Synthesis of magnetic core-shell Fe3O4@MCM-41-NH2 and its application for the removal of Alizarin Red S from wastewater samples and optimization by Response Surface Methodology (RSM)

A core-shell Fe3O4@MCM-41-NH2 was synthesized by hydrothermal method and it modified by 3-aminopropyltriothoxysilane (APTES) as amine function on surface nanocomposite as a magnetic mesoporous nanocomposite to be used as an adsorbent for the effective and rapid removal of anionic dye, Congo Red. The Fe3O4@MCM-41-NH2 nanocomposite were characterized by FT-IR, SEM, TEM and XRD. The 26 experiments were designed by response surface methodology. The selected removal conditions, obtained with a Central Composite Design (CCD) under Response Surface Methodology (RSM). Quadratic model was used to predict the variables .Analysis of variance was used for investigation of variables and interaction between them. High F-value (54.38), very low P-value ( 0.00001), non-significant lack of fit, the determination coefficient (R2 = 0.9899) demonstrate good correlation between experimental and predicted values of the response. The optimum parameters are achieved: pH 3.68, mass of adsorbent 0.012gr, stirring time 4 min and dye concentration 9 mg/l. At these conditions maximum dye removal efficiency was obtained 98.53 %. The maximum sorption capacity was obtained for ARS, 192.27 mg g-1. The adsorption isotherms at different temperatures were fitted well with Langmuir model. Various kinetics models were examined and the results showed that pseudo-second-order could be best model to the adsorption