极距和流速对海水电解用阳极的影响

主要探讨极距和流速对海水电解过程的电流效率和槽电压的影响。当电流密度较低时,析氯反应受电化学控制,极化曲线符合Tafel方程;当电流密度较高时,析氯反应受扩散控制,极化曲线不符合Talel方程。极距对电流效率影响较小,极距增大电解槽的槽电压增大。流速增加电解槽槽电压下降,电流效率上升。     

乙二醛电氧化合成乙醛酸产物的分离

采用电渗析法实现乙二醛电氧化合成乙醛酸体系产品的分离,以淡化室储槽中溶液的组分含量为分析对象,分别考察电流密度、淡化室流速、温度、阴离子交换膜对电渗析作用的影响。实验结果表明,随着电流密度增大,氯离子迁移速率先增大后减小,初期电流密度可为628.7A·m-2;当盐酸通过率为50%,则电流密度应调整为456.6A·m-2,此时乙醛酸的迁移量最少,分离效果最好。当流速为3.37cm·s-1时,各组分迁移速率最大;当流速为4.21cm·s-1时,乙醛酸的迁移量较少,分离效果最好。温度升高,各物质的迁移量增大,选择性下降,操作温度在30℃最适宜;ASV膜的透过性比AHT膜大,AHT膜选择性好。     

铅板的阴极刻蚀

一、实验现象我们为了对Pb/Pt阳极进行予处理,曾将140×400毫米电渗析器作为一些改造。在纯铝板上嵌入铂丝(φ0.2mm)作为阳极,阴极铅板没有嵌入铂丝,极水用2.5％民用细食盐,流速为6升/时,阳极极筐厚度为16毫米,阴、阳极室各一个,中间仅用一块阳离子异相膜隔开。第一组的极水,先经阴极室再到阳极室,然后排放。第二组的极水,先经阳极室再到阴极室,然后排放。第一组连续极化的顺序见表1;第二组连续极化的顺序见表2。     

工艺参数对Al/Pb复合阳极电化学性能的影响

在甲基磺酸铅电解液中制备了Al/Pb复合阳极,并研究了温度和电流密度对其电化学性能的影响。结果表明:随着温度的升高,Al/Pb复合阳极的腐蚀速率增大;随着电流密度的增大,Al/Pb复合阳极的腐蚀速率降低。     

电沉积通孔铜箔数值模拟与实验研究

采用有限元方法通过Comsol Multiphysics软件模拟了电沉积通孔铜箔的过程.研究了镀液流速和电流密度对电沉积过程中铜离子浓度分布的影响,以及电流密度和极间距对通孔铜箔厚度分布均匀性的影响.模拟结果表明,镀液循环使铜离子分布均匀,利于铜箔沉积;通孔环形阵列分布和增大极间距可提高通孔铜箔的厚度分布均匀性.该模型...     

电化学氧化法处理垃圾焚烧发电厂沥滤液生化出水

垃圾焚烧发电厂储坑沥滤液是一种高污染、高氯离子和高胶体含量的废水,经过传统生化处理后仍难达标排放。根据生化出水中氯离子浓度较高的特点,面向实际工程应用,设计了板框式电化学反应器,以钛基氧化钌-氧化铱涂层电极(Ti/RuO₂-IrO₂)作为阳极,304钢板作为阴极,开展了电化学氧化去除废水中难生物降解有机物的研究。重点考察了电流密度、表观流速、氯离子浓度、电极极距等因素对去除废水COD的影响。结果表明:当电流密度为65.35 mA·cm^-2,反应器内表观流速为2.72 cm·s^-1,初始氯离子浓度为5000 mg·L^-1时,废水中COD的去除具有良好的效果。研究了COD去除的动力学过程,提出了反应体系中活性氯的减少可能是第二阶段COD去除速率降低的主要机理。对几种结构电化学反应器的能耗进行了对比分析表明,极距减小50%,去除COD的平均能耗可节约25%以上,紧凑多通道小电极极距结构在设计工业电化学反应器时值得考虑。     

离子交换膜-硫酸铵溶液体系的极限电流密度

采用六室膜组合的膜堆研究离子交换膜-硫酸铵溶液体系的电流-电压曲线,考察了离子交换膜(JCM-15和JAM-15)-硫酸铵溶液体系中硫酸铵浓度、流速和温度对极限电流密度的影响. 实验结果表明,离子交换膜-硫酸铵溶液体系的电流-电压曲线明显有3个区域：欧姆区域、平缓增加区域和过极限电流区域. 增加硫酸铵浓度、流速和操作温度均能提高单极膜的极限电流密度. 在相同的操作条件下,阴膜(JAM-15)的极限电流密度明显高于阳膜(JCM-15). 离子交换膜-硫酸铵溶液体系的极限电流密度与流速和硫酸铵浓度的关系符合Wilson修正式,对本工作所采用的膜,ilim=17.647C0.4570V0.5725(JAM-15), ilim=13.003C0.2918V0.3697(JCM-15).     

