Synthesis of a superabsorbent hybrid hydrogel with excellent mechanical properties: Water transport and methylene blue absorption profiles

Abstract This paper reports the synthesis of a superabsorbent hybrid based on Arabic gum (AG) and a cross-linkable inorganic material for water dye absorption with enhanced mechanical properties. The inorganic material (MOF-UIO-66) was modified with acrylic acid (AA) using solvent-assisted ligand incorporation for further chemical hydrogelation with AG. This approach leads to a stable structure whose constituent phases are covalently bonded to each other. The mechanical properties and swelling degree were evaluated, and the effects of the pH, time, concentration, and reuse were investigated using absorption measures. The superabsorbent hydrogel (HAGMA, without MOF-UIO-66) absorbed 1014 g of water per 1 g of dry polymer, while the superabsorbent hybrid (AGMOF@AA) swelled hundreds times beyond its dry weight and maintained its three-dimensional shape. The elastic modulus of AGMOF@AA increased by 535% compared with that of HAGMA. The hybrid absorbs five times more energy until the fracture than the hydrogel. In the absorption process, AGMOF@AA showed a high amount of absorbed MB (768.03 mg g−1). Both samples exhibited pH-dependent absorption, and the Langmuir isotherm model correlated well with the experimental data. HAGMA and AGMOF@AA exhibited excellent regeneration capacity and were successfully used over five absorption-desorption cycles.