9 research outputs found
New Calix[4]arene-monobenzo- and -dibenzo-crown-6 as Cesium Selective Ionophores in the Radioactive Waste Treatment: Synthesis, Complexation and Extraction Properties
No full textCesium possesses two long lived isotopes Cs-135 and Cs-137 and the first one has a very long (2.3 x 10(6) y) half life and is one of the most mobile nuclides in a repository. Calix[4]arene-crowns-6 in the 1,3-alternate conformation are emerging as a new class of ionophores exhibiting a very high efficiency and selectivity in the complexation of cesium ion and its removal from highly acidic ([HNO3] = 3-4 M) radioactive waste having also high sodium nitrate concentration ([NaNO3] = 2-4 M). In order to improve both efficiency and cesium selectivity we have synthesised the novel calix[4]arene dibenzo-crowns-6 1 and 2 and the calix[4]arene-monobenzocrown-6 3 in 1,3-alternate conformation and evaluated their complexation properties towards alkali metal cations in homogeneous solution and in two phase systems, together with their performance in radioactive waste treatment. All data confirm the higher Cs/Na selectivity of the 1,3-alternate calix[4]crown-6 1-3 containing aromatic rings in the polyether loop, in comparison to previously synthesised compounds of the same series
Muang Rae Geothermal System: Drilling and Borehole Geophysics, 1000-m Core Hole into Granitic Rock, Amphoe Pai, Mae Hong Son Province, Northern Thailand
No full textIn 2015, a 1-km core hole was drilled into granitic rock at the Muang Rae geothermal area. Previous drilling in 1993 to 200 m was unsuccessful in obtaining flows, but one of the “dry” wells began flowing in August, 2013 at 9.75 L/s of 96.9°C water from a fracture zone 80 m deep. In the sandy bed of the Pai River, 150 m south of that well is a 600-m long line of hot seeps, oriented NE, with highest temperature measured at 94.5°C. Geology is foliated Triassic (?) granitic rock cut by a NE-SW-trending normal fault zone (dip 65° NW) with extensive fluorite mineralization. Mineral equilibrium geothermometer analysis predicts a reservoir temperature of 132°C. The core hole was sited NW of the seep zone to drill into the fault zone at 600 m. MT indicated a low-resistivity anomaly 150-500 m deep at the site. The well did not flow, but was pumped at 6.4 L/s of 86°C water with 2.5 m of drawdown. Temperature logs indicate the well intersects a fracture with flowing hot water of 91.5°C at 600 m. The log shows a temperature inversion related to the transient effect of conductive heating of the surrounding rock by hot-water flow in the fracture. The bottom 150 m of the well shows a 23°C/km temperature gradient, which reflects the regional crustal conductive gradient
Photophysical Properties of Bis-8-Hydroxyquinoline-Armed Diazatrithia-15-Crown-5 and Diazatrithia-16-Crown-5 Ligands
No full textChemInform Abstract: Bis-8-hydroxyquinoline-Armed Diazatrithia-15-crown-5 and Diazatrithia-16-crown-5 Ligands: Possible Fluorophoric Metal Ion Sensors.
