飞机用铝合金-CFRP搭接结构的电偶腐蚀预测研究

目的通过有限元仿真,预测飞机复合材料-铝合金搭接试件可能产生的腐蚀部位和腐蚀深度。方法采用动电位极化的方法,测得温度为40℃的5%NaCl溶液中铝合金和复合材料两种材料的极化曲线。以极化曲线及其拟合的电化学动力学参数作为边界条件,建立电偶腐蚀仿真模型。通过模型计算,分别得到两种材料的腐蚀预测结果,将其结果与实验室腐蚀试验结果进行对比。结果电偶试件模型预测得到的电偶电位值与实验测量得到的电偶电位值对比误差为4.2%。搭接试件的腐蚀部位为偶接处3 mm内,其腐蚀分布与搭接件电偶腐蚀模型预测的电位分布规律基本一致,腐蚀深度的预测值和腐蚀实验的实测值对比误差为12.5%。结论该研究的仿真预测结果与试验结果在一定程度上具有一致性,证明了仿真模型的正确性。     

Virus retention and transport through Al-oxide coated sand columns: effects of ionic strength and composition

Knowledge of the factors that influence the fate and transport of viruses in porous media is very important for accurately determining groundwater vulnerability and for developing protective regulations. In this study, six saturated sand column experiments were performed to examine the effects of a positively charged Al-oxide, which was coated on sand particles, on the retention and transport of viruses (phiX174 and MS-2) in background solutions of different ionic strength and composition. We found that the Al-oxide coating on sand significantly removed viruses during their transport in a phosphate buffered saline (PBS) solution. Mass balance calculations showed that 34% of the input MS-2 was inactivated/irreversibly sorbed on the surface of Al-oxide coated sand whereas 100% of phiX174 was recovered. Results from this study also indicated that higher ionic strength facilitated the transport of both phiX174 and MS-2 through the Al-oxide coated sand. This was attributed to the effect of ion shielding, which at higher ionic strength decreased the electrostatic attraction between the viral particles and the sand surface and consequently decreased virus sorption. Strong effect of the ionic strength indicates that an outer-sphere complexation mechanism was responsible for the virus sorption on the Al-oxide coated sand. Ion composition of the background solutions was also found to be a significant factor in influencing virus retention and transport. Virus transport was enhanced in the presence of phosphate (HPO(4)(2-)) as compared to bicarbonate (HCO(3)(-)), and the effect of HPO(4)(2-) was more significant on MS-2 than on phiX174. The presence of bivalent cations (Ca(2+) and Mg(2+)) increased virus transport because the cations partially screened the negative charges on the viruses therefore decreased the electrostatic attraction between the positively charged sand surface and the negatively charged viruses. Mass recovery data indicated that bivalent cations gave rise to a certain degree of inactivation/irreversibly sorption of phiX174 on the surface of Al-oxide coated sand. On the contrary, the bivalent cations appeared to have protected MS-2 from inactivation/irreversibly sorption. This study provides some insights into the mechanisms responsible for virus retention and transport in porous media.     

添加剂升温烧蚀法在制备新型介孔水环境净化材料中的应用

首次探索了一种破坏式造孔与有机复合相结合的新方法以制备介孔复合水环境净化材料,使最终产品成为一种具有广谱孔结构分布的复合环境材料。详细介绍了该方法的第二步工艺即添加剂升温烧蚀法,在优化后的最佳条件下,产品的孔径得到了进一步扩大,其中部分孔道直径可达至介孔级,同时材料的表面得到了进一步活化。经此步工艺后,所制备的中间产品染料吸附量是原材料的194倍,是酸洗刻蚀后产品的122倍;24h吸湿率是原材料的38倍,是酸洗刻蚀后产品的19倍。     

Impact of density of coating agent on antibacterial activity of silver nanoparticle impregnated plasma treated activated carbon

