Methyl alcohol surface tension

Fig. 2. Surface tension of amyl alcohols compared with 1-butanol and 1-hexanol (15). a, 2-methyl-2-butanol b, 2-methyl-1-butanol c, 1-butanol d,...

The most effective solvents for use in atomic absorption are medium weight, low volatile aliphatics, alcohols and ketones. Frequently used solvents are methyl isobutyl ketone (MIBK) and ethyl propionate. These solvents have viscosities and surface tensions such that the efficiency of nebulisation is increased. 

A correlation of surface tension and vapour pressure of binary liquid mixtures was attempted by Worley,2 who thought they changed in opposite directions, but this relation was said not to hold for chloroform and methyl alcohol. De Carvalho found dplp=—kdajRT(fc=const.), hence ... 

Surface tension of hydrocarbon + alcohol mixtnres The surface tension of the binary hydrocarbon (benzene, toluene, cyclohexane, methyl-cyclohexane) + alcohol (ethanol, t-pentyl alcohol) mixtures were reported5 at 303.15 K (30°C). 

Not only the vapour pressure, but also the vapour density and surface tension of a liquid may be altered by intensive drying. Moreover, in contact with charcoal, ether, methyl alcohol and benzene were found to have a higher vapour pressure than in its absence. 

When organic solvents are used, such as alcohol or methyl isobutyl ketone, the absorption for a given element concentration is enhanced by factors between 2 and 5. As with nearly everything else having to do with burners, the reasons for the improvement are under debate. One plausible explanation is that the organic solvents, having a lower surface tension, produce smaller droplets and thus promote higher eflBciency. 

If the solvent in gel pores is a mixture of water and methanol (or ethanol), appreciable amount of water may be left when drying is finished because methyl alcohol is easier to volatilize than water. But if some surfactants of low surface tension and volatility (for example, A,A -dimethylformamide [DMF]) are added to the wet gel before drying, the possibility of gel cracking is reduced. 

Fig. 8.7. Pure CO2/CH4 permeance ratio of asymmetric poly(phenylene oxide) membranes as a function of surface tension of chloroform/alcohol mixtures. Nonsolvent additives include 2-ethyl-1-hexanol (1m), 1-octanol (2m), 2-propanol (3d), 2-decanol (4m), 3,5,5-trimethyl-1-hexanol (5m), 2,4-dimethyl-3-pentanol (6d), 2,4,4-trimethyl-1-pentanol (7d), and 2-methyl-3-hexanol (lOd). Merged is indicated by m discrete is indicated by d. Reprinted from [22], with kind permission from J. Tan...

The next step in the development of these ideas is the transition from a line spectrum to a continuous spectrum, that is, the use of aqueous solutions of polar and of some weakly polar fluids as liquid media. Figure 1.29 shows the values of X Aa/(( ) for methylated surfaces immersed in aqueous solutions of alcohols, where 4) is the volume fraction of the alcohol [21,23]. The values of/ fl//of Aa (< >) = F are reported for easier comparison with the values of the surface tension. 

Methyl ester ethoxylates and their alcohol ethoxylate counterparts have similar surface properties. Gibbs plot for pure C14 7-mol (no other ethox-ymers except the 7-mol homolog) methyl ester ethoxylate is compared to its pure Ci4 7-mol alcohol ethoxylate counterpart in Fig. 11. The methyl ethoxylate shows a higher CMC and a lower surface tension at the CMC than its alcohol ethoxylate equivalent. This increase in CMC is presumably due to the presence of the ester moiety which adds rigidity and steric constraint to the methyl ester ethoxylate molecule. This would likely reduce the tendency of a molecule to micellize, leading to a slightly higher CMC. 

There is also a difference in dynamic surface properties between methyl ester ethoxylates and alcohol ethoxylates. As shown in Fig. 12 for pure 7-mol homologs, the methyl ester ethoxylate maintains a lower surface tension than its alcohol ethoxylate counterpart as measurements become more dynamic (bubble rate of bubble tensiometer is increased). This suggests that methyl ester ethoxylate is more effective in lowering surface tension (can achieve the same surface tension reduction with a lower surfactant concentration at the interface) and/or it diffuses through aqueous solution at a faster rate. 

FIG. 12 Surface tension (nM/m) vs. bubble rate for C14 pure 7-mol methyl ester and alcohol ethoxylates. (Ethoxylates are pure 7-mol ethoxylates there are no other homologs.)... 

There is also a difference in dynamic surface properties between methyl ester ethoxylates and alcohol ethoxylates. As shown in Figure 12 for pure 7-mole homologs, the methyl ester ethoxylate maintains a lower surface tension than its al-... 

The temperature range for liquid ammonia is from -78 to -33°C. The temperature range for liquid methyl alcohol is from -94 to - -65°C. The parameter surface tension for ammonia and alcohol (ethanol, methanol) is only 1/3 that of water. 

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