Magnetic hybrid gels for emulsified oil adsorption: an overview of their potential to solve environmental problems associated to petroleum spills

Abstract

Hydrogels (HGs) based on gelatin and crosslinked with gum Arabic have been prepared by the thaw–freezing method, employing two different concentrations of gum Arabic (15 and 50% w/w). Magnetic gels or ferrogels (FGs) were prepared by applying the breath in method to incorporate iron oxide magnetic nanoparticles to the HG matrix. The obtained HG and FG were characterized by XRD, FTIR, and SEM, and the FG composition was estimated by atomic absorption spectroscopy in terms of Fe content. The adsorption of crude oil onto HG and FG was explored achieving very satisfactory results. FG was regenerated by washing with toluene, maintaining efficiency of almost 90% after the fourth cycle. Equilibrium studies were performed to determine the capacity of the prepared FG for adsorption of crude oil from seawater synthetic solutions. The experiments were carried out as a function of different initial concentrations of oil residue (24 to 240 mg/L) exploring different contact times. Equilibrium data were found to fit very well with the Sips models. The kinetic data adsorption of oil onto the FG-15 was better fitted by a pseudo-second-order kinetic indicating that at the initial stages of adsorption, external mass transfer could control the whole rate of the crude oil uptake while intraparticle diffusion controlled the global rate of adsorption at later stages. The obtained results showed that the FG prepared by employing 15% of gum Arabic as the crosslinker (FG-15) has a high removal efficiency of crude oil reaching 1.53 g/g of FG at pH 5.5 and 0.59 g/g for oil/water emulsions in the order of 0.1 g/L. The magnetic properties extend its application. The reached data suggest that the materials presented here may be useful to further the design of systems or devices intended for the remediation of petroleum spills and/or its derivatives in marine water as well as other surfaces such as polluted rocks or soil.