Sustainable and recyclable starch-based ion exchange resin with superior exchange capacity and swelling resistance

Biomass-derived adsorbents present a sustainable and cost-effective approach for industrial wastewater treatment. However, their effectiveness is often constrained by low adsorption capacity and significant swelling in water. In this work, a novel porous starch-based ion exchange resin was developed to address these limitations. The ion exchanger was synthesized by modifying tertiary amines onto starch, followed by dual-network crosslinking in an emulsion system. The synthesis of this ion exchanger was systematically investigated and confirmed through comprehensive characterization. This adsorbent demonstrates an ultra-high adsorption capacity of over 1500 mg · g⁻¹ for water-soluble dyes, due to the introduction of weakly basic adsorption sites from the triazine-based modifier and melamine resin-based crosslinker, along with a porous structure that increases the specific surface area for adsorption. In dynamic adsorption–desorption studies with Reactive Blue X-BR as a model dye, the average desorption rate was found to be as high as 98.5 %, and the peak concentration of the dye in the desorbent was 32000 mg·g⁻¹. The dual-network crosslinking and the incorporation of hydrophobic groups endow the resin with superior water resistance and a minimal swelling ratio (<15 %), which is crucial for maintaining consistent performance across multiple recycling cycles. Thus, the developed starch-based ion exchanger offers a promising alternative to petroleum-based ion exchange resins.