双极膜电渗析处理生物质水解液的过程性能研究

在由双极膜和阴离子交换膜组成的两室双极膜电渗析装置中,研究了生物质水解液糖、酸分离和酸回收的过程性能。考察了不同膜对、进料浓度、电流密度、处理室循环流量及操作温度等因素对于处理水解液过程中的电流效率和平均功耗的影响。结果表明,由BP-1双极膜与A501SB阴离子交换膜组成的膜对的性能最佳;过程的电流效率随进料液酸浓度的增大而下降,过高酸浓度的水解液进料对电渗析分离过程不利;较高操作电流密度条件下电流效率高,利于降低功耗,本装置的处理室适宜循环流量为30.0 mL/m in;操作温度的升高,对提高电流效率作用不明显,但利于降低平均功耗,本实验装置的合适操作温度为35℃。     

射流电沉积工艺参数对沉积层形貌的影响

射流电沉积技术具有特殊的定域性和材料特性,可用于机械零件修复,但沉积层的均匀性和质量需要改善。研究了电解液喷射流速、电流密度、沉积层数等对沉积层形貌的影响。结果表明:喷射流速在1~10m/s范围内,随着喷射流速的增大,沉积层的表面质量逐渐改善;电流密度在100~600A/dm2范围内,随着电流密度的增大,沉积层形貌逐渐恶化,产生析氢副反应;沉积层数在400~1 600层范围内,沉积层的表面质量随层数的增加而逐渐恶化。得到了一系列的优化参数,有助于改善沉积层的质量。     

草酸电还原制备乙醇酸

用循环伏安法确定了草酸可以还原为乙醇酸,证明了从草酸研制乙醇酸的可行性。工艺采用以铅电极作阴极材料的阳离子交换膜电解槽,电解草酸制备乙醇酸,并以电流密度、电量、温度和电解液的流速作了四因素四水平的正交实验,得出最佳工艺条件为电流密度1400A/m2,电量1 7F/mol,温度40℃,电解液流速0 15m/s,产率达88%以上。     

电渗析与萃取耦合技术分离Ni(Ⅱ)与Co(Ⅱ)

为实现混合溶液中Ni(Ⅱ)与Co(Ⅱ)的分离,设计了电渗析与萃取耦合的集成分离技术,借助自行设计的设备,在选P507为萃取剂后,考察了电流密度、酸用量、体积流量、萃取剂皂化率、原料与萃取剂摩尔比、萃取方式等对分离效果的影响。结果表明:在实验范围内,电流密度3.8 mA/cm2,酸用量为理论用量的1.3倍,体积流量60 L/h、皂化率60%,原料与萃取剂摩尔比1∶1.7为优取的操作条件;料液循环重复萃取,能显著提高分离效果。由此表明,电渗析与萃取耦合的分离技术,可分离混合体系中的Ni(Ⅱ)、Co(Ⅱ),且无需溶剂参与。     

电渗析法再生化学镀镍废液工艺

采用电渗析法处理化学镀镍废液,重点考察了3种工艺条件(电流密度、老化液pH、流量)对各种离子去除(损失)率的影响,得出优化的工艺条件为:J= 65 mA/cm2,pH=4.5,v＝1 L/45 s.对再生镀液的性能进行了测试.结果表明,其镀速、镀层磷含量和显微硬度均达到第三周期的生产水平,耐色变性与盐雾试验符合生产需求...     

二氧化碳在双极膜电渗析系统中溶解吸收过程的研究

在二氧化碳捕集、利用和封存（CCUS）技术中,海水固碳技术绿色环保、安全可靠,具有很好的发展前景。其中,双极膜电渗析法海水固碳技术的关键之处在于二氧化碳在系统中的溶解吸收。考察了结晶器中添加晶种、通气体系成分、模拟烟道气流量、双极膜电渗析装置的电流密度对海水固碳过程中二氧化碳溶解吸收效果的影响,结果表明：系统外加晶种、模拟烟道气作为通气体系时更有利于二氧化碳在双极膜电渗析系统中的溶解吸收,促进碳酸钙生成。在上述基础上,随着模拟烟道气流量的增加,二氧化碳的比吸收速率降低,二氧化碳在溶液中大部分转化成碳酸氢根,碳酸根和碳酸钙的生成速率则会降低;随着电渗析装置电流密度的提高,碳酸氢根、碳酸根和碳酸钙的生成速率均会随之提高。该研究为酸性气体在双极膜电渗析系统中溶解吸收和矿化利用提供了指导。     

