Using Maghemite Nanosorbcats for Adsorptive Removal of Alizarin Dye from Aqueous Solution for Wastewater Treatment and Catalyst Regeneration
An-Najah National University
In this study, maghemite iron oxide (γ-Fe2O3) nanoparticles (NP's) were used as adsorbents for the removal of Alizarin (ALZ) dye from aqueous solution. Different experimental parameters such as effect of amount of adsorbent, solution pH, shaking-contact time and temperature have been studied. It was observed that adsorption was affected by the amount of maghemite NP's until the equilibrium level. The optimum pH value for ALZ adsorption was ca.11 and the equilibrium was established within the first hour. It was also evident that the adsorbed ALZ was decreasing as temperature was increased, suggesting an exothermic adsorption. Pseudo-order kinetic models were used to test the experimental data in order to elucidate the kinetic adsorption process. It was found that ALZ adsorption kinetics has followed pseudo-second-order. Experimental data were analyzed using three model equations: Langmuir, Freudlinch and SIPS isotherms at pH range 8-12 and it was found that the data fitted well with Langmuir isotherm model. The maximum sorption capacity at 298 K for ALZ dye was 28.5 mg g-1. The thermodynamics of ALZ adsorption onto the NP’s was investigated and the thermodynamics parameters, such as standard Gibbs free energy (∆G°), standard enthalpy (∆H°), and standard entropy (∆S°) were calculated and indicated that the process is spontaneous, exothermic in nature and follows physisorption mechanism. This study shows that the γ-Fe2O3 NP's can be regenerated four cycles using HNO3 without impacting its adsorption capacity. Catalytic properties of γ-Fe2O3 NP's were investigated by photocatalytic degradation under UV-light; the results showed that the removal efficiency of ALZ was increasing without affecting the γ-Fe2O3 NP’s magnetic properties with near complete removal of ALZ dye.