Valorization of Agroindustrial Wastes as Biosorbent for the Removal of Textile Dyes from Aqueous Solutions

The goal is to determinate the technical feasibility of using agroindustrial wastes for adsorption of dyes. The pHpzc of Brewer’s spent grains and Orange peel is 5.3 and 3.5, respectively. The equilibrium isotherms of Basic Blue 41, Reactiive Black 5, and Acid Black 1 were carried out without pHs control which ranging between 4 and 5.5. The equilibrium concentrations for both adsorbents were fitted by the Freundlich and Langmuir models. The maximum adsorption capacity measured for Basic Blue 41, Reactive Black 5, and Acid Black 1 was 32.4, 22.3, and 19.8 mg g-1 for Brewer’s spent grains; and 157, 62.6, and 45.5 for orange peel, respectively. The kinetic of process was fitted by the model of pseudo-second order. The constant rate for orange peel decreased to extend the initial concentration of dye increased, obtaining 4.08 * 10−3−0.6 * 10−3 (Basic Blue 41), 2.98 * 10−3−0.36 * 10−3 (Acid Black 1), and 3.40 * 10−3−0.46 * 10−3 g mg−1 min−1 (Reactive Black 5). The best removal efficiency was obtained in orange peel with values started from 63% to 20%. Consequently, according the results obtained there are two positive effects, the reuse of agricultural wastes and its use as low-cost adsorbent of the dyes