Optimization using the response surface methodology for adsorption of polychlorinated biphenyls (PCBs) from transformer oil by magnetic CMCD-Fe3O4@SiO2 nanoparticles

Abstract

The main objective of this work was to synthesis a novel magnetic nanoparticles functionalized with β-cyclodextrin and use it to refine transformer oil contaminated with high concentration of PCBs. Carboxymethyl-β-cyclodextrin modified Fe3O4@SiO2 magnetic nanoparticles (CMCD-Fe3O4@SiO2) were fabricated by grafting onto the core-shell silica magnetic nanoparticles surface using carbodiimide. The successful synthesis of nanocomposites was characterized by FTIR, XRD, VSM, SEM, TEM, VSM, TGA and EDX analysis. Hereinafter, the application of response surface methodology (RSM) based on the central composite design (CCD) was employed for optimization of the interactive effects of the three main variables on the removal efficiency of PCBs. A quadratic model was applied as a final model to measure the adequacy and the significance of the individual and interactive effects of variables via analysis of variance. The design matrix under the optimum conditions exhibited that the maximum PCBs removal of 82% was attained to be at adsorbent dosage, contact time and temperature of 10 mg/mL, 30 min, and 50 °C, respectively. The obtained results revealed that the adsorbent dosage is known as the key operating parameter (P < 0.0001) affecting PCB removal efficiency. Thermodynamic parameters (ΔH0 > 0, ΔG0 > 0, ΔS0 > 0) were confirmed that the adsorption process was nonspontaneous and endothermic and assess physical phenomena occurring on the surface of adsorbent. The experimental results were proposed that the as-synthesized β-cyclodextrin -modified magnetic nanoparticles could be an ideal candidate for purification of PCB compounds from contaminated transformer oil owing to its simple process and rapid separation and good reusability after five times.