Adsorptive removal of synthetic food dyes using low-cost biochar: Efficiency prediction, kinetics and desorption index evaluation

Abstract

Low-cost biochar prepared from Bilghia sapida wastes (BSAB) was utilized in the adsorption of Allura red (ARFD) and Sunset Yellow (SYFD) food dyes. The activation process increased the BET surface area from 970.25 to 1122.05 m2/g. The maximum adsorption capacities were obtained as 15.17 and 33.27 mg/g for ARFD and SYFD respectively. The kinetic model's analysis indicated that both internal and surface diffusion occurred in the adsorption systems. The desorption investigations revealed that all of the desorbing agents had low efficiency. This was substantiated by the desorption index values (1.0188 and 1.3831) for ARFD and SYFD, indicating low degree of reversibility. As predicted by the ANN model, the best transfer function, MSE and R2 values were (Logsig, 9.96, 0.9771) for ARFD and (Tansig, 10.88, 0.9835) for SYFD. Consequently, BSAB have a considerable potential for the adsorption of food dyes from confectionary industrial wastewaters.