共查询到19条相似文献,搜索用时 546 毫秒
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选择20种脂肪族及杂环化合物作为模型污染物,分别测定了三种不同纳滤膜对脂肪族及杂环化合物的截留率.结果表明,脂肪族及杂环化合物的截留率受到分子的分枝结构、环状结构、酸性和膜特性的影响:对于同分异构体,分枝结构愈多,截留率愈高;环状有机物与分子量相近的直链有机物相比,截留率明显偏高;脂肪酸的截留率高于绝大多数醇类、醚类和酮类等不离解的化合物;孔径小、荷电量大的纳滤膜截留率更高.通过基于遗传算法结合偏最小二乘回归法(GA-PLS)建立了纳滤膜对脂肪族及杂环化合物截留率的定量构效关系模型,通过分析回归方程,可以看出膜与脂肪族及杂环化合物之间的电性作用并不是影响截留率的主要因素,而分子形状和大小对截留率的影响很显著. 相似文献
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本文以对位芳香族聚酰胺(PPTA)超滤膜为基膜,无水哌嗪(PIP)与1,3,5-苯三甲酰氯(TMC)分别作为水相单体和油相单体,采用界面聚合法制得高通量耐热PPTA/PA复合纳滤膜.研究了反应条件对PPTA/PA复合纳滤膜高温纳滤性能影响,观察了复合纳滤膜表面形貌与致密层结构,考察了渗透通量、耐热性以及抗污染等性能.结果表明,当PIP浓度为15%wt,TMC浓度为2.5%wt,热处理温度和时间分别为60℃和8 min时,所得PPTA/PA复合纳滤膜对不同染料分子截留率可达95%以上,对二价盐截留率可达90%以上.在高温条件下,所得PPTA/PA复合纳滤膜表现出优良的染料脱盐性能,在刚果红染料与Na2SO4截留率保持在99%的同时,渗透通量可达50 L·m-2·h-1·MPa-1以上. 相似文献
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4-氨基安替比林比色法测定水中微量芳胺的研究 总被引:8,自引:1,他引:7
在六次甲基胺-盐酸缓冲体中,邻、对位未被全部取代的各种芳胺均可同4-氨基安替比林和过硫酸铵反应,生成紫红色化合物。用3cm比色糟在波长530nm测定吸光度,可测定0.15—1.5ppm的对位无取代基的芳胺。对位被取代,但邻位未全部被取代的芳胺的检测范围是10—100PPm。本方法的回收率为97%,变异系数为±1.6%。还原性物质、酚类化合物等对本方法有干扰。 相似文献
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本文以聚砜和磺化聚砜为原料,制备了低截留分子量的共混超滤膜,此种膜具有适中透水量,对分子量3000的PEG截留率在90%以上,对膜的制备参数,如聚合物浓度,不同溶剂,不同添加剂和凝胶介质对膜性能的影响进行了较详细的的研究。 相似文献
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乙酰丙酮(AA)作为光活化剂在水中可高效转化染料、硝酸盐、亚砷酸等污染物,但光反应发生的具体机理尚不清楚.本文选取AA及AA中心碳上的氢被不同基团取代的4种衍生物(AAs)为研究对象,初步探究AAs在水溶液中的光化学性质,包括:未经光照时和光照过程中的紫外吸收光谱,并选择3种不同类型的染料进行光反应实验,从取代基效应的角度出发比较不同取代基的存在对自身性质及其光化学活性的影响.实验结果表明,取代基的存在对物质在水中的稳定性、自身的紫外吸收光谱以及转化染料的光化学活性产生影响.吸电子基的存在对AA光化学转化染料的活性无明显的影响.推电子基的存在则会促进AAs的自身光降解,取代基的推电子能力越强,在水中越不稳定,转化染料的光活性越高.研究结果为选取合适的AAs用于光化学脱色提供了理论依据. 相似文献
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以同质增强型凯夫拉(PPTA)中空纤维膜为基膜,吡咯(Py)和三氯化铁(FeCl3)分别为反应单体和活化剂,采用化学气相沉积法制备了结构稳定、可控的聚吡咯(PPy)/PPTA中空纤维复合纳滤膜.采用FTIR、SEM、AFM、接触角测定仪以及固体表面Zeta电位仪对基膜和PPy/PPTA中空纤维复合纳滤膜的微观形貌、化学组成、亲水性、表面荷电性进行了表征.结果表明,经PPy气相沉积后,PPy/PPTA中空纤维复合纳滤膜表面形成具有图灵结构特征的分离层,并均匀覆盖膜表面.在0.6 MPa室温下,PPy/PPTA中空纤维复合纳滤膜具有较高的的脱盐性能,其顺序为RNa2SO4 (93.59%)>RMgSO4(91.58%)>RCaCl2(83.45%)> RNaCl (54.04%),同时对带负电染料表现出较高的截留率(?98.82%).当运行温度从25℃升高到90℃时,PPy/PPTA中空纤维复合纳滤膜的水通量较明显增加,而截留率几乎保持稳定,表现出优异的热稳定性,为纳滤膜在更高运行温度... 相似文献
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以原子类型电拓扑状态指数(ETSI)表征19个酚类化合物的分子结构,应用基于预测的变量选择与模型化(VSMP)方法,建立了酚类化合物在产甲烷和脱氮两种厌氧环境下的降解效果与分子结构的定量相关模型.结果表明:在产甲烷环境中,影响酚类化合物厌氧降解的主要结构因素是由4个ETSI描述子对应的子结构碎片,即aCHa,aaC-,-NH2和-OH,其中子结构aCHa和aaC-与酚环母体骨架密切相关,而-NH2和-OH反映取代基的变化.通过多元线性回归法建立的产甲烷条件下酚类化合物的结构-厌氧降解性相关模型(QSBR)发现,其模型估计相关系数,r=0.9173,LOO检验相关系数q=0.8461;反硝化条件下,影响酚类化合物厌氧降解的主要结构因素是=(C),aaC-,=O和-Cl,其中子结构aaC-与酚环母体骨架相关,而=(C),=O和-Cl反映支链或取代基的变化.其模型估计相关系数r=0.8953,LOO检验相关系数q=0.8488.以上结果均表明模型具有良好的估计能力与稳定性,进而从建模的角度证明了厌氧环境中,电子受体的选择影响酚类化合物的降解效果和机理. 相似文献
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通过比较分子力场分析方法(CoMFA)建立酚类化合物对梨形四膜虫极性麻醉毒性(pT)的三维定量结构-活性相关(3D-QSAR)模型.基于训练集41个化合物建立了预测模型,10个化合物作为验证集(含模板分子).训练集的CoMFA模型显示立体场、静电场对麻醉毒性贡献依次为53.9%和46.1%.其交叉验证相关系数(R2cv)为0.735,非交叉验证相关系数(R2)为0.971.对训练集、测试集中的化合物麻醉毒性进行预测,显示出较强的稳定性和良好的预测能力.根据CoMFA模型的立体场和静电场三维等势线图可知,在羟基的间、对位上引入小体积基团,以及邻、对位有负电性基团,有利于提高酚类衍生物的麻醉毒性.基于此,设计了7种具有更高麻醉毒性的酚类化合物,有待生物医学实验验证. 相似文献
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Yang-ying Zhao Fan-xin Kong Zhi Wang Hong-wei Yang Xiao-mao Wang Yuefeng F. Xie T. David Waite 《Frontiers of Environmental Science & Engineering》2017,11(6):20
