Efficient separation and removal of dyes from single and multiple systems by magnetic/silver/carbon nanocomposite: Mechanism and mathematical modeling

Abstract

In this study, a new magnetic iron oxide/silver/carbon nanocomposite (MSC) was synthesized by solution combustion method and characterized by the most indicated, and modern methods. The synthesized material was applied as an efficient adsorbent for removal of anionic and cationic dyes, from single and multi-component systems. The main effect of adsorption process parameters: pH, initial concentration, adsorbent dose and temperature, and their interactions on the removal efficiency were determined. The response surface optimization (RSM) was successfully used to evaluate the performance of MSC as adsorbent, and to optimize process parameters. A highly significant (p-values E−06 magnitude order) second-order polynomial model with the correlation coefficients R2 and R2adj greater than 0.92, provided great removal rates. The optimal conditions were identified for each dye taking into account the reduction of secondary pollution, and the predicted and experimental results were found to be in good agreement (>94%). Under the optimal working conditions, the highest removal efficiency in adsorption using MSC was 99.92% for Methylene Blue, 97.19% for Safranine T and 92.86% for Acid Blue 80 respectively. The second-order kinetic model and the Sips isotherm model fit best with experimental data for investigated dyes. The maximum adsorption capacity in single component system, 150.61 mg/g for MB, 166.21 mg/g for ST, 81.54 mg/g for AB support high efficiency of MSC as adsorbent. Thermodynamic analysis indicated that the adsorption is an endothermic, spontaneous and physisorption process. In addition, reusability of the MSC was evaluated in six adsorption/desorption cycles with good results.