Rapid synthesis and optimization of UV-photopolymerized cassava starch-based superabsorbent hydrogels as a biodegradable, low-cost, and effective adsorbent for MB removal

In this work, eco-friendly superabsorbent hydrogel (SAH) films based on cassava starch (CSt) and poly -acrylic acid (PAA) were successfully fabricated and optimized via a one-pot synthesis and UV-photopolymerization under an air atmosphere to obtain the highest swelling ratio (Seq) and to be employed as an effective adsorbent for removing methylene blue (MB). The optimal CSt-g-PAA film exhibited uniform porous structures with a high specific surface area (24.99 m2/g), acceptable Young's modulus (60.9 MPa), and a relatively high Seq value (35,645% or 356 g/g). It also revealed selective adsorp-tion toward MB dye. The adsorption process of MB onto CSt-g-PAA SAH followed the pseudo-second -order and Langmuir isotherm models. The maximum adsorption capacity (qm), partition coefficient (PC), and removal efficiency for MB adsorption were evaluated to be 1,044 mg/g, 4.08 mg/g.lM-1, and 95%, respectively, making the CSt-g-PAA SAH film one of the most efficient starch-based adsorbents for MB removal. Thermodynamic studies indicated spontaneous and endothermic adsorption. The plau-sible adsorption mechanism was mainly described by electrostatic interaction and hydrogen bonding. Furthermore, the prepared CSt-g-PAA SAH film displayed excellent reusability, remarkable biodegrad-ability, good biosafety, and low cost. Therefore, it may be a promising and sustainable adsorbent for removing dye pollutants and enhancing the ecosystem.(c) 2022 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.