New technology was developed for molding of membranes for ultrafiltration from and the conditions of their fabrication were optimized. It was shown that the method of spontaneous phase separation on a calender allows regulating the structure of the membranes.The problems related to the most complete use of the constituent parts of milk have been partially solved by using the membrane method of ultrafiltration.New technology for dry-wet molding of membranes from cellulose diacetate (CDA) solutions in acetone, including spontaneous gelation in the first stage and prolonged completion of constructing the structure of the gel (pore structure) in the second stage was proposed.Spontaneous formation of the gel structure was conducted on the heated metal roller of a vertical calender. The temperature was varied within the limits of (35-45)__. 1 ~ and the rate of rotation of the calender roller was varied from 25 to 100 rpm. The rate of evaporation of the solvent increased with an increase in the temperature and roller rotation rate, which accelerated phase separation.Films (0.005-1.250)_+0.002 mm thick and 0.5-0.6 m wide were fabricated. The thickness and porosity of the films were varied by altering the concentration of the starting CDA acetone solution (7, 10, 15, 20 wt. % CDA), the volume of the solution applied to the calender roller, and the gap between rollers.The duration of the stage of dry molding (intermediate) conducted on the calender was 2-3 min. The stage of modification of the films in aqueous medium for 12 h at room temperature was then followed. Back diffusion of acetone and water occurred on contact of the film with the aqueous medium. The maximum degree of swelling was approximately 25%, so that membranes modified with water were used for the subsequent studies.The membranes obtained were used for ultrafiltration of curd whey to concentrate it.

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Addition of ethyl alcohol in the amount of 5 to 25 wt. % significantly reduces the viscosity of secondary cellulose acetate (SCA)acetonewater spinning solutions. The effective viscosity of the spinning solutions decreases significantly when the shear stress changes. SCA membranes made from solutions with lower viscosity have higher permeability both for water and for cheese whey. The data obtained can be used to vary the performance properties of ultrafiltration membranes within wide limits.Membranae processes for separating liquid mixtures have already demonstrated their high efficiency in different sectors of industry and agriculture. The use of membrane technology not only allows solving manufacturing problems but also preventing problems related to environmental pollution. However, the problems of searching for and selecting membranes and membrane materials that satisfy the specific requirements for solving a certain separation problem and identifying the basic factors that affect separation efficiency still restrict the industrial use of membrane technology [1]. Membrane processes are also widely used for ultrafiltration of milk and cheese whey [2]. We propose a new formula for fabricating ultrafiltration membranes from secondary cellulose acetate (SCA) in the present article.We propose adding ethyl alcohol to the SCAacetone and SCAacetonewater spinning solutions for fabrication of ultrafiltration membranes which we previously developed [3] in order to increase the homogeneity of the solution and correspondingly form a more homogeneous structure of the membranes and decrease their thickness nonuniformity.Solutions of SCA contain microgel particles (MGP), fragments of cellulose and hemicellulose (xylan, mannan, etc.) which did not undergo acetylation during etherification. These crystalline microblocks are joined in one aggregate by H bonds of different energy levels. Such aggregates can decompose into smaller fragments (disaggregate) up to the elementary fragment 0.02 μm in size under the effect of protophilic substances, and the solution becomes more homogeneous. The presence of MGP in solutions of cellulose derivatives causes process difficulties in manufacturing fibres, films, and membranes: clogging of filters, perturbation of filtration stability, appearance of thickness nonuniformity of film materials. Disaggregation is usually accompanied by a decrease in the effective radius and an increase in the number of MGP per unit of volume, which can reduce the viscosity of the system. Degradation of the supramolecular structure of the polymer decreases the viscosity of the polymer solution. With an increase in shear strain, the viscosity of the polymer solution usually decreases due to gradual breakdown of the three-dimensional network of hydrogen bonds because of destruction of the structure of the aqueous environment of the macromolecules, a decrease in hydrophobic hydration and intermolecular interaction, and unfolding of the polymer chain under the effect of hydrodynamic flow and the reciprocal orientatio...

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Studies showed that industrial PA membranes can be used for comprehensive treatment of whey containing substances of value to the food industry and allow separating 80% of the protein components in it. PA membranes have ion-exchange properties that allow separating from 20 to 40% of salt cations and anions from the whey and using them in production of food products.Secondary dairy stock (whey and buttermilk) frequently enter the wastewaters of industrial enterprises together with industrial waters and other production wastes. In pouring secondary dairy stock in the sewage system, we not only pollute the environment, but we also lose the additional commercial product that can be made from it.An analysis of the experience of the leading companies in the sector shows that as a function of the product volumes and lines pressed from whey and buttermilk, the additional profit would be 15-35% of the profit obtained from the basic product. It is thus not possible to underestimate the value of secondary dairy stock as product and raw material whose processing is unusually promising, economically advantageous, and environmentally necessary.Membrane methods, ultrafiltration in particular, are the most promising for processing secondary dairy stock. Despite the unconditional promise of membrane methods, they are not sufficiently utilized in industry due to the low output of membrane equipment.Increasing the specific separating surface per unit of working volume of the equipment has been successfully solved by using hollow fibres with semipermeable walls as membranes [1]. We used semipermeable polyamide (PA) membranes in the form of hollow fibres for separating whey. Proteins and mineral salt ions were separated from whey with PA membranes and the performance characteristics of the membranes were determined the permeability for water and whey, selectivity for protein, and ability to retain mineral salt ions.Whey obtained as the usual product of the dairy industry is a valuable protein-carbohydrate raw material. It basically contains protein nitrogenous compounds, organic acids, mineral salts, and a small amount of carbohydrates, vitamins, lipids, enzymes, and trace elements. Whey can be fractionated by ultrafiltration and food additives with the required composition and properties can be obtained. Ultrafiltration is widely used for production of protein concentrate from whey, which is the most valuable of the existing food proteins.Industrial semipermeable VPU-15-PA membranes made of an aromatic polyamide were used for the first time in the study. Ultrafiltration was conducted on a laboratory setup consisting of a nitrogen tank, a manometer, intermediate and receiving tanks, and ultrafiltration module filled with membranes.Ultrafiltration was conducted under 0.2 MPa pressure and 1.5 liters of product was investigated per cycle. The permeability and selectivity of the PA membranes were determined. The permeability is the amount of filtrate obtained per unit of time per unit of working membrane surface. To determine the permeab...