Synthesis and application of dual-functional sorbent SBA-15-Fe 3 O 4-PDA-ODA for removing both water soluble and insoluble pollutants

Abstract

In this study, inorganic -organic hybrid sorbent SBA-15-Fe 3 O 4 -PDA-ODA with functional groups having affinity for both water-soluble and insoluble pollutants was synthesized for treatment of wastewater where Malachite Green (MG) dye and motor oil coexist. In order to enhance the specific interactions between the sorbent and dye via functional groups of polydopamine (PDA), Fe 3 O 4 nanoparticles were encapsulated with SBA -15 and surface functionalization with PDA was accomplished and then the surface of Fe 3 O 4 -SBA-15-PDA was modified with octadecylamine (ODA) to remove the oil present in the same environment with dye. While the SBA-15-Fe 3 O 4 - PDA-ODA directed to the aqueous phase by magnet provided MG removal thanks to the hydrophilic groups of PDA, it provided motor oil removal thanks to hydrophobicity of ODA when directed to the oil phase. 99.20 % dye removal and 9.24 g/g oil adsorption capacity were achieved from the environment where oil and dye were present together. Besides, the adsorption of MG on Fe 3 O 4 -SBA-15-PDA was searched at various pH, dye concentration, adsorbent dosage, and temperature in order to propose optimum experimental conditions for removal of dye and maximum adsorption capacity was determined as 95.83 mg g -1 at optimum conditions (10 mg adsorbent, 10 mg L -1 MG concentration, pH 9). Interaction mechanism between dye and Fe 3 O 4 -SBA-15-PDA was explained by studying the adsorption behavior of sorbent derived from the isotherm and kinetic results. The sorbents were characterized by FT-IR, XRD, SEM, N 2 -adsorption/desorption, water -contact -angle, and VSM measurements. SBA-15-Fe 3 O 4 -PDA-ODA sorbent was tested for three successive adsorption cycles for both dye and oil and eventuated insignificant loss in activity when they were recycled. Easy and low-cost fabrication protocol, controllable removal ability of dye and oil will facilitate its versatility in environmental cleanup process for water soluble and insoluble pollutants.