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Abstract
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In recent years, hydrogel-based absorbents have proven effective for removing water from oils. In this study, superwetting gum-based nanocomposite hydrogels were synthesized and applied to water adsorption from edible oils. To prepare the hydrogel, xanthan gum, a natural polymer that is biocompatible and biodegradable, and polyvinyl alcohol (PVA) were used as the primary ingredients, with calcium chloride and boric acid serving as the crosslinkers. Optimal conditions for synthesis of hydrogels with the highest stability in aqueous and oily solutions were determined by investigating the type and concentration of crosslinkers (5–10 wt%), polymer composition (xanthan: PVA weight ratio) and drying technique. The use of various composite components, such as activated carbon, alumina, silica, and zeolite, was also examined to produce nanocomposite hydrogels that significantly enhanced swelling and water absorption. Hydrogels composed of a 0.5 wt ratio of xanthan to PVA, crosslinked with 10 % calcium chloride to boric acid at a 0.4 wt ratio, and incorporating 1 % silica as a composite component, exhibited enhanced stability, swelling, superhydrophilicity, and underwater superoleophobicity. In this formulation, the calcium chloride-to-gum and boric acid-to-PVA weight ratios were 1.5 and 1.4, respectively. Fourier-transform infrared spectroscopy (FTIR), x-ray crystallography (XRD), field emission scanning electron microscopy (FESEM), and energy dispersive x-ray spectroscopy (EDS) analyses were performed to characterize the hydrogel structure. The synthetic nanocomposite hydrogel at optimal conditions in the form of spherical grains with a 0.03 g/ml dosage enabled the separation of water from 2 % water-in-edible oil emulsions with an efficiency of 90 %. This study confirms that this absorbent can effectively be applied to remove moisture from oil.
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