Hexane

About: Hexane is a research topic. Over the lifetime, 3759 publications have been published within this topic receiving 57996 citations. The topic is also known as: CH3-[CH2]4-CH3 & hexyl hydride.

Factors Affecting the Stability of Crude Oil Emulsions

Abstract: Crude oils are typically water in crude oil (w/o) emulsions, which are often very stable. Among the indigenous natural surfactants contained in the crude oils, asphaltenes and resins are known to play an important role in the formation and stability of w/o emulsions. Asphaltenes are defined as the fraction of the crude oil precipitating in pentane, hexane, or heptane, but soluble in toluene or benzene. Asphaltenes are the most polar and heaviest compounds in the crude oil. They are composed of several poly nuclear aromatic sheets surrounded by hydrocarbon tails, and form particles whose molar masses are included between 500 and 20,000 g mol-1. They contain many functional groups, including some acids and bases. Resins are molecules defined as being soluble in light alkanes (pentane, hexane, or heptane), but insoluble in liquid propane. They consist mainly of naphthenic aromatic hydrocarbons; generally aromatic ring systems with alicyclic chains. Resins are effective as dispersants of asphaltenes in crude oil. It was postulated that asphaltenes stabilize w/o emulsions in two steps. First, disk-like asphaltene molecules aggregate into particles or micelles, which are interfacially active. Then, these entities upon adsorbing at the w/o interface aggregate through physical interactions and form an interfacial network.

The Mechanism of Extraction by Tributyl Phosphate— n -Hexane Solvents: Part I. Water Extraction

Abstract: The mechanism of water extraction into tributyl phosphate—n-hexane solvents has been investigated in a stirred-vessel transfer cell. The effects of stirrer speed, temperature, and the comparison of...

Enhancement of R123 Pool Boiling by the Addition of N -hexane

Abstract: This paper presents the heat transfer data used to file international patent WO 94/18282. The data consisted of pool boiling performance of a GEWA-TTM surface for three fluids: (1) pure R123, (2) R123/n-hexane (99/1), and (3) R123/n-hexane (98/2). The heat flux and the wall superheat were measured for each fluid at 277.6 K. A (47 + 7)% increase over the pure R123 heat flux was achieved with the addition of 1% mass hexane to R123. Similarly, the R123/hexane (99/2) mixture gave a maximum percent heat flux enhancement over pure R123 of (29 ± 7)%. The boiling was filmed with a 16 mm high-speed camera. The observations were used to describe various boiling modes on the GEWA-TTM surface. The addition of hexane to pure R123 caused a simultaneous reduction in the bubble diameter and increase in the site density. The increase in site density enhanced the boiling despite the reduction in bubble size. Presumably, the site density enhancement was caused by a layer enriched in hexane at the heat transfer surface. The addition of hexane to R123 also improved natural convection. The natural convection was influenced by the greater thermal conductivity of the excess layer which may have contained 55% mass hexane.

Supercritical fluid extraction of fig leaf gourd seeds oil: Fatty acids composition and extraction kinetics

Abstract: Fig leaf gourd ( Cucurbita ficifolia , Bouche) seeds oil was extracted in a Soxhlet apparatus (oil content of 43.5%) and by supercritical fluid extraction (SFE) in the temperature and pressure ranges of 308–318 K and 18–20 MPa, respectively. Both oil batches showed similar fatty acids compositions. Main fatty acids were ω6-linoleic acid (about 60%), palmitic acid (about 15%) and oleic acid (about 14%). The induction time was used to determine the oxidative stability, 4.2 and 8.3 h being obtained for SFE extracted oil and n -hexane extracted oil, respectively. Regarding the kinetics of supercritical fluid extraction, the Sovova’s model was selected and successfully applied to the description of the oil extraction curves. The fitted parameters, the overall mass transfer coefficient for the fluid phase, K f , and the overall mass transfer coefficient for the solid phase, K s , vary in the ranges 2.34–4.57 × 10 −2 s −1 and 1.73–4.34 × 10 −4 s −1 , respectively. The free oil content for milled seeds, f k , was calculated as 61%. These parameters are consistent with those published for several other oils.