Hydrophobic carbons

Alkanesulfonates are the petrochemically derived sulfur analogs of soaps, which are alkane carboxylates based on renewable resources. The main difference between alkanesulfonates and soaps is, however, that alkanesulfonates consist of a rather complex mixture of homologs with different carbon chain lengths and isomers with an almost statistical distribution of the functional group along the hydrophobic carbon chain (Fig. 1), whereas soap is a mixture of homologs of alkane 1-carboxylates with an even number of carbon atoms. 

Effect of hydrophobe carbon number on AOS calcium tolerance. The hydrophobe chain branching and the di monosulfonate ratio were held constant in these experiments (5-7% branching and 5-7% disulfonate). Increasing AOS carbon number from 14-16 to 16-18 and finally to 20-24 greatly decreases the calcium ion tolerance of AOS see Fig. 3. Addition of less than 200 ppm calcium ion reduced the transmittance of an AOS 2024 surfactant to less than 10% of its initial value. Addition of more than 300 ppm calcium ion was required to reduce AOS 1618 solution transmittance by a similar amount. AOS 1416 was the most calcium-tolerant surfactant. Approximately 400 ppm calcium ion was required to reduce the transmittance of AOS 1416 solution to 10% of its initial value. 

Comparison of the second (IOS 2024) and last (linear IOS 2024) surfactants in Table 7 shows that the calcium ion tolerance of the linear hydrophobe surfactant is significantly greater than that of the partially branched hydrophobe surfactant. While branching was reduced substantially (33% to 6.6%) in going from IOS 2024 to linear IOS 2024, the hydrophobe carbon number and the disulfonate content of the surfactant were held constant. 

Comparison of results for the first and last entries in Table 7 (AOS 2024 and IOS 2024) was for samples for which the hydrophobe linearity, hydrophobe carbon number, and relative disulfonate content were held nearly constant. The major differences in these surfactants were possible differences in the relative locations of the double bond and the sulfonate group in the alkenesulfonate and in the relative locations of the hydroxy group and the sulfonate group in the hydroxyalkanesulfonate. Analyses to determine these are quite difficult. At calcium ion concentrations below 100-250 ppm, AOS 2024 appeared to be more salt-tolerant than linear IOS 2024. At higher calcium concentrations, the calcium ion tolerance of the two surfactants was similar. 

TABLE 10 Effect of Hydrophobe Carbon Number on Interfacial Tension of Olefinsulfonates ... 

The next two series of experiments were conducted at a much higher di monosulfonate ratio, approximately 40 60 by weight. The results in entries 10 and 11 and 12-14 (Table 10) indicate that the IFT between saline AOS surfactant solutions and Kern River stock tank oil follow the same trend of decreasing IFT value with increasing hydrophobe carbon number. 

AOS 2024. At low di monosulfonate ratios (entries 1-5, Table 16), adsorption did not appear to significantly increase with increasing hydrophobe carbon number. However, at a higher disulfonate content (entries 9-11, Table 16), some increase was noted when the hydrophobe carbon number was increased to 20-24. 

In the presence of decane and a decane-toluene mixture, C16 HAS gives more stable foams than C16 AS. However, such is not the case for the corresponding C18 compounds. In the presence of the decane-toluene mixture, C18 AS and C18 HAS produce foams of approximately equal stability. In the presence of decane, C18 HAS produces a more stable foam than C18 AS. The reason for the differences in behavior between the C16 and C18 compounds is not understood. However, the cause may be related to the hydrophobe carbon number and the oil phase polarity. 

The results in Table 22 for a series of one atmosphere 75 °C foaming experiments indicate the effect of hydrophobe carbon number. The foam stability of C18 AS is greater than that of C16 AS in the absence of an oil phase, in the presence of decane, and in the presence of the decane-toluene mixture. The foam stability of C18 HAS is greater than that of C16 HAS in the absence of an oil phase. In the presence of decane and in the presence of the decane-toluene mixture, the foam stability of the C18 HAS is, if anything, slightly less than that of C16 HAS. This may have been the result of partitioning effects. 

Effect of Hydrophobe Carbon Number, Temperature, and Oil Phase1... 

The porous hydrophobic film of previous electrode designs has now been substituted with a new layer based on a mixture of particles of hydrophobic carbon and PTFE binder. This mixture is very similar in composition to the catalytic layer. This particular modification provides several advantages ... 

The neuronai membrane is composed of a phosphoiipid biiayer. The phosphoiipid moiecuies iine up in two iayers to form the membrane, with their hydrophobic carbon ends directed inward to the center of the membrane, and their hydrophiiic heads pointed out at the extraceiiuiar fluid and cytopiasm. Severai types of protein moiecuies are fixed in this membrane and carry out activities essentiai to the normai function of the neuron. For exampie, action potentiais are propagated by protein ion channeis in the membrane. 

A well-distributed deposition of Pt/C nanocatalyst and Nafion ionomer on bofh hydrophilic and hydrophobic carbon-based electrodes has been successfully obfained using a Pt/C concentration of 1.0 g/L, an electrical field of 300 V/cm, and a deposition time of 5 minutes [118]. The deposition of Pt/C nanocatalysts and Nafion solution via the electrophoretic process gives rise to higher deposition efficiency and a uniform distribution of catalyst and Nafion ionomer on the PEMFC electrodes. 

The carbon chains on fatty acids may be saturated or unsaturated. Fatty acids are amphipathic, meaning they contain a hydrophobic and a hydrophilic end. Since the hydrophobic carbon chain predominates, fatty acids are nonpolar. 

The parameters of the electrical oxidation of hydrogen and reduction of oxygen were compared using the materials like AD-100 hydrophobic carbon-black, ASM 1/05 grade statically synthesized diamond submicron powders, tungsten and vanadium carbides. 

Figure 6 compares the current exchange densities on the AD-100 hydrophobic carbon- black (1), the initial diamond nanopowders (2), diamond powders of 0,7 pm (3), nanopowders with palladium precipication (4). It is seen that the exchange current density after the promotion with palladium to be increased by a factor of 3 and 1.3 as compared with the initial diamond nanopowders and AD-100 carbon-black. 

Micelle solutions were originally characterized with a bulk aqueous phase where the hydrophobic carbon chains were turned inward to help stabilize the oil phase. Later, reverse micelles were also characterized, where the conditions were reversed. A bulk oil phase was used with the hydrophilic head groups turned inward to help stabilize the aqueous phase. Micelles require very stringent conditions, dictated by the molar proportions of oil, water, and surfactant. However, the formation of micelle solutions is driven by the differences in the polarity of the two groups any factor that affects the polarity, such as temperature,... 

---