Explore chapters and articles related to this topic
Recent Trend and Future Prospects
Published in Randeep Singh, Piyal Mondal, Mihir Kumar Purkait, pH-Responsive Membranes, 2021
Randeep Singh, Piyal Mondal, Mihir Kumar Purkait
To prepare pH-sensitive membranes, polyelectrolytes or weak polyelectrolytes can be used directly, but the strength of the membranes are not always enough for use as separation membranes. These membranes, however, can be used as ion exchange membranes. Today, ion exchange membranes (IEMs) are receiving considerable attention and are successfully used for desalination of sea and brackish water and for treating industrial effluents. They are efficient tools for the concentration or separation of food and pharmaceutical products containing ionic species as well as the manufacturing of basic chemical products [21]. For IEM, a large IEC is needed for binding metal ions. For pH-sensitive membranes, however, small IECs sometimes lead to good pH sensitivity and large water flux change [22,23]. Of course, pH-sensitive membranes with larger IEC could also be used as IEM, and the barrier properties might play their specific function, especially the pH-sensitive hollow fiber membrane devices.
Membrane Technologies for Water Purification
Published in P.K. Tewari, Advanced Water Technologies, 2020
Ion-exchange membranes consist of swollen gels carrying fixed positive or negative charges. The membrane-making procedure and properties of ion-exchange membranes are closely related to ion-exchange resins. There are two types of ion-exchange membranes: (1) cation-exchange membrane having negatively charged groups fixed to the polymer matrix; and (2) anion-exchange membrane having positively charged groups fixed to the polymer matrix. In a cation-exchange membrane, the fixed anions are in electrical equilibrium with mobile cations in the interstices of the polymer. Figure 2.9 shows the matrix of a cation-exchange membrane with fixed anions and mobile cations, which are referred to as counter-ions. In contrast, the mobile anions, called co-ions, are more or less completely excluded from the polymer matrix because of their electrical charge which is identical to that of the fixed ions. Due to the exclusion of the co-ions, a cation-exchange membrane permits transfer of cations only. Anion-exchange membranes carry positive charges fixed on the polymer matrix, thus permeating anions only. The desirable properties of ion-exchange membranes include high perm-selectivity, low electrical resistance, good mechanical stability and high chemical stability.
Deacidification of Fruit Juices by Electrodialysis Techniques
Published in M. Selvamuthukumaran, Applications of Membrane Technology for Food Processing Industries, 2020
There are two different kinds of ion-exchange membranes, which are available: the homogenous membrane and the heterogeneous membrane. The first is manufactured using phenol polycondensation or phenol-sulphonic acid with formaldehyde. The later is manufactured using dry ion-exchange resins, which are melted and pressed with polymer granules. The membrane consists of greater than 65% w/w of cross-linked ion-exchange particles, which results in poor mechanical strength and dimensional stability; therefore, the use of a heterogeneous membrane is recommended, which is prone to a higher electrical resistance and a higher uneven charge distribution than the homogeneous one.
Recovery of phosphorus from wastewater: A review based on current phosphorous removal technologies
Published in Critical Reviews in Environmental Science and Technology, 2023
Yulin Zheng, Yongshan Wan, Yue Zhang, Jinsheng Huang, Yicheng Yang, Daniel C. W. Tsang, Hailong Wang, Hao Chen, Bin Gao
Electrodialysis (ED) is another membrane-based wastewater treatment process that separates ammonium and P with the use of ion-exchange membranes in a direct electrical field (Dong et al., 2020). Ion-exchange membranes usually comprise with cation-selective, anion-selective, and bipolar membranes (Xie et al., 2016). To some extent, the conditions of the wastewater can influence the performance of ED. Feed solution at high pH can promote P enrichment; however, transformation of ammonium ions into ammonia gas also occurs and reduces the N recovery. ED also suffers from membrane foiling due to the characteristics of ion-exchange membranes. Negatively charged organic matters and humic substances can significantly hampered anion-exchange membranes. High Ca2+ content of the wastewater also triggers the calcium scaling and calcification of cation-exchange membranes (Yan et al., 2018). Considering the membrane fouling and high energy consumption as big challenges for the single membrane separation process, ED is also employed with many other biological or bioelectrochemical systems as hybrid technologies for advanced P removal and recovery (Nancharaiah et al., 2016). Membrane technologies have been designed to upgrade the conventional WWTPs by replacing secondary clarifier and sludge thickening for advanced P removal and recovery (Figure S3, Supporting Information).
Prospects on utilization of biopolymer materials for ion exchange membranes in fuel cells
Published in Green Chemistry Letters and Reviews, 2022
Angelo Jacob Samaniego, Richard Espiritu
Research into biopolymer-based ion exchange membranes have grown over the past two decades, however they remain a small part of the overall focus despite the high potential in cost reduction and competitive performance with a greener approach. In this review, studies on various types of cellulose-containing membranes were considered and many positive prospects and strategies were found. Membranes with a good mix of mechanical and ion conducting properties were primarily observed in those utilizing biopolymer as an enhancement rather than as the bulk matrix, with multiple examples exhibiting comparable or better performance than commercial counterparts such as those with swelling-inhibiting structures (i.e. interpenetrating or semi-interpenetrating framework). Membranes with high cellulosic content however, typically manifest heightened hydrophilic character, increasing water uptake and membrane swelling. The challenge therefore lies on the researchers to consider the application of cellulose and chitosan as the bulk component in IEM, while exploring effective modifications for ion transport functionalization and incorporating swelling-inhibiting macrostructures. Additionally, a large portion of existing literature investigates biopolymer utilization in PEM applications, and it is thus further suggested to explore its application in AEM fuel cells.
An Advance Control of Grid Integrated Wind Turbine Driven DFIG-Battery System with Grid Power Shaping Under Gust Wind Variation
Published in IETE Journal of Research, 2023
Alok Ranjan, Manoja Kumar Behera, Lalit Chandra Saikia
In the charging and discharging process, the vanadium ions are exchanged via the oxidation and reduction process in both positive and negative half cells of a battery. During charging the is converted into by oxidation process and converted into by reduction process in both the positive and negative side of the battery respectively. Throughout the process, an ion-exchange membrane acts as a conduit for the exchange of ions. Thus, the equilibrium potential of the cell is taken as ECell_eq (at 50% SOC)= 1.39 V [42].