Purification
and collection of industrial products from oil–water
mixtures are commonly implemented processes. However, the efficiencies
of such processes can be severely influenced by the presence of emulsifiers
that induce the formation of small oil droplets dispersed in the mixtures.
Understanding of this emulsifying effect and its counteractions which
occur at the oil/water interface is therefore necessary for the improvement
of designs of these processes. In this paper, we investigated the
interfacial mechanisms of protein-induced emulsification and the opposing
surfactant-induced demulsification related to corn oil refinement.
At corn oil/water interfaces, the pH-dependent emulsifying function
of zein protein, which is the major storage protein of corn, was elucidated
by the surface/interface-sensitive sum frequency generation (SFG)
vibrational spectroscopy technique. The effective stabilization of
corn oil droplets by zein protein was illustrated and correlated to
its ordered amide I group at the oil/water interface. Substantial
decrease of this ordering with the addition of three industrial surfactants
to corn oil–zein solution mixtures was also observed using
SFG, which explains the surfactant-induced destabilization and coalescence
of small oil droplets. Surfactant–protein interaction was then
demonstrated to be the driving force for the disordering of interfacial
proteins, either by disrupting protein layers or partially excluding
protein molecules from the interface. The ordered zein proteins at
the interface were therefore revealed to be the critical factor for
the formation of corn oil–water emulsion.
Different polydimethylsiloxane (PDMS) nanocomposite membranes were synthesized by incorporating various contents of nanosized silica particles to improve the PDMS pervaporation (PV) performance. A uniform dispersion of silica nanoparticles in the PDMS membranes was obtained. The nanocomposite membranes were characterized morphologically by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The results showed that surface roughness increases by incorporating silica, and this decreases absorption of penetrants on the membrane. Swelling studies showed that the presence of silica nanoparticles into the PDMS membranes decreases degree of swelling, which can be attributed to rigidification of the PDMS matrix. Additionally, the results revealed that helium permeability decreases through the nanocomposite membranes, due to the more polymer chains packing. Effects of silica on recovery of isopropanol (IPA) from water mixtures were also investigated. Based on the results, incorporating silica nanoparticles promotes significantly the PDMS membrane selectivity because the polymer chains are rigidified and also the polymer free volume decreases. However, permeation flux decreases as diffusion of the penetrants reduces in the presence of silica nanoparticles within the PDMS membranes. As PV performance depends on operating conditions, effects of feed composition, and temperature were also studied. Moreover, recoveries of IPA, ethanol, and methanol from water mixtures were compared using the PDMS-silica nanocomposite membranes. The results demonstrated that polarity and solubility of alcohols affect permeation flux and selectivity resulting in the higher permeation flux and selectivity for IPA.
In this study, conversion of soybean oil was carried out in a continuous pyrolysis system with feed injected through an atomizer. This allowed introduction of micron-sized droplets of oil that could be rapidly vaporized inside the reactor. With this novel design, we were able to achieve feed vapor residence times (τ) of 6-300s without use of carrier gas, which would significantly reduce the overall cost of pyrolysis. Effects of reaction temperature (450C 12), 33% long-chain fatty acids (C 16-C 18 , but primarily oleic acid) and 15% short-chain fatty acids (C 6-C 12). Upon distillation of the liquid products, the long-chain fatty acids were cleanly separated from the hydrocarbons. Overall, our results demonstrate the feasibility of producing liquid products at high yields, including a wide range of fuels (gasoline, jet and diesel) and enriched oleic acid (for oleochemicals production), using our reactor design for pyrolytic conversion of vegetable oil.
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