共查询到20条相似文献,搜索用时 140 毫秒
1.
木质素-聚吡咯复合纳米粒子的制备及其Ag+吸附性能 总被引:1,自引:0,他引:1
以酶解木质素和吡咯单体为原料,通过原位聚合法制备了木质素-聚吡咯(EHL-PPY)复合纳米粒子。而后以银离子为吸附质,系统地研究了EHL-PPY复合纳米粒子的银离子吸附性能,考察了吸附剂浓度,吸附时间和银离子初始浓度对吸附容量和吸附率的影响。在35℃时,该复合纳米粒子对银离子的饱和吸附容量为882.0 mg/g,吸附完成后,银离子被还原为直径为22~56 nm的单质银颗粒。研究表明,EHL-PPY复合纳米粒子可作为低成本银离子吸附剂使用。 相似文献
2.
3.
《材料导报》2020,(9)
随着工业的快速发展,金属电镀、肥料制造、电池、采矿等行业排放出大量含重金属离子的废水,不但严重污染环境,而且危害人类身体健康。因此,如何实现对废水中重金属离子的快速有效处理成为人们关注和亟待解决的关键技术问题。近年来去除废水中重金属离子的方法不断涌现,主要有:氧化还原法、化学沉淀法、离子交换法、膜分离法和吸附法等。其中吸附法因具有吸附剂的材料来源广泛、种类繁多、较强的吸附能力等优点被广泛应用于废水处理领域。但是传统吸附材料因吸附效率低、吸附材料不能回收等问题已经不能满足日益严格的环境法规,因此,制备具有良好吸附效果、操作简单且可以回收的新型吸附材料一直是研究的重点。磁性纳米颗粒具有很大的比表面积、良好的吸附性能,作为吸附剂能在外加磁场的作用下快速从液相中分离出来,避免二次污染,但磁性纳米颗粒具有较高的比表面能,易于团聚和氧化,限制了磁性纳米颗粒作为吸附剂在废水处理领域的应用。聚苯胺是一种导电高分子聚合物,对重金属离子具有良好的吸附性能。将聚苯胺材料引入磁性纳米颗粒中,不但可以提高磁性纳米颗粒的分散性和稳定性,使其能够适应各种复杂的吸附环境,还提高了磁性纳米颗粒对废水中重金属离子的吸附性能。本文综述了磁性聚苯胺复合材料的结构、性质和制备方法,以及磁性聚苯胺复合材料的合成条件、形貌和吸附条件等因素对重金属离子吸附性能的影响机制。最后分析了磁性聚苯胺复合材料在处理工业废水时有待解决的问题,并展望了该材料的发展趋势,为含有重金属离子的废水处理提供更加充足的理论依据。 相似文献
4.
功能纳米氧化物的结构和性能研究是无机功能材料研究领域的一个研究热点。一般认为纳米氧化物的性能主要由形貌,表面效应和颗粒尺寸效应所决定。目前已经有大量的文献报道介绍各种形状的纳米材料的合成,但材料的性能和大颗粒体相材料相比没有明显的差别。人们利用表面效应来研究纳米氧化物的化学活性及其在光催化环境净化和重金属离子吸附等方面的应用,或通过尺寸效应来解析纳米氧化物出现的奇特的光、电、磁等现象,但普遍忽略纳米材料发生性质改变的结构因素。事实上,纳米材料的性能是由其电子结构和表面吸附的水分子来决定的:电子结构完全依赖于材料的晶体结构和晶格尺寸,而表面吸附的水分子常常会导致光猝灭或发光性能变差的现象。我们对多种氧化物纳米材料进行系统研究,初步构筑了其结构-性能的关系。(1)纳米TiO_2表面吸附大量的水分子。高温脱水导致纳米颗粒度变大。金属纳米材料和金属氧化物材料的比热都大于大颗粒材料,文献都归结于尺寸效应。最新研究表面,扣除吸附水分子的贡献后,裸露的纳米材料TiO_2的比热在实验范围内和大颗粒的基本相同。(2)利用本征黄光作为探针研完了量子尺寸效应对高结晶度ZnO纳米棒的结构和能带结构的修饰。随着ZnO纳米棒直径的增加,... 相似文献
5.
6.
7.
磁性纳米材料具有较高的生物相容性、良好的吸附性能、易于固液分离等特点,在水处理方面越来越受到关注。本文主要综述铁基磁性纳米颗粒的分类、常见形态、功能化方法、铁基磁性纳米颗粒和功能化铁基磁性纳米复合材料吸附废水中重金属离子的研究进展,讨论不同铁基磁性纳米粒子的功能化机理及其在重金属离子吸附过程中的吸附机理,分析铁基磁性纳米材料在重金属离子吸附应用中易团聚、氧化、稳定性差等问题,并展望功能化对铁基磁性纳米颗粒吸附废水中重金属离子的发展前景,为重金属废水的吸附提供更加充足的理论依据。 相似文献
8.
9.
10.
11.
采用化学沉淀-热分解法,合成粒度在20~120 nm的氧化镁粉体。采用透射电镜及X射线衍射分析,研究纳米氧化镁的粒度和形状的控制因素对纳米氧化镁颗粒形成过程的影响。结果表明:镁源及分散剂的种类、沉淀反应温度、样品干燥方式都是影响氧化镁粒度和形状的重要因素。在以Mg(NO3)2为镁源、n(Mg2+):n(OH-)=2:1、沉淀温度为30℃、体积分数为8%的乙二醇为分散剂、微波低火干燥2 min条件下,得到平均粒径为40 nm的氧化镁产品。前驱物的形状与产物纳米氧化镁的形状存在对应关系。 相似文献
12.
