ABSTRACT
The rates of the copper [II]/zinc cementation reaction in organic- water mixtures were measured at 25C using atomic absorption spectrophotometer. The relation between In Co/C and t in the absence of nonaqueous solvent and at a very diluted CuSO4 solution was given by In Co/C = K.A.t/V; while in the organic-water mixtures, the data fitted the equation of In Co/C = B + K.A.t/V. The rate constant of the cementation reaction increased with increasing the dielectric constant of the mixture. The rate of cementation increased in the order: Water > methanol > ethanol > n-propanol > 2-propanol
Subject(s)
Pharmacokinetics , Solvents/statistics & numerical data , Cementation/methodsABSTRACT
The refining of cottonseed oil by selective extraction of free fatty acids using methanol, ethanol, n. propanol, isopropanol, n. butanol and acetonitril has been investigated. On the basis of the equilibrium composition of the oil and solvent phases, the selectivities of the different solvents to extract the fatty acids in preference to the neutral lipids were estimated. It was found that 90% methanol, 90% ethanol and 90% acetonitril are the most selective among the solvents tried. Ethanol is advantageous over the two other solvents in view of its capacity to dissolve more fatty acids using same volume of solvent. The selectivity of each of the different solvents to extract the oil pigments together with the fatty acids has been also determined and compared. Ethanol, the most selective solvent to extract the fatty acids was found also to be the most selective to extract the oil pigments
Subject(s)
Solvents/statistics & numerical dataABSTRACT
Electrochemical behavior of stainless steel type 430 in acidic solutions of methanol, ethanol and in their binary mixtures with water [covering the whole range from 0 to 100% alcohol] at 25C have been studied. Potentiostatic polarization and weight loss methods were used. The corrosion rate of the metal was influenced by the physicochemical properties of the media such as, viscosity, state of solvation, molar volume contraction, proton availability and dielectric constant. It was demonstrated by the potentiostatic study that the active-passive transition depends strongly on the concentration of the acid, and the water content of the media
Subject(s)
Solvents/statistics & numerical dataABSTRACT
El presente trabajo incluye una revisión bibliográfica actualizada sobre solventes orgánicos, toxicocinética de los solventes, efectos sobre la salud de los trabajadores, la higiene ocupacional, vigilancia epidemiológica, monitoreo biológico, alguna información sobre los solventes utilizados por los trabajadores de la empresa, limites de exposición, métodos de control eliminación de desechos y normativa legal vigente en esta materia. Luego se presenta un diagnóstico preliminar como marco de referencia a futuras investigaciones en la materia y para la empresa, en relación a condiciones de trabajo, stress, factores psicosociales, alteraciones funcionales, salud y manejo de solventes. Esto se obtuvo mediante la aplicación de encuestas a un total de 78 trabajadores expuestos, apreciandose en ellos un desconocimiento manifiesto sobre SOLVENTES, prevención en la manipulación de los mismos y los efectos a la salud. Se hizo la revisión a 68 historias clínicas de estos mismos trabajadores y en 11 de ellos se encontró cifras de cuenta blanca y fórmula alterada, uno con leucopenia y linfocitosis diagnosticada como etiología a precisar. Así mismo se encontro patologías asociadas como dermatitis, cefaleas, alteraciones cardíacas y respiratorias
Subject(s)
Humans , Male , Female , Occupational Health/prevention & control , Occupational Risks/prevention & control , Solvents/toxicity , Solvents/statistics & numerical data , Occupational GroupsABSTRACT
Phenytoin tablets were formulated using different concentrations of PVP as a binder. Four different techniques of incorporating the drug and PVP in tablets were used; namely, coprecipitation and solvent deposition during granulation [A], coprecipitation [B], solvent deposition [C], and wet granulation [D]. The prepared tablets were found to exhibit good physical and mechanical properties. The disintegration time and dissolution rate of the drug were increased with the increase in PVP concentration in all tablet formulations. The dissolution rate of phenytoin from different formluae was in the following order: A > B > C > D. The dissolution data were mathematically analyzed to evaluate the effect of PVP and the method of preparation on the dissolution rate of the drug. In addition, the solubility in different concentrations of PVP revealed that a 1: 1 drug to PVP complex was formed
Subject(s)
Pharmacokinetics , Solvents/statistics & numerical dataABSTRACT
Propylene glycol has been tested as a substitute for alcohol in some pharmaceutic preparations including peppermint spirit, lemon spirit, cinnamon water and diazepam injection. The preparations were evaluated by determining oil content for peppermint spirit, aldehyde content for lemon spirit and cinnamon water, and the behavior upon dilution [with saline or glucose solution] for diazepam injection. The formulae containing propylene glycol were compared with those containing alcohol and found to be suitable
Subject(s)
Solvents/statistics & numerical dataABSTRACT
Hydrolysis of isatin by sodium hydroxide was followed spectrophotometrically in 0, 10, 20, 30, 40, 50, 60 and 70% [v/v] t- butanol-water mixtures and at various temperatures [30-45C]. Addition of a small amount of the organic solvent to water decreased largely the ring opening process. No linearity was observed for the plot of log k versus 1/D, or for the variation of delta E* with X2. The change in delta H* and delta S* with X2 showed maxima at the region where solvent structure changed. The isokinetic temperature [433K] indicated that the process was controlled by delta S* and not delta H*