Adsorption behavior of phosphate on Lanthanum(Ⅲ) doped mesoporous silicates material

A series of lanthanum doped meosoporous MCM-41 (La_xM41, x is Si/La molar ratio) was prepared by sol-gel method. The surface structure of the materials was investigated with X-ray diffraction and N_2 adsorption/desorption technique. The content of La in the materials was determined by ICP. It was found that the La content of La_(25)M41, La_(50)M41 and La_(100)M41 was 7.53%, 3.89% and 2.32%, respectively. The phosphate adsorption capacities increased with increasing amount of La incorporation. With 0.40 g La_(25)M41 99.7% phosphate could be removed. The effects of Si/La molar ratio, La_xM41 dose, pH, initial concentration of phosphate solution, co-ions on phosphate adsorption were also evaluated. The phosphate adsorption kinetics of La_xM41 could be well-described by the pseudo second-order model, and Langmuir isotherm fit equilibrium data much better than the Freundlich isotherm.     

柴油车燃料添加型催化剂研究进展

现代柴油机油耗低、动力强,但是排放的尾气中黑烟颗粒物PM(particulate matter)会对环境和人类健康造成危害。随着排放法规的日益严格,净化处理刻不容缓。当前对其排放控制的主要手段是使用颗粒物捕集器DPF(diesel particulate filter)捕集PM,并采用催化剂或提高尾气温度促其燃烧以实现DPF再生。燃料添加型催化剂FBC(fuel borne catalyst)能保证催化剂与PM紧密接触,使DPF在尾气温度范围内即可再生。文章对近年来FBC的研究开发进展进行了总结,并指出了该类催化剂的发展方向,即发展纳米级FBC。     

多壁碳纳米管序列修饰聚氯乙烯超滤膜的制备及性能研究

采用硫酸、硝酸混酸改性多壁碳纳米管(MWCNTs),通过化学水热法在改性的MWCNTs表面负载纳米Fe_3O_4,将负载Fe_3O_4的MWCNTs(MWCNTs/Fe_3O_4)与PVC在无磁场、有磁场作用下共混制膜,获得MWCNTs无序排列、有序排列修饰的PVC超滤膜,同时,制备了纯PVC膜以作比较.对共混膜有序修饰机制及断面形态进行了分析,对相关性能参数如接触角、膜的溶胀、膜孔隙率、膜平均孔径、纯水通量、截留性能及吸附性能等进行了研究.研究结果表明:MWCNTs/Fe_3O_4的加入使膜的亲水性、纯水通量、截留性能等有了显著提高,MWCNTs有序排列修饰使膜在表皮层形成了更加致密,更为狭长的微孔结构,具有了更优异的导流网络通道,在长时间运行条件下仍能保持良好的过滤负荷,提高了膜的性能.     

Preliminary investigation on cytotoxicity of fluorinated polymer nanoparticles

As well-known persistent organic pollutants(POPs), organofluorine pollutants such as perfluorooctane sulfonate(PFOS) have been proven to be bioaccumulated and harmful to health. However, toxicological assessment of organofluorinated nanoparticles, which have emerged as a novel tool for biomedical and industrial applications, is lacking, to the best of our knowledge. To assess the biological effects and health risk of fluorinated nanoparticles,trifluoroethyl aryl ether-based fluorinated poly(methyl methacrylate) nanoparticles(PTFEPMMA NPs) were synthesized with various fluorine contents(PTFE-PMMA-1 NPs 12.0 wt.%,PTFE-PMMA-2 NPs 6.1 wt.% and PTFE-PMMA-3 NPs 5.0 wt.%), and their cytotoxicity was investigated in this study. The in vitro experimental results indicated that the cytotoxicity of PTFE-PMMA NPs was mild, and was closely related to their fluorine(F) contents and Fcontaining side chains. Specifically, the cytotoxicity of PTFE-PMMA NPs decreased with increasing F content and F-containing side chains. After exposure to PTFE-PMMA NPs at a sublethal dose(50 μg/m L) for 24 hr, the phospholipid bilayer was damaged, accompanied by increasing permeability of the cell membrane. Meanwhile, the intracellular accumulation of reactive oxygen species(ROS) occurred, resulting in the increase of DNA damage, cell cycle arrest and cell death. Overall, the PTFE-PMMA NPs were found to be relatively safe compared with typical engineered nanomaterials(ENMs), such as silver nanoparticles and graphene oxide, for biomedical and industrial applications.     

