Recoverable magnetic nanoparticles as hydrate inhibitors

Abstract

This work investigates a mixed emulsifier system composed of Fe3O4 nanoparticles and Span 20 for the development of reusable hydrate inhibitors. Hydrophobic Fe3O4 nanoparticles were prepared by adsorption of Span 20 on the particle surface, and this was confirmed through UV-absorbance and elemental analysis. Water-in-oil Pickering emulsion droplets with Span 20-adsorbed Fe3O4 nanoparticles were analyzed using a confocal microscope and observed through SEM and EDS mapping of solidified emulsion samples. Due to the physical hindrance of the Span 20-adsorbed Fe3O4 nanoparticles, they can act as both kinetic hydrate inhibitors and anti-agglomerants. The induction time is significantly increased by hindering the nucleation, and the torque is lowered by the anti-adhesive behaviors of the hydrophobic particles. The additional injection of the nanoparticles induces the formation of a capillary water bridge, which increases the contact area and hydrate former supersaturation and reduces the dispersion of the emulsion droplet. Therefore, there would be an optimal concentration of Span 20-adsorbed Fe3O4 nanoparticles which maximizes the inhibition performance. A boot drum separator with a magnetic field shows excellent recovery performance for magnetic hydrate inhibitors with the injection of acetone into the boot separator to break the Pickering emulsions. Overall, the Span 20-adsorbed Fe3O4 nanoparticles provide dual roles as kinetic hydrate inhibitors and anti-agglomerants, providing a new approach for the recovery of hydrate inhibitors with superparamagnetic properties. © 2020 Elsevier B.V.