The paper presents the results of experimental data on the kinetic characteristics of ultrafiltration tubular elements, such as the output specific flow, retention coefficient, diffusion permeability coefficient, distribution coefficient. To study the purification of milk whey, we used tubular ultrafilters BTU 05/2 with membrane material fluoroplast (F), polyethersulfone (PESF), polysulfone (PS). For theoretical calculation of the retention coefficient, output specific flux, diffusion permeability coefficient, distribution coefficient, mathematical expressions were developed and empirical coefficients were obtained. The developed mathematical expression describes the experimental data with good reliability. The obtained experimental and calculated data can be used with high reliability in calculating mass-transfer fluxes of substances through a semi-permeable membrane, as well as in engineering methods for calculating and predicting efficiency, and using membrane processes for concentrating serum. The protein concentration in real milk whey was determined by formol titration. On the basis of the studies carried out, the dependence of the growth of the output specific flow on pressure was established, that the optimal pressure for concentrating milk whey on the ultrafiltration membranes we have chosen is 0.25 MPa. For three types of ultrafilters, the experimental value of the coefficient was within 99% for protein. For the theoretical calculation of the retention coefficient, a program in the MAXIMA language was developed and registered. Due to the method of applying the membrane to the reinforcing element, the membrane material polyethersulfone (PESF) and polysulfone (PS) have a substrate, due to which they sorb more substances on themselves, because of this, the diffusion permeability coefficient and the distribution coefficient are much higher than that of a filter element with membrane made of fluoroplastic (F), which does not have a substrate.
In work were investigated processes of a transmittivity, dairy components through ultrafiltrational polymeric membranes of a type of UPM100, UAM150 and UPMK. Two types of installation a diffusion transmittivity were described. The first installation with use of the roll-type membranous module, the second installation has an appearance of a flat-chamber cell. Preferences for carrying out the pilot studies it is given to a flat-chamber cell. Researches are conducted at change of concentration and temperature of solution. It is noted that with strengthening the diffusion transmittivity decreases, and with solution temperature increase the transmittivity increases. Decrease in a diffusion transmittivity is caused by formation of the boundary diffusion layers reducing transfer of substance through boundary and fissile layers of a membrane. Increase in a diffusion transmittivity is caused by body height of ionic mobility and molecules of substance with solution temperature increase that leads to partial destruction of boundary diffusion layers at a membrane surface. Mathematical expressions are developed for theoretical calculation of coefficient of a diffusion transmittivity and numerical values of sizes of empirical coefficients are received. The developed mathematical expressions with good reliability describe the experimental data’s on a diffusion transmittivity. The obtained experimental and calculation data can be applied with big reliability in calculations of streams of substances through the semipermeable membranes and also in engineering calculation procedures and predictions of effectiveness of application of membranous processes to division, cleanings and concentratings of industrial and technological solutions. By results of experiments and design data’s curves which demonstrate influence of concentration on a diffusion transmittivity for all types of the studied ultrafiltrational polymeric membranes were constructed.
The paper examines the specific output stream and the rate of detention of a semi-permeable ultrafiltration membranes, UPM, UAM150, UAM200 in the separation process, waste starch and syrup production JSC., the company "Krakhmaloprodukt" low-pressure baromembrane method. As a result of the analysis of experimental data, the dependence of the retention factor of ultrafiltration membranes UPM-K, UAM150, UAM20 at different concentrations of the dissolved substance was obtained and analyzed. For the theoretical calculation of the process of ultrafiltration separation technology solutions of starch and syrup production modified mathematical expression for the factor of detention and the specific output stream and the numerical values of the empirical coefficients. Ultrafiltration for the separation of waste starch and syrup production the technological scheme of purification, separating the main elements of which was the pre-filter, biofilter, cascade ultrafiltration apparatus, centrifugal and plunger pumps, as well as the adsorption column.The application expediency of the selected apparatus with flat chambers lies in the simplicity of their production technology and in the self-selection possibility of optimum type membranes. It is possible in the presented apparatuses to usemembranes of different types and in the course of the evaluation experiment to establish to what extent they correspond to the most important technological parameters of the process, such as specific output flow, retention factor and resistance to pollution. It is noted that the specific output flow of ultrafiltration membranes decreases with the increase of the initial concentration of the dissolved substance, as the viscosity of the solution increases and its osmotic pressure increases, and the decrease in the retention factor of ultrafiltration membranes is caused by the formation of diffusion boundary layers on the active layer of membranes.
The relevance of the use and development of sweeteners is reflected in the article. The main requirements for sweeteners were given: the sweetness quality, color and odor absence, a pleasant taste, harmlessness, complete elimination from the body, good solubility in water, chemical resistance. Due to its beneficial properties, the sweetener obtained from stevia leaves is increasingly used. A method of obtaining stevia extract with subsequent drying is presented. The leaves and stems of the Stevia rebaudiana Bertoni plant were used for the experiment. The extract was obtained using water-alcohol extraction at a temperature of 85–87 ?С, a water module of 1.0: 4.5, and a duration of 115–118 min. using three rinsings, the water and alcohol extracts were combined. The extract filtered from suspended impurities on a deep filter was concentrated under a vacuum of 0.08 MPa at a temperature of 60 ° C to a content of 35%. The resulting concentrate was dried on an experimental spray dryer. The temperature of the dried particles did not exceed 60 ° С, and the drying process lasted 15–30 s. High-quality stevioside powder was obtained due to instant drying and low temperature of sprayed solution particles. Thus obtained sweetener from stevia does not need intermediate purification from ballast substances and does not require further modification to improve organoleptic properties - to enhance sweetness and reduce the residual bitter aftertaste characteristic of some natural glycosides. The authors believe that the resulting sweetener makes it possible to develop new products with dietary and therapeutic purposes.
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