In various industries, membrane separation and purification processes are becoming increasingly important: reverse osmosis, micro- and ultrafiltration, electrodialysis. These processes make it possible to create closed production cycles for water consumption.
Separation and purification of substances contribute to solving problems related to the need to improve the quality of chemical industry products (reducing the content of impurities), using raw materials with a low content of valuable compounds, and the need to protect the environment (reducing the discharge of industrial wastewater, wastewater treatment).
Returning valuable components of industrial wastewater to the production cycle allows not only to protect the environment from pollution, but also to increase the efficiency of various stages of industrial production and reduce the amount of raw materials consumed. Recycling of valuable components of wastewater from food and microbiological industries is an additional source of raw materials for the production of food and feed.
Currently, the quality of natural waters is deteriorating due to an increase in their salt content. To avoid degradation of natural waters, closed water circulation systems are needed at enterprises. The current ecological situation is such that without membrane processes it is impossible to preserve the vital qualities of water. However, for some technological stages of production, membrane processes do not yet provide a high effect, so their combination with traditional methods of purification and separation is required, taking into account the technical and economic indicators of water consumption.
The economic efficiency and competitiveness of membrane processes can be significantly increased with an integrated approach to the processing of process and mineralized waters, which provides for the return of not only the main component - water, but also other valuable substances - to the production cycle. To do this, not only the separation of impurities must be carried out, but also their separation, i.e., it is necessary to increase the selectivity of membranes and membrane processes. In many processes of chemical technology, when using acid and alkali, neutralization occurs, i.e., degradation of enormous quantities of these compounds, ultimately leading to the pollution of natural water sources.
Membrane purification and separation processes can be fundamental in the synthesis of chemical compounds, removal of substances from the reaction mixture, regulation of process conditions: pH, reagent concentration, etc. The membrane surface can have catalytic activity or redox properties.
Research on membrane processes is developing in several directions: the development of new membrane materials, models of transfer phenomena, methods for calculating membrane modules, and carrying out optimization calculations for various objects and production stages. The greatest effect is expected to come from research in the field of hydrodynamics and surface chemistry.
Membrane processes have been successfully used to separate mixtures of organic and inorganic substances. These processes differ primarily in their driving forces. Hydrostatic pressure difference - ultrafiltration and reverse osmosis (baromembrane processes); difference in electrical potential - electrodialysis, difference in concentration - dialysis. There are also “cross” membrane processes that use two or more driving forces: piezodialysis, electroosmosis, etc. This division of membrane processes is reflected in the material of the membranes used: semipermeable - for reverse osmosis, ultrafiltration - for ultrafiltration, ion exchange - for electrodialysis etc.
This traditionally established classification of membrane processes is based on their division into groups based on physical and chemical properties used to separate mixtures into components. However, this natural or natural classification to some extent restrains the development of membrane processes as a whole due to the drawing of sharp lines between individual processes.
Definition of membrane.
Currently, most researchers working in the field of membrane technology understand a membrane as the area separating two phases. In this regard, membranes can be gaseous, liquid, solid, or a combination of these three states. The concept of “area” in this definition is used instead of the usual concept of “surface boundary”. At the same time, the interphase boundaries of two immiscible liquids, gas and liquid, gas and solid, should not be considered membranes. Each researcher, as a rule, has his own idea of the membrane. In this context, it is difficult to give a precise and complete definition of a membrane covering all its aspects. However, it becomes easier to give such a definition if we limit ourselves to synthetic structures only. In its most general sense, a synthetic membrane serves as a boundary that separates two phases and limits the transfer of various substances from one phase to the other in a specific manner.
Membranes can consist of a variety of materials and have different structures. Membranes can be homogeneous or heterogeneous, symmetrical or asymmetrical in structure, can be “neutral”, conduct only negative or only positive charges, or both. Mass transfer across a membrane can be caused by diffusion or convective flow, which are caused by gradients of hydrostatic pressure, temperature, chemical or electrochemical potential. Many materials are actually membranes, such as protective coatings and packaging. All materials that act as membranes have one thing in common: they restrict the passage of various chemicals through the membrane in a strictly defined way.
