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1.
纳米颗粒的分散及其在水与废水处理中的应用   总被引:11,自引:1,他引:10  
纳米颗粒由于其吸附活性而极易产生自身团聚,这不利于纳米颗粒在使用介质中的分散并影响其应用。本文综述了近年来有关纳米颗粒在水中的分散方法、原理及影响因素,归纳总结了分散的纳米颗粒在强化水处理中的若干应用。  相似文献   

2.
分别单独以醇胺(MDEA)和氯化铁水溶液为基液,引入4种不同的纳米颗粒(纳米氧化铝、二氧化硅、碳纳米管及纳米铜颗粒),构建不同质量分数的纳米流体体系,并测定不同体系对硫化氢气体的动态脱除性能,以考察纳米流体体系的构建对碱性(MDEA)及氧化性(氯化铁)水溶液脱硫性能的影响。分别对4种纳米颗粒进行了扫描电镜和透射电镜分析,发现其尺寸均在纳米级别。气液吸收研究结果表明,在2种不同基液的纳米流体体系中,添加Al2O3和SiO2纳米颗粒形成的纳米流体体系对原水溶液的脱硫性能均未产生明显影响。而碳纳米管和纳米铜颗粒的添加对H2S气体的去除则有不同程度增强。对于碳纳米管型纳米流体而言,对MDEA和氯化铁水溶液的脱硫强化性能在纳米颗粒质量分数为0.05%时最高。而对纳米铜颗粒而言,在2种水溶液中最佳质量分数分别为0.05%和0.02%。本研究表明纳米铜颗粒的引入对碱性及氧化性水溶液脱硫性能的增强作用最为明显,可为新型纳米流体型脱硫剂的开发提供参考。  相似文献   

3.
纳米零价铁的制备及其去除水中对氯硝基苯的研究   总被引:6,自引:2,他引:4  
通过FeSO4与KBH4反应,利用液相还原法制备纳米零价铁颗粒(NZVI),用XRD、SEM和BET对其性能进行表征。在常温常压下利用纳米铁还原废水中的对氯硝基苯(p-CNB),探讨了反应条件对还原率的影响。结果表明,制备过程中碱性物质(NaOH)的添加可以明显减小颗粒粒径,增大比表面积,提高纳米铁还原反应的效率。NZVI对于对氯硝基苯有很好的去除效果,NZVI用量、p-CNB初始浓度和pH值均对其去除效率产生影响。在纳米铁投加量为1 g/L,pH=2的条件下,添加NaOH的纳米铁能在120 min内将质量浓度为50 mg/L的对氯硝基苯基本完全降解,降解率为98.8%。此外,还对NZVI还原对氯硝基苯的机理进行了初步探讨。  相似文献   

4.
金属掺杂纳米塑料已被广泛应用在纳米塑料的环境行为与生物效应研究中,但其中掺杂的金属是否会对其生物效应产生影响尚不清楚。以厌氧颗粒污泥为研究对象,基于乳液聚合的方法合成钯(Pd)掺杂的纳米塑料(Pd-NPs),研究它对污泥厌氧消化系统产甲烷性能、微生物群落分布和污泥胞外聚合物的影响。结果表明,Pd-NPs中的Pd会随时间的推移溶出,并通过提高厌氧消化系统中地杆菌(Geobacter)的相对丰度促进电子传递进而促进污泥厌氧消化系统产甲烷量;傅立叶变换红外光谱和三维荧光光谱结果显示,Pd-NPs能够与厌氧颗粒污泥表面胞外聚合物中蛋白质和腐殖酸类物质发生相互作用,使污泥颗粒更易絮凝。这些结果为评估金属掺杂的纳米塑料对厌氧消化系统的影响提供了一定的数据支撑。  相似文献   

5.
选取柠檬酸盐改良磁性纳米颗粒汲取液作为正渗透汲取液,研究其在浓盐水处理中的应用效果,采用热合成方法控制温度为30、60和90℃时制成了柠檬酸盐改良磁性纳米颗粒(MNP0、MNP1和MNP2)。对3种磁性纳米颗粒进行表征的结果显示,随反应温度的升高,分散性提高,同时温度升高,更有利于柠檬酸盐包覆到磁性纳米颗粒的表面。不同温度条件下合成的3种柠檬酸盐磁性纳米颗粒处理浓盐水测定水通量和反向盐通量研究表明,MNP2的水通量较MNP0和MNP1高,为23 L·(m2·h)-1,且水通量下降较稳定,反向盐通量较小。不同粒径的MNP2处理浓盐水研究结果表明,水通量随粒径的减小呈现增加趋势,粒径为3.5 nm时的渗透压和水通量最高且减压渗透(pressure relief osmosis,PRO)模式下水通量较正渗透(forward osmosis,FO)模式高。  相似文献   

