Investigation of ion-selective binding equilibrium of phosphate in redox-polymeric films

Nutrients such as phosphorus (P) play an essential role as fertilizers in production of high crop yields. However, most of the P fertilizer is derived from imported phosphate rock, which are extracted from non-renewable deposits. State of the art removal and recovery systems face limitations in selectivity and regeneration, thus, there is a need to develop ion-selective systems for phosphorus recovery. We aim to investigate the behavior of selective redox-polymer interfaces in the presence of Phosphate (PO4x-) anions; in particular, we will address the following points: (i) does solvation of the anion and interface play a role in determining selectivity (e.g., solvent volume fraction entering in the film); (ii) how does polymer structure affect redox-mediated reversibility and solvation (e.g., what is the impact on solvation and ion ingression by adding/removing hydrophilic/hydrophobic moieties to the polymer structure). The flow-cell setup available at ISIS will be essential for screening of electrolytes with different phosphate concentration and pH, allowing to map the redox-polymer response to changes in electrolyte composition within the same experiment.

磷（P）等营养元素作为肥料，在作物高产生产中发挥着不可或缺的作用。然而，绝大多数磷肥均源自进口磷矿石，而磷矿石采自不可再生矿床。当前最先进的磷去除与回收系统在选择性与再生性能方面存在局限，因此亟需开发具备离子选择性的磷回收体系。本研究旨在探究选择性氧化还原聚合物（redox-polymer）界面在磷酸根（PO₄ˣ⁻）阴离子存在条件下的行为特性，具体将围绕以下要点展开：（i）阴离子与界面的溶剂化作用是否会影响选择性（例如，进入聚合物膜的溶剂体积分数）；（ii）聚合物结构如何影响氧化还原介导的可逆性与溶剂化作用（例如，向聚合物结构中引入或移除亲水/疏水基团，会对溶剂化过程与离子侵入产生何种影响）。ISIS现有的流动池（flow-cell）实验装置，将成为筛选不同磷酸根浓度与pH值电解液的核心工具，可在单次实验中完成氧化还原聚合物响应随电解液组分变化的规律映射。