纳米铁氧化物吸附处理重金属废水的研究进展

概述了用于吸附重金属的主要纳米铁氧化物的种类及其吸附效果,介绍了常见的纳米铁氧化物制备方法及改性方法,讨论了影响纳米铁氧化物吸附重金属的主要因素,并对纳米铁氧化物在水环境保护领域中的研究方向提出了展望:如发展绿色、高效的纳米铁氧化物制备工艺,探讨纳米铁氧化物结构调控和表面功能化对其吸附性能的影响等。     

Ti3C2纳米层状材料对废水中Cr（Ⅵ）的光催化去除性能

以Ti₃AlC₂为原料,采用HF刻蚀工艺制备出12种Ti₃C₂纳米层状材料,对其形貌进行了表征,并考察了以其作为光催化剂对废水中Cr（Ⅵ）的处理效果。实验结果表明：HF体积分数为80%、刻蚀时间为48 h时得到的MX-80-48的形貌较好;MX-80-48具有类似石墨烯的二维层状结构,纳米层厚度约20~50 nm,孔径2~10 nm,比表面积14.8 m²/g,在400~700 nm可见光范围内表现出强烈的吸光性;当Cr（Ⅵ）的初始质量浓度为40.00 mg/L、MX-80-48投加量为200 mg/L、pH=2、反应时间4 h（暗反应1 h+光照3 h）时,Cr（Ⅵ）去除率可达100%。     

Challenges for modelling and integrating environmental performances in concept design: the case of an automotive component lightweighting

The objective of this paper is to discuss the main barriers for modelling and integrating the environmental performances in the automotive concept design. Incorporating environmental assessment in the early design phase of a vehicle component is known as an important challenge that car makers need to face in order to develop more sustainable design solutions; in this regard, the Life Cycle Assessment is the most widespread methodology for the environmental assessment and comparison of alternatives. The present work illustrates the combination of such methodology with the traditional design procedure at two different levels of the component design phase, material choice and concept design. In particular, the potential benefits originated by a lightweight solution for the automotive component Throttle Body are evaluated by considering environmental and technical implications at the same level. The case study shows that a multi-disciplinary approach for design effectively allows the integration of the environmental issue in the company’s established procedures. However, interpretation of results is still a challenging aspect due to the inevitable contradicting elements which should not discourage to develop comprehensive sustainability assessment within the early design stage.     

单宁为模板制备纳米二氧化钛 及其对钍的吸附性能

以杨梅单宁(BT)为模板,水热法合成纳米二氧化钛(BT-NTO)。采用XRD、FTIR、SEM和TEM技术对BT-NTO的结构及形貌进行了表征。将BT-NTO用于吸附溶液中的Th~(4+),在溶液pH为3.5、温度为25℃、Th~(4+)初始浓度为0.5 mmol/L的条件下,BT-NTO对Th~(4+)的吸附量为0.905 8 mmol/g;吸附过程符合准二级动力学方程和Langmuir等温吸附方程;溶液中共存的Zn~(2+)、Ni~(2+)、Co~(2+)、Sr~(2+)、Yb~(3+)、Nd~(3+)、Sm~(3+)、Gd~(3+)、La~(3+)、Cl-、ClO4-离子对Th~(4+)吸附量影响较小;BT-NTO的重复使用性能较好。     

Effects of bed materials on the performance of an anaerobic sequencing batch biofilm reactor treating domestic sewage

The objective of this study was to determine the best performance of an anaerobic sequencing batch biofilm reactor (AnSBBR) based on the use of four different bed materials as support for biomass immobilization. The bed materials utilized were polyurethane foam (PU), vegetal carbon (VC), synthetic pumice (SP), and recycled low-density polyethylene (PE). The AnSBBR, with a total volume of 7.2L, was operated in 8-h batch cycles over 10 months, and fed with domestic sewage with an average influent chemical oxygen demand (COD) of 358+/-110mg/L. The average effluent COD values were 121+/-31, 208+/-54, 233+/-52, and 227+/-51mg/L, for PU, VC, SP, and PE, respectively. A modified first-order kinetic model was adjusted to temporal profiles of COD during a batch cycle, and the apparent kinetic constants were 0.52+/-0.05, 0.37+/-0.05, 0.80+/-0.04, and 0.30+/-0.02h(-1) for PU, VC, SP, and PE, respectively. Specific substrate utilization rates of 1.08, 0.11, and 0.86mg COD/mgVS day were obtained for PU, VC, and PE, respectively. Although SP yielded the highest kinetic coefficient, PU was considered the best support, since SP presented loss of chemical constituents during the reactor's operational phase. In addition, findings on the microbial community were associated with the reactor's performance data. Although PE did not show a satisfactory performance, an interesting microbial diversity was found on its surface. Based on the morphology and denaturing gradient gel electrophoresis (DGGE) results, PE showed the best capacity for promoting the attachment of methanogenic organisms, and is therefore a material that merits further analysis. PU was considered the most suitable material showing the best performance in terms of efficiency of solids and COD removal.     