6.
一种新型纳米固相萃取吸附剂,由阴离子表面活性剂十二烷基磺酸钠(SDS)包裹在Fe3O4磁性纳米颗粒表面形成,用于吸附水溶液中的重金属离子。研究了吸附过程的主要影响因素(如SDS浓度、溶液pH等)以及解吸过程的最佳条件,并对其机理进行了初步的探讨。研究结果表明,共沉淀法制备的Fe3O4颗粒粒径分布均匀,平均粒径约为54 nm;SDS浓度为300 mg/L时,Fe3O4/SDS磁性纳米颗粒吸附Cd2+和Zn2+的能力最强;在一定浓度范围内,Fe3O4/SDS体系对Cd2+和Zn2+的吸附平衡数据符合Langmuir吸附等温方程,饱和吸附量分别为22.42 mg/g和13.95 mg/g。最终结果表明,Fe3O4/SDS磁性纳米颗粒具有较强磁分离能力和较好的吸附效果。  相似文献   

7.
Fe3O4/SDS磁性纳米颗粒吸附水体中的Cd2+和Zn2+   总被引:3,自引:1,他引:2  
黄文  周梅芳 《环境工程学报》2012,6(4):1251-1256
一种新型纳米固相萃取吸附剂,由阴离子表面活性剂十二烷基磺酸钠(SDS)包裹在Fe3O4磁性纳米颗粒表面形成,用于吸附水溶液中的重金属离子。研究了吸附过程的主要影响因素(如SDS浓度、溶液pH等)以及解吸过程的最佳条件,并对其机理进行了初步的探讨。研究结果表明,共沉淀法制备的Fe3O4颗粒粒径分布均匀,平均粒径约为54 nm;SDS浓度为300 mg/L时,Fe3O4/SDS磁性纳米颗粒吸附Cd2+和Zn2+的能力最强;在一定浓度范围内,Fe3O4/SDS体系对Cd2+和Zn2+的吸附平衡数据符合Langmuir吸附等温方程,饱和吸附量分别为22.42 mg/g和13.95 mg/g。最终结果表明,Fe3O4/SDS磁性纳米颗粒具有较强磁分离能力和较好的吸附效果。  相似文献   

8.
众所周知,纳米颗粒在去除水中污染物的过程中易团聚,还会造成水体的二次污染。磁性Fe3O4纳米颗粒因其能迅速从水中分离的特性而被广泛关注。改性之后的磁性Fe3O4纳米颗粒在水中污染物的去除方面有很好的应用。对磁性Fe3O4纳米颗粒及其载体或复合物的制备方法进行了概述,重点对水中污染物的去除从3个方面进行了阐述:磁性Fe3O4纳米材料对水中重金属的吸附、有机物的吸附及水中细菌和医疗废物的处理。  相似文献   

9.
采用化学沉淀法将高分散纳米Ag_3PO_4颗粒负载到纯化的凹凸棒石(ATP)表面,得到了具有可见光响应、高活性的纳米复合可见光催化剂Ag_3PO_4/ATP。采用X射线衍射、扫描电子显微镜、紫外—可见漫反射光谱、红外吸收光谱、热重和比表面积分析等技术对催化剂的相结构和微观形貌等进行了表征。结果表明,ATP因其具有较大的负载表面使得负载的Ag_3PO_4纳米颗粒变小、分散程度增强且光吸收边红移,增加了Ag_3PO_4/ATP的活性位点。可见光条件下,当Ag_3PO_4负载量为45%(质量分数)时,Ag_3PO_4/ATP对亚甲基蓝的准一级动力学表观速率常数是Ag_3PO_4的2.39倍。  相似文献   

10.
好氧颗粒污泥的性质及其在脱氮除磷中的应用   总被引:1,自引:0,他引:1  
阐述了好氧颗粒污泥的污泥特性、培养条件和影响因素 ,比较了三种SBR反应器中颗粒污泥特性的差异 ,介绍了好氧颗粒污泥的形成机理及其在脱氮除磷过程中的应用情况  相似文献   