Eduard Buchner was born on May 20, 1860 in Munich (Germany) into a family of hereditary scientists originating from Bavarian Swabia. His father, Ernst Buchner (1812-1872), was a professor of forensic medicine, organizer and editor of the Munich Medical Weekly. The heavy scientific organizational workload did not prevent him, however, from being married three times. From the third marriage to Frederica Martin, the daughter of a cashier, two sons were born - Hans in 1850 and Eduard, after the death of his father Hans, who later became a famous hygienist and epidemiologist, according to Eduard, “did the impossible for me to get an education.” Exceptional friendship, mutual support and scientific cooperation unite the brothers throughout their lives.
After passing the matriculation exams in 1877, at the Munich Real Gymnasium, Eduard served in the Field Artillery Regiment as a volunteer one-year student. “He was a soldier in body and soul,” K. Harries wrote about him. This was true both literally and figuratively - he was always a fighter, overcoming any difficulties in achieving his goal. However, the gift of a researcher very early subjugated all his hobbies. Having entered the chemical laboratory of the Higher Polytechnic School, Buchner completely devoted himself to the study of chemistry under the guidance of E. Erlenmeyer, but constrained financial circumstances forced him to soon interrupt his work and enter a canning factory. Later, the factory was relocated to Mainz, and Buchner left Munich, work at the factory did not remained without a trace for him, here he explored the opportunity to get acquainted with the area that later became the main work of his whole life - the chemistry of fermentation production.
Buchner was able to resume his research activities only in 1884, when he entered the laboratory of the famous A. Bayer at the University of Munich and at the same time the Institute of Plant Physiology, headed by K. Nägeli. Here, in the laboratory headed by Buchner’s brother, Hans, he conducted a study “On the influence of oxygen on fermentation”, as a result of the second, in contrast to L. Pasteur, he came to the conclusion that oxygen does not affect fermentation.
During these years, Buchner met G. Peschmann and T. Curtius. The latter, who soon became Buchner's closest friend and colleague, invited him for one semester to Erlanger, to the chemical laboratory, the head of which he became at the suggestion of O. Fischer. The deep influence of Curtius was reflected in the fact that it was from him that Buchner received his love and skills for the painstaking work of a researcher. In 1888 Buchner became a doctor, and in 1891 he took the position of privatdozent at the University of Munich. In 1893 Buchner. at the invitation of Curtius, he followed him to Kiel, where in 1895 he became a professor. A year later, Peschmann invited him to take up the vacant position of extraordinary professor at the University of Tübingen, where Buchner carried out and published in 1897 the work “Alcoholic fermentation without yeast cells.” The subsequent development of this topic at the Berlin Agricultural School, where in 1898 he was invited to the position of professor of general chemistry, quickly brought Buchner recognition in the scientific world. In 1905, he was awarded the J. Liebig gold medal, awarded by the Society of German Chemists. In 1907, Buchner was awarded the Nobel Prize "for biochemical research and for the discovery of cell-free fermentation."
Intense research activity, frequent travel, and a life rich in hobbies were apparently the reason why Buchner, only at the age of 40 in 1900, married Lotte Stahl, the daughter of a Tübingen mathematician. From this marriage he had two sons and a daughter.
Buchner lived in Berlin for 11 years. In 1909, in connection with the departure of Ladenburg, he was offered a chair in Breslau (now Wroclaw). In 1911, he became head of the department at the Chemical Institute of Würzburg, where, according to Harry, he “felt especially at home.” Buchner was a man of exceptionally lively and warm-hearted disposition. These character traits invariably attracted numerous and loyal friends to him and contributed to the creation of a joyful and happy environment in his family. A keen interest in politics (Buchner was an ardent supporter of Bismarck) was combined with a love of fine art. In his youth, an orthodox adherence to Catholicism, but at the age of 40, a completely conscious transition to Protestantism, a passionate interest in hunting and mountaineering (he climbed about a hundred mountain peaks!) - all this was imbued with a special love for the fight against difficulties, a penchant for adventure. Exceptional memory and vivid imagination, courage, cordiality - these are the distinctive features of Buchner, preserved in the memory of his friends and collaborators. When the First World War began, 54-year-old Captain Buchner was born on August 11, 1914. Joined the army. Already in December he was awarded the Iron Cross, and in January 1916 he was promoted to the rank of major. In February, Buchner was called from the front to Würzburg to continue his scientific and teaching activities, but in June 1917 he returned to the front. On August 11, in Romania (near Focsani), Buchner was mortally wounded. He died on August 12, 1917 and was buried there in the brotherly cemetery.
