Effect of Ca(II), Fe(II), and Fe(III) on Cu(II) adsorption by a polyvinylidene fluoride-based chelating membrane from Cu(II)–EDTA complex solution

A polyvinylidene fluoride-based membrane bearing the diethylenetriaminepentaacetic acid chelating group was employed to recover Cu(II) from the Cu(II)-ethylenediaminetetraacetic acid complex aqueous solution. Effects of Ca(II), Fe(II), and Fe(III) on Cu(II) uptake were investigated by static batch adsorption tests and dynamic adsorption filtration. Isotherms, kinetics, and breakthrough curves of Cu(II) uptakes in the presence of the three cations at concentrations of 1 mmol L^?1 were elucidated. The three cations showed a positive effect on the Cu(II) uptake; the stimulative roles were in the order of Fe(III) > Fe(II) > Ca(II). They did not alter the adsorption behavior of the membrane; adsorption isotherms and kinetics could be described by Langmuir and Lagergren second-order models, and Cu(II) adsorption was a spontaneous and exothermic process. The presence of Ca(II), Fe(II), and Fe(III) increased the sorption capacity of the membrane stack by 1.3, 1.9, and 3 times. Breakthrough time and the exhaustion time of membrane stacks were also extended.     

有机复合填料生物滤床对甲苯气体的净化

利用一种新型有机复合填料作为生物滤床中微生物的附着载体,接种经过驯化筛选的专性甲苯降解菌,填装于生物过滤塔中净化低浓度甲苯气体。研究了新型有机复合填料在长期运行时的情况,考察了进气流量、入口浓度、床层温度和填料湿度对生物滤床的影响,最终经过优化得出,此种填料的生物滤床能够为微生物提供良好的附着生长环境,并能保持滤床的高效稳定运行,当进气流量为0.4 m3/h,入口浓度为400 mg/m3,床层温度为30℃,填料湿度为50%时,生化去除量达到30.6 g/(m3.h),并且在此条件下滤床具有良好的耐冲击性能。     

Differential sorption of herbicides as related to soil topography and organic matter 1

Abstract

The sorption of bromacil and simazine by the surface soil (0–15 cm) sampled at various positions along an 8% slope citrus grove (Candler fine sand; Typic Quartzipsamment) and at various depths (0–200 cm) at upper, middle, and lower positions along the slope were investigated. The sorption of both herbicides by the top 15 cm soil decreased considerably from the upper to mid position along the slope and increased at the lower position. The organic matter content and concentrations of Ca, Mg, K, P, and Cu in the soil showed evidence of transport of organic matter and mineral nutrients from the mid position on the slope and accumulation in the lower position. The differential sorption of herbicides by the soil samples taken at various positions along the slope was closely related to changes in organic matter content. Although sorption of bromacil and simazine varied considerably at various positions along the slope, the sorption of bromacil was very similar at depths below 30 cm regardless of positions along the slope. In the case of simazine, however, the sorption was much greater at all depths in the lower than in the upper and mid position of the slope. The sorption of both herbicides decreased considerably at depths below 30 cm at all positions along the slope, thus, indicating the potential for rapid leaching of the herbicides down the soil profile.     

Epidemiological assessment of food aid in the Bosnian conflict, 1994-97

Surveys in emergency settings are important for the accountability of food aid. Four household surveys conducted between 1994 and 1997 measured the performance of the Bosnia food aid programme, covering a random sample of clusters in Bosnia and Herzegovina and the Republica Srpska. The team calculated coverage, exclusion and inclusion errors, programme misses, and under-supply. Despite intended universal coverage from 1994-96, 15, 19, and 31 per cent, respectively, did not receive food across the three-year time frame. Households categorised as vulnerable were somewhat more likely to receive food. Programme misses were rare, whereas under-supply fell from 30 per cent in 1994 to four per cent in 1997, as the availability of other food increased. Extrapolation suggested that 61 per cent of the food distributed did not reach households. The programme introduced priority categories for targeting in 1997, yet nearly one-half of the highest priority households did not receive food. Incomplete coverage and weak targeting were related to political constraints.     

