Dual purpose application of cobalt nanoparticles embedded arrowroot-based hydrogel for the adsorptive removal of MB dye and use as water reservoir for enhancing plant growth

Methylene blue (MB) dye is a common pollutant present in the effluents from industries and is recognized as a hazardous material, presenting a significant threat to human health. Therefore, to resolve this issue, an environmentally friendly, biodegradable arrowroot-based cobalt nanoparticle-embedded hydrogel (AW/Poly(Am)/Co NPs hydrogel) has been fabricated for the efficient elimination of MB dye and, after desorption, developed as a water reservoir for augmenting plant growth. Ideal parameters obtained from batch adsorption studies were affirmed with the Box-Behnken Design model and showed that 0.01 g of AW/Poly(Am)/Co NPs hydrogel can remove 10 mg/L MB dye (10 mL) in 120 min at a pH of 7 at room temperature. The Langmuir isotherm model gave 872.43 mg/g maximum adsorption capacity. Ten consecutive adsorption-desorption cycles efficiently removed MB upto 87%. To convert waste into opportunity, the desorb dye solution is reused to dye the fresh cloth and hydrogel as a water-holding reservoir for the Vigna radiata plant growth. The water-holding capacity of soil-mixed hydrogel was 43.24%, which was greater than soil (16.72%) and gave better plant growth as compared to soil. The developed hydrogel has superior reusability and adsorption capacity for the methylene blue dye compared to conventional options. After its initial use, it can be recycled and utilized repeatedly, contributing to resource efficiency and cost savings. Its recyclability and dual application in wastewater remediation and agricultural enhancement highlight its potential as a sustainable and cost-effective alternative for environmental management.