11.
This study investigated water-soluble ions in the sized particles (particularly nano (PM(0.01-0.056))/ultrafine (PM(0.01-0.1))) collected using MOUDI and Nano-MOUDI samplers near a busy road site and at a rural site. The analytical results demonstrate that nano and coarse particles exhibited the highest (16.3%) and lowest (8.37%) nitrate mass ratios, respectively. The mass ratio of NO(3)(-) was higher than that of SO(4)(2-) in all the sized particles at the traffic site. The secondary aerosols all displayed trimodal distributions. The aerosols in ultrafine particles collected at the roadside site exhibited Aitken mode distributions indicating they were of local origin. This finding was not observed for those ultrafine particles collected at the rural site. The mass median diameters (MMDs) of the nano, ultrafine, and fine particles were smaller at the traffic site than at the rural site, possibly related to the contribution of mobile engine emissions.  相似文献   

12.
采用仿生矿化法制备了壳聚糖/纳米CdS复合颗粒光催化剂,并用于可见光光催化降解猩红B染料模拟废水,研究了猩红B初始浓度、pH、催化剂投加量和催化剂重复使用次数等因素对猩红B光催化降解的影响.X射线衍射(XRD)分析表明,壳聚糖能有效负载CdS纳米微晶.采用Langmuir-Hinshelwood模型描述壳聚糖/纳米CdS复合颗粒可见光光催化降解猩红B反应动力学行为,在猩红B初始质量浓度较低(≤20 mg/L)时,光催化降解过程符合假一级动力学方程.降低猩红B初始浓度和溶液pH都可显著增大光催化降解速率常数;催化剂投加量小于0.7 g/L时,光催化降解速率随其增加而增大,但催化剂投加量过大会使光催化降解速率减小;催化剂重复使用第5次时,猩红B光催化降解速率常数仍为第1次使用时的63.4%.  相似文献   

13.
以十六烷基三甲基溴化胺(CTAB)为分散剂,制备改性纳米零价铁颗粒(CNZVI)。比表面积、XRD、SEM和TEM表征结果表明改性的CNZVI比未改性纳米零价铁颗粒(BNZVI)粒径更小、更均匀,具有更好的分散性能和抗氧化性。首次考察了CNZVI对于水中染料橙黄Ⅱ的脱色降解效果。CNZVI对橙黄Ⅱ的脱色率和降解速率均优于未改性纳米铁颗粒BNZVI,脱色率在反应进行10 min后趋于稳定。考察了溶液pH、初始浓度、NZVI投加量和温度对反应脱色率的影响。pH值和初始浓度越高,脱色率越低;脱色率随着投加量和温度提高而增大。最后优化反应条件为:pH值5.96,初始浓度100 mg/L,NZVI投加量0.2 g/L,反应温度293 K,CNZVI对橙黄Ⅱ的脱色率为91.8%,比BNZVI的脱色率高出16.1%。动力学分析表明,CNZVI对橙黄Ⅱ降解反应符合伪一级反应动力学。  相似文献   

14.
Although the toxicological impact of metal oxide nanoparticles has been studied for the last few decades on aquatic organisms, the exact mechanism of action is still unclear. The fate, behavior, and biological activity of nanoparticles are dependent on physicochemical factors like size, shape, surface area, and stability in the medium. This study deals with the effect of nano and bulk CeO2 particles on marine microcrustacean, Artemia salina. The primary size was found to be 15 ± 3.5 and 582 ± 50 nm for nano and bulk CeO2 (TEM), respectively. The colloidal stability and sedimentation assays showed rapid aggregation of bulk particles in seawater. Both the sizes of CeO2 particles inhibited the hatching rate of brine shrimp cyst. Nano CeO2 was found to be more toxic to A. salina (48 h LC50 38.0 mg/L) when compared to bulk CeO2 (48 h LC50 92.2 mg/L). Nano CeO2-treated A. salina showed higher oxidative stress (ROS) than those treated with the bulk form. The reduction in the antioxidant activity indicated an increase in oxidative stress in the cells. Higher acetylcholinesterase activity (AChE) was observed upon exposure to nano and bulk CeO2 particles. The uptake and accumulation of CeO2 particles were increased with respect to the concentration and particle size. Thus, the above results revealed that nano CeO2 was more lethal to A. salina as compared to bulk particles.  相似文献   

