The discharge of toxic effluents from various industries causes the serious effects on water resource, soil fertility, aquatic organisms and ecosystem integrity. Among all the treatment methods, adsorption is one of the most effective methods for removal of dyes from wastewater. The objectives of this research using of Fe 3 O 4 nanoparticles encapsulated with alginate beads and investigate their efficiency in removal of methylene blue dye from aqueous solution. In this study, Fe 3 O 4 nanoparticles coated with citrate ions and then encapsulated with sodium alginate. Atomic absorption spectroscopy (AAS) was used for determination ofmagnetic beads compositions and Uv-visible spectrophotometer was used for determination of dye adsorption rate. Methylene blue adsorption was conducted in two system of batch and continuous. The studies of adsorption isotherm and kinetic were done in continuous system. The parameters of initial dye concentration, content of adsorbent in dry basis, contact time, pH and intensity of magnetic field were studied with design of experiment by taguchi method and orthogonal array by 16 experiments in batch system. The optimum condition of experiments were calculated with taguchi method in batch system: initial dye concentration: 20 ppm, content of adsorbent in dry basis: 1 g, contact time: 180 min, pH: 11 and intensity of magnetic field: 293 gauss, which in condition mean of dye removal predicted %59.122 and achieve to mean of dye removal %60.8 during confirmentional experiments. The parameters of initial dye concentration, dose of Fe 3 O 4 used in adsorbent, contact time and intensity of magnetic field were studied with design of experiment by taguchi method and orthogonal array by 16 experiments in equal optimum pH 11 and content of wet adsorbent 10 g in continuous system. The optimum conditions of experiments were calculated with taguchi method in continuous system: initial dye concentration: 20 ppm, dose of Fe 3 O 4 used in adsorbent: 1 g, contact time: 60 min and intensity of magnetic field: 440 gauss. In these conditions, predict of Taguchi method for mean of dye removal was %85.68 that the mean of dye removal obtainedfrom conformational experiments %86.88 is in good agreement with predicted value. Equilibrium time of dye adsorption in continuous system calculated 90 min and the pseudo-first-order model has a good fitting with experimental data than pseudo-second-order and intraparticle diffusion models. The experimental data have a good agreement with freundlich isotherm and dye adsorption onto adsorbent were physisorption and exothermic. The maximum value of adsorption capacity at 293.15 K was calculated 106.38 mg.g -1 . Keywords : Adsorption, Iron oxide nanoparticles, Methylene blue, Taguchi method,Isotherm and kinetic adsorption.
