treated with external Cd and watered with LAS solutions.Meanwhile, soil exchangeable Cd and Cd bound to carbonates decreased;Cd bound to amorphous iron and manganese oxides and Cd bound to organic matter increased.In addition,LAS application could reduce enrichment of Cd in soybean plants, resulting in decreased Cd in the soybean plants.Thus,suitable LAS application could decrease bioavailability and mobility of soil Cd.

Kinetic Model of Hydrogenation for Removal of Trace Olefins from Alkylation Mixture Formed during Linear Alkylbenzene Synthesis

Through the hydrogenation experiments for removal of olefin impurities in effluent mixture obtained from alkylation reactor for linear alkylbenzene synthesis, the reaction kinetics was studied. The experimental results showed that the catalytic activity of Pd/Al2 O3 among four kinds of catalysts was the highest, and the olefin conversion reached 100%when the reaction temperature was higher than 140 ℃. The kinetic model was established through parameters estimation.The experimental validation of the kinetic model showed that the kinetic model had higher simulation accuracy. The results of prediction by the kinetic model indicated that with the intensification of reaction conditions, the olefin conversion would increase and the bromine index of the linear alkyl benzene would decrease. Under the conditions covering a WHSV of 2.0 h^(-1),a temperature of 90 ℃, and a hydrogen partial pressure of 1.5 MPa, the olefin conversion was 99.67%, and the bromine index of the linear alkyl benzene could be reduced to less than 20.00 mgBr/(100 g).

Linear Alkylbenzene Sulfonates in the Groundwater and Surface Waters： Ergene Basin Case Study

Ergene Basin is one of the most important industrial centers due to the geographical location in Turkey. Uncontrolled and rapidly increasing industrialization brings together a large number of environmental problems in the basin. In this study, pollution was investigated in the water samples taken at time intervals and different parts of groundwater and surface water resources located within Ergene Basin by methylene blue anionic surfactants （MBAS） analysis method. Turbidity, temperature, pH, electrical conductivity （EC）, concentrations of total P and linear alkylbenzene sulfonates （LAS） were simultaneously determined in the investigated water resources. The results were compared with the Turkish Water Pollution Control Regulation specified in the Quality Criteria of the Inland Water Resources according to their class. The total P and LAS concentrations of surface waters are generally higher than groundwater. In terms of LAS concentrations, the groundwater is Ⅰ-Ⅱ class and the surface water is Ⅱ-Ⅳ class.

Synthesis of Linear Alkylbenzene in a Novel Liquid-Solid Circulating Moving Bed Reactor

For the alkylation of benzene with long-chain olefins, using Hβzeolite catalyst as replacement of HF or AlCl3 has the advantages of no corrosion, less environmental pollution, and much more 2-phenyl isomer, which has the highest biodegradability and solubility, and better detergent properties among the related isomers. The characterization of the coke shows that the deactivation of catalyst is caused by the jam of bulkier molecules, such as naphthalene, indane and linear alkylbenzenes, which are too big to move quickly in the intracrystalline pores of catalyst. The deactivated catalyst can be regenerated by benzene washing at higher temperature. To make the processes of reaction and regeneration continuous, a novel moving bed reactor is developed. Comparing with the processes with fixed bed reactors, the processes in this work have the advantages of continuous operation, low temperature, low pressure, low mole ratio of benzene to olefins, and high weight hourly space velocity.

Investigating the potential of using acoustic frequency on the degradation of linear alkylbenzen sulfonates from aqueous solution

The effectiveness of using acoustical （sonochemical） reactor for degradation of linear alkylbenzen sulfonate （LAS） from aqueous solution was investigated. LASs are anionic surfactants, found in relatively high amounts in domestic and industrial wastewaters. In this study, experiments on LAS solution were performed using methylene blue active substances （MBAS） method. The effectiveness of acoustical processor reactor for LAS degradation is evaluated with emphasis on the effect of treatment time and initial LAS concentration. Experiments were performed at initial concentrations of 0.2, 0.5, 0.8 and 1.0 mg/L, acoustic frequency of 130 kHz, applied power of 500 W and temperature of 18℃-20℃. At the conditions involved, LAS degradation was found to increase with increasing sonochemical time. In addition, as the concentration increased, the LAS degradation rate decreased in the acoustical processor reactor.

Silicon Labs公司新增100多款时钟IC产品 扩展定时产品组合

2011年5月17日,高性能模拟与混合信号IC领导厂商Silicon Laboratories（芯科实验室有限公司）宣布对时钟IC产品组合进行重要扩展,以满足市场对具有成本效益和可编程定时元器件的强劲需求。该公司新增添了100多款时钟发生器和时钟分配器产品,可满足对成本敏感、有大批量生产需求的消费、工业、通信和嵌入式领域的应用需求。这项时钟产品组合的扩展,得益于最近对SpectraLinear公司的收购,进一步确立了Silicon Lab公司作为业界最全面的定时IC供应商的地位,

Silicon Labs:2014年至少取得定时元件市场亚军

＂Silicon Labs最开始是从高性能细分市场开始进入定时元件市场的,在高性能市场已有10年的经验。从高端市场出发,我们不断地向更为广阔的市场进军,3年前推出了面向中端市场的产品,今年开始大举进入低端大批量市场,包括收购spectra linear公司,这让我们拥有了更为丰富的产品线。同时我们内部在开发新的时钟技术。

Silicon Labs挑战大批量时钟市场,发布高性能4-PLL时钟IC应对光网络挑战

新增100多款时钟IC产品满足大批量市场需求 近日,Silicon Laboratories公司（芯科实验室有限公司）宣布对时钟IC产品组合进行重要扩展,以满足市场对具有成本效益和可编程定时元器件的强劲需求。该公司新增添了100多款时钟发生器和时钟分配器产品,可满足对成本敏感、有大批量生产需求的消费、工业、通信和嵌入式领域的应用需求。这项时钟产品组合的扩展,得益于最近对SpectraLinear公司的收购,如此,

