不同国产纳滤膜对饮用水中氟离子的去除影响研究

选用两种国产纳滤膜NF1和VNF2进行除氟的实验研究,考察了不同的原水pH、操作压力、进水F-浓度、温度以及腐殖酸的浓度对纳滤除氟截留率以及膜通量的影响.实验结果表明:VNF2膜的截留率高于NF1膜,而膜通量则低于NF1;同时两种膜的最佳操作条件为pH在6.5～7.0,温度在18～23℃,操作压力为0.4 MPa,进水...     

纳滤膜淡化苦咸水技术现状及进展

介绍了苦咸水的危害,综述了纳滤的原理及其独特的分离特点、影响纳滤膜脱盐效率的因素以及纳滤膜在苦咸水淡化中的应用现状。     

Nanofiltration of Magnesium Chloride,Sodium Carbonate,and Calcium Sulphate in Salt Solutions

Abstract

Nanofiltration (NF) membranes have been employed in pre‐treatment unit operations in both thermal and membrane seawater desalination processes. This has resulted in reduction of chemicals used in pretreatment processes as well as lowering the energy consumption and water production cost and, therefore, has led to a more environmentally friendly processes. In order to predict NF membrane performance, a systematic study on the filtration performance of selected commercial NF membranes against brackish water and seawater is required. In this study, three commercial nanofiltration membranes (NF90, NF270, N30F) have been used to treat highly concentrated different salts solutions (MgCl₂, Na₂CO₃, and CaSO₄) at salinity level similar to that of brackish water and seawater. The main parameters studied in this paper are salt concentration and feed pressure. The experimental data were correlated and analysed using the Spiegler‐Kedem model. In particular, the reflection coefficient (σ) of all studied membranes and the solute permeability (P_s) have been determined for all membranes and at different salinity levels of studied salts. All the studied membranes fitted the model well for all investigated salts except the experimental data of MgCl₂ using N30F membrane, which did not fit well at low rejection. The results showed that NF90 produced a high rejection around 97% for all salts with medium permeate flux while NF270 gave a high flux with medium rejection and N30F gave low rejection and flux.     

纳滤膜去除水中双酚A的研究

酚类环境激素双酚A(BPA)在各种水体中都有检出,且检出浓度有逐年增大的趋势;酚类有一定的毒性,加之它在水中的溶解度小,常规方法不易去除。本试验研究了NF-270型纳滤膜在不同压强、浓度、温度下对双酚A的去除效果。结果表明:原水中微量双酚A浓度的变化对膜通量基本无影响,截留率会随原水中双酚A浓度的增大而略有增加;随着操作压力的增加,膜通量增加,截留率增大,温度增加,截留率也增大,但超过30℃时,截留率明显下降。     

无机盐水溶液体系的纳滤膜分离实验研究

选择了NF45和SU200两种纳滤膜对1－1型（KC1、NaCl、LiCl)、2－1型MgCl2)、1－2型（K2SO4）及2－2型（MgSO4)等6种无机盐水溶液体系进行分离实验；考察了纳滤膜分离性能随操作压力、料液浓度及电解质种类等因素的变化所受到的影响。实验结果表明，纳滤膜对盐的截留率随操作压力的增加而增大，并趋向于定值（即膜的最大截留率，又称为膜的反射系数）；纳滤膜对盐的截留率随电解质种类的不同而改变，随盐浓度的增大而下降，但当盐浓度很高时，截留率趋向于一定值，该值并不等于0，说明与纳滤膜的孔径相比，不可忽视电解质离子大小的影响。     

Fluoride and Arsenic Removal by Nanofiltration Technology from Groundwater in Rural Areas of China: Performances with Membrane Optimization

Nanofiltration (NF) membrane configuration for fluoride and arsenic removal from groundwater has a key role in controlling operation performances and membrane fouling. Some bench-scale contrast experiments using commercial NF membranes were done to obtain the optimum arrangement performances. The NF membrane arrays included one-stage, two-stage, and three-stage systems. The NF membrane surface was negatively charged above its isoelectric point (approximately at pH 5.9–6.4). Accordingly, the raw groundwater was initially adjusted to a neutral or alkaline pH to enhance the effect of electrical charge repulsion and improve the ion removal efficiencies by NF. The encouraging results indicated that a membrane in a parallel-linear arrangement with staging 2:1 was the preferable arrangement to remove fluoride and arsenic from low-salinity groundwater in rural areas of China. With this optimal arrangement, the NF system obtained fluoride and arsenic removal efficiencies of 70?73% and 92?94% respectively, a preferable permeate flux of 73.37 L h^?1 m² and acceptable water flux recovery rate of 65% at 16°C. This optimal arrangement can further limit the potential membrane fouling by lowering the interstage Reynolds number. Moreover, the water product cost was lowest by the NF system with this optimal arrangement.     

