Investigation of patterned and non-patterned poly(2,6-dimethyl 1,4-phenylene) oxide based anion exchange membranes for enhanced desalination and power generation in a microbial desalination cell

Abstract

Quaternary ammonium poly(2,6-dimethyl 1,4-phenylene oxide) (QAPPO) anion exchange membranes (AEMs) with topographically patterned surfaces were assessed in a microbial desalination cell (MDC) system. The MDC results with these QAPPO AEMs were benchmarked against a commercially available AEM. The MDC with the non-patterned QAPPO AEM (Q1) displayed the best desalination rate (a reduction of salinity by 53 ± 2.7%) and power generation (189 ± 5 mW m − 2 ) when compared against the commercially available AEM and the patterned AEMs. The enhanced performance with the Q1 AEM was attributed to its higher ionic conductivity and smaller thickness leading to a reduced area specific resistance. It is important to note that Real Pacific Ocean seawater and activated sludge were used into the desalination chamber and anode chamber respectively for the MDC – which mimicked realistic conditions. Although the non-patterned QAPPO AEM displayed better performance over the patterned QAPPO AEMs, it was observed that the anodic overpotential was smaller when the MDCs featured QAPPO AEMs with larger lateral feature sizes. The results from this study have important implications for the continuous improvements necessary for developing cheaper and better performing membranes in order to optimize the MDC.

Comparative Performance of Microbial Desalination Cells Using Air Diffusion and Liquid Cathode Reactions: Study of the Salt Removal and Desalination Efficiency

“…It is important to note that for the air diffusion cathode MDC, the salt removal was around 20%, indicating that only partial desalination was achieved. The partial desalination has been also reported in the literature with similar MDC configuration using oxygen reduction as cathode reaction (decrease of 58 to 22 mS•cm −1 , salt removal 50%) (Zhang and He, 2015;Moruno et al, 2018). This effect could be attributed to the low available potential to drive the migration of the ions.…”

Commercial Anion Exchange Membranes (AEMs) for Fuel Cell and Water Electrolyzer Applications: Performance, Durability, and Materials Advancement

“…It is noteworthy that extensive research and advancements in the field of anion exchange resin membranes have been taking place for over seven decades [55]. Because of this, Table 1 only includes a selection of membranes that have been primarily investigated for use in AEMFCs and AEMWEs, respectively, over the most recent half decade, even though there are many other membrane companies and membranes available for other applications, such as those from Asahi Chemical Industry [56], AGC Engineering Co., Ltd. [57], Mega a.s. [58,59], Solvay Specialty Polymers [60], and Tianwei Membrane Technology [61][62][63]. Additionally, not all available membranes or grades are shown in the table; often, additional membranes with different thicknesses, porous supports, or other reinforcements are available upon request.…”

A comprehensive review on membranes in microbial desalination cells; processes, utilization, and challenges

“…183 Typically, electrodialysis with modified membranes has a much higher desalination efficiency than electro-dialysis with non-modified membranes. [184][185][186] The membrane facing the anode compartment usually becomes biofouling. This occurs due to organic substrates and bacteria bonding together to form a less homogeneous biofilm than the biofilm on the anode surface.…”

“…The transport of ions is generally possible through conductive membranes 183 . Typically, electro‐dialysis with modified membranes has a much higher desalination efficiency than electro‐dialysis with non‐modified membranes 184‐186 …”