混合添加剂对PVDF平板疏水膜结构及性能的影响

以不同添加剂采用浸没沉淀相转换法制备基于无纺布支撑的聚偏氟乙烯(PVDF)平板疏水膜,考察了不同添加剂的加入对膜性能与结构的影响;并利用扫描电子显微镜(SEM)、原子力学显微镜(AFM)、红外光谱(FTIR)、接触角测量及膜蒸馏实验等对疏水膜的结构及性能进行表征。结果表明,引入混合型添加剂制备的膜具有较高通量和盐截留率,其疏水性最强,而添加剂对聚合物的晶型影响较小。以35 g/L的NaCl盐溶液为进料液对制备的平板膜进行直接接触式膜蒸馏实验,在热侧进水温度为50℃、冷侧温度为20℃的条件下,所制备的疏水膜通量最高可达12.45 kg/(m2.h),截留率为99.99%。     

碳酰肼对烧结过程二噁英生成的抑制作用

研究了碳酰肼对钢铁厂烧结工序产生的二噁英的抑制效果。结果表明,添加了0.01%(质量分数,下同)、0.02%、0.05%、0.10%的碳酰肼之后,二噁英的排放质量浓度降为0.560、0.506、0.270、0.174ng-TEQ/m3,相对于基准值(0.821ng-TEQ/m3)大幅减少。碳酰肼对二噁英的从头合成以及前驱物生成都能起到一定的抑制效果。碳酰肼与Cu2+结合生成稳定的氮化物,削弱Cu2+的催化活性;与HCl反应,减少了生成二噁英的氯源;对FeCl3、CuCl2的催化活性也会产生影响。碳酰肼添加后,对多氯代二苯并呋喃(PCDFs)生成中高氯代二噁英的脱氯行为也有明显的抑制。     

中国突发环境事件时间序列分析

突发性环境事件时间序列特征可表征环境风险管理成效及存在问题。研究表明2000年以来中国突发环境事件预防、控制与管理取得了显著成效,其中,突发性水污染事件、大气污染事件以及噪声振动危害年发生频次呈大幅度降低趋势,但固废污染事件自2003年以来的年发生频次变化不大,而其它突发性环境事件自2002年以来的年发生频次则呈快速增长态势,说明中国在强调突发性水环境和大气环境事件监管的同时,还需加强固废污染事件及其它类型突发环境事件的监控与管理。     

环境监测信息化建设的问题分析与对策建议

环境监测信息化是环境管理现代化的重要手段,信息化建设是监测现代化的重要组成部分。基于当前环境监测信息化建设的现状,分析了建设过程中经常存在的"信息孤岛"、系统失衡、进度延期等问题,提出了建设初期做好IT规划、实施阶段重视项目管理的对策和建议,并依据监测站的实践经验对实施要点加以阐述。解决好这些问题,将推动环境监测信息化建设工作更加高效合理地进行,提升监测信息化程度,对提高环境管理和环境决策的水平具有重要意义。     

Quantification of the inhibitory effect of methyl fluoride on methanogenesis in mesophilic anaerobic granular systems

The inhibitory effect of CH₃F on methanogenesis in mesophilic anaerobic granules was tested at different concentrations (0-10% v/v, in the gas phase) and verified by the stable carbon isotopic signatures of CH₄ and CO₂. The results showed that the inhibitory effect increased with the initial CH₃F concentration up to 5%. The CH₃F concentration causing 50% metabolic inhibition was 0.32%. Complete inhibition of acetoclastic methanogenesis with a 91% reduction in total methanogenic activity was achieved when 5% CH₃F was initially added to the headspace, which resulted in 870 μM dissolved CH₃F in the liquid. It was much higher than that applied in other natural anoxic non-granular systems, indicating that the layered granular structure influenced the inhibitory effect. The obvious increase in hydrogen content indicated that high concentrations of CH₃F (?5%) suppressed hydrogenotrophic methanogenesis as well. The stable inhibition lasted for at least 6 d as the CH₃F concentration decreased slowly with incubation time. These results suggested that CH₃F could be used for investigating methanogenic processes in anaerobic granular systems after the CH₃F concentration and incubation time for specific inhibition of acetoclastic methanogenesis were carefully determined. In the present system, CH₃F concentration of 5% was suggested to be optimal.     

