Impact of operating conditions for the continuous‐flow removal of dye effluents in a fixed‐bed reactor using light expanded clay aggregate as a green adsorbent with ultrasound‐assisted desorption

Abstract

AbstractThe adsorption of Reactive Red 33 dye from aqueous solution onto light expanded clay aggregate (LECA) in a batch mode, fixed‐bed reactor has been investigated. The adsorption studies were determined as a function of dye initial concentration, pH, flow rate, temperature, and adsorbent size using response surface methodology. The maximum amount of dye removal (85.11%) was obtained in the optimized conditions (pH = 2, C0 = 20 mg/L, and T = 20°C; flow rate: 40 L/min and smaller size of LECA granules). Also, high‐frequency ultrasound waves have been applied for desorption process which improved the desorption efficiency by 81%. Equilibrium data are fitted well with Langmuir isotherm model and obeyed the Weber–Morris and external diffusion kinetic models. The exothermic nature and negative amount of Gibbs free energy change confirmed the spontaneous nature of this process. The maximum adsorption capacity, qmax, as estimated by Langmuir isotherm model was 1.363 mg/g.