Sodium Carbonate Salts Research Articles

Flotation of sodium carbonate and sodium bicarbonate salts from their saturated brines

The flotation behavior of sodium carbonates and sodium bicarbonate has been studied with dodecyl amine hydrochloride (DAH) and sodium dodecyl sulfate (SDS) as part of a research program to evaluate the potential of flotation technology for use in the trona industry. Laboratory microflotation experiments generally show that flotation of sodium carbonate salts is possible at least to some extent with cationic (DAH) and anionic (SDS) collectors if the salt is thermodynamically stable under the prevailing experimental conditions. Anhydrous sodium carbonate does not float at any collector concentration because of its instability at the temperatures considered. Sodium carbonate monohydrate can be floated to completion with DAH and SDS at temperatures higher than 40 °C where it is thermodynamically stable but not at lower temperatures. Sodium carbonate decahydrate is difficult to float (30% yield) even at room temperature where it is thermodynamically stable. Even modest flotation of decahydrate is not possible for temperatures exceeding 32 °C under which conditions the decahydrate salt becomes unstable. In general, the sodium carbonate salts are difficult to float even when they are thermodynamically stable because of their strong water structure making influence.In contrast, strong and complete flotation of sodium bicarbonate can be achieved with both DAH and SDS at all temperatures. Such a flotation response was expected since sodium bicarbonate is stable at these temperatures and since the sodium bicarbonate salt does not promote the formation of water structure. Addition of sodium carbonate to the saturated bicarbonate solution, however, destroys the flotation of sodium bicarbonate completely. It is evident that the amount of sodium carbonate in the saturated solution is a most important parameter which controls the flotation response of sodium bicarbonate.Finally trona, sodium sesquicarbonate, the double salt of sodium carbonate and bicarbonate, was found not to float at room temperature with either the DAH or SDS collectors. These flotation results are discussed with regard to interfacial water structure as influenced by salt properties.

Alkoxide-catalysed hydrolyses of a chlorotriazine in alcohol–water mixtures. A new indirect probe for hydroxide-catalysed hydrolysis

Pseudo-first order rate constants (kobs) and product ratios are reported for competing hydrolyses and alcoholyses of the reactive dichlorotriazine dye (2) in water containing small amounts (usually <0.05 M) of added alcohols (methanol, propan-1-ol, and four polyols: α- or β-methylglucopyranoside, mannitol or sorbitol) at pH 11.2. Additional data are reported in the presence of ethane-1,2-diol, prop-2-yn-1-ol and 2,2,2-trifluoroethanol. Dissection of kobs for solvolysis of the dye (DX) into the separate contributions from hydrolysis (kDOH) and alcoholysis (kDOR) shows that kDOH increases in polyol–water mixtures for 2, but not for the monofluorotriazine (1), and kDOH also increases for 2 in aqueous trifluoroethanol. The results are consistent with alkoxide-catalysed hydrolysis for 2, but with an uncatalysed or weakly-catalysed hydrolysis for 1, and provide indirect support for the possibility of a third order process in which hydroxide could act as a base catalyst. Additional kinetic data for 2 in methanol–water mixtures, containing both sodium carbonate and tetraalkylammonium salts, show rate enhancements particularly when the amount of sodium carbonate is low.

Procedure for calibration of a coulometric system used for total inorganic carbon measurements of seawater

A calibration procedure is described for measurements of total inorganic carbon (C T) in seawater using a coulometric system. In contrast to a previously published protocol which is based on pure CO 2 gas as a calibration standard, the present procedure is based on measurements of standard solutions treated similarly to seawater samples. We show that standard solutions for C T measurements can be easily prepared both in the laboratory and at sea from distilled water and preweighed sodium carbonate salt. With reasonable care, 1 l of standard solution can be used regularly over a period of a week. The precision of this calibration procedure ranges from ± 0.02 to ± 0.06%, allowing measurements of seawater samples to within ± 0.3 to ± 1.3 μmol C kg −1; such precision is necessary for detection of any increase in C T as a result of anthropogenic input. A preliminary comparison to assess the accuracy of these measurements when compared with an established manometric method performed on the same seawater shows close agreement, with a mean of 1978.4 ± 1.3 μmol C kg −1 for the coulometric method and 1978.8 μmol C kg −1 for the manometric analysis. The difference between these measurements (0.4 μmol C kg −1) is within the precision of either method. These standard solutions are simple, practical and inexpensive to prepare and measure, making them ideal for measurements at sea.

Groundwater evolution, chemical sedimentation and carbonate brine formation on an island in the Okavango Delta swamp, Botswana

The Okavango Delta of semi-arid northern Botswana is a large alluvial fan (22,000 km 2) covered by permanent and seasonal swamps from which 96% of the annual discharge is lost by evapotranspiration. Many small islands (∼1ha) within the permanent swamps are the sites of accumulation of sodium carbonate salts and many contain saline pans. The associated alkaline soils are toxic to vegetation. An understanding of the processes involved in alkalinization could be of potential benefit to long-term conservation planning in this unique ecosystem. The relation between soil chemistry and mineralogy, and swamp and groundwater chemistry were investigated on an island in the swamps. The study revealed that the water table beneath the island is depressed and swamp water enters the groundwater regime of the island from the margins and below, and flows toward the centre. The water becomes progressively more saline, initially owing to transpiration by trees and ultimately by evaporation in the central parts of the island. As a result of increasing salinity, amorphous SiO 2 and magnesium calcite precipitate in the soils beneath the marginal zone of the island, raising the land surface, while the more soluble alkali carbonates are concentrated in the centre of the island as surface crusts and brine ponds. Leaching of these salts into the soil during the rainy season and gravity-driven flow of saline brines in the dry season causes the downward movement of Al and Fe in the central zone of the island. K-feldspar and possibly amorphous allophane develop in the deeper soils under the central zone of the island.

