Surface modification of magnetite using silica coating: Spectroscopic, structural, morphological characterization and interaction with Cristal Violet dye

The essential goal of this work is to produce an eco-friendly and economically nano-adsorbent that may separate organic dye, especially, cationic dye, from polluted water prior to making use of this adsorbent in industrial filed. This work suggests a way for fabricating magnetite and silica. The proposed approach concerned three steps : the preparation of magnetite (Fe 3 O 4 ) nanoparticles by co-precipitation method, then of silica using sodium silicate prepared from siliceous sand, and finally magnetite coating of silica Fe 3 O 4 /SiO 2 . The nanocomposite Fe 3 O 4 @SiO 2 were investigated by XRD, BET, FT-IR and TEM. The XRD characterization displayed that silica formed an amorphous phase and that magnetite shaped a spinel phase. To optimize the diverse experimental variables affecting the elimination performance of CV, the effects of four experimental parameters including solution pH, adsorbent amount, contact time and ionic strength were evaluated. Adsorption kinetic disclosed that pseudo-second-order is the best model (R 2  > 0.99, q e,cal = 6.68 mg g − 1 ). The negative ΔH° and ΔG° values exhibited the exothermic and spontaneous nature of CV sorption on the nanoparticles, respectively.