| Summary: | This paper carried out the study on the adsorption of Acid Orange 7 (ACO7) from aqueous solutions by mesoporous goethite (MPG). The adsorbent was characterized by XRD, FE-SEM, BJH desorption and BET. The effect of process variables such as MPG dosage, reaction time, concentration of ACO7, pH, and reaction temperature on the ACO7 uptake capacity were systematically investigated in an attempt to illustrate adsorption performance of MPG. Optimal conditions for the adsorption process was 1 g/L adsorbent dosage, temperature of 328 K, pH of 3, 75 minutes’ contact time and 100 mg/L ACO7 concentration. The adsorption kinetic was best fit to the intra-particle diffusion model while the equilibrium isotherm was best fit to the Langmuir model, suggesting that homogeneous uptake was the principal mechanism adopted in the process of ACO7 adsorption. The study revealed that the pseudo-second order model and the Langmuir isotherm model were the best-fit kinetics and isotherm models to describe the process. The uptake of ACO7 by MPG was endothermic and spontaneous. The major mechanisms for ACO7 uptake onto MPG were pore diffusion, hydrogen bonds, π – π stacking interactions and hydrophobic interactions. MPG has excellent reusability potential with only an 8% drop in performance after 8 cycles. These results indicate that MPG has wide application prospects in removing ACO7 from wastewater.
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