基于核心资本变迁的产业可持续竞争力研究

当前,生态环境已经成为经济发展的主要约束条件,与生态环境相协调的可持续发展也是当前产业发展的主要趋势。本文通过对经济增长核心要素及约束条件变迁的考察,明确了可持续发展是经济与产业发展的必然趋势,同时拓宽了产业竞争力的视域,提出了产业可持续竞争力的概念。在此基础上,本文运用复杂系统动力学理论,探讨了产业核心资本变迁与产业可持续竞争力以及生态环境之间的关系。文章得出结论,在资源环境成为经济发展根本约束条件的前提下,环境质量的改善可以内化于产业可持续竞争力的提升过程中,途径就是增强产业对核心资本的使用程度。基于理论推导和实际数据的支持,本文最后从贯彻可持续发展和生态文明的理念、运用循环经济相关理论优化生产经营行为、推进面向资源环境的生态创新、加强人力资源投资、提高产业核心资本构成等方面,提出了相应的政策建议。     

基于多任务阶段的复杂系统可靠性评估模型

目前工程中对可靠性评估只考虑一个典型任务剖面,且不区分分系统的工作时间,这种计算模型对最后的结果会造成偏差。本文提出了基于实验数据的复杂系统可靠性评估模型,该模型综合考虑了多任务剖面,多任务阶段和多个分系统。在此基础上,对可靠性评估流程进行描述,给出关键步骤中数学模型。最后通过一个典型案例,验证了该模型的合理性和适用性。     

湿法脱硫P＆D型pH值及密度复合测量技术介绍

阐述了石灰石—石膏湿法脱硫装置pH值及密度测量的重要性,介绍了一种新型pH值及密度复合测量系统及其应用实例,为类似装置提供了借鉴和参考。     

ZnO的制备及其光催化性能

分别采用草酸沉淀法和柠檬酸络合法制备了纤锌矿型ZnO,通过X射线粉末衍射仪、扫描电子显微镜和透射电子显微镜对ZnO的结构和形貌进行了表征,并研究了所制备的ZnO对溶液中甲基橙的光催化降解性能.实验结果表明:草酸沉淀法制备的ZnO为小颗粒堆积而成的空心类柱状体,柠檬酸络合法制备的ZnO为小球形颗粒;草酸沉淀法制备的ZnO...     

铒钇异核脯氨酸配合物:[ErY(Pro)4(H2O)8](ClO4)6的合成及晶体结构

为了研究稀土离子与氨基酸 (Pro)的相互作用 ,在pH≈ 3.5水溶液中合成了高氯酸八水·(脯氨酸 )合铱 (Ⅲ )铒 (Ⅲ ) ,获得了单晶 ,并经四圆衍射仪测定了结构 .配合物组成为C2 0 H52 Cl6ErN4 O4 0 Y ,属三斜晶系 ,P1空间群 .晶胞参数a =0 .986 0 (2 )°nm ,b =1.30 2 0 (5 )nm ,c=1.36 32 (5 )nm ,α =10 9.32 (3)° ,β=110 .19(2 )° ,γ =10 0 .96 (2 )°,V =1.45 6 (1)nm3,Z =1,Dc=1.6 6 3g/cm3,μ =2 .797mm-1,F(0 0 0 ) =72 9.配合物分子中 ,Y3 ‘、Er3 在相应位置上出现的几率各为 5 0 % ,相邻两个金属离子被两个以桥式双齿配位的Pro分子连接 ,每个金属离子除了与 4个羧基O配位外 ,还与 4个水分子的氧配位 ,配位数为 8,形成变形的四方反棱柱 .图 4表 3参 10     

絮体分形结构形成机制探讨

基于统计力学和无标度网络框架分析了絮凝过程,并从物理角度导出了絮体的分形结构,探讨了分形维数与外界控制条件的关系.在此基础之上,根据能量守恒对模型进行了理论计算,发现在湍流条件或外界能量交换强烈的情况下,分形维数较高;反之,若在层流条件或能量交换较弱的条件下,则分形维数较低.将理论计算结果与实验结果进行比较,二者较为一致.