No full textMixtures of anionic and cationic surfactants with single and twin head groups: solubilization and adsolubilization of styrene and ethylcyclohexane
No full textABSTRACT: This research reports on the adsorption and precipitation of mixtures of anionic and cationic surfactants having single and twin head groups. The surfactant mixtures investigated were: (i) a single-head anionic surfactant, sodium dodecyl sulfate (SDS), in a mixture with the twin-head cationic surfactant pentamethyl-octadecyl-1,3-propane diammonium dichloride (PODD)-adsorption was studied on negatively charged silica; and (ii) a twin-head anionic surfactant, sodium hexadecyldiphenyloxide disulfonate (SHDPDS), and the single-head cationic surfactant dodecylpyridinium chloride (DPCl)-adsorption was studied on positively charged alumina. Whereas the mixed surfactant system of SHDPDS/DPCl showed adsorption on alumina that was comparable to that of SHDPDS alone, the mixed surfactant system of SDS/PODD showed increased adsorption on silica as compared with PODD alone. The adsorption of the SDS/PODD mixture increased as the anionic and cationic system approached an equimolar ratio. Precipitation diagrams for mixtures of single-and twin-head surfactant systems showed smaller precipitation areas than for single-head-only surfactant mixtures. Thus, the combination of single-and doublehead surfactants helps reduce the precipitation region and can increase the adsorption levels, although the magnitude of the effect is a function of the specific surfactants used. Paper no. S1508 in JSD 9, 21-28 (Qtr. 1, 2006). KEY WORDS: Alumina, anionic surfactant, cationic surfactant, mixed surfactant, precipitation, silica. Mixtures of anionic and cationic surfactants act synergistically, as evidenced by ultralow critical micelle concentrations (CMC), increased surface activity (1,2) and improved detergency performance (3). The main disadvantage of mixed anionic and cationic surfactant systems is their tendency to form precipitates or liquid crystal phases (4). Precipitation negatively affects surfactant use in many applications, such as detergency performance and subsurface remediation of oil contamination (4,5). The main goals of this work are to evaluate synergism of surfactant adsorption onto solid surfaces by using anionic and cationic surfactant mixtures, and to determine how properties of these adsorbed mixtures affect the co-adsorption or adsolubilization of different types of solutes. While of secondary interest, we also evaluate the precipitation of anionic/cationic surfactant mixtures to define isotropic concentration regimes in which to conduct the adsorption studies. We hypothesize that by using mixtures of anionic and cationic surfactants we will observe a synergistic adsorptive behavior as evidenced by having higher surfactant adsorption at sub-CMC surfactant concentrations and by reaching the adsorption plateau (Region IV) at lower surfactant concentrations compared with single surfactant systems; this hypothesis is based on the lower CMC observed for mixtures of anionic and cationic surfactants compared with mixtures of similarly structured surfactants. We also hypothesize that an increased level of plateau surfactant adsorption will result because of the tighter packing density in adsorbed aggregates of these mixed surfactants owing to a reduction in charge repulsion between adjacent adsorbed surfactants compared with single surfactant systems
Mixtures of anionic and cationic surfactants with single and twin head groups: Adsorption and precipitation studies
No full textMixtures of anionic and cationic surfactants with single and twin head groups: Solubilization and adsolubilization of styrene and ethylcyclohexane
No full textInfluencia de los Surfactantes en la Remediación de Suelos Contaminados con Hidrocarburo
No full textLa aplicación de los surfactantes en un proceso de remediación de suelo contaminado con hidrocarburos llevado a cabo por un lavado de suelo, que está condicionado por las propiedades fisicoquímicas del surfactante entre las que se destacan, la adsorción en interfases, emulsión, HLB, tensión en interfase y superficie, CMC, movilidad, formación de micelas, solubilidad y punto nube. En la presente revisión se describen y se discuten las propiedades de los surfactantes que influyen en el potencial para la remediación. Además se analizan las principales variables del lavado de suelo en presencia de surfactantes, tales como los coeficientes de adsorción-desorción, mojabilidad y ángulo de contacto
Influencia de los Surfactantes en la Remediación de Suelos Contaminados con Hidrocarburo
No full textLa aplicación de los surfactantes en un proceso de remediación de suelo contaminado con hidrocarburos llevado a cabo por un lavado de suelo, que está condicionado por las propiedades fisicoquímicas del surfactante entre las que se destacan, la adsorción en interfases, emulsión, HLB, tensión en interfase y superficie, CMC, movilidad, formación de micelas, solubilidad y punto nube. En la presente revisión se describen y se discuten las propiedades de los surfactantes que influyen en el potencial para la remediación. Además se analizan las principales variables del lavado de suelo en presencia de surfactantes, tales como los coeficientes de adsorción-desorción, mojabilidad y ángulo de contacto
