MTRODUCTIONThe use of synthetic osmotic membranes for desalting saline waters was proposed by Reid1 in 1953. This process involves reversal of osmotic flow from a solvent cell to a solution cell across a semipermeable membrane. Pressure more than sufficient to counterbalance the osmotic pressure of the solution applied to the solution cell will reverse the direction of flow. The feasibility of the process depends upon the discovery or the synthesis of a suit,able semipermeable membrane. Such a membrane must: (a) be semipermeable with respect to an ionic solution; (b) resist chemical reaction with the solution; and (c) possess a physical structure which permits a reasonable rate of water diffusion.Breton2 investigated the semipermeability of films prepared from a variety of polymers and concluded that, among those tried, cellulose acetate film possessed the most desirable features as a semipermeable membrane for sodium chloride solutions: 96y0 of the ions were rejected from solutions ranging in concentration from 0.1M to 0.6M. Nevertheless, cellulose acetate could not conceivably be used in an economic application of this process. The efficient flow rate was of the order of 25~1. l./hr. cm.2 for film one-half mil thick in contact with 0.1M sodium chloride under a pressure of 600 psi. Furthermore, the selectivity of the film failed after six to fourteen days. This failure was shown by Kuppers3 to be associated with the hydrolysis of acetyl groups from polymer chains.Although cellulose acetate was not suited to practical application of osmotic desalting of saline waters, it did offer a means of studying the mechanism by which water is selectively transported across such membranes. It was hoped that this mechanism could be elucidated to the extent that a more practical membrane could be synthesized. Hence, Breton2 initiated an investigation from which stemmed the following theory."Those ions and molecules that cannot enter into hydrogen bonding with the membrane are transferred by hole-type diffusion. The rate of diffusion appears to be governed by a water-cellulose acetate structure. The reaction between water and the cellulose acetate polymers to form bound water regions is induced by compressing the membrane. As pressure is applied on the membrane, more bound water is produced which causes the rate of hole-type diffusion to decrease." "On the other hand, those ions and molecules that can associate with the membrane through hydrogen bonding actually combine with the membrane and are transported through it by alignmenttype diffusion. The formation of the watercellulose acetate structure does not appreciably diminish the diffusion rate of water through the membrane."Hole-type diffusion was interpreted as a process with low activation energy wherein molecules migrated through free-volume between polymer chains with a diffusion coefficient differing little from the self-diffusion coefficient of the diffusing fluid. Alignment-type diffusion, on the other hand, was visualized as a process in which molecules migrated by d...

A1 reacts directly with the lower aliphatic alcohols only under anhydrous conditions at elevated temperatures or when amalgamated (1), or when highly stressed surfaces are freshly exposed (2). The reaction of Mg metal with moist ethanol at reflux is accelerated with the addition of small amounts of iodine or an aliphatic halogen compound such as chloroform or CC14. A1 and its alloys, brasses, bronzes, and iron alloys are subject to corrosion under some stringent conditions such as mechanical stress, high temperatures, or amalgamation (5-9). Some A1 alloys undergo a rapid, autocatalytic reaction with CCl4-methanol mixtures, initiated at room temperature and leading to complete dissolution of the metal (10). The corrosion of metals in halogenated hydrocarbons is currently under intensive study by Heitz and Kyriazis (11).My interest in this subject stems from reports of corrosion problems encountered in a brass thermal diffusion cell containing CC14-alcohol mixtures (12, 13). I report some novel leatures of this class of reactions. ExperimentalReactions in sealed tubes.--Separate 125 mg samples of Cu, Zn, Ag, Pt, and Au (each at least 99% pure) were sealed in NMR tubes with 500 mg of CCt4-methanol mixture (40% CC14, air not excluded) and held at 25~ Zn metal was decomposed overnight leaving a white solid and a colorless solution. Cu metal was consumed after two weeks leaving a yellow-brown solution and no solid residue. Ag metal was faintly discolored after two weeks but otherwise unaffected.Pt and Au remained bright with no visible indication of reaction. The course of the reaction with Zn and Cu was monitored with proton magnetic resonance spectra. Although the methyl and hydroxy proton signals were progressively shifted downfield (approximately 0.3 ppm in all) no new proton signal developed.In particular, nothing was seen which would indicate the formation of halohydrocarbons, aldehydes, or compounds containing methylene protons. The methyl and the hydroxy proton signals in the Cu tube were significantly broadened at the end of the reaction. When ethanol, 2-propanol, or 1-butanol were substituted for methanol, the reaction with Zn in sealed tubes was progressively more sluggish in order of increasing molecular weight of the alcohol and NMR spectra revealed no new proton signals which were not present at the beginning of the reaction. The induction period.--The time required for the initiation of a vigorous, autocatalytic reaction of Zn with CC14-methanol mixtures in open containers was sensitive to the composition of the mixture as well as to the presence of certain chemical initiators. This reaction was self-initiated at 25~ over a range of concentrations from 0.60 to 0.98 mole fraction of methanol. The minimum induction period, 2 hr, corresponded to a methanol concentration of approximately 0.90 mole Key words: corrosion, organic solvents, water. fraction when used with 30 mesh Fisher Reagent Grade Zn powder. The induction period was completely eliminated by adding traces of soluble salts of some less active me...

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Partial volume expansibility of some representative organic solujtes, in aqueous solution at 3.98°and infinite dilution, were computed from shifts in the temperature of maximum density. Interplay of electrostrictive disruption of solvent structure by polar groups and the solvent ordering effects associated with the hydrocarbon moiety of solute molecules are thereby brought into focus.

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