Nano-TiO2 enhances the toxicity of copper in natural water to Daphnia magna

The acute toxicity of engineered nanoparticles (NPs) in aquatic environments at high concentrations has been well-established. This study demonstrates that, at a concentration generally considered to be safe in the environment, nano-TiO₂ remarkably enhanced the toxicity of copper to Daphnia magna by increasing the copper bioaccumulation. Specifically, at 2 mg L⁻¹ nano-TiO₂, the (LC₅₀) of Cu²⁺ concentration observed to kill half the population, decreased from 111 μg L⁻¹ to 42 μg L⁻¹. Correspondingly, the level of metallothionein decreased from 135 μg g⁻¹ wet weight to 99 μg g⁻¹ wet weight at a Cu²⁺ level of 100 μg L⁻¹. The copper was found to be adsorbed onto the nano-TiO₂, and ingested and accumulated in the animals, thereby causing toxic injury. The nano-TiO₂ may compete for free copper ions with sulfhydryl groups, causing the inhibition of the detoxification by metallothioneins.     

A possible new mechanism involved in ferro-cyanide metabolism by plants

Background, aim, and scope  

Ferro-cyanide is one of the commonly found species at cyanide-contaminated soils and groundwater. Unlike botanical metabolism of KCN via the β-cyanoalanine pathway, processes involved in the plant-mediated assimilation of ferro-cyanide are still unclear. The objective of this study was to investigate a possible mechanism involved in uptake and assimilation of ferro-cyanide by plants.     

建筑屋顶雨水径流初期冲刷效应研究

以无量纲化后的雨水径流污染物和径流输送量为基础,通过引入间隙函数,建立了雨水径流污染物的初期冲刷效应定量评价公式,对建筑屋顶雨水初期冲刷现象进行了研究.结果表明:(1)建筑屋顶雨水径流污染物浓度总体上呈现出前期高于后期的现象,且污染物浓度较低,建筑屋顶雨水利用可作为雨水利用的优先方向.(2)间隙函数存在峰值区域,峰值区...     

阴极氧还原产电生物可渗透反应栅的研究Ⅱ.酸蚀处理对不锈钢丝电极性能的影响

不锈钢毛虽然用作阴极氧还原产电生物反应栅（CORE—PRB）的电极材料虽然有很多优点,但是反应电流较小。尝试对不锈钢毛进行酸蚀处理后用作电极材料,并分别研究比较了4种不同电极组合的产电反应性能。酸蚀处理显著提高不锈钢毛阳极的反应性能,并对提高不锈钢毛阴极的反应性能有一定作用。酸蚀的作用主要是使不锈钢毛表面变得粗糙,有利于提高电极表面积和材料的生物亲和性。虽然生物产电反应对COD降解的直接贡献不到10％,但是不同电极组合下COD的去除率与它们生物产电反应的贡献率呈现高度正相关性。     

饮用水源水无机金属污染的应急处理

根据密云水库供水现状,针对突发性无机金属污染事件,采用聚合氯化铝辅助化学沉淀法进行应急处理。选用Cu2＋、Fe2＋、Zn2＋和Cd2＋ 4种金属离子为目标污染物,首先通过小试实验确立了最佳混凝处理条件。结果表明,调节pH值为8．0左右,可使初始浓度为5mg／L和10mg／L的Cu2＋浓度降至0．96mg／L和0．67mg／L;初始浓度为1．5mg／L和3mg／L的Fe2＋浓度降至0．27mg／L和0．24mg／L;初始浓度为0．05mg／L和0．1mg／L的Cd2＋浓度降为0．0089mg／L和0．0078mg／L;调节pH值为9．0时,可使初始浓度为5mg／L和10mg／L的Zn2＋浓度降至0．57mg／L和0．48mg／L。4种污染物出水浓度均低于国家饮用水标准。在小试基础上,在北京第九水厂开展无机金属污染处理的中试实验,结果表明所选用的聚合氯化铝辅助化学沉淀法简便易行,可实现污染物快速、有效去除。