Removal of excess fluoride ions from Saharan brackish water by adsorption on natural materials

Water supply for people in the Sahara region is mainly assured by poor quality ground water which has excessive minerals, hardness and high concentration of fluoride. This leads to many teeth and bones diseases such as fluorosis. The purpose of this study is to eliminate the excess of fluorides from the El Oued Souf City water supply located in the South East of the Algerian Sahara by retention process onto montmorillonite clay using potentiometric method. Two types of natural clays were tested. The first one contains a higher percentage of calcium (AC) and the second one without calcium (ANC). These adsorbents were activated chemically and thermally with temperatures ranging between 200 and 500 °C. Experimental results showed that chemical activation proved effective adsorption reaching up to 88% whereas the thermal activation is ineffective and reached only around 5%. Moreover, the acidity of the medium and the alkalinity affect the adsorption considerably. The retention predicted from the adsorption isotherms is in agreement with Langmuir's model. The kinetic analysis of the reactions indicates that reaction is slow with diffusional control. The low values obtained for the heat of adsorption mean that the adsorption is exothermic with no specific type. An ionic mechanism exchange for fluoride removal is proposed in this study.     

纳滤膜对无机盐水溶液脱盐性能的研究

选择了NE和HL两种纳滤膜对NaCl、KCl、Na2SO4、MgCl2、CaCl2及MgSO4等6种无机盐水溶液体系进行分离实验;考察纳滤膜分离性能随操作压力、料液浓度、无机盐种类等变化的影响及纳滤膜脱盐的稳定性,得到纳滤膜一些脱盐的规律。     

饮用水除氟技术的现状及进展

综述了国内对于饮用水除氟的方法,包括吸附法、沉淀法、电凝聚法,电渗析法,同时讨论了除氟方法的机理,并且对这些方法进行了总结,以促进实践发展。     

Estimation of Separation of Electrolytes and Organic Compounds by Nanofiltration Membranes Using an Irreversible Thermodynamic Modei

Nanofiltration separation has become a popular technique for removing large organic molecules and inorganic substances from water. It is achieved by a combination of three mechanisms: electrostatic repulsion, sieving and diffusion. In the present work, a modei based on irreversible thermodynamics is extended and used to estimate rejection of inorganic salts and organic substances. Binary systems are modeled, where the feed contains an ion that is much less permeable to the membrane as compared with the other ion. The two modei parameters are estimated by fitting the modei to the experimental data. Variation of these parameters with the composition of the feed is described by an empirical correlation. This work attempts to describe transport through the nanofiltration membranes by a simple model.     

纳滤膜分离机理及其在水处理中的应用

对纳滤膜的定义和特点作了简介，着重论述了纳滤膜的分离机理，对纳滤膜在水处理中的应用进行了较为全面的综述。     

用不可逆过程热力学模型估算通过纳米过滤膜电解质和有机化合物的分离

Nanofiltration separation has become a popular technique for removing large organic molecules and inorganic substances from water. It is achieved by a combination of three mechanisms: electrostatic repulsion,sieving and diffusion. In the present work, a model based on irreversible thermodynamics is extended and used to estimate rejection of inorganic salts and organic substances. Binary systems are modeled, where the feed contains an ion that is much less permeable to the membrane as compared with the other ion. The two model parameters are estimated by fitting the model to the experimental data. Variation of these parameters with the composition of the feed is described by an empirical correlation. This work attempts to describe transport through the nanofiltration membranes bv a simple model.     