Buchner's scientific activity can be divided into two areas: research in the field of organic chemistry; development of a method of cell-free fermentation, study of the biochemistry of a number of fermentations and the enzyme complex of yeast cells.
The main theme of the first line of research carried out with Curtius was the study of reactions between diazoacetic acid esters and unsaturated compounds esters and esters of acetylene carboxylic acid, on the one hand, and with benzene and its homologues, on the other. If at the first stage of these studies the authors were able to isolate only secondary products of the interaction of esters, then later they were able to isolate in pure form the primary product, which contained the nitrogen of the diazoacetic ester - pyrazoline carboxylic acid ester.
The reason for the beginning of research into the biochemistry of fermentation was the observation of Hans Buchner, who in 1890 discovered that protein substances could be extracted from many bacteria by appropriate treatment. Injected under the skin of animals, it causes an inflammatory process, but serves as protection against infections. Confirmation is R. Koch's tuberculin, obtained by him by extracting bacterial mass.
In connection with the need to invent a method for preserving microbial cell extracts, among which, as Buchner showed in 1893, brewer's yeast juice turned out to be the most convenient, a method for obtaining sterile cell-free yeast juice was developed in detail. To preserve the juice from rotting, Hans Buchner suggested the usual sugar preservation. During his vacation in Tübingen, E. Buchner discovered typical signs of fermentation in a cell-free sugar mixture and immediately understood the enormous general biological significance of the discovered fact. Nothing escaped his attention. An inquisitive mind and scientific intuition suggested to him the opportunity to finally find out the truth in the deeply fundamental debate between Liebig and Pasteur about the reason behind such a complex process as fermentation.
Subsequent studies by Buchner and his colleagues led to the conclusion that it was possible to reproduce the fermentation of various sugars in the absence of a living organism using “the product of the transformation of the protein bodies of protoplasm, which is a chemical substance devoid of metabolism.” Bukhner called this substance “zimaza,” using P. Veshan’s term. Further work (in collaboration with J. Meisenheimer) also revealed the possibility of reproducing lactic and acetic acid fermentation using “lactic acid bacterial zymase” and “alcohol-oxidizing enzyme” isolated from bacterial cells.
Buchner's discovery caused a strong reaction in scientific and philosophical circles. It did not correspond to generally accepted ideas, according to which fermentation could only be the result of the vital activity of a full-fledged living organism. Buchner's research was criticized for his alleged methodological inaccuracies. In turn, Buchner’s theoretical conclusions were the subject of sharp criticism from neovitalists, who intensified their activity at the end of the 19th century. However, confidence in his rightness, courage and exceptional persistence in achieving his goal allowed Buchner to convincingly prove the impeccability and scientific significance of his discovery. It is no coincidence, therefore, that Buchner's research quickly received high praise, and his scientific authority was widely recognized. Even before being awarded the Nobel Prize in 1907, Buchner was unanimously elected chairman of the German Chemical Society in 1904. This was followed by his election as a corresponding member of the Academy of Sciences of Bologna. He was invited to Paris and Vienna to give a special course of lectures on the chemistry of fermentation. He entered the history of science as a researcher who, according to the head of the Nobel Committee on Chemistry G. Söderbaum, “drew a demarcation line between two different eras, indicating the direction towards the development of a new phase in the history of fermentation chemistry.”
LITERATURE
1. Les Prix Nobel en 1907. Stockholm, 1908.
2. S. Harries. Chem. Ztg., 41, 753 (1917).
3. S. Harries. Ber. Dtsch. Ges., 50, 1843 (1918).
4. Dtsch. biograph. Jahrb. 1917-1920, Berlin - Leipzig, 1928.
, Kingdom of Bavaria
During World War I, Buchner served in a field hospital in Romania with the rank of major. He was wounded on 3 August 1917 and died from these wounds nine days later in Munich at the age of 57.
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Excerpt characterizing Buchner, Eduard
– Dieu, quelle virulente sortie [Oh! what a cruel attack!] - answered, not at all embarrassed by such a meeting, the prince who entered, in an embroidered court uniform, in stockings, shoes, with stars, with a bright expression on his flat face. He spoke in that refined French language, in which our grandfathers not only spoke, but also thought, and with those quiet, patronizing intonations that are characteristic of a significant person who has grown old in the world and at court. He walked up to Anna Pavlovna, kissed her hand, offering her his perfumed and shining bald head, and sat down calmly on the sofa.– Avant tout dites moi, comment vous allez, chere amie? [First of all, tell me, how is your health?] Reassure your friend,” he said, without changing his voice and in a tone in which, due to decency and sympathy, indifference and even mockery shone through.