15.
采用液相还原法制备出纳米零价铁铜双金属,研究纳米零价铁铜双金属对土壤浸提液中Cr(Ⅵ)的修复作用。利用响应面分析方法,以处理时间、土壤浸提液的pH值和温度3个影响因素,纳米零价铁铜双金属对土壤浸提液中的Cr(Ⅵ)的去除率为响应值进行了3因素3水平的实验设计,得到响应曲面模型。对得到的响应曲面和方差进行分析。结果表明,模型的方差分析得到的F值和R2分别为15.18和0.951 3,处理时间、土壤浸提液的pH值和温度对土壤浸提液中Cr(Ⅵ)去除率的影响是显著的,模型在整个回归区域内拟合程度好,其影响顺序为处理时间 > 土壤浸提液的pH值 > 反应温度。  相似文献   

16.
TSI Inc. (Shoreview, MN) has introduced three new water-based condensation particle counters (WCPCS) that were designed to detect airborne particles larger than 2.5 nm (model 3786), 5 nm (model 3785), and either 10 or 20 nm (model 3782). These WCPCs are well suited for real-time, environmental monitoring of number concentration of airborne ultrafine particles. Their unique design incorporates the use of water as the working fluid instead of alcohol. Water is odor free, readily available, and eliminates the problem of water condensation and absorption into alcohol working fluids during operation in humid environments. In this study, the performance of three TSI WCPCs was characterized for several aerosol compositions, including sucrose, salt (NaCl), dioctyl sebacate (DOS), dioctyl phthalate (DOP), emery oil (poly-alpha-olefin), silver, impurity residue particles, and ambient aerosol particles. All particles were size selected using a nano differential mobility analyzer (nano-DMA; model 3085, TSI Inc.) to create monodisperse challenge aerosols. The challenge aerosol was mixed uniformly with clean makeup flow and split into a WCPC and a reference instrument to determine the counting efficiency of the WCPC. For the model 3785 WCPC, the D50 (i.e., the particle diameter with 50% counting efficiency) was determined to be 3.1 nm for salt particles, 4.7 nm for sucrose and ambient particles, 5.6 nm for silver particles, and >50 nm for ultrapure oil particles. The sensitivity to oil droplets increased dramatically (D50 < 10 nm) when the oil was slightly contaminated. The D50 of model 3786 ultrafine water-based CPC (UWCPC) was 2.4 nm for impurity residue particles. The D50 of the model 3782 WCPC was 10.8 (with a nominal setting of 10 nm) or 19.8 nm (with a nominal setting of 20 nm) for sucrose particles. All three WCPCs have response times of less than 2 or 3 sec and are therefore able to detect fast-changing events.  相似文献   

17.
As the production of nanoparticles of ZnO, TiO2 and CuO is increasing, their (eco)toxicity to bacteria Vibrio fischeri and crustaceans Daphnia magna and Thamnocephalus platyurus was studied with a special emphasis on product formulations (nano or bulk oxides) and solubilization of particles. Our innovative approach based on the combination of traditional ecotoxicology methods and metal-specific recombinant biosensors allowed to clearly differentiate the toxic effects of metal oxides per se and solubilized metal ions. Suspensions of nano and bulk TiO2 were not toxic even at 20 g l(-1). All Zn formulations were very toxic: L(E)C50 (mg l(-1)) for bulk ZnO, nanoZnO and ZnSO4.7H2O: 1.8, 1.9, 1.1 (V. fischeri); 8.8, 3.2, 6.1 (D. magna) and 0.24, 0.18, 0.98 (T. platyurus), respectively. The toxicity was due to solubilized Zn ions as proved with recombinant Zn-sensor bacteria. Differently from Zn compounds, Cu compounds had different toxicities: L(E)C50 (mg l(-1)) for bulk CuO, nano CuO and CuSO4: 3811, 79, 1.6 (V. fischeri), 165, 3.2, 0,17 (D. magna) and 95, 2.1, 0.11 (T. platyurus), respectively. Cu-sensor bacteria showed that toxicity to V. fischeri and T. platyurus was largely explained by soluble Cu ions. However, for Daphnia magna, nano and bulk CuO proved less bioavailable than for bacterial Cu-sensor. This is the first evaluation of ZnO, CuO and TiO2 toxicity to V. fischeri and T. platyurus. For nano ZnO and nano CuO this is also a first study for D. magna.  相似文献   

