Hydrophobic Plasma Polymer Coated Silica Particles for Petroleum Hydrocarbon Removal

In recent years, functionalized hydrophobic materials have attracted considerable interest as oil removal agents. This investigation has applied plasma polymerization as a novel method to develop hydrophobic and oleophilic particles for water purification. 1,7-Octadiene was plasma polymerized onto silica particles using a radio frequency inductively coupled reactor fitted with a rotating chamber. Plasma polymerized 1,7-octadiene (ppOD) films were deposited using plasma power of 40 W and monomer flow rate of 2 sccm, while polymerization time was varied from 5 to 60 min. The surface chemistry of ppOD coated particles was investigated via X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectroscopy, while Washburn capillary rise measurements were applied to evaluate the hydrophobicity and oleophilicity of the particles. The effectiveness of ppOD coated particles for the removal of hydrophobic matter from water was demonstrated by adsorption of motor oil, kerosene, and crude oil. Petroleum hydrocarbon removal was examined by varying removal time and particle mass. The morphology of oil-loaded ppOD coated particles was examined via environmental scanning electron microscopy observations. Increasing the polymerization time increased the concentration of hydrocarbon functionalities on the surface, thus also increasing the hydrophobicity and oil removal efficiency (ORE). The ppOD coated particles have shown to have excellent ORE. These particles were capable of removing 99.0-99.5% of high viscosity motor oil in 10 min, while more than 99.5% of low viscosity crude oil and kerosene was adsorbed in less than 30 s. Plasma polymerization has shown to be a promising approach to produce a new class of materials for a fast, facile, and efficient oil removal.