Vapor pressure of hexane‐soybean oil solutions at low solvent concentrations

Physical properties of (jojoba oil+n-hexane) compared with other (vegetable oil+n-hexane) mixtures

“…As can be observed in the soybean rich oil mixtures, the excess Gibbs free energy of mixing G E (348.15 K, x 1 < 0.5) is also negative, but the order and magnitude of the other excess thermodynamic functions of mixing are different compared with the jojoba oil mixtures, TS E (T, x 1 ) % H E (T, x 1 ) ) jG E (T,x 1 )j. The results obtained from the data of Smith and Wechter [20] and Aeberhard and Spekuljak [23] are consistent, if the behaviour of G E , H E , and TS E is considered ( figure 5). Figure 6 presents the values of the excess Gibbs free energy of mixing in (n-hexane + cottonseed oil) calculated using the vapour pressure measurements of Aeberhard and Spekulak [23] and Pollard et al [24].…”

“…In the case of the data of Smith and co-workers [20][21][22], an inconsistency was observed in the values of the excess energy of Gibbs, if its temperature dependence is considered. The change of G E (T, x 1 ) with T is considerably larger if the vapour pressures values of Smith and Florence [22] are analyzed compared with those of Smith and Wechter [20]. These differences have no effect on the behaviour of the excess thermodynamic functions as a function of concentration, but their absolute values are different.…”

“…Only three related examples have been reported and these have been conducted within limited experimental ranges (we were unable to obtain the Kovalenko paper [19]). Smith and coworkers [20][21][22] reported the vapour pressures of (n-hexane + soybean oil) system only for oil rich mixtures (x 1 < 0.5) and at considerably higher temperatures (from 348.15 K to 393.15 K) than those investigated by us with jojoba oil mixtures at significantly lower temperatures ((298. 15 and 303.15) K, also for the rich in oil region).…”

“…Since the data reported in the literature for the vapour pressure of n-hexane in various oils [20][21][22][23][24] are presented without any thermodynamic analysis, we proceeded to analyze them using the same procedure as used for our results for the system (n-hexane + jojoba oil). In all the cases, equation (8) was used to correlate the activity coefficients of n-hexane (the ratio of molar volumes was based on densities taken from the literature and the average molar mass of commercial oils was assumed to lie in (873 to 875) range.…”

“…This oil is unique compared with commercial oils coming from soybeans, corn, peanuts, and olives, because it contains the esters of fatty acids with straight chain fatty alcohols and not of glycerol with fatty acids. Jojoba oil is mainly composed of the monoesters of C 20 and C 22 acids and C 20 and C 22 alcohols, with one double bond on each side of the ester bond. The oil has found a wide range of important industrial and cosmetic applications, but one is of special interest, the possibility to replace sperm whale oil.…”