Screening specialty adsorber and anion exchange resins to improve understanding of natural organic matter removal mechanism

“Anion exchange resins (AERs) effectively remove a significant portion of natural organic matter (NOM) from water. For anionic NOM, electrostatic interactions are recognized as predominant removal mechanism. However, the role of non-electrostatic interactions and mechanisms involved in removing NOM with low charge density are not yet fully understood. To address these limitations, nine specialty adsorber and AERs, with different backbones and, in the case of the AERs, different functionalities were screened. A small-scale column setup was used to assess their removal of biopolymers, humics, and low molecular weight NOM from pre-treated surface water, sampled at a drinking water treatment plant, and an isolated biopolymer fraction. Speciality adsorber resins preferentially removed low molecular weight NOM, while humic removal through non-electrostatic interactions was limited. Speciality strong basic AERs (S-SBAs) characterised with low ion exchange capacities exhibited the highest overall removal. Their performance is attributed to a synergistic effect between the resin backbone and functional groups, enabling both electrostatic and non-electrostatic interactions. Moreover, S-SBAs in Cl- counter ion form, showed selectivity toward more aromatic humics, while resins in OH- counter ion form removed less aromatic, hydrophilic NOM, explained by hydrogen bonding. A speciality weak basic AER with secondary and tertiary amine functionalities and a S-SBA with a hydrophilic-lipophilic balanced backbone were most effective for biopolymer removal, especially in the OH- form. These findings provide insights into how resin characteristics affect NOM removal mechanisms and selectivity, which is essential for the optimized design and application of AER-based water treatment processes.”

(Citation: Laforce, E., Cornelissen, E.R., Vermeir, P., Clercq, J. de – Screening specialty adsorber and anion exchange resins to improve understanding of natural organic matter removal mechanism – Journal of Environmental Chemical Engineering 13(2025)5, art. no. 118890 – https://doi.org/10.1016/j.jece.2025.118890)

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