Novel chitosan–ethylene glycol hydrogel for the removal of aqueous perfluorooctanoic acid

It is urgent to explore an effective removal method for perfluorooctanoic acid (PFOA) due to its recalcitrant nature. In this study, a novel chitosan-based hydrogel (CEGH) was prepared with a simple method using chitosan and ethylene glycol through a repeated freezing–thawing procedure. The adsorption of PFOA anions to CEGH agreed well to the Freundlich–Langmuir model with a maximum adsorption capacity as high as 1275.9?mg/g, which is higher than reported values of most adsorbents for PFOA. The adsorption was influenced by experimental conditions. Experimental results showed that the main removal mechanism was the ionic hydrogen bond interaction between carbonyl groups (COO^?) of PFOA and protonated amine (NH⁺) of the CEGH adsorbent. Therefore, CEGH is a very attractive adsorbent that can be used to remove PFOA from water in the future.     

Influence of anionic, cationic and nonionic surfactants on adsorption and desorption of oxytetracycline by ultrasonically treated and non-treated multiwalled carbon nanotubes

High adsorption capacity of carbon nanotubes (CNTs) may greatly determine the bioavailability and mobility of organic contaminants. The fate of contaminants adsorbed by CNTs may be substantially influenced by surfactants used both in the synthesis and dispersion of CNTs. The aim of this research was to determine the influence of surfactants (nonionic - TX100, cationic - CTAB and anionic - SDBS) on adsorption and desorption of oxytetracycline (OTC) by multiwalled carbon nanotubes (MWCNTs). The surfactants used had a substantial influence on both adsorption and desorption of OTC. The direction of changes depended clearly on the type of surfactant. In case of anionic SDBS, increased adsorption of OTC by MWCNTs was observed. The presence of TX100 and CTAB decreased the adsorption of OTC by MWCNTs significantly. The increase of OTC adsorption after ultrasonic treatment was observed in case of MWCNTs alone and MWCNTs with SDBS and TX100. However, ultrasonic treatment caused OTC adsorption decrease in the presence of CTAB. The change of pH had also an important effect on OTC adsorption in the presence of surfactants. Depending on the surfactant and pH, an increase or decrease of OTC adsorption was observed. The presence of surfactants increased OTC desorption from MWCNTs significantly as follows: SDBS = CTAB < TX100. The results obtained suggest new potential threats and constitute a basis for further research considering the bioavailability and toxicity of antibiotics in the presence of MWCNTs and surfactants.     

循环流化床烟气脱硫技术及其环境经济可行性探讨

简要介绍了循环流化床烟气脱硫技术的原理和国内外研发的现状,并与目前得到广泛应用和继续发展的其它3种烟气脱硫工艺进行比较,得出循环流化床烟气脱硫净化工艺具有投资相对较低、脱硫效率较高、运行可靠、操作维护方便等优点。再通过实例,从投资、技术、运行成本等方面论述其环境经济的可行性,得出循环流化床烟气脱硫技术符合江阴现阶段经济发展状况,能满足中、小型锅炉脱硫要求,是一种较为可行的大气污染控制技术。     

600 MW机组除尘器升级改造及效益评价

元宝山发电有限责任公司2号600 MW机组配套电除尘器由于设计效率低、燃烧煤种变化、设备老化等多方面原因,除尘效率下降,除尘器出口烟尘排放浓度超标严重。为了满足新的《火电厂大气污染物排放标准》的要求,对元宝山发电有限责任公司2号机组配套电除尘器进行升级改造,将原有的4台四电场静电除尘器增效改造为4台电袋复合式除尘器。通过电除尘器的改造,降低了除尘器出口粉尘排放浓度,提高了除尘效率,保证了2号机组电除尘器的安全稳定运行。     

Particle concentrations in data centers

Cooling buildings with large airflow rates of outside air when temperatures are favorable is an established energy-saving measure. In data centers, this strategy is not widely used, owing to concerns that it would cause increased indoor levels of particles of outdoor origin, which could damage electronic equipment. However, environmental conditions typical of data centers and the associated potential for equipment failure are not well characterized. This study presents the first published measurements of particle concentrations in operating data centers. Indoor and outdoor particle measurements were taken at eight different sites in northern California for particulate matter 0.3–5.0 μm in diameter. One of the data centers has an energy-efficient design that employs outside air for cooling, while the rest use conventional cooling methods. Ratios of measured particle concentrations in the conventional data centers to the corresponding outside concentrations were significantly lower than those typically found in office or residential buildings. Estimates using a material-balance model match well with empirical results, indicating that the dominant particle sources and losses have been identified. Measurements taken at the more energy-efficient site show nearly an order of magnitude increase in particle concentration when ventilation rates were high. The model indicates that this increase may be even higher when including particles smaller than the monitoring-equipment size limitation. Even with the increases, the measured particle concentrations are still below concentration limits recommended in industry standards.     