To use stabilized nanoparticles(NPs) in water as disinfectants over a very long period, the amount of coating agent(for NP stabilization) needs to be optimized. To this end, silver nanoparticles(Ag-NPs) with two different coating densities of tri-sodium citrate(12.05 and46.17 molecules/nm~2, respectively), yet of very similar particle size(29 and 27 nm, respectively)were synthesized. Both sets of citrate capped NPs were then separately impregnated on plasma treated activated carbon(AC), with similar Ag loading of 0.8 and 0.82 wt.%, respectively. On passing contaminated water(containing 10~4 CFU Escherichia coli/m L of water) through a continuous flow-column packed with Ag/AC, zero cell concentration was achieved in 22 and 39 min, with Ag-NPs(impregnated on AC, named as Ag/AC) having lower and higher coating density, respectively. Therefore, even on ensuring similar Ag-NP size and loading, there is a significant difference in antibacterial performance based on citrate coating density in Ag/AC.This is observed in lower coating density case, due to both:(i) higher Ag~+ ion release from Ag-NP and(ii) stronger binding of individual Ag-NPs on AC. The latter ensures that, Ag-NP does not detach from the AC surface for a long duration. TGA-DSC shows that Ag-NPs with a low coating density bind to AC with 4.55 times higher adsorption energy, compared to Ag/AC with a high coating density, implying stronger binding. Therefore, coating density is an important parameter for achieving higher antibacterial efficacy, translating into a faster decontamination rate in experiments, over a long period of flow-column operation.     

磁性核壳CoFe2O4@SiO2@PIL-AO复合材料的制备及其吸附U (VI)性能研究

通过化学合成法制备了磁性核壳CoFe₂O₄@SiO₂@PIL-AO复合材料,采用傅立叶变换红外光谱（FTIR）、扫描电镜（SEM）和X射线光电子能谱（XPS）对其进行了表征,研究了溶液pH、吸附时间、U （VI）初始浓度和温度等参数对U （VI）吸附性能的影响.实验结果表明：在c₀=0.2 mg·L^-1、pH=6.00±0.05、T=298.15 K、m=0.02 g和t=8 h的条件下,CoFe₂O₄@SiO₂@PIL-AO对U （VI）的吸附作用最强,吸附率达到了97.54%;CoFe₂O₄@SiO₂@PIL-AO吸附U （VI）是一个自发进行的吸热反应,U （VI）吸附动力学符合准二级动力学模型,吸附等温线符合Freundlich模型;CoFe₂O₄@SiO₂@PIL-AO复合材料具有良好的可循环使用性,循环使用5次后它对U （VI）的吸附容量没有明显下降,可重复使用.     

异质结型SnO2-TiO2纳米纤维光催化降解柴油机多环芳烃

采用同轴静电纺丝法制备了SnO_2-TiO_2纳米纤维,用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、红外光谱仪(FTIR)和紫外-可见光谱能谱仪(UV-Vis),表征了SnO_2-TiO_2纳米纤维相组成和微观形貌,评价了催化剂表面化学形态和吸光特性,研究了SnO_2含量、光源条件、温度和催化稳定性对降解萘污染物的影响规律.结果表明,催化剂Sn25对萘降解效率最高.在暗光、可见光和紫外光条件下,萘降解效率分别为13.8%、37%和98%.Sn25对萘降解稳定率(标准差率)为0.36%.利用催化剂Sn25对柴油机尾气中多环芳烃(PAHs)排放污染物光催化降解应用发现,Sn25对低苯环PAHs、中苯环PAHs和高苯环PAHs的平均催化降解效率分别为80.2%、75.4%和60.2%.表明SnO_2-TiO_2纳米纤维具有较强光催化降解多环芳烃污染物能力.     

