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.

Automated summary

In this study, eco-friendly superabsorbent hydrogel (SAH) films based on cassava starch (CSt) and poly-acrylic acid (PAA) were successfully synthesized and optimized. The optimized CSt-g-PAA film exhibited uniform porous structures and high swelling ratio, making it an efficient adsorbent for removing methylene blue (MB). The adsorption process followed pseudo-second-order and Langmuir isotherm models, and the maximum adsorption capacity, partition coefficient, and removal efficiency were evaluated. Thermodynamic studies showed spontaneous and endothermic adsorption, and the adsorption mechanism involved electrostatic interaction and hydrogen bonding. The prepared SAH film also demonstrated excellent reusability, biodegradability, biosafety, and low cost, making it a promising and sustainable adsorbent for dye pollutant removal.