Sodium Salt Treated Catchments for Water Harvesting

ABSTRACT Apaired catchment study of field-sized water-harvesting plots showed that precipitation runoff efficiency from an area treated with a spray application of a sodium carbonate salt solution at a rate of 44.9 g of salt per m^ was 46% of the total precipitation compared to 33% from an untreated catchment for a 3-yr period. After 3 yr the treatment was no longer effective. Runoff efficiency evaluations with a small sprinkler of a 14-yr old, operational-sized, runoff-farming catchment treated with granulated sodium chloride salt mixed into the soil at a rate of 1120 g of salt per m^ showed that runoff was over 80% of the total precipitation from the treated areas compared to 55% from similar untreated areas. Measured runoff from sprinkler evaluations of treatment effectiveness was higher when distilled water was used than when using the local top water. Soil erosion was not a problem on soils which developed a gravel protective layer on the catchment surface. Water costs from salt treated catchments are estimated at $0.08 to 0.59/1000 L in a 500 mm rainfall zone.

Na&lt;SUB&gt;2&lt;/SUB&gt;CO&lt;SUB&gt;3&lt;/SUB&gt;-Na&lt;SUB&gt;2&lt;/SUB&gt;O-SiO&lt;SUB&gt;2&lt;/SUB&gt;系融体と溶銅間の相平衡

The equilibrium between the molten system of Na2CO3-Na2O-SiO2 and metallic copper was studied at 1250°Cunder a flow of argon gas. The results are as follows:1) Two miscibility gaps were observed and the conjugate relations were established. One is the miscibility gap between sodium carbonate salt and Cu, O-base slag and another is between sodium silicate slag and Cu2O-hase slag.2) Copper solubility in the melts of Na2CO3-Na2O-SiO2 was determined. The copper solubility in Na2CO3 melt is very small and copper is the most soluble to the slag near 0.7 soda-ratio.3) Activity coefficient of CuO0.5 in this system was calculated, based on the data of the copper solubility.4) From the relation between the amount of retained CO2 in slag and the amount of added acidic oxides, it can be concluded that two moles of Na2CO3 are decomposed by one mole of SiO2 and three moles of Na2CO3 are decomposed by one mole of As2O5 or Sb2O5.

Détermination de la provenance des céramiques par analyse des géopolymères contenus dans les pates céramiques cuites à basse température

A low temperature ceramic material is obtained with curing temperature ranging from 250 to 500° C, using a chemical reaction, a polycondensation into a geopolymer, between a clayish mineral and caustic soda. Caustic soda is easily obtained by reacting a lime solution with sodium carbonate (salt natron of Egypt and Africa). With the different types of clays, soils, the polycondensed geopolymer has the structure of the feldspathoîd sodalite or hydrosodal ite, except illitic material which does not react and has to be fired at high temperature. Lateritic soil and Nil mud necessit an addition of a soluble silica source, such as mica, flint, chrysocolla.

ChemInform Abstract: CATALYTIC CARBOXYLATION OF FATS, CARBOXY ACIDS FROM POLYUNSATURATES

AbstractAn Leinsamen‐, Sojabohnen‐, Saflor‐öl, ‐säuren und ‐estern werden katalytische Carboxylierungen an Palladiumdichlorid‐triphenylphosphin mit Wasser‐Kohlenmonoxid bei 120‐160°C bei 280 at mit oder ohne Aceton als Lösungsmittel durchgeführt.

Catalytic carboxylation of fats: Carboxy acids from polyunsaturates

AbstractStudies with a palladium chloride‐triphenylphosphine catalyst have been extended to the carboxylation of polyunsaturated fats. Linseed, soybean, and safflower oils, acids, and esters were carboxylated catalytically with water‐carbon monoxide (4000 psig) at 120–160 C with or without acetone as a solvent. Main products were monocarboxy, 1,3‐ and 1,4‐dicarboxy and tricarboxy acids. Minor products were carbomethoxy esters and disubstituted 2‐cyclopentenone. Optimum reaction conditions were determined for the carboxylation of linseed oil and methyl esters by statistically designed experiments. Yields of total carboxy and tricarboxy acids were maximized at low triphenylphosphine and water levels, low temperatures, and high palladium‐chloride concentrations. Carboxylated soybean esters were separated by ether extraction of the palladium catalyst from sodium carbonate or hydroxide carboxylate salts. This salt extraction permits catalyst recycling.

Anionic polymerization of caprolactam—XL. Estimation of the content of active base from the rate of polymerization and from the increase of the number of polymer molecules in activated polymerization

At high ratios of acylcaprolactam to sodium caprolactam ( C a C s > 2·5 ), the lactam anions disappeared so quickly that the polymerization slowed down considerably even before attaining polymerization equilibrium. Under these conditions, the content of catalytically active bases was estimated from the rate of polymerization. At initial concentrations C a ≤3 Cs , the content of active base could be estimated from the change in the number of polymer molecules. At 190–250°, the concentration of active bases decreased very rapidly during the first minutes to a value C a ≤3 Cs . A further decrease in basicity is related to the increase in the number of polymer molecules by disproportionation. On the average, 1 · 5 basic groups were formed per new polymer molecule. Above 200°, the calculated effective content of active base, expressed in equivalents of sodium caprolactam, decreased during 30 min to below 1% of the initial concentration of sodium caprolactam. This value corresponds very well to the basicity of sodium carbonate or sodium salts of carboxylic acids which represent the main products of the decay of sodium caprolactam.