| dc.description.abstract | Oil-water separation has been vital in many aspects of our society’s operations. This is particularly highlighted during the environmental cleanups of industrial oily wastes and disasters involving petroleum oil spills. These damaging and ever-challenging conditions require novel, adaptive, cost effective materials and technologies that go beyond current practices. Carbon-based materials such as graphene have excellent potential hydrophobic and oleophilic properties. Some of the challenges to date with these adsorbent based materials include structural and stability issues, which hinder their advantages affording it good but limited properties as oil adsorbents. Although there are numerous novel adsorbents with outstanding adsorption capacities and excellent recyclability, there is still a gap between their performances in a laboratory setting and their actual field application. Under field conditions, other parameters such as buoyancy, geometry, strength and durability, transportation, economics, actual amount of oil recovered as well as its quality etc. must be considered altogether. This paper explores some of these topics with a focus on the development of new experimental parameters that allow investigators to study the oil retention efficiency, adsorption capacity efficiency, and adsorption flux efficiency of an adsorbent. There have been many explorations and investigations on the net adsorption capacities of new materials, however, very few focus on the optimization of an adsorbent as a system, maximizing the synergistic effects between its porous structure, morphology and surface chemistry.
In this thesis study, a super-oleophilic and hydrophobic polyurethane sponge (PU) was created by undergoing an acid-pretreatment and subsequently coated with 3-methacryloxypropyl trimethoxysilane (MPTS) functionalized reduced graphene oxide (RGO). Oil adsorption performances were compared between the samples and the controls in order to quantify the effects of acid-pretreatment, RGO and MPTS functionalization. Water and oil contact angles and water uptake were measured to study the hydrophobicity, oleophilicity and selectivity of the samples. Oil adsorption capacities were measured with protocols specifically designed to study oil retention efficiencies. Recyclability and kinetics studies were also performed experimentally. Pump oil was used as the adsorbate for all experiments in this study. The samples were characterized using SEM, Raman, XRD, and FTIR to understand their morphologies and surface chemistries.
Results indicated the net adsorption capacity of the tested adsorbent improved from 18.5 g/g to 28.61 g/g. More importantly, efficiency studies suggest potential further improvement of over 20% in addition to the volumetric oil adsorption, an additional of 10% or so in oil retention, and over 50% in addition to the adsorption mass flux. The recyclability was stable at over 99.4% after 10 adsorption-desorption cycles. | en |