18.
For a full estimation of the risk related with the presence of engineered nanoparticles (ENPs) in the environment, the use of the current ecotoxicological methods may prove insufficient. In the study presented herein, various methods of assessment of ecotoxicity were applied to compare the phytotoxicity of three ENPs: nano-ZnO, nano-TiO2 and nano-Ni. The toxicity was assayed both for aqueous solutions of the ENPs (the germination/elongation test and Phytotestkit FTM) and for ENPs added to soil (Phytotoxkit FTM and modified Phytotoxkit FTM). Lepidium sativum was used as a test plant. The scope of the study also included the assessment of the effect of the method of ENP application to the soil (as powder and aqueous suspension) on their phytotoxicity. In the course of the study, no effect of the studied ENPs and their bulk counterparts on the germination of seeds was observed. The root growth inhibition of L. sativum depended on the kind of test applied. The trend between concentration of ENPs and effect depended on the method used and kind of ENPs. For most nanoparticles (despite of the method used), the differences in phytotoxicity between nano and bulk particles were observed. Depending on the kind of ENPs, their phytotoxicity differs between water and soil. ZnO (nano and bulk) and nano-Ni were more toxic in soil than in water. For TiO2 and bulk-Ni, reverse trend was observed. A different method of ENP application to soil differently affects the phytotoxicity.  相似文献   

19.

At present, tetracycline hydrochloride (TCH) is a widely used antibiotic, and is often detected in water, posing a serious harm to human and ecological health. In this study, spent bleaching earth (SBE) was pyrolyzed to obtain spent bleaching earth carbon (SBE@C) and the nano Fe0/SBE@C prepared after zero-valent iron loading was adopted to remove TCH in water for the first time. The combination of nano Fe0/SBE@C and PS, the strong adsorption of SBE@C coupled with the oxidation of free radicals could achieve TCH efficient removal. The effects of nano Fe0 load, nano Fe0/SBE@C dosage, solution initial pH, and PS/TCH molar ratio on TCH removal efficiency in nano Fe0/SBE@C?+?PS system were studied. The results indicate that the optimal reaction conditions are 5% nano Fe0 load, 0.2 g/L nano Fe0/SBE@C dosage, initial pH of 3, PS/TCH molar ratio of 100:1. Under these conditions, TCH removal efficiency could reach 91%. Meanwhile, response surface methodology (RSM) was applied to predict optimal value of reaction conditions. The removal efficiency corresponding to the predicted optimal conditions was consistent with the actual removal efficiency obtained from the experiment. Moreover, six reaction systems were tested, and TCH removal efficiency in the SBE@C?+?PS system was 22.6%. When nano Fe0 was loaded on SBE@C, TCH removal efficiency in Fe0/SBE@C?+?PS system increased to 78.2%, in which TCH was first adsorbed on the surface of nano Fe0/SBE@C, and then was degraded by the oxidation of SO4?? and ?OH. Totally, the nano Fe0/SBE@C?+?PS system displayed excellent TCH removal efficiency, good stability and reusability, exhibiting a promise toward TCH removal.

  相似文献   

20.
随着纳米材料的广泛应用,越来越多的纳米材料会泄露到水环境中,但目前关于纳米材料对混凝过程的影响还缺乏充分的研究。针对不同浊度,不同纳米SiO2浓度,不同pH以及腐殖酸对混凝去除Pb2+的影响进行了一系列的研究。结果表明,在低投加量(40 mg/L) 条件下,Pb2+的去除率受浊度影响较大,然而在高投加量(80 mg/L) 条件下,Pb2+的去除率受浊度的影响反而较小,且随着浊度从15.0 NTU增加到90.0 NTU,Pb2+的去除率从70.172%下降到63.925%。当浊度为45.0 NTU,投加量为40 mg/L时,铅离子的去除率在 SiO2投加量达到0.8 mg/L时达到最高(92.34%)。由于在低浊度条件下絮体形成不充分,以至于生成的絮体对SiO2的吸附去除率较低,所以吸附在SiO2表面的Pb2+会悬浮在溶液体系中,造成Pb2+去除率的下降。随着pH的升高,Pb2+去除率呈先升高后降低的趋势,且在偏碱性条件下达到最高。pH对Pb2+去除率的影响主要体现在其对纳米SiO2表面电荷的影响,SiO2表面负电荷增多可有效提高Pb2+的去除率,说明纳米SiO2的吸附作用在去除Pb2+的过程中起重要的作用。在高混凝剂投加量(80.0 mg/L)下腐殖酸对Pb2+的去除有促进作用,且当腐殖酸存在时,SiO2的含量对Pb2+的去除率无明显影响。  相似文献   

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