介质阻挡放电处理水中3,4-二氯苯胺机理研究

采用介质阻挡放电产生低温等离子体来处理水中3,4-二氯苯胺(3,4-DCA),考察了放电功率、空气流量、金属离子(Fe2+、Cu2+)浓度、光催化剂二氧化钛对3,4-DCA去除率的影响,并分析了降解产物及可能的降解机理.实验结果表明,介质阻挡放电方法对3,4-DCA有良好的去除效果,在3,4-DCA初始浓度为30mg·L-1,放电功率为80W,空气流量为1L·min-1时,放电处理6min后3,4-DCA的去除率可达92.5%.增加空气流量能显著地提高3,4-DCA的去除率,添加亚铁离子(Fe2+)浓度和光催化剂TiO2均能提高3,4-DCA的去除率,且存在最佳添加量值.介质阻挡放电方法对3,4-DCA的降解去除反应符合一级反应动力学.通过气质联用仪(GC-MS)分析检测发现,反应主要为脱氯、脱氨基和苯环开环反应,二氯乙烯为其主要的降解产物.     

基于 分析的余热发电对水泥熟料生产能源利用率影响评价

本文研究水泥熟料生产过程中各个生产系统的效率,并对余热发电前后每个系统的效率进行分析对比,从而得出各个系统的资源能源利用程度以及余热发电工程对每个系统能量利用率的影响,诊断水泥熟料生产过程的损失发生位置并发现系统的节能和余热回收利用的潜力,为管理者实施节能降耗的方案提供技术支持.研究表明,实施余热发电工程前,水泥熟料生产的原料制备系统、煤粉制备系统、回转窑系统的效率分别为4.5%、1.4%和33.7%;实施余热发电工程后,效率分别为7.8%、2.8%和38.1%.余热发电工程可回收回转窑系统总投入的3.7%,同时使原料制备系统、煤粉制备系统、回转窑系统的效率分别提高3.3%、1.4%和4.3%.     

Twenty five years of industrial development: a study of resource use rates and macro-efficiency indicators for five Asian countries

Economic and population growth in Asia over the last three decades has been unprecedented. While conventional economic indicators have been increasing consistently, indicators of resource and environmental quality have been deteriorating, raising questions about the implications of future growth. Economic growth in the future is considered to be contingent on ensuring a more efficient use of natural resources, while simultaneously striving to reduce environmental impacts. We examine time trends of three efficiency indicators; agricultural efficiency, energy efficiency of economic production and carbon efficiency of energy use, for the five most populous countries in Asia in order to assess whether industrial development has lead to increased resource use efficiency and an associated reduction in total resource use and environmental impacts. Our results indicate that agricultural efficiency has decreased in all five countries. Results are mixed for energy and carbon efficiencies. Where increases in energy and carbon efficiency have occurred, they have been completely overwhelmed by absolute increases in energy use and carbon emissions caused by increases in the scale of economic activity. Based on this analysis, we study the potential for further improvements and policy implications for future food supply, energy consumption and carbon emissions in the region.     

环境因素对聚乙烯醇降解菌系降解效果的影响研究

针对在前期研究中已筛选到的一种聚乙烯醇(PVA)降解混合菌系,考察了种龄、菌悬液接种量、培养基装液量、培养温度、初始pH、渗透压及光照等外部环境因素对其PVA降解能力的影响.结果表明,种龄对混合菌系降解PVA的能力影响较小,实际运用中保持种龄为24～48 h较佳;菌悬液接种量过多时,会影响其正常生长,最佳的接种量为4～...     

移动床生物膜反应器内气液传质性能研究

采用移动床生物膜反应器,利用清水进行了在不同悬浮填料体积含率和曝气强度时反应器内气液传质性能研究。结果表明,随着曝气强度增加,传质系数增大,但曝气强度过大,并不利于移动床操作;当填料体积含率大于40%时,氧传质系数出现最大值后逐渐减小。在填料体积含率为30%~50%、曝气强度为4.5~7 m3/(h.m)时,传质效果良好,氧转移效率较高。