Beyond the surface area: The effect of electrospinning versus casting on molecular packing and its impact on the production of efficient PVA-pectin-Fe adsorbents.

The processing method used to create polymeric blends of poly(vinyl alcohol) (PVA) and pectin (PE) can significantly alter their structural and functional properties. This work compares cast films with electrospun mats, demonstrating that electrospinning not only increases surface area but also induces a different molecular reorganization of the blend with respect to the cast. Mat morphology enhances accessibility of PE carboxyl groups and improves the capture of Fe3+ ions, increasing the capacity for pollutant removal. Normalizing to the PE content, the mat captures over 260 % more Fe3+ ions than pure PE casts do, confirming the critical role of the morphology-driven carboxyl group accessibility. SEM micrographs reveal significant differences in the nanoscale morphology of the mat before and after the addition of Fe3+, whereas the continuous cast morphology remains unchanged, indicating different interactions between PE and Fe3+. Through SAXS, FT-IR, and thermal analysis, we provide strong evidence that electrospinning promotes a homogeneous open structure where the carboxyl groups are more accessible. Instead, the casting method embeds PE-rich regions within PVA-rich regions. This defines the material behavior for contaminant removal by Fe3+. We evaluated the adsorption efficiency of tetracycline, as a model pollutant remediated by Fe3+, over the two morphologies. The iron-doped electrospun mat exhibits excellent performance even in the presence of other contaminants and it has the potential for reuse, while the iron-doped cast film is a poor adsorbent. This significant difference is due to the packing of the constituents obtained by each method, in addition to changes in surface area.