– How can you be healthy... when you suffer morally? Is it possible to remain calm in our time when a person has feelings? - said Anna Pavlovna. – You’re with me all evening, I hope?
– What about the holiday of the English envoy? It's Wednesday. “I need to show myself there,” said the prince. “My daughter will pick me up and take me.”
– I thought that the current holiday was cancelled. Je vous avoue que toutes ces fetes et tous ces feux d "artifice commencent a devenir insipides. [I confess, all these holidays and fireworks are becoming unbearable.]
“If they knew that you wanted this, the holiday would be cancelled,” said the prince, out of habit, like a wound-up clock, saying things that he did not want to be believed.
- Ne me tourmentez pas. Eh bien, qu"a t on decide par rapport a la depeche de Novosiizoff? Vous savez tout. [Don’t torment me. Well, what did you decide on the occasion of Novosiltsov’s dispatch? You know everything.]
- How can I tell you? - said the prince in a cold, bored tone. - Qu "a t on decide? On a decide que Buonaparte a brule ses vaisseaux, et je crois que nous sommes en train de bruler les notres. [What did they decide? They decided that Bonaparte burned his ships; and we too, it seems, are ready to burn ours.] - Prince Vasily always spoke lazily, like an actor speaking the role of an old play. Anna Pavlovna Sherer, on the contrary, despite her forty years, was full of animation and impulses.
Thanks to the help of his brother Hans, B. was able to resume his studies in 1884. Soon after, he received a three-year scholarship. He studied chemistry with Adolf von Baeyer at the University of Munich and botany with Karl von Nägeli at the Institute of Botany. The scientist’s brother, Hans Buchner, who later became a famous specialist in hygiene and bacteriology, worked at this institute. B. began research into the process of alcoholic fermentation under his leadership. In 1885, he published his first article on the effect of oxygen on the fermentation process. The experiments carried out by B. refuted the prevailing point of view at that time, which was also held by Louis Pasteur, that fermentation cannot take place in the presence of oxygen.
In 1888, B. received his doctorate, and two years later, after a short period spent in Erlangen, he became Bayer's assistant. In 1891, B. was appointed privatdozent (freelance teacher) at the University of Munich. With private donations provided by Bayer, B. founded a small laboratory, where he continued research in the field of fermentation chemistry. In 1893 he left Munich and headed the section of analytical chemistry at the University of Kiel, and in 1895 he became a professor at this university. The following year, B. taught analytical chemistry and pharmacology at the University of Tübingen. In 1898, he was elected professor of general chemistry at the Higher Agricultural School in Berlin and appointed director of the Institute for Industrial Application of Fermentation Processes.
In 1893, when B. began the search for active substances that promote fermentation, two competing theories of fermentation prevailed. According to the mechanistic theory, yeast, by constantly decomposing into a liquid state, creates a chemical stress that causes sugar molecules to decompose. In accordance with this point of view, alcoholic fermentation was, although complex, but, in general, a common chemical reaction. This theory was objected to by the vitalists, who, like Louis Pasteur, believed that living cells contained a certain vital substance that was “responsible” for fermentation. In their opinion, without some “vital”, although as yet undiscovered, component in living cells, chemical substances alone could not cause the fermentation process. Although proponents of the mechanistic theory have shown that substances found in living cells can be synthesized, no one has yet been able to isolate the substance that promotes fermentation or induce this process in non-living substances.
Encouraged by his brother, B. decided to find the active substance by obtaining pure samples of the internal fluid of yeast cells. Using the method proposed by his brother's assistant Martin Gan, B. crushed yeast in a mortar along with sand and earth, thus avoiding the destructive effects of high temperatures and without using solvents that distorted the results obtained by his predecessors. The cellular substance squeezed out in gauze under pressure released liquid. B. suggested that this liquid is capable of causing fermentation. Later, however, when he and Hahn tried to preserve this liquid by adding a concentrated solution of sucrose, carbon dioxide was released. This was astonishing, for even though the yeast cells were dead, it was clear that something in the liquid they secreted had caused the fermentation. B. hypothesized that the active substance is an enzyme, or enzyme, which he called zymase. His discovery meant that fermentation occurs as a result of the chemical activity of the enzyme both inside and outside the yeast cