Effect of Al-Doping on Structural and Adsorption Properties of NiFe2O4 via Modified Sol-Gel Approach for CO2 Adsorption

Aluminium doped nickel ferrite (NiFe2-xAlxO4) with different Al content ranging from 0.3 <= x <= 1.0 was prepared via modified sol-gel approach. The Al-dopant composition was controlled based on Al/Fe precursor ratio. The structural, morphological and adsorption performance were investigated to understand the influence of non-magnetic Al in the samples. XRD measurement showed the single-phase with inverse spinel ferrite structure. The increment of crystallite size as the Al content increases has been confirmed by XRD analysis. Furthermore, all samples were investigated to determine the CO2 capture efficiency and to analyze the adsorption kinetics model. NiFe2-xAlxO4 (x = 1.0) showed the most efficient CO2 adsorption as it obtained an adsorption capacity of 28.71 mg/g. A recyclability test revealed that CO2 adsorption at 30 C-degrees exhibits the optimum adsorption with only 8.56% loss in adsorption capacity after five cycles of CO2 adsorption-desorption. The pseudo-second-order kinetics best fit the adsorption with R-2 = 0.99981. The relative error between calculated and experimental adsorption capacity is only 0.425%.