Design and Synthesis of Hybrid Inorganic/Organic Networks for the Sequestration of Pollutants from Aqueous Environments and the Stabilization of Emulsions
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The contamination of water with hydrocarbons caused by the extraction and transportation of crude oil is a devastating problem for the environment. Typically, mechanical methods are employed to remove the bulk of the oil; however, they cannot efficiently remove oil sheen. Additionally, surfactants are used to break down the oil but the difficulty in their removal from water could cause further contamination. For these reasons, we have designed magnetically-active hybrid composite materials capable of absorbing oil, and of being removed from the water, known as magnetically-active hybrid networks (MHNs). The MHNs were synthesized from the coupling of amine-functionalized iron oxide nanoparticles and polymeric shell cross-linked knedel-like (SCK) nanoconstructs. An efficiency of ca. 400% towards the capture of crude oil was determined, with ca. 90% recovery of the oil sequestered, and recyclability of at least 3 cycles without compromising performance. The performance of the MHNs in solutions that more closely resemble marine environments was also investigated. This was done by sequestering model aromatic (toluene) and aliphatic (dodecane) components of crude oil from water, and a 10% w/w NaCl solution (brine). An increase in the loading capacity of ca. 9x was observed, with no preference for either contaminant when sequestering from water. However, lower loadings were found when salts were present in the system; with a preference for toluene over dodecane. Hand shaking of the oil/MHN/water system during remediation led to the formation of emulsion droplets, which led to further examination of the mechanism of interaction between the pollutants and the MHNs. The data showed that the MHNs operate via the mechanisms of absorption and emulsification, with the latter being responsible for the decrease in the loading capacity when sequestering from brine. The capability of the MHNs to form emulsions was also explored. Stable, magnetically-active toluene-in-water and dodecane-in-water Pickering emulsions were obtained at a water-to-oil ratio of 3:1 and MHN concentrations as low as 1 mg/mL. Their magnetic property was explored to separate the emulsified oil phase from the water phase, and they could be used in the extraction of hydrocarbons from unconventional reservoirs.
Flores Delgado, Jeniree Andreina (2017). Design and Synthesis of Hybrid Inorganic/Organic Networks for the Sequestration of Pollutants from Aqueous Environments and the Stabilization of Emulsions. Doctoral dissertation, Texas A & M University. Available electronically from