Synthesis of gum tragacanth-starch hydrogels for water purification

Abstract

The increasing demand for environmentally friendly materials to address environmental toxicity has prompted a shift towards natural products. This study focuses on the development of biodegradable starch-based (ST) hydrogels modified with gum tragacanth (GT) using polyvinyl alcohol (PVA) as a cross-linker. These hydrogels were utilized as efficient adsorbents for the removal of methylene blue (MB) and congo red (CR) dyes from aqueous solutions. The hydrogels were synthesized via the solution casting method, yielding four variants by adjusting the weights of ST and GT in ratios of ST/GT (2 : 0, 1.5 : 0.5, 1 : 1, and 0.5 : 1.5). Characterization of the hydrogels was performed using FTIR, FESEM, and TGA-DSC. During MB dye adsorption, ST/GT (0.5 : 1.5) exhibited a remarkable removal efficiency of 97.6% within 90 minutes, at pH 10 and an initial dye concentration of 30 ppm. Similarly, for CR dye, the highest removal efficiency of 93.7% was observed with ST/GT (0.5 : 1.5) under optimal conditions of 90 minutes, pH 2, and a dye concentration of 10 ppm. Kinetic studies indicated that the adsorption process followed a pseudo-second order model. Biodegradability tests confirmed the complete breakdown of the hydrogels in soil. This study successfully demonstrates the potential of using plant-based hydrogels for efficient pollutant removal and sustainable water treatment.