Response Surface Optimization on Adsorption of Methyl Blue onto Magnetic (1 − x)NiFe2O4/xSiO2 Nanocomposites

: Methyl blue (MB) was adsorbed from aqueous solution by magnetic (1 - x)NiFe2O4/xSiO2 (x = 0-0.2) nanocomposites prepared via the facile solution combustion process. The effects of pH of MB solutions, silica content in nanocomposites and the calcination temperature for nanocomposites on the adsorption capacity of MB onto nanocomposites were investigated. Response surface methodology (RSM) based on three-level three-factorial Box-behnken design (BBD) was employed to optimize the adsorption technology of MB onto magnetic (1 - x)NiFe2O4/xSiO2 (x = 0-0.2) nanocomposites, the optimum adsorption conditions (pH value of 7.3, the silica content in nanocomposites of 10.3 wt.%, and the calcination temperature of 423 °C) were determined by the results of statistical analysis, and the linear term of the pH value, the silica content and the calcination temperature, the quadratic term of the silica content and the calcination temperature, and the interaction of pH value and the silica content in nanocomposites were significant factors to affect the adsorption. The adsorption capacity could reach 37.40 mg/g with the initial MB concentration of 100 mg/g under the optimum adsorption conditions.