Mechanistic\nInsights into the Removal of Surfactant-Like\nContaminants on Mesoporous Polydopamine Nanospheres from Complex Wastewater\nMatrices

The\ndetrimental environmental effects of surfactant-like contaminants\n(SLCs) with distinctive amphiphilic structures have garnered significant\nattention, particularly since perfluorooctanesulfonate was classified\nas a persistent organic pollutant. Despite the numerous absorbents\ndeveloped for SLCs removal, the underlying interaction mechanisms\nremain speculative and lack experimental validation. To address this\nresearch gap, we elucidate the mechanistic insights into the selective\nremoval of SLCs using mesoporous polydopamine nanospheres (MPDA) fabricated\nvia a novel soft-template method. We employed low-field nuclear magnetic\nresonance to quantitatively characterize the hydrophilicity of the\nabsorbents using water molecules as probes. The results demonstrated\nthat MPDA with uniform mesopores exhibited a remarkable threefold\nenhancement in SLCs’ adsorption capacity compared to conventional\npolydopamine particles via intraparticle diffusion. We further demonstrated\nthe dominant effects of electrostatic and hydrophobic interactions\non the selective removal of SLCs with MPDA by regulating the isoelectric\npH value and performing a comparative analysis. The mechanism-inspired\nSLC-removal strategy achieved an average removal rate of 76.3% from\nhighly contaminated wastewater. Our findings offer new avenues for\napplying MPDA as an efficient adsorbent and provide innovative and\nmechanistic insights for targeted SLC removal in complex wastewater\nmatrices.