A Sustainable and Cost‐Effective Bioadsorbent for the Removal of Allura Red from Contaminated Water

Food grade dyes pose severe health hazards when consumed in excessive amounts or enter body via contaminated water. Despite its harmful effects, Allura Red (AR) is very less explored dye for its removal, especially using agricultural/fruit waste. This study presents efficient removal of an important and unsafe food grade dye, AR via adsorption. Waste watermelon peel waste has been used for the first time for treatmenting wastewater contaminated with AR. Waste was converted to two types of adsorbents, with and without subjecting it to pyrolysis. Both the adsorbents were characterized for functionality and crystallinity and used for conducting adsorption studies. Removal of dye was evaluated by intrinsic strategy of monitoring the model solutions under pre‐ and post‐adsorption conditions. Removal percentage of dye was determined by calculating its initial (Co) and final (Cf) concentrations in solution using the formula (see Eq. (1)). Various reaction parameters important for adsorption, viz. pH, adsorbent dose, residence time, reaction temperature and particle size were optimized. Results indicate that ~80 % and >92 % dye could be removed using 0.5 g/L adsorbent before and after pyrolysis respectively in 3.5 h from its 2 ppm concentration in modelled water. Present study offers a cost‐effective solution for the elimination of a significant food grade dye (allura red) from wastewater. The adsorbent prepared from watermelon peel waste before and after pyrolysis successfully removes ~80 % and >92 % dye using 0.5 g/L adsorbent respectively in 3.5 h from its 2 ppm concentration in modelled water.