Modeling and optimizing of adsorption of Reactive Blue B25 on the nickel ferrite magnetic nanoparticles via response surface methodology

The discharge of dyes into wastewaters from coloring industries (particularly the textile industry) is one of the major environmental problems, because not only does it damage the esthetic nature of the contaminated water, but also causes inhibitory effect on photosynthesis activity in aquatic systems. In addition, some dyes may degrade into the compounds, causing toxic, mutagenic, and carcinogenic effects on living organisms [1]. Therefore, the dye removal from industrial effluents, before being released to the environment is of great importance. The removal of pollutants by adsorption is one of the most attractive techniques for treatment of contaminated water. Recently, magnetic nano-sorbent have gained much more attention because these materials possess the advantages of the nano-scale sorbent and magnetic separation simultaneously [2]. In this study, nickel ferrite (NiFe2O4) nanoparticles (NFNs) was prepared and used as magnetic nano-sorbent for the adsorption removal of Reactive Blue B25 (RB B25) as a model of azo dye. The NFNs was synthesized by co-precipitation method using nickel nitrate and ferric nitrate [3]. Optimization and modeling of the RB B25 using NFNs were performed through the response surface methodology (RSM) based on central composite design (CCD). The structure and morphology of the prepared nano-sorbent were characterized using X-ray diffraction (XRD) and transmission electron microscopy (TEM). Effect of the important factors on the adsorption of Reactive Blue B25 including solution pH, initial concentration of the dye, adsorbent dose, contact time and temperature was considered as input variables for RSM. The analysis of variance showed a high correlation coefficient (R2=0.992) between experimental and predicted response. The removal efficiency of the dye was more than 99 % at the optimum conditions proposed by RSM. Furthermore, the adsorption kinetic studies revealed that the adsorption process followed the pseudo-second-order model. Moreover, adsorption isotherms investigation indicated that the experimental data were well fitted to Langmuir isotherm model and, accordingly, the maximum adsorption capacity (qm) was found to be 79.0 mg/g.