Synthesis of starch-based smart hydrogel derived from rice-cooked wastewater for agricultural use

Abstract

The synthesis of biodegradable hydrogel based on naturally available macromolecules is an important area of research. We synthesized new hydrogel using rice-cooked wastewater (starch), acrylamide, and 2-acrylamido-2-methylpropansulfonic acid in an aqueous medium. The synthesis approach is facile, low-cost, eco-friendly, and novel. The synthesized materials were characterized by scanning electron microscope, X-ray diffraction, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, and Thermogravimetric analysis. The hydrogel exhibited maximum tap water absorbency (158.3 g/g) at pH 7, saline water absorbency (50 g/g), urea solution absorbency (141.2 g/g) at 24 h, and excellent water retention capability (47 wt% at 70 °C, 12 h, and 89 wt% at 30 °C, 24 h). Chili plants, mung beans, and pea seeds germinated and grew well in the hydrogel and hydrogel-mixed soil, respectively. The biodegradability study shows 34.6 % at 120 days in soil and 6.5 % at 30 days in the open air. These findings could entice agricultural development in dry soil.

Keywords: Acrylamide; Biodegradable hydrogel; Natural macromolecules; Plant growth; Polysaccharide.