氯化钙去除铝工业废水中低浓度氟离子的研究

文章对铝工业废水中的氟离子采用氯化钙除氟方案,通过对反应时间、氯化钙添加量、搅拌强度等影响因素进行控制,得出将废水中氟离子浓度降低到1 mg/L以下的实验参数为搅拌强度100转/分钟,氯化钙添加量过量50%,反应时间20分钟,添加氯化钙后的pH在11.33左右。     

石煤氯化钠焙烧水浸液纳滤提钒过程

采用石煤氯化钠焙烧浸出液为原料,研究了驱动压力、料液pH值及钒浓度对钒纳滤浓缩效果的影响,并考察了Cl-在纳滤过程中的行为. 结果表明,在驱动压力10.0~12.5 kg/cm2和pH值5.16~6.15的优化条件下,料液中的钒(V2O5)可纳滤浓缩到35 g/L以上. pH值6.15时,钒的截留率最高,达92%. 浓缩液按沉钒化学计量的2.2倍加入NH4Cl,沉淀得到的NH4VO3经500℃煅烧1 h得到的V2O5产品纯度为98.6%.     

纳滤膜技术去除水中内分泌干扰物

传统的污水处理工艺对内分泌干扰物（EDCs）的去除效果不稳定,而且不能彻底去除水中EDCs,使之达到产生危害的阈值浓度以下。大部分EDCs是分子量在200,500Da之间的有机物,这些污染物大多数是疏水性分子,纳滤膜对小分子有机物良好的筛分作用和吸附作用,运用纳滤技术去除EDCs是一种切实可行和安全有效的方法。     

雷诺数及流道结构对纳滤膜分离性能的影响

采用自制的平板式纳滤膜分离系统进行膜分离实验,考察雷诺数和流道结构对膜分离性能的影响。研究结果表明,雷诺数对膜通量的影响不明显,但对Mg2＋的截留率的影响显著,雷诺数越大,离子截留率越大;流道结构对膜通量的影响不明显,但对Mg2＋的截留率的影响显著,且螺旋形流道和蛇形流道的离子截留率差别不大,但均大于无绕流板流道对Mg...     

Removal of API's (Active Pharmaceutical Ingredients) from Organic Solvents by Nanofiltration

Abstract

The removal of 5 specific active pharmaceutical ingredients (API's) with molecular weight of 189, 313, 435, 531, and 721, respectively, from toluene, methylene chloride, and methanol was studied by using solvent resistant nanofiltration. Three membranes of the StarMem series (120, 122, and 228), with cut‐off values of 200, 220, and 280 respectively, were used in the experiments. Although the rejections expected from the size difference between solutes and membrane pores are high, the results largely depended on the solvent used. For toluene, rejections were rather small, due to the low molecular weight of the solutes of interest (all API's except for the largest compound). Modelling of the rejection curve showed that the minimum molecular weight of a solute to obtain a rejection of 90% in toluene with the membranes used, is ca. 600. The application in methylene chloride was unsuccessful due to partial dissolution of the membrane top layer; other polymeric membranes such as the Solsep series might be more successful. The rejections in methanol were sufficiently high (>90%) to allow implementation: the rejection can be significantly increased by using a module design with double membrane passage and recirculation of the retentate, as was calculated from mass balances. A comparison of a (single pass) nanofiltration system with a throughput distillation unit, currently in use, showed that the energy consumption is 200 times lower in the nanofiltration system.     

纳滤膜分离技术在矿井水处理中的研究

介绍了用纳滤膜处理含悬浮物矿井水的工艺流程．考察了纳滤膜不同操作特性对膜过滤性能的影响及组合工艺对矿井水的处理效果。试验结果表明：纳滤膜在过滤周期为30min采用反曝气方式冲洗,能够有鼓减少膜污染,恢复膜通量。该工艺对矿井水的处理效果明显,出水稳定,出水达到国家饮用水标准,是一种高效、经济的处理工艺。     

Removal of Zinc Ions from Aqueous Chloride Solutions by Solvent Extraction Using Alamine 308

Abstract

A study has been undertaken to develop a solvent extraction system for zinc with Alamine 308 in aqueous chloride medium. The parameters investigated included reagent concentration, acid concentration, pH, aqueous to organic phase ratio, and rate of extraction and stripping. The study shows that zinc can be extracted rapidly and efficiently from aqueous chloride solutions. A number of aqueous stripping reagents removed more than 90% of the zinc from the organic phase with only one equilibration.