Synthesis of Fe3O4@PAC as a magnetic nano-composite for adsorption of dibutyl phthalate from the aqueous medium: Modeling, analysis and optimization using the response surface methodology

A magnetic nano-composite of Fe3O4@powdered activated carbon (PAC) was synthesized and evaluated its ability to adsorb dibutyl phthalate (DBP) from aqueous media with a focus on optimization by the central composite design (CCD)-based response surface method (RSM). The synthesized nano-composite structural properties were studied. The effectiveness of pH, initial DBP concentration, absorbent dose, and contact time on DBP adsorption were investigated. The synthesized Fe3O4@PAC nano-composite had high specific surface area (264.04 m2/g) and magnetic properties (39.53 emu/g). In optimal conditions, the DBP adsorption efficiency using Fe3O4@PAC in the real (Sample # 1 = 81.85% and Sample # 2 = 85.22%) and synthetic wastewaters (87.55%) was satisfactory. Furthermore, kinetic and isotherm studies indicated that second-order kinetic and Langmuir models better describe DBP adsorption on the Fe3O4@PAC. The thermodynamic analysis depicted that the process of adsorbing DBP using Fe3O4@PAC was endothermic and spontaneous. After five runs, the Fe3O4@PAC demonstrated high efficiency and chemical stability. The adsorption process had a good efficiency in removing the toxicity of wastewater samples. The cost of treating 1 m3 of wastewater containing DBP (10 mg/L) with Fe3O4@PAC was 17.745 USD/m3. Our results indicated that the Fe3O4@PAC effectively adsorbed DBP from wastewater.