Fast synthesis of an eco-friendly starch-grafted poly(N,N-dimethyl acrylamide) hydrogel for the removal of Acid Red 8 dye from aqueous solutions

The aim of this work is to synthesize an eco-friendly, biodegradable, low-cost and efficient hydrogel based on starch-grafted poly(N,N-dimethyl acrylamide). This process can be done by a microwave-assisted method in a heterogenic aqueous solution, and so, the hydrogel is used for the removal of Acid Red 8 (anionic dye) from an aqueous solution using single-batch adsorption technique. The prepared hydrogel has been characterized by FTIR, SEM and TGA. The swelling behavior of hydrogel in both dye and water at different pHs has been studied. The factors which affect the adsorption of Acid Red 8 dye on hydrogel such as pH, percentage of grafting, contact time, hydrogel dose and dye initial concentration have been examined. The obtained results showed that the maximum dye removal percentage (90%) was attained at pH = 1. The percentage of dye removal has improved from 58% after 10 min to 89% after 60 min. Also the percentage of dye removal using hydrogel concentration of 0.3 g l−1 was about 44% which has been improved to 89% on using hydrogel dose up to 2.0 g l−1. The data obtained from the adsorption study were found to fit well with Langmuir adsorption model with maximum adsorption capacity of 120.48 mg g−1. The prepared hydrogel is economic, reusable, efficient and eco-friendly that can be used for the removal of acidic dyes from aqueous media.