了解氨在减轻离子交换膜电透析中的度极化作用
Abdallah Timmaoui1, Mahmoud Ferhat1, Nesrine Souad Ferhat1
1Mechanics Laboratory, Faculty of Sciences, University of Amar Telidji, Laghouat, Algeria.
Turkish journal of chemistry
|January 9, 2025
概括
添加氨气缓冲剂有效地减轻了离子交换膜中的度极化,增强了硫酸盐离子运输. 这可以防止电透析和类似过程中的效率损失和运行问题.
科学领域:
- 电化学 电化学 电化学
- 膜科学 膜科学 膜科学
- 化学工程是化学工程的重要组成部分.
背景情况:
- 膜接口上的度极化限制了电透析等过程中的离子运输效率.
- 这种现象随着电流密度的增加而加剧,导致盐分沉,膜降解和能源使用增加.
- 了解和减轻度极化对于提高膜性能和降低运营成本至关重要.
研究的目的:
- 研究氨气缓冲剂 (NH4+/NH3) 对硫酸盐离子通过离子交换膜传输的影响.
- 专门研究在恒定电流条件下限制电流密度和度偏振的影响.
- 阐明氨会影响离子运输和膜接口反应的机制.
主要方法:
- 进行了电化学测量,包括电流-电压曲线和时间电位计.
- 电化学阻抗光谱 (EIS) 用于分析接口现象.
- 使用不同氨缓冲度的离子交换膜 (AMX).
主要成果:
- 添加氨有效地消除了度极化,这是当前电压曲线中没有平原和时刻电压图中的过渡时间所证明的.
- 电化学阻抗光谱显示了华堡阻抗弧的消失和格里舍弧的占主导地位的增加.
- 在0.1M氨,度极化对质量运输的影响显著减轻,允许不受阻碍的硫酸盐离子运输.
结论:
- 添加氨气缓冲剂以催化方式加速了膜界面上的质子转移和水解离反应.
- 这种催化效应防止了扩散边界层的形成,促进了硫酸对子离子通过离子交换膜传输.
- 缓解度极化将超限电流区域转移到离米区域附近,而不会改变限制电流密度.
相关概念视频
01:17Ion Exchange
540
Ion exchange chromatography separates charged molecules from a solution by reversibly exchanging them with mobile, or 'active', ions associated with the oppositely charged stationary phase. This method can be used to separate ions, soften and deionize water, and purify solutions. The polymers comprising the ion-exchange column are high-molecular-weight and chemically stable polymers, crosslinked to be porous and essentially insoluble. They are also functionalized with either acidic or...
540
01:15Dialysis
583
Dialysis is a diffusion-based purification process that separates analyte molecules from a complex matrix. This is accomplished by allowing molecules in the solution to pass through a semipermeable membrane into a liquid on the other side. The membrane is usually made of cellulose acetate or cellulose nitrate, and the second liquid must be miscible with the solution. Ions (e.g., chloride or sodium) or organic molecules (e.g., glucose) can pass through the membrane pores, which generally have...
583
01:15Potentiometry: Membrane Electrodes
450
Membrane electrodes, also known as p-ion electrodes, use membranes that selectively interact with free analyte ions, generating a potential difference across the membrane. The resulting membrane potential, known as the asymmetry potential, is not zero even when analyte concentrations on both sides of the membrane are equal. The membrane's response is typically not selective to a single analyte but proportional to the concentration of all ions in the sample solution capable of interacting at...
450
03:24Common Ion Effect
41.0K
Compared with pure water, the solubility of an ionic compound is less in aqueous solutions containing a common ion (one also produced by dissolution of the ionic compound). This is an example of a phenomenon known as the common ion effect, which is a consequence of the law of mass action that may be explained using Le Châtelier’s principle. Consider the dissolution of silver iodide:
41.0K
00:53Extraction: Effects of pH
430
Consider a neutral form of an amine, B, with a partition coefficient, K, in a liquid mixture containing organic and aqueous phases. The pH of the aqueous phase affects the charge on acidic and basic solutes, and the charged form is usually more soluble in the aqueous phase. Suppose the conjugate acid form of the amine is soluble only in the aqueous phase while the base form is soluble in both phases. Then the distribution coefficient, D, can be given as the ratio of amine concentration in the...
430
01:25Basicity of Heterocyclic Aromatic Amines
5.6K
Heterocyclic amines, where the N atom is a part of an alicyclic system, are similar in basicity to alkylamines. Interestingly, the heterocyclic amine having a nitrogen atom as part of an aromatic ring has much less basicity than its corresponding alicyclic counterpart. For this reason, as presented in Figure 1, piperidine (pKb = 2.8) is significantly more basic than pyridine (pKb = 8.8).
5.6K