This study was conducted to assess the merits and limitations of various high-pressure membranes, tight nanofiltration (NF) membranes in particular, for the removal of trace organic compounds (TrOCs). The performance of a low-pressure reverse osmosis (LPRO) membrane (ESPA1), a tight NF membrane (NF90) and two loose NF membranes (HL and NF270) was compared for the rejection of 23 different pharmaceuticals (PhACs). Efforts were also devoted to understand the effect of adsorption on the rejection performance of each membrane. Difference in hydrogen bond formation potential (HFP) was taken into consideration. Results showed that NF90 performed similarly to ESPA1 with mean rejection higher than 95%. NF270 outperformed HL in terms of both water permeability and PhAC rejection higher than 90%. Electrostatic effects were more significant in PhAC rejection by loose NF membranes than tight NF and LPRO membranes. The adverse effect of adsorption on rejection by HL and ESPA1 was more substantial than NF270 and NF90, which could not be simply explained by the difference in membrane surface hydrophobicity, selective layer thickness or pore size. The HL membrane had a lower rejection of PhACs of higher hydrophobicity (log D>0) and higher HFP (>0.02). Nevertheless, the effects of PhAC hydrophobicity and HFP on rejection by ESPA1 could not be discerned. Poor rejection of certain PhACs could generally be explained by aspects of steric hindrance, electrostatic interactions and adsorption. High-pressure membranes like NF90 and NF270 have a high promise in TrOC removal from contaminated water. 相似文献
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Xiaomao WANG Hongwei YANG Zhenyu LI Shaoxia YANG Yuefeng XIE 《Frontiers of Environmental Science & Engineering》2015,9(1):155
High-pressure membrane process is one of the cost-effective technologies for the treatment of groundwater containing excessive dissolved solids. This paper reports a pilot study in treating a typical groundwater in Huaibei Plain containing excessive sodium, sulfate and fluoride ions. Three membrane systems were set up and two brands of reverse osmosis (RO), four low-pressure RO (LPRO) and one tight nanofiltration (NF) membranes were tested under this pilot study. An apparent recovery rate at about 75% was adopted. Cartridge filtration, in combination with dosing antiscalent, was not sufficient to reduce the fouling potential of the raw water. All RO and LPRO systems (except for the two severely affected by membrane fouling) demonstrated similar rejection ratios of the conductivity (~98.5%), sodium (~98.5%) and fluoride (~99%). Membrane fouling substantially reduced the rejection performance of the fouled membranes. The tight NF membrane also had a good rejection on conductivity (95%), sodium (94%) and fluoride (95%). All membranes rejected sulfate ion almost completely (more than 99%). The electricity consumptions for the RO, LPRO and NF systems were 1.74, 1.10 and 0.72 kWh?m-3 treated water, respectively. The estimated treatment costs by using typical RO, LPRO and tight NF membrane systems were 1.21, 0.98 and 0.96 CNY?m-3 finished water, respectively. A treatment process consisting of either LPRO or tight NF facilities following multi-media filtration was suggested. 相似文献
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Hydrophobic acid organic matter (HpoA) extracted from treated effluent has been known to improve the rejection of steroid hormone estrone by reverse osmosis (RO) and nanofiltration (NF) membranes. In this study, the effects of solution chemistry (solution pH and ionic strength) on the estrone rejection by NF membrane with the presence of HpoA were systematically investigated. Crossflow nanofiltration experiments show that the presence of HpoA significantly improved estrone rejection at all pH and ionic strength levels investigated. It is consistently shown that the “enhancement effect” of HpoA on estrone rejection at neutral and alkaline pH is attributed to the binding of estrone by HpoA macromolecules via hydrogen bonding between phenolic functional groups in feed solutions, which leads to an increase in molecular weight and appearance of negative charge. The membrane exhibited the best performance in terms of estrone rejection at pH 10.4 (compared to pH 4 and pH 7) as a result of strengthening the electrostatic repulsion between estrone and membrane with the presence of HpoA. At neutral pH level, the ability of HpoA macromolecules to promote estrone rejection became stronger with increasing ionic strength due to their more extended conformation, which created more chances for the association between estrone and HpoA. The important conclusion of this study is that increasing solution pH and salinity can greatly intensify the “enhancement effect” of HpoA. These results can be important for NF application in direct/indirect potable water reuse. 相似文献