污水处理厂不同单元工艺水中重金属及其纳米颗粒的分布

以成都双流国际机场污水处理厂中连续处理废水工艺中的9个不同处理单元工艺为研究对象,通过电感耦合等离子体质谱法（ICP-MS）和单颗粒电感耦合等离子体质谱法（SP-ICP-MS）分别对污水处理厂中不同处理单元工艺中的重金属总质量浓度以及重金属纳米颗粒的数量浓度和粒径分布进行了分析,并研究了不同处理单元工艺对重金属元素及重金属纳米颗粒的去除效果.结果表明,不同处理单元工艺对不同重金属元素的去除效果存在差异,对Fe元素的影响最为显著,主要在二沉池中被去除,去除率达98.53%;不同处理单元工艺对不同重金属纳米颗粒的去除效果存在显著差异,对Ni、Pd和Fe纳米颗粒的影响最为显著,不同重金属纳米颗粒在不同处理单元工艺（曝气沉砂池、二沉池和高效沉淀池）中被去除;重金属纳米颗粒在不同处理单元工艺中的粒径分布为23.28~147.83 nm,不同处理单元工艺不会对各重金属纳米颗粒的粒径造成显著影响;pH与Fe元素和Fe纳米颗粒呈显著负相关关系,除Fe元素和Fe纳米颗粒外,其他重金属元素与其纳米颗粒之间均属于不显著相关,不同处理单元工艺对重金属元素和重金属纳米颗粒的去除机制存在差异.     

SBA-15介孔分子筛负载金属酞菁催化氧化甲醛

采用浸渍法将钴或铁酞菁组装进有序介孔材料SBA-15中,通过XRD和N₂吸附方法对组装体进行了表征,研究了常温常压下,该组装体催化氧化甲醛的活性.结果表明,组装体具有优良的处理甲醛性能.钴酞菁比铁酞菁组装体的催化氧化活性高;钴和铁酞菁的协同作用使组装体具有更强的催化氧化活性,当二者摩尔比为1:1时,催化氧化活性最高;并借鉴金属酞菁处理有机巯醇的原理探讨了金属酞菁催化氧化甲醛的原理.     

两种纳米颗粒对沸石吸附环丙沙星的影响

为了探明纳米颗粒（NPs）共存对抗生素在黏土矿物上的吸附的影响,以沸石为供试黏土矿物,环丙沙星（CIP）为目标污染物,研究了不同温度、 pH值和离子强度条件下,纳米氧化锌（ZnO NPs）和纳米二氧化钛（TiO₂ NPs）这2种NPs对沸石吸附CIP的影响,并结合沸石的表面特征探讨不同类型NPs对CIP吸附的影响机制.结果表明,除5 mg·L^-1ZnO NPs共存时,轻微促进了CIP的吸附,其他NPs浓度均对CIP产生不同程度的抑制,抑制程度表现出TiO₂ NPs>ZnO NPs的顺序;随温度升高,NPs的存在增强了沸石对CIP吸附的增温正效应;当离子强度由0.001mol·L^-1增加到0.01mol·L^-1时,CIP的吸附量下降,但2种NPs的存在均减弱了离子强度的负效应;溶液pH会影响CIP的存在形态和NPs的性质,进而影响CIP的吸附.沸石对单一CIP的吸附存在静电引力、氢键和孔径填充作用,ZnO NPs主要通过静电引力竞争吸附位点对CIP吸附产生影响,而TiO     

