phase diagram

A critical review of the literature on the methods of concentration and extraction of biobutyric acid from fermentation solutions has been carried out. The best results of these processes are achieved by combining extraction with salting. It is proposed to use polyethylene glycols with diff erent molecular weights as non-fl ammable and environmentally friendly extractants.

A technique of laboratory  synthesis  of potassium formate has  been developed. Phase equlibria in mixtures  of the components  of the binary  system potassium formate - water in the range from -70 to +170°C were investigated by  the visual-polythermal method. For the first time the phase diagram of the specified system has  been con­ structed and the coordinates  of an eutectic  point has  been estab­ lished. The formation of a crystalline hydrate КНСООИ.бНгО incon­ gruous  melting at -9.2°C was  found in this  system.

The phase diagram of the potassium thiocyanate–water binary system was studied by the visual polythermal method and by the method of time–temperature curves over а temperature range – 35–180 оС. There is an eutectic equilibrium at –32.6 оС in the system; the solid phases of this equilibrium are ice and individual potassium thiocyanate. The composition of the liquid phase of the eutectic state was determined.

Phase equilibria and critical phenomena in the water-i-butyric acid binary system were studied by the visual polythermal method over the temperature range –10–30°C. The system is characterized by delamination with an upper critical solution temperature (UCST) equal 25.8°C. In the system at –1.8°C, these occurs a nonvariant monotectic equilibrium whose solid phase are ice crystals. The phase diagram of the system is plotted.

Phase equilibria and critical phenomena in component mixtures of the cut 1 of the quaternary system Potassium Nitrate – Water – Pyridine – Butyric Аcid whose constituent ternary liquid system had a closed binodal curve were studied by means of the visualpolythermal method within 5–60oC. The volumes of two monotectic states in the composition tetrahedron have been found to be in contact via critical tie lines with increasing temperature.

The phase diagrams of the ternary systems potassium carbo- nate+water+hydrocarbon (toluene, n.dodecane) at 25°С were first studied by means of the methods of sections and isothermal titration. The phase diagrams of both systems belong to those of ternary systems with salting-out of the binary heterogeneous system. Potassium carbon- ate sesquihydrate is the solid phase of monotectic equilibrium. Nine tie lines were drawn on the delamination field of the phase diagram of each ternary system.

Studying of the influence of the salt nature and temperature on the liquid-liquid equilibrium in the ternary systems “salt – binary solvent” is topical for the development of the salting-in–salting- out theory. In addition, the ternary potassium iodide-water-alcohol systems are constituents of the quaternary iodine – potassium iodide – water – alcohol ones, studying of which is of practical interest in terms of determining the mixed solvent compositions with the highest iodine-dissolving power.

Potassium dihydrogen phosphate is widely used in industrial and agri- culture. The solvent extraction method for producing KH2PO4 from the more cheap extraction phosphoric acid and potassium chloride has gained growing attention recently. To evaluation influence SO42– on the crystallization KH2PO4 it is nessesary comprehensive knowledge of the phase equilibria in the system K+// H2PO42–, SO42– – H2O. The ternary system KH2PO4 – K2SO4– H2O was determined at 25 °C by the improved isothermal method of section.

Dipropylamine is one of the promising antisolvents for extractive salt crystallization, but its solubility in water and phase equilibria in its aqueous solutions over a wide temperature range has not been studied in detail until now. The review of the literature shows that the water-dipropylamine system is classified as a self-separating system with a lower critical solution temperature (LCST). We used the visual-polythermal method in a –25–90°C range to study phase equilibria in the binary system water-dipropylamine and to plot the phase diagram of the system.

Silver thiostannates and chalcostannates are widely used as promising functional materials which have semiconductor, thermoelectric, and photoelectric properties. The goal of this research is to study the Ag2SnS3-Sb2S3 phase diagram and determine the boundaries of solid solutions based on both components. Alloys were investigated using methods of physicochemical analysis. Based on the results of the study, a condition diagram of the Ag2SnS3-Sb2S3 system was constructed.