Abstract
In this work, we present the study of an efficient method of separating “contaminants” from water produced from oil reservoirs, using magnetic nanoparticles (MNPs). Micron-scale, highly stable oil droplets as well as divalent cations such as Ca2+ can be removed from the produced water through the adsorption onto functionalized MNPs. The method employs MNPs to initially attach to the oil droplets or to the cations, and then to separate them from the liquid phase using a magnetic field. After separating out the “contaminant”-free water, the MNPs can be regenerated and re-used. As the collection of the contaminant-attached MNPs by the application of magnetic field gradient is a critical step for the process, we developed a 1D mathematical model for the description of the dynamics of the MNP collection in the framework of the sedimentation theory. The conservation equation for MNPs is coupled with the flux function, which accounts for not only gravity force but also magnetic force and Brownian interaction. The model describes both the behavior of colloidal particles during settling and the enhancing effects of the magnetic field due to attraction of MNPs towards a magnet. Simulations were compared with measurements from settling tests of a suspension of MNPs.
