Hexadecane removal

Figure 7. Plots of hexadecane removal percentage as micellarly solubilized, middle phase microemulsified. and free phase against the number of flushed surfactant system pore volumes. Also plotted is the effluent concentration of micellarly solubilized oil.

In summary, directly hydrolyzed IOS has good n-hexadecane solubilizing kinetics. This class of compounds then is attractive for detergent formulations where the kinetics of apolar soil removal is imperative. Also, it is observed that shifting the ionic head group toward the middle of the alkyl chain results in an... 

Leaf discs from rapidly expanding V.faba leaves incorporated 14C-labeled palmitic acid into cutin. After removal of the soluble lipids and other materials, the insoluble residue was subjected to LiAlH4 hydrogenolysis and the labeled reduction products of cutin monomers were identified by chromatography as hexadecane-... 

Volatilization of an organic mixture of contaminants, distributed vertically in the subsurface, may induce not only a decrease in the component concentrations but also an enrichment of the deeper layers during the volatilization process. Figure 8.13 shows the actual content of three representative hydrocarbons—m-xylene (C ), n-decane (Cj ,), and hexadcane (Cj )—which originated from the applied kerosene found along a 20 cm soil column, 18 days after application on dry soil. Roughly 30% of the initial content of m-xylene still remained in the soil after 18 days. Furthermore, the content of m-xylene increased somewhat after the third day a similar trend was found for the n-decane distribution. Hexadecane was partially removed from deeper layers and redistributed near the soil surface. 

There are several features to note about Figure 4.7. While water will bead on a surface prepared with PTFE or an FA, it will wet a nylon-6,6 surface. For the case of hexadecane, botlr PTFE and FA surfaces will show appreciable contact angles, while a nylon-6,6 surface will be wetted completely (0 = 0). This is the reason that oily soils are relatively difficult to remove from materials made from nylon-6,6. The surface of a material prepared with a FA using perfluoroalkyl chains often has a lower surface tension than PTFE. For comparison, the surface tensions of nylon-6,6, PTFE " and FAs are estimated to be about 46, 24, and 10-20 mN/m, respectively. 

The surface tensions of materials prepared with are some of the lowest attainable with the reagents commonly available, which is why many carpet and textile repellents are based on the chemistry of perfluoroalkyl chains. For example, a nylon-6,6 carpet would be wetted by oily soils, which, according to Eq. (4), would be difficult to remove. The presence of a FA coating on die fiber lowers its surface tension and repels the oil contaminant. In general, a liquid dial has a high surface tension will not wet a solid with low surface tension (e.g., water on PTFE). The converse is also true. A low-surface-tension liquid will wet a high surface tension solid (e.g., hexadecane on nylon-6,6). 

The surfactant system AOT/TWEEN 80 removed 99.4% of residual hexadecane from glass beads in 4.7 pore volumes with a total of 49.6% recovered as free phase, 31.1% recovered as micellarly solubilized, and 18.7% recovered as microemulsified in the middle phase. These results demonstrate the potential efficiency of supersolubilization (i.e., enhanced solubilization as the type I-III boundary is approached), and mobilization (even if just into the type III system but not yet optimal) in expediting extraction of hydrophobic NAPLs. 

Hexadecane Studies. Figure 2 also indicates that the removal of low viscosity liquid soils such as hexadecane (Cj6) is difficult to monitor with this spectroscopic approach because of the rapidity of removal. The run performed with surfactant-free water, however, indicates that a stable C16-water interface is achieved after 5 minutes. The somewhat hydrophobic ZnSe surface of the IRE can be considered a reasonable model of the polyester fabric surface. Water alone cannot completely clean the C16 from the surface, indicating a significant adhesion energy of hydrocarbon to the ZnSe. 

Figure 3.22 (right) represents the three-phase temperature intervals for Q2E4 and Q2E5 vs the number n of carbon atoms of n-alkanes (for the phase behaviour of ternary systems see Section 3.4.2, Figure 3.26). The left part of Figure 3.22 shows the detergency of these surfactants for hexadecane. Both parts of Figure 3.22 indicate that the maximum oil removal is in the three-phase interval of the oil used (n-hexadecane) [22]. This means that not only the solubilisation capacity of the concentrated surfactant phase, but probably also the minimum interfacial tension existing in the range of the three-phase body is responsible for the maximum oil removal. Further details about the influence of the polarity of the oil, the type of surfactant and the addition of salt are summarised in the review of Miller and Raney [23].

A. 1,4-Dithiaspiro[4.11]hexadecane. A mixture of 46.5 g (0.26 mol) of cyclododecanone (Note 1), 24.1 g (21.5 mL, 0.26 mol) of 1,2-ethane-dithiol (Note 1), and 0.75 g (0.004 mol) of p-toluenesulfonic acid monohydrate (Note 2), in 200 mL of benzene (Note 3) is placed in a 500-mL, three-necked reaction flask equipped for reflux under a water separator.2 The mixture is heated at reflux for several hours until the theoretical amount of water (0.26 mol = 4.6 mL) has collected in the Dean-Stark trap. The reaction mixture is cooled and transferred to a separatory funnel. The mixture is washed with water, the benzene is removed on a rotary evaporator, and the residue is placed under reduced pressure (<0.1 mm) for several hours to remove traces of solvent. Approximately 66 g (99%) of a white solid is recovered (0.26 mol, mp 84-86°C). The crude material is pure by GLC and TLC, and is used in the next step with no further purification. 

The use of Fenton s reagent as an oxidant has been applied to the removal of soil contamination.1617 It has been shown that pentachlorophenol and tri-fluoralin are extensively degraded18 while hexadecane and dieldrin are only partially transformed in a soil suspension at an acidic pH.19... 

The results from the last set of contaminants surveyed for removal efficiencies from the 49 different substrates are listed in Tables 13-15. These contaminants are representative of larger classes of contaminants which may be encountered in cleaning operations. For example, hexadecane and tetracontane can be found in kerosene and diesel. Waxes, such as paraffin wax, are used as lubricants and mold releases. Carbowax and Microwax are... 

Fig. 8.5. Two-dimensional imprinting using hexadecane (hatched rods) as a template in an ODS (filled rods) matrix covalently attached to a Sn02 substrate. Removal of the template by washing leaves behind sites in the film that can bind vitamin K, which has an isoprenyl appendage, but not vitamin Kj.

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