The differential scheme is developed to evaluate the effective elastic properties of nano-composites with interface effect through the solution of an infinitely dilute dispersion of nano-particles in a matrix. The differential equations presented in this paper for overall modulus of composites extend the application of classic differential scheme to the nano-scale, and they are valid for both mono-sized and poly-sized nano-particle composites. Particle size distribution functions are introduced. Continuous and discrete size distributions are taken into consideration for poly-sized filled nano-particles. The numerical examples exhibit that the effective properties of mono-sized nano-particle composite are size dependent, which agrees well with previous studies. As for poly-sized particle composite, the results show that the elastic properties are dependent on particle size distributions. Some distribution parameters, such as the mean size and the standard deviation, may significantly affect the effective mechanical properties. The proposed differential equations can be reduced to the classic ones, and are supposed to be in wider application. 相似文献
13.
14.
采用一步法制备出EVA/纳米T iO2及EVA/纳米S iO2复合材料,研究纳米微粒在EVA基体中的分散性、结构变化及对力学性能、流变性能的影响。结果表明,加入的纳米微粒粒径越小,纳米粉体在基体中的分散就会更加均匀,分散微粒的粒径也会更小;纳米微粒和硅烷偶联剂之间,硅烷偶联剂和EVA之间会形成一定的键合结构。适量的纳米微粒能够改变断裂机理,有效地提高材料的力学性能,降低熔体的表观黏度,从而改善加工流动性。 相似文献
15.
为获得颗粒尺寸、形貌等比较规则的纳米CdS颗粒,通过逐层自组装技术和"两步法"相结合的方法在介孔分子筛SBA-15孔道内制备CdS纳米粒子,首先应用带电聚合物聚二烯丙基二甲基氯化铵(PDDA)、聚苯乙烯磺酸钠(PSS)将SBA-15孔道表面功能化,然后引入CdS前驱体Cd(CH3COO)2.2H2O,再将产物在H2S气氛中硫化得到最终产物SBA-15-PDDA-PSS-CdS。采用X射线衍射、N2吸附-脱附等手段进行测试表征,并将所制样品用于降解甲基橙来测试其光催化性能。结果表明:所制得的纳米CdS颗粒较小,分布均匀;纳米CdS在紫外光下对甲基橙具有良好的降解能力。 相似文献
16.
纳米SiO_2在水性介质中的分散稳定性研究 总被引:4,自引:0,他引:4
纳米SiO2特殊的性能使其在很多领域都得到了广泛的应用,而纳米SiO2能否在水性介质中稳定分散将会影响产品的最终质量。本实验选择了九水合硅酸钠和聚丙烯酰胺作为分散剂,并通过激光粒度分析仪和沉降实验对纳米颗粒的分散稳定性进行评价。发现高速研磨能够使聚丙烯酰胺充分地吸附到纳米颗粒表面,聚丙烯酰胺能使纳米SiO2颗粒在水溶液中保持良好的分散稳定性,但是,聚丙烯酰胺的加入量过饱和反而会引起纳米SiO2颗粒的团聚,九水合硅酸钠和聚丙烯酰胺结合起来使用可以发挥协同效应,从而显著改善纳米SiO2颗粒在水溶液中的分散稳定性。 相似文献
17.
SnO2 is an important functional material having a wide range of applications in gas sensors and optoelectronic devices. There is a great interest for finding new cost-effective and straight-forward methods for production of these particles. In this research, hydrogel thermal decomposition method (HTDM) is used for production of high purity SnO2 nano-particles. Cost effective reactants and green routs of production are the advantages of polysaccharide based hydrogel as starting material for this method. Visual observations indicated that there is very little tendency for agglomeration in the SnO2 nano-particles produced by this method which can be considered as an advantage for this method over other methods for production of SnO2 nano-particles. SnO2 nano-particles are also characterized by X-ray diffraction (XRD) in terms of purity and the sizes. It is found that high purity SnO2 nano-particles in the size range of 25-36 nm can be produced by HTDM. 相似文献
18.
19.
A.I.Y. Tok F.Y.C. Boey S.W. Du B.K. Wong 《Materials Science and Engineering: B》2006,130(1-3):114-119
This paper studies the feasibility of using flame spray to produce ZrO2 nano-particles using a liquid precursor. The effects of varying precursor concentrations and ratio of diluting medium on the phase composition, size and morphology of ZrO2 nano-particles are discussed. The morphology and size of the ZrO2 nano-particles was very much dependent on the precursor concentration. The solvent ratio of H2O:ethanol also played a part in determining the characteristics of the ZrO2 nano-particles. The nano-particles had the best characteristics when the precursor concentration was low and ethanol (added as solvent) content was high. In particular, the best characteristics were obtained using precursor concentration of 0.25 M, H2O:ethanol ratio of 0:1. The nano-particles had very small particle size (50 nm), relatively high specific surface area (28.6 m2/g) and high degree of crystallinity. However, particles synthesized tend to be agglomerated. 相似文献
20.
The sol-gel method was used to prepare SiO(2) thin films co-doped with In(2)O(3) nano-particles and Eu(3+). The formation of nano-sized In(2)O(3) particles after annealing at 900?°C was confirmed by the x-ray diffraction technique. A novel phase transition from a hexagonal rhombic centered to a body centered cubic structure of In(2)O(3) nano-particles was observed at around 1100?°C. It is found that the particle size and the particle density of In(2)O(3) can be tuned by changing the annealing temperature and the indium doping concentration, respectively. The characteristic emission bands from Eu(3+) ions can be observed at room temperature and the luminescence intensity is increased 20 times by introducing In(2)O(3) nano-particles into Eu(3+)-doped silica films. The integrated luminescence intensity was gradually enhanced by increasing the In(3+) concentration, suggesting effective energy transfer from nano-sized In(2)O(3) to Eu(3+) ions. 相似文献