Synergy of adsorption and visible light photocatalysis to decolor methyl orange by activated carbon/nanosized CdS/chitosan composite

Activated carbon/nanosized CdS/chitosan (AC/n-CdS/CS) composites as adsorbent and photoactive catalyst were prepared under low temperature (≤60 °C) and ambient pressure. Methyl orange (MO) was chosen as a model pollutant to evaluate synergistic effect of adsorption and photocatalytic decolorization by this innovative photocatalyst under visible light irradiation. Effects of various parameters such as catalyst amount, initial MO concentration, solution pH and reuse of catalyst on the decolorization of MO were investigated to optimize operational conditions. The decolorization of MO catalyzed by AC/n-CdS/CS fits the Langmuir-Hinshelwood kinetics model, and a surface reaction, where the dyes are absorbed, is the controlling step of the process. Decolorization efficiency of MO is improved with the increase in catalyst amount within a certain range. The photodecolorization of MO is more efficient in acidic media than alkaline media. The decolorization efficiency of MO is still higher than 84% after five cycles and 60 min under visible light irradiation, which confirms the reusability of AC/n-CdS/CS composite catalyst.     

Laccase biosensor using magnetic multiwalled carbon nanotubes and chitosan/silica hybrid membrane modified magnetic carbon paste electrode

A simple and rapid strategy to construct laccase biosensor for determination of catechol was investigated. Magnetic multiwalled carbon nanotubes (MMCNT) which possess excellent capability of electron transfer were prepared by chemical coprecipitation method. Scanning electron microscope (SEM) and vibrating sample magnetometer (VSM) were used to identify its surfacetopography and magnetization, respectively. Laccase was immobilized on the MMCNT modified magnetic carbon paste electrode by the aid of chitosan/silica (CS) hybrid membrane. Using current-time detection method, the biosensor shows a linear response related to the concentration of catechol in the range from 10⁻⁷ to 0.165×10⁻³ mol/L. The corresponding detection limit is 3.34×10⁻⁸ mol/L based on signal-to-noise ratios (S/N) ≥3 under the optimized conditions. In addition, its response current retains 90% of the original after being stored for 45 d. The results indicate that this proposed strategy can be expected to develop other enzyme-based biosensors.     

变压吸附技术净化分离有机蒸气的研究进展

从变压吸附分离回收低沸点和中高沸点有机蒸气、变压吸附用吸附剂以及变压吸附分离回收有机蒸气工艺及其过程的计算机模拟等方面,评述了变压吸附技术在净化分离有机蒸气方面的研究进展。指出今后的研究方向为:新型变压吸附用吸附剂;多种分离过程的集成技术;过程优化设计;智能型控制系统;多成分有机气体的变压吸附分离;利用计算机进行变压吸附过程模拟的基础研究;吸附和脱附的传质、传热基础理论等。     

胶团强化超滤处理含镉废水

采用聚砜中空纤维超滤膜,十二烷基硫酸钠为表面活性剂,对含镉废水进行胶团强化超滤．研究了运行时间、十二烷基硫酸钠(SDS)浓度、膜操作压力、溶液pH、溶液中电解质浓度、与非离子表面活性剂Brij复配等因素对该工艺的影响．结果表明,该工艺对镉的去除率可达99％以上．但该工艺不适用于强酸性废水,电解质的存在会降低截留率,SDS与Brij复配能提高截留率．     

高举利剑保护自己

我国自2000年9月1日开始,实施了新的《产品质量法》.新《产品质量法》建立了企业产品质量的约束机制,补充完善了产品质量监督管理的行政执法手段和必要的强制措施,加大了对产品质量违法行为的法律制裁力度.以利最大限度地打击假冒伪劣产品的制售者,保护广大消费者的合法权益,维护正常的市场秩序.那么,作为消费者应如何运用这一法律赋予的利剑,保护自己并受用终生,就是今天本文讨论的话题.     

模拟退火算法在水资源预测中的应用及发展研究

通过对模拟退火算法在国内外众多学科领域中的发展及应用实例的分析，总结概括模拟退火算法的发展演进历程，结合水资源优化配置中存在的不确定性、复杂性特征，提出了粒子群模拟退火算法在水环境资源预测中的应用前景。     

Prediction of dust fall concentrations in urban atmospheric environment through support vector regression

Support vector regression (SVR) method is a novel type of learning machine algorithms, which is seldom applied to the development of urban atmospheric quality models under multiple socio-economic factors. This study presents four SVR models by selecting linear, radial basis, spline, and polynomial functions as kernels, respectively for the prediction of urban dust fall levels. The inputs of the models are identified as industrial coal consumption, population density, traffic flow coefficient, and shopping density coefficient. The training and testing results show that the SVR model with radial basis kernel performs better than the other three both in the training and testing processes. In addition, a number of scenario analyses reveal that the most suitable parameters (insensitive loss function e, the parameter to reduce the influence of error C, and discrete level or average distribution of parameters σ) are 0.001,0.5, and 2 000, respectively.     

塑料和木屑的共液化以及催化液化实验研究

在温度为613～693K、压力为20～30MPa的条件下,以去离子水为溶剂在1L间歇式高压反应釜中对塑料和木屑进行共液化研究,实验考察了反应时间、溶剂填充率、温度、催化剂对液化行为的影响。结果表明:木屑的加入能降低塑料液化对高温的要求,共液化能获得较高的液化油收率。在未添加催化剂的情况下,共液化反应在653K的温度下油收率达最大值24.0%,转化率达83.5%,油的热值为44.6MJ/kg。催化剂的使用能降低反应所需要的温度并获得较高的液化油收率以及转化率。研究发现,HZSM-5分子筛的催化作用最为明显。