再开发利用工业场地土壤重金属含量分布及生态风险

选取上海市普陀、宝山、闵行和嘉定这4个区内50块典型场地,测定1847个不同垂直剖面深度土壤样品中重金属Hg、Cd、Pb、Cr和As含量,并通过内梅罗综合指数法和潜在生态风险指数法进行评价.从总体上看,Hg、Cd、Pb、Cr和As在表层土壤样品中的平均含量分别为0.33、0.37、74.55、69.23和9.05 mg ·kg^-1,其中Hg、Cd和Pb均超过上海市土壤背景值,分别是背景值的2.75、2.85和2.93倍;5种重金属含量随着土壤垂直剖面深度的增加逐渐降低,深层和饱和带土壤重金属含量接近或低于背景值水平,这表明人类活动扰动影响主要局限于表层.普陀区表层土壤中Hg、Cd和Pb的累积程度最为明显,平均含量是背景值的4.25、4.85和3.09倍;宝山区的Hg和Pb平均含量则为背景值的4.92和6.43倍.宝山区和普陀区的内梅罗综合指数分别为3.70和3.20,属重污染等级;普陀区潜在生态风险指数最高为398.59,具有很强风险,宝山潜在生态风险指数为303.08,具较强风险.闵行和嘉定土壤重金属含量和生态风险水平相对较低.综上,再开发利用工业场地土壤重金属污染受企业生产年限、行业类型及历史管理水平等因素的综合影响,工业发展较早的普陀和宝山土壤重金属累积程度明显高于闵行和嘉定.工业场地土壤中重金属Hg、Cd和Pb的污染值得关注.     

基于FLAC3D的复合煤岩受载破裂数值模拟及试验研究

采用FLAC~(3D)对复合煤岩模型的单轴压缩破裂进行数值模拟及试验,研究复合煤岩受载破裂应力与应变关系变化规律。针对煤样厚度、复合煤岩组合比、煤层参数、顶底板岩性等参数,对复合煤岩模型进行加载仿真研究,仿真及试验结果表明:单一煤样模型随着高度的减小,应力应变曲线整体阶段存在尺寸效应;改变煤岩组合比例时,其抗压强度基本不变,随煤样比例增大,复合煤岩的整体弹性模量减小,整体刚度减小;单一改变复合煤岩的煤样参数时,随煤样弹性模量增大,复合煤岩的弹性模量越强,应力应变曲线峰值点越高,对应应变越小;单一改变顶底板岩性,对复合煤岩模型的应力应变曲线影响不大。试验结果和仿真结果变化趋势一致,表明所建模型具有一定正确性和适用性。     

复合药剂对不同类型重金属污染土壤的固化修复

为了考察复合药剂对Pb、Hg、Cr、Cd、Zn、Cu和Ni污染土样的固化修复效果,以重污染企业用地、冶炼厂河道底泥和自配土壤为污染土样进行试验,试验中的普适复合药剂主要为含磷酸盐沉淀剂、黏土和水泥,视情况辅以无机还原助剂和有机络合助剂。在普适药剂(相对原土样的质量分数15%)、还原剂(5%)和有机助剂(2%)的组配下,处理后的重金属浸出质量浓度低于GB 18598—2001标准值。普适药剂对Pb、Cd、Zn、Cu、Ni的固化有效,磷酸盐是促成Pb固化的关键成分,黏土和水泥分别起到吸附固定和物理包封的作用。无机助剂中的还原/络合性成分和硫化物分别对Cr(VI)和Hg的固化有明显的促进作用。对于Pb、Cd、Zn、Cu复合污染土壤的修复,分析了重金属浸出质量浓度随普适药剂投加量变化的特征曲线,结果表明,Pb比Cu的曲线斜率更大,表明Pb的固化效率更高;Cd和Zn具有相似的曲线形状,推测二者具有类似的固化机理。     

汽车涂装废水除镍的试验研究

镍是国家严格控制的一类污染物,采用化学沉淀法对汽车涂装废水进行除镍的试验研究。结果表明：投加氢氧化钙300mg／L,pH控制在11．0左右时,镍的去除率可以达到90．5％,出水完全满足《上海市污水综合排放标准（DB31／199）》。