Performance studies of heterogeneous ion exchange membranes in the removal of bivalent metal ions in an electrodialysis stack

Heterogeneous anion and cation exchange membranes have been prepared by solution casting technique with poly(vinyl chloride) as inert binder and anion/cation exchange resins (?300 + 400 mesh) in a blend ratio of 60 : 40. The membranes were characterized with respect to their physical, mechanical, and electrochemical behavior. Anion and cation exchange membranes (10 cell pairs) were packed in an electrodialysis stack in a parallel plus series flow pattern. Desalting experiments were carried out with four different salt solutions, such as calcium chloride, magnesium chloride, cupric chloride, and nickel chloride (varying in their total dissolved solid from 500 to 1000 ppm), at different applied potentials and flow rates. The resultant current, percentage reduction in total dissolved solid, current efficiency, and energy consumption were calculated. The maximum current density in the electrodialysis stack was observed for calcium chloride solution and at any applied potential and flow rate the percentage reduction in total dissolved solid for Ca⁺⁺ > Cu⁺⁺ > Ni⁺⁺ > Mg⁺⁺. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Determination of the limiting current density in electrodialysis desalination as an empirical function of linear velocity

Electrodialysis is known to be a useful membrane process for water desalination. The limiting current density (LCD) in the electrodialysis process is an important parameter which determines the electrical resistance and the current utilization. Usually, LCD depends on membrane and solution properties as well as on the electrodialysis stack construction and various operational parameters such as the flow velocity of the diluate solution. Therefore, a reliable determination of LCD is required for designing an efficient electrodialysis plant. In this study, LCD was measured in an electrodialysis flow cell system of given geometry and spacer configuration as a function of the linear velocity. The coefficients a and b of an equation describing LCD as a function of the linear flow velocity of the diluate solution, i_lim=aCu^b, were determined from a plot of the measured LCD over the electrolyte concentration versus the linear velocity on a double logarithmic scale. It was found that the coefficient b was related to the hydrodynamic conditions, while the coefficient a was affected by the cell geometry, electrolyte concentration and the membrane properties.     

Relation between mass transfer and operation parameters in the electrodialysis recovery of acetic acid

The recovery of acetic acid from dilute wastewater by means of bipolar membrane electrodialysis is studied in more detail. The current efficiency of the electrodialysis recovery of acetic acid from dilute wastewater is related to the current density and other operation parameters. There exists a highest value of current efficiency at optimal current density. The highest concentration of recovered acid is also related to current efficiency. The experimental data are analyzed on a theoretical basis.     

电解法制备高纯四甲基氢氧化铵的研究

用电解 电渗析法 ,以四甲基氯化铵为原料 ,石墨为阳极 ,不锈钢为阴极 ,采用 8A/dm2 的电流密度 ,制得高纯度的四甲基氢氧化铵 ,电流效率为 79.4% ,同时研究了影响制备四甲基氢氧化铵纯度和电流效率的因素。     

电渗析法处理污染三甘醇工艺优化研究

以长庆靖边气田被污染的三甘醇溶液为实验对象,采用四室电渗析反应器对其进行净化处理,研究了操作电压、运行时间、淡室进液流量、进液总溶解性固体(TDS)浓度等因素对处理后溶液品质的影响。在单因素实验的基础上,采用响应面分析法对电渗析工艺进行了优化。优化的工艺条件为:操作电压48.92 V,运行时间128.09 min,淡室进液流量12.00 L/h,当被污染的三甘醇溶液TDS质量浓度为1 968 mg/L时,在此工艺条件下处理后TDS浓度可降至(38.3±1.2)mg/L。实验中对电渗析过程的极限电流进行了测定,在淡室进液流量为12.00 L/h时,测得极限电流为0.189 A,对应的极限电压为66 V,说明装置在优化条件下运行不会出现浓差极化等不正常现象。     

Designing of an electrodialysis desalination plant

The design and operation of an electrodialysis desalination process are based on a set of fixed and variable parameters such as stack construction, feed and product concentration, membrane properties, flow velocities, current density, recovery rates, etc. These parameters are interrelated and may be rather different for different applications. For an efficient operation of an electrodialysis desalination plant, the process has to be optimized in terms of overall costs considering component properties and operating parameters. In this study the design and optimization of an electrodialysis plant to be used for brackish water desalination has been treated. The required equations were derived or, as in the case of the limiting current density, were experimentally determined. As an example, an electrodialysis plant with a sheet-flow stack construction and given feed solution composition was designed and optimized in terms of overall costs and the sensitivities of the different parameters are analyzed.