基于LabVIEW和Matlab混合编程的在线信号与线性系统实验

针对信号与线性系统课程的实验教学的需要,结合Matlab的较强的数值分析及信号与系统处理功能和Lab VIEW软件开发平台的友好的用户界面及Web发布功能,建立了交互式虚拟信号与线性系统实验平台。本文主要介绍了Matlab与Lab VIEW各自的优点所在和混合编程技术平台的实现及在建立交互式虚拟信号与线性系统实验平台时的几个仿真实验实例;从理论上分析了几个仿真实验的实验原理并演示了交互实验的运行过程、说明了混合编程的代码实现、对比分析了实验结果及展示了Web发布过程。结果表明:利用该实验平台可较方便地增强"信号与线性系统"教学的交互性,提高教学质量。同时也演示了一种基于Lab VIEW和Matlab混合编程的实验平台搭建的方法。

线性方程组的迭代解法及其Matlab实现程序

介绍了求解线性方程组的迭代法的基本思想和两种常见迭代方法,推论出迭代的收敛条件,并且用Matlab软件编制出迭代法的实现程序。

基于MATLAB的模拟线性通信系统可视化设计

采用MATLAB语言对模拟通信系统中的线性调制系统进行了仿真,实现了各种模拟线性系统的可视化设计,通过本设计,可以直观地理解和领会模拟线性通信系统的基本原理。

Using monochromatic light to measure attenuation length of liquid scintillator solvent LAB

Linear alkylbenzene(LAB) will be used as solvent for the liquid scintillator in the central detector of Jiangmen Underground Neutrino Observatory. The sheer size of the detector imposes significant challenges and the necessity to further improve the optical transparency of high-quality LAB. In order to study high optical transparencies, we continuously improve our measurement setup and use monochromatic light to measure the attenuation lengths of LAB samples. Moreover, the effects of organic impurities on LAB samples are studied to understand their interaction mechanisms and further improve the optical transparency of LAB.

Nafion/SiO_2 Nanocomposites:High Potential Catalysts for Alkylation of Benzene with Linear C_9-C_(13) Alkenes

High surface area Nafion/SiO2 nanocomposites with nano-sized Nafion resin particles entrapped and dispersed within the highly porous silica matrix exhibited significantly enhanced activity, high selectivity and long-term stability for the alkylation of benzene with linear C9-C13 alkenes owing to the increased accessibility of Nafion resin-based acid sites to reactants.

分子筛结构与直链烷基苯催化合成性能的构效关系

研究了不同拓扑结构的分子筛在直链烷基苯(LAB)催化合成反应中的构效关系,对性能较优的Y型分子筛进行了孔道和酸性调变,并进行了苯和1-十二烯烷基化催化性能评价。采用X射线荧光光谱(XRF)、X射线衍射(XRD)、NH_(3)程序升温脱附(NH_(3)-TPD)、N_(2)低温吸附-脱附等方法对分子筛物化性质进行了表征。结果表明:酸性是影响分子筛催化活性的关键因素,中强酸酸量较高的分子筛烷基化初活性及稳定性较好;具有一维孔道结构的分子筛催化合成LAB产物中2-LAB质量分数高达83.9%,但烷基化稳定性较差;多维孔道更有利于产物扩散,烷基化稳定性较好。较小孔道尺寸的分子筛直链度和2-LAB含量较高;超笼结构不利于产物择形。Y型分子筛具有较高的中强酸酸量和十二元环多维孔道结构,烷基化活性和稳定性最优,对其进行扩孔改性、增加介孔比例,寿命可提高约33%。

直链烷基苯催化剂研究进展

综述了直链烷基苯(LAB)合成中涉及固体酸和离子液体等新型催化剂的研究进展,并介绍了提高2-LAB选择性和催化剂稳定性的研究,综合对比了新型催化剂的优缺点。结果表明:负载型杂多酸、分子筛、黏土、离子交换树脂、离子液体等催化剂在烷基化反应中展现出良好的稳定性、催化活性,并在催化剂再生与产物分离方面有较好的优势,但在烷基苯的收率、选择性以及再生方面还存在许多不足。研究结果对苯与长直链烯烃烷基化反应催化剂的选型具有一定的指导意义。

TH-06催化剂合成直链烷基苯Ⅰ-工艺条件的研究

对ＴＨ－ ０６ 分子筛催化剂上长链烯烃与苯烷基化反应过程进行了研究。首先考察了工业原料中杂质及水含量对反应的影响，并提出了原料精制的方法；然后采用精制工业原料对反应的工艺条件进行了探讨。结果表明，该催化剂活性高，稳定性好，可反复再生，且产物分布好。

直链重烷基苯磺酸盐的驱油能力研究

研究了所合成的各种结构的直链烷基苯磺酸盐单剂及其复配体系在不同碱质量分数情况下对大庆四厂油 /水界面张力情况。结果表明 :对同一碳链长度的直链烷基苯磺酸盐 ,带甲基的比带乙基、异丙基和苯环上不带取代基的烷基苯磺酸盐降低界面张力的能力强 ;同样结构的十六碳链长的烷基苯磺酸盐又较其他碳链长度的烷基苯磺酸盐效果更优 ;长、短碳链的带甲基的直链烷基苯磺酸盐按一定比例复配 ,协同效应显著 ;与支链烷基苯磺酸盐复配后 ,体系的驱油能力、抗稀释性和抗Ca2 +、Mg2 +能力明显增加。