电渗析废水处理技术

对电渗析技术在工业废水方面的应用进行了一般总结 ,并指出了电渗析技术在水处理方面具有的一些优点。     

Development of thermoplastic polyurethane/polyaniline-doped membranes for the separation of glycine through electrodialysis

Recently, membrane-based separation processes, particularly electrodialysis, have attracted attention for the separation and purification of organic and amino acids from animal feedstock waste. In this study, cation exchange membranes were synthesized by making a composite of thermoplastic polyurethane and polyaniline (PANI) via the doping of various aromatic sulfonic acids, such as β -naphthol sulfonic acid and phenol sulfonic acid. The PANI was prepared using a standard method, which was further used in the composite blending at varying concentrations of 10%–20%. The impact of the concentration of PANI and the nature of the dopant on the membrane characteristics were comparatively studied. The membranes were analyzed by electric conductivity, water swelling, morphological studies (SEM), and thermogravimetric analysis. The membranes were used for the separation of glycine hydrochloride via electrodialysis.     

Irreversible dissociation of water molecules on the ion-exchange membrane-electrolyte solution interface in electrodialysis

The fluxes of hydrogen ions through the cation-exchange membrane and hydroxyl ions through the anion-exchange membrane in the electrodialysis were measured using the method of selective polarization. The experiments, which were conducted in a wide range of current densities, enabled us to obtain the results of ionic transport different from the literature data and to explain them on the basis of chemical reactions proceeding in the system. It is shown that a decrease in the hydration of ionogenic groups intensifies the ionic fluxes of the medium in the electrodialysis.     

Direct evidence for the electroconvective mechanism of neutral amino acid transport during electrodialysis

For the first time, direct evidence was obtained using laser interferometry and flicker-noise spectroscopy that the main cause of the increase in the transport of amino acids through a sulfonated cation-exchange membrane in intense current modes is electroconvection. The turbulent nature of electroconvective vortices at the solution/membrane interface, acidification of the solution in the demineralization compartment and a substantial intensification of amino acid fluxes under over-limiting current modes were revealed. This indicates the electroconvective destruction of the barrier effect of the solution layer with a high pH value near the cation-exchange membrane.     

氯化锂溶液为工质的溶液浓差发电实验研究

利用配制的氯化锂溶液作为工作介质,通过实验研究稀溶液和浓溶液浓度变化对逆向电渗析电池组(REDCs)开路电压、内阻以及功率密度等电池特性参数的影响.研究结果表明,由10个电池单元构成的REDCs在所研究的浓度范围内,最大开路电压为1.88V,最大功率密度为1.67 W/m~2.电池的开路电压随稀溶液浓度增大而降低,而随浓溶液浓度增大出现先增后降的趋势.电池内阻随浓、稀溶液的浓度增大而降低.电池的端电压与功率密度受电流影响.随电流增大,端电压呈线性下降的趋势,而功率密度变化却呈上凸的二次曲线.当电路总电阻为电池内阻两倍时,电池功率密度达到最大值.     

Modeling of clarified tropical fruit juice deacidification by electrodialysis

Electrodialysis (ED) using two-stack configurations with homopolar or bipolar membranes was investigated for deacidification of tropical fruit juices (passion fruit, mulberry, naranjilla). The objective was to develop a mathematical treatment for ED to predict the behavior of a fruit juice at industrial scale from ED performances at laboratory scale. From parameters such as current efficiency, electric resistance of the anion exchange membrane, and coefficients of variation with temperature determined in a laboratory-scale stack, modeling was applied to a pilot-scale stack that has a total effective membrane area 70 times larger. If no fouling took place, and except for conductivity at pH higher than 3.8, the differences between the experimental and simulated values for pH, titrable acidity, voltage, and energy consumption were inferior to 7%, 16%, 20%, and 15%, respectively, for all the fruit juices and operating conditions. Moreover, the average electrical charge of citric acid species transferred was 2.16 for all fruit juices, indicating that the current transport was mainly due to the ionic species issued from the secondary dissociation of the citric acid.     

The Combination of 2D Layered Graphene Oxide and 3D Porous Cellulose Heterogeneous Membranes for Nanofluidic Osmotic Power Generation

Salinity gradient energy, as a type of blue energy, is a promising sustainable energy source. Its energy conversion efficiency is significantly determined by the selective membranes. Recently, nanofluidic membrane made by two-dimensional (2D) nanomaterials (e.g., graphene) with densely packed nanochannels has been considered as a high-efficient membrane in the osmotic power generation research field. Herein, the graphene oxide-cellulose acetate (GO–CA) heterogeneous membrane was assembled by combining a porous CA membrane and a layered GO membrane; the combination of 2D nanochannels and 3D porous structures make it show high surface-charge-governed property and excellent ion transport stability, resulting in an efficient osmotic power harvesting. A power density of about 0.13 W/m² is achieved for the sea–river mimicking system and up to 0.55 W/m² at a 500-fold salinity gradient. With different functions, the CA and GO membranes served as ion storage layer and ion selection layer, respectively. The GO–CA heterogeneous membrane open a promising avenue for fabrication of porous and layered platform for wide potential applications, such as sustainable power generation, water purification, and seawater desalination.     

异相膜电渗析法处理苯酚废水

提出通过向苯酚溶液中加入碱,然后用异相离子交换膜电渗析法去除酚氧离子的含酚废水处理工艺,考察了加碱量、苯酚初始浓度、操作电压、流量对苯酚去除率的影响,并测定极限电流密度,计算了能耗。实验结果表明,电渗析法处理含苯酚废水,能耗低,操作方便,具有较好的效果,对于质量浓度为1000mg/L的含苯酚废水,加入氢氧化钠的量使n苯酚∶n氢氧化钠=1∶5,操作电压为26 V,流量均为50 L/h,实验时间为120 min的条件下,淡室苯酚去除率达到了98.2%。     

BMED 解离硫酸盐高效清洁制酸碱工艺

 随着工业生产的快速发展,工业废水的排放量迅猛增加,其中大部分工业废水中都含有硫酸盐,硫酸盐的过量排放会对环境水体造成严重的污染与破坏。本研究以硫酸钠废液为原料,采用双极膜电渗析(BMED)新型工艺,实现含硫酸盐废水的回收再利用,高效、清洁地制取酸、碱。实验主要考查了电流密度、原料液浓度及初始酸碱浓度对膜堆性能的影响,并对两种离子交换膜的性能进行对比。结果表明,实验范围内,氢氧化钠的收率高达84.08%,平均电流效率为54%,能耗为5.29 kW·h/kg;氢氧化钠收率和过程能耗均随电流密度的增大而增加;电流密度恒定时,较高的原料液浓度可使膜堆电阻维持在较低的水平,进而降低能耗;适量加入初始酸碱能够降低能耗,但也会降低电流效率。