Optimizing surface properties and particle morphology for metal ion adsorption: precise tuning via Pickering emulsion polymerization

Abstract

Tuning the chemistry and morphology of polymer microparticle adsorbents for metal ion adsorption is a complex synthetic challenge. Recently, Pickering Emulsion Polymerization Technology (PEmPTech) has emerged as a straightforward and effective method, presenting a compelling alternative to traditional synthesis techniques. In this study, we explore the versatility of PEmPTech by fine tuning of the composition and morphology of the polymer microspheres to maximize their adsorption capacity for metal ions. By systematically varying the amounts of crosslinker, monomer and porogen, we generated several homologous series of microsphere adsorbents and evaluated their Cu(ii) ion removal efficiency from aqueous solutions. The data reveal a clear structure-activity relationship, highlighting the influence of crosslinker and porogen levels on the structure and morphology of the polymer microspheres and consequently on their metal ion adsorption capacity. The adsorption performance was found to decrease with increasing degree of cross-linking and to improve with higher porosity induced by the porogen. Influence of other factors on the adsorption capacity of the microparticles, such as the nature of the crosslinker, size of the microparticles, water contact angle is also discussed. This study advances our understanding of the design parameters critical for developing effective polymer microsphere adsorbents via PEmPTech as a sustainable method for producing high-performance adsorbents in a completely aqueous and surfactant-free environment.