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.     

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.     

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。     

污水磷回收中磷酸盐沉淀法的影响因素及应用

磷是一种不可再生、十分有限的资源,它的回收再利用已成为水处理工业关注的焦点.污水中的磷可以以磷酸盐沉淀的形式回收,其中以鸟粪石和磷酸钙的形式从污水中回收磷被认为是最具有前景的磷回收途径.作者对生成鸟粪石和磷酸钙的主要影响因素及鸟粪石和磷酸钙沉淀法在污水磷回收中的应用作了全面的概述,并对存在的问题作了简要分析.     

全程自养脱氮新工艺

介绍了全程自养脱氮新工艺，分析了工艺实现条件及特点，并进一步从理论上阐述了全程自养脱氮和好氧颗粒污泥结合的可行性。     

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。