双孔介孔碳的合成及其对亚甲基蓝的吸附

以三嵌段共聚物F108为模板剂,苯酚/甲醛为碳源,在中性条件下制备了平均孔径为3.14 nm,最可几孔径分布为3 nm和8 nm,BET比表面积为1541 m2·g-1,孔容为1.01 cm3·g-1的双孔分布介孔碳.通过静态实验法测定了介孔碳对亚甲基蓝的吸附特性,分析了初始浓度、溶液p H、温度对吸附量的影响,并从热力学及动力学角度探讨了介孔碳对亚甲基蓝的吸附机理.结果表明,溶液初始浓度、溶液p H以及温度对吸附量有较大的影响,介孔碳对亚甲基蓝的吸附随着初始浓度、p H、温度的上升而增大,吸附为吸热反应,提高温度有利于吸附的进行.实验制备的介孔碳对亚甲基蓝的最大吸附量为421 mg·g-1,相比于普通活性炭,双孔分布介孔碳对亚甲基蓝显示了更优的吸附性能.亚甲基蓝在介孔碳上的吸附行为符合Langmuir吸附等温线和Elovich动力学模型.计算得到的吸附吉布斯自由能(ΔG0)0,吸附标准焓变(ΔH0)70 k J·mol-1,说明亚甲基蓝在介孔碳上的吸附是自发进行的单分子层吸热反应,且化学反应在吸附过程中发挥了重要作用.     

纳米四氧化三铁同步去除水中的Pb（Ⅱ）和Cr（Ⅲ）离子

采用共沉淀方法制备纳米四氧化三铁颗粒（MNPs）,通过扫描电镜（SEM）、X射线衍射（XRD）和光电子能谱分析（XPS）等表征手段对材料进行分析。同时考察了不同MNPs投加量、pH值、温度和初始浓度条件下对纳米四氧化三铁同步去除水中Pb（Ⅱ）和Cr（Ⅲ）离子的影响。结果表明,在pH为6.0、温度为25℃、纳米四氧化三铁的投加量为4.0 g/L下,吸附3 h后,Pb（Ⅱ）-Cr（Ⅲ）复合溶液中Pb的去除率为70.5%,Cr的去除率可达77.4%。pH和温度对去除过程影响较大。SEM和XRD分析证实成功制备了纳米级四氧化三铁,XPS结果表明,复合溶液中Pb（Ⅱ）和Cr（Ⅲ）离子的去除过程为同步吸附。吸附等温线研究说明,Pb（Ⅱ）的吸附是放热过程且为单相吸附;相反Cr（Ⅲ）的吸附是吸热过程且为多相吸附。重复利用实验表明,MNPs利用3次后对Pb和Cr的去除率几乎未受影响。因此,MNPs可用于实际工程中多种重金属离子共存废水的原位处理。     

Reductive transformation of 2,4-dichlorophenoxyacetic acid by nanoscale and microscale Fe3O4 particles

Reductive transformation of 2,4-dichlorophenoxyacetic acid (2,4-D) by nanoscale and microscale Fe₃O₄ was investigated and compared. Disappearance of the parent species and formation of reaction intermediates and products were kinetically analyzed. Results suggest that the transformation of 2,4-D followed a primary pathway of its complete reduction to phenol and a secondary pathway of sequential reductive hydrogenolysis to 2,4-dichlorophenol (2,4-DCP), chlorophenol (2-CP, 4-CP) and phenol. About 65% of 2,4-D with initial concentration of 50 μ M was transformed within 48 h in the presence of 300 mg L^?1 nanoscale Fe₃O₄, and the reaction rates increased with increasing dosage of nanoscale Fe₃O₄. The decomposition of 2,4-D proceeded rapidly at optimum pH 3.0. Chloride was identified as a reduction product for 2,4-D in the magnetite–water system. Reductive transformation of 2,4-D by microscale Fe₃O₄ was slower than that by nanoscale Fe₃O₄. The reactions apparently followed pseudo-first-order kinetics with respect to the 2,4-D transformation. The degradation rate of 2,4-D decreased with the increase of initial 2,4-D concentration. In addition, anions had a significant adverse impact on the degradation efficiency of 2,4-D.