氨基改性生物炭负载纳米零价铁去除水中Cr(VI)

以聚乙烯亚胺（PEI）为功能单体,玉米秸秆生物炭为载体,制备了氨基改性生物炭负载型纳米零价铁（nZVI@PEI-HBC）,并利用扫描电镜（SEM）、红外光谱（FTIR）和X射线光电子能谱（XPS）等手段对材料进行了表征,分析了溶液pH、温度、材料投加量等因素对其去除Cr（VI）的影响及其去除机理.结果表明：在投加量为0.5 g·L^-1,温度为20℃,pH值为5,Cr（VI）初始浓度为20 mg·L^-1条件下,各材料对Cr（VI）的去除率大小为nZVI@PEI-HBC > nZVI > PEI-HBC > HBC.SEM显示nZVI颗粒较均匀地分散在生物炭表面,FTIR分析表明PEI改性后材料表面增加了氨基等重金属配位基团,这可能是nZVI@PEI-HBC去除Cr（VI）效果更好的原因.影响因素研究表明,材料具有较好稳定性,老化28 d后其Cr（VI）去除性能变化不大;酸性环境、升温、增大材料投加量均有利于nZVI@PEI-HBC对Cr（VI）的去除.机理研究发现,水中溶解氧加速了nZVI的腐蚀和Fe（II）的释放,促进Cr（VI）还原为Cr（III）,然后通过共沉淀作用和氨基等基团的吸附作用被去除.     

石期河流域地下水化学特征及物质来源分析

为明确典型岩溶溶丘洼(谷)地区域地下水化学特征及其成因,以石期河流域为研究对象,运用Gibbs图、Piper图、端元分析及离子比例系数等方法,对地下水水化学特征及物质来源进行了定性和定量分析.结果表明,研究区内地下水pH值介于6.06～8.07之间,Ca~(2+)、 Mg~(2+)和HCO~-_3是地下水中的主要离子,其质量浓度范围分别为2.61～108.7、 0.54～27.61和8.1～370.74mg·L~(-1),符合岩溶水高钙弱碱性特征;地下水物质成分中, Ca~(2+)和Mg~(2+)主要受到碳酸参与的灰岩和白云岩风化作用的控制, Na~+主要来源于硅酸盐岩的溶解,同时, Ca~(2+)和Na~+在地下水流动过程中进行阳离子交替吸附作用; K~+、 Cl~-和NO~-_3主要受到农业化肥施放和生活废水排放的影响.此外,大气降水作为该区域地下水的主要补给来源,对当地地下水化学特征和物质来源也有一定的影响.     

磁性氧化石墨处理乳化含油废水及磁致增强效应

以高铁酸钾为氧化剂,基于改进Hummers法制备了新型磁性氧化石墨材料,在SEM、FTIR、氮气吸脱附和表面接触角表征基础上,探究了该材料处理乳化含油废水的效果及磁致增强效应.结果表明：相较于石墨,磁性氧化石墨比表面积增大,表面有卷曲结构并负载着Fe₃O₄颗粒,具有含氧官能团,存在疏水性较强的微观孔隙结构.在外加磁场条件下,磁性氧化石墨团聚,形成疏水性宏观孔隙结构,利于乳化油滴的吸附和附着.磁性氧化石墨处理乳化含油废水的能力远好于石墨与粉末活性炭,且处理效率与磁场强度成正相关,COD去除率可达95%以上.使用后的磁性氧化石墨进行溶剂萃取或热处理,可以循环使用.磁性氧化石墨经过4次循环使用,热再生效率为92%,溶剂萃取再生效率为86%.以上研究为乳化含油废水的处理提供了一种有效的方法.     

中国乘用车塑料的动态物质流分析

结合行业信息并基于动态物质流模型,本文对1950~2050年间中国乘用车塑料流量与存量进行了历史测算与情景分析.历史测算表明：1950~2018年国内乘用车行业累计消耗了以聚丙烯（PP）、聚氨酯（PU）等为主的塑料3278万t,产生了337万t塑料废弃物;报废汽车拆解后的车用废塑料仅28%得到回收利用.针对未来情况,本文设计了乘用车保有量、单车塑料使用量两大关键因素下的不同情景组合.结果显示车用塑料存量及废塑料产生量将大幅增长,到2050年存量将达到0.7~2.7亿t,废塑料产生量将达到500~1600万t,汽车拆解和塑料再生等相关行业对此应充分关注.到2050年车用废塑料回收率若能提升至80%,将减少376万t/a的车用废塑料填埋或焚烧,显著减少环境风险.     

农业经营规模化发展对环境效率的影响——基于地块层面的实证分析

为探析农业规模化经营与农业环境可持续性之间的关系,对农业经营规模对农业环境效率的影响进行理论分析,并在此基础上构建了物料平衡原则下农业环境效率测算模型和农业环境效率影响模型.基于2004~2016年浙江省农户水稻种植地块层面的面板数据,实证检验了土地面积、劳动投入、资本投入和农业产出等农业经营规模指标对农业环境效率的影响.结果显示,农业规模化发展将因投入和产出的扩张以多种方式影响其环境效率,其中土地面积规模与农业环境效率之间呈倒U型关系,劳动投入和资本投入对农业生产环境效率均有负向的影响,而农业产出规模的增加将促进农业环境效率的提升.