چكيده به لاتين
In this work, several magnetic nanoparticles (Fe3O4) with silica (SiO2) and Mg-Fe-CO_3^(2-) layered double hydroxide (LDH) as the shell was prepared then modified with manganese dioxide (MnO2) to the removal of iron (Fe2+) and manganese (Mn2+) ions. The structural variation of prepared nanocomposites confirmed by several characterization techniques. Investigating the effect of chemical modification show that Fe3O4@LDH@MnO2 is very effective in the adsorption of Fe2+ and Mn2+ from aqueous solutions. The central composite design (CCD) defined under response surface methodology (RSM) was employed to optimize and interaction effects of variables like adsorbent dose, adsorption time, pH as well as initial concentration on removal efficiency of iron and manganese with Fe3O4@LDH@MnO2. From RSM results, the optimum values in the range of amounts studied for the maximum response of adsorption capacity were achieved to be 100 and 80 (mg L-1) of iron and manganese concentrations, 0.01 (g) of adsorbent, contact time 30 (min), pH 6 and the maximum adsorption capacity of Fe2+ and Mn2+ were found to be 238.09 and 81.30 mg/g respectively. The equilibrium data were checked by Langmuir, Temkin, and Freundlich isotherm models. The pseudo-first and -second order, Elovich, intra-particle diffusion, and particle diffusion kinetic models were applied to describe the adsorption rates. Thermodynamic parameters studies indicated that heavy metals adsorption onto Fe3O4@LDH@MnO2 is a spontaneous and endothermic. Regeneration process was performed with NaCl and proven it was a suitable desorbing reagent in the discharge of Fe2+ and Mn2+. The reusability of prepared magnetic Fe3O4 nano particle was investigated up to six cycles. The adsorption method was utilized for the adsorptive removal of Fe2+ and Mn2+ in two water samples.
