Advancing the Electrosorption Selectivity of Nitrate Through Fine-Tuning Hydrophobic Ammonium Functional Groups in Anion Exchange Membranes for Membrane Capacitive Deionization
Year: 2024
Type: article
Abstract: High Resolution Image Download MS PowerPoint Slide Selective NO 3 – separation is a crucial aspect in the valorization of nutrient resources from wastewater. This study aims to investigate the effect of membrane hydrophobicity on the selectivity of NO 3 – over monovalent anions of similar hydrated sizes, such as Cl –, in the single-pass membrane capacitive deionization (MCDI) process. Heterogeneous anion exchange membranes (AEMs) were fabricated using ion exchange resins with different ammonium functional groups, namely methyl, ethyl, and propyl chains. As demonstrated, ion exchange and electrodialysis experiments indicated a rising trend in NO 3 – selectivity over Cl – under both kinetic and equilibrium conditions as the length of the alkyl groups on the AEM increased. Single-pass MCDI experiments further showed that the NO 3 – selectivity increased with the longer alkyl chain length on ammonium groups. The enhanced hydrophobicity of the propyl-AEM resulted in a NO 3 – selectivity factor of up to 2.01, outperforming that of conventional MCDI (1.39). Meanwhile, the NO 3 – selectivity factor was maintained in the range of 2.01–2.26 at varied cell voltages, suggesting that the membrane hydrophobicity determines the selective ion transport process instead of the external electrical field. These findings offer a promising strategy of fine-tuning the membrane hydrophobicity to enhance the NO 3 – separation selectivity in MCDI, especially for applications in nutrient recovery from wastewater.
Source: ACS ES&T Water
Language: English
Subfield: Biomedical Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $4,500
OpenAlex ID: W4404235822