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Nathalie Tanne Rui Xu Mingyue Zhou Pan Zhang Xiaomao Wang Xianghua Wen 《Frontiers of Environmental Science & Engineering》2019,13(2):19
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The availability of clean water has become a critical problems facing the society due to pollution by human activities. Most regions in the world have high demands for clean water. Supplies for freshwater are under pressure. Water reuse is a potential solution for clean water scarcity. A pressure-driven membrane process such as nanofiltration has become the main component of advanced water reuse and desalination systems. High rejection and water permeability of solutes are the major characteristics that make nanofiltration membranes economically feasible for water purification. Recent advances include the prediction of membrane performances under different operating conditions. Here, we review the characterization of nanofiltration membranes by methods such as scanning electron microscopy, thermal gravimetric analysis, attenuated total reflection Fourier transform infrared spectroscopy, and atomic force microscopy. Advances show that the solute rejection and permeation performance of nanofiltration membranes are controlled by the composition of the casting solution of the active layer, cross-linking agent concentration, preparation method, and operating conditions. The solute rejection depends strongly on the solute type, which includes charge valency, diffusion coefficient, and hydration energy. We also review the analysis of the surface roughness, the nodule size, and the pore size of nanofiltration membranes. We also present a new concept for membrane characterization by quantitative analysis of phase images to elucidate the macro-molecular packing at the membrane surface. 相似文献
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Danyang Liu Johny Cabrera Lijuan Zhong Wenjing Wang Dingyuan Duan Xiaomao Wang Shuming Liu Yuefeng F. Xie 《Frontiers of Environmental Science & Engineering》2021,15(4):69
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Xiaowei Wang Wenjun Liu Desheng Li Weifang Ma 《Frontiers of Environmental Science & Engineering》2009,3(4):428-433
A laboratory-scale investigation was performed to study arsenic (As (V)) removal by negatively charged GE-HL nanofiltration (NF) membrane in simulated drinking water. Effects of As (V) concentration (0–200 μg·L?1), pH, and co-ions and counter-ions were investigated. The NF membrane presented good stability, and the rejection rates exceeded 90%. The rejection rates of As (V) decreased with the increase of As (V) concentration, while it increased with the increase of pH (reached 96% at pH 6.75). Moreover, a negative relationship was observed between the co-existing ions of Cl?, Na+, SO 4 2? , and Ca2+ and the removal of As (V), in which bivalent ions presented more significant effects than monovalent ions. 相似文献
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Ruobin Dai Hongyi Han Yuting Zhu Xi Wang Zhiwei Wang 《Frontiers of Environmental Science & Engineering》2022,16(4):40
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Yufeng Liao Mengmeng Tang Mengyuan Li Peng Shi Aimin Li Yangyang Zhang Yang Pan 《Frontiers of Environmental Science & Engineering》2023,17(10):125