Assessing the ageing process of cation exchange membranes in bioelectrochemical systems

Abstract

Bioelectrochemical systems (BES) encompass a group of biobased technologies capable of directly converting organic matter into electricity. In these systems, which are derived from conventional electrochemical technologies, the ion exchange membrane represents a key element because of its influence on the economic feasibility and on the performance of BES. This study examines the impact of long-term operation of a BES on the mechanical, chemical and electrochemical properties of five different kind of cation exchange membranes (Nafion-117, CMI-7001, Zirfon UTP 500, FKE and FKB) through several techniques: (i) scanning electron microscopy (SEM) and atomic force microscopy (AFM) to assess the changes on the membranes surface, (ii) thermogravimetric analysis (TGA) to evaluate the structural stability of the membranes, and (iii) ion exchange capacity (IEC) to monitor any change in their electrochemical properties. Results confirmed that there is not an ideal membrane for BES. While Nafion and CMI-7000 exhibited the strongest chemical structure, they also underwent the highest fouling as revealed by a fast increase in surface roughness.

Sulfonated silica-based cation-exchange nanofiber membranes with superior self-cleaning abilities for electrochemical water treatment applications

“…This is comparable to state-of-the-art polymeric cation-exchange nanofibers and commonly used commercial membranes (e.g. the IEC of Nafion© and CMI-7000 is 0.9 and 1.6 mmol g -1 , respectively) [33], [53], [54].The nanofibers could be electrospun for several hours with a stable process, resulting in a thick, coherent membrane (Supporting information Figure S1), optimal for implementation in lab-scale EC setups, as shown in Figure 2. The membrane has a thickness of ±100 µm, consisting of many layers of fibers with a diameter of 352 ± 149 nm.…”

Recent Advances in Bioelectrochemical Systems for Nitrogen and Phosphorus Recovery Using Membranes

“…Although membranes are of great importance in the recovery of nutrients in BESs, reactor performance has been reported to be significantly affected by IEMs since they generally increase the internal electrical resistance and coulombic efficiencies, but also in relation to capital cost, as they represent up to 40% of the total cost of BESs [ 19 ]. Nevertheless, membrane-based BESs for nutrient recovery are a subject of great interest, as demonstrated by the 49 papers published since 2016 included in this review related to ammonia recovery (63%) and combined ammonia and phosphate recovery (37%).…”

Electro-fermentation: Sustainable bioproductions steered by electricity

“…In addition, some electro-fermentation configuration could require sacrificial counter-electrodes that are consumed and need periodic replacement. Similarly, ion exchange membranes need to be exchanged, since they lose selectiveness and a long-term use negatively affects their mechanical, chemical, and electrochemical properties (San-Martín et al, 2019b, 2019a. Modular designs should be preferred when replacement of electrodes and membranes is required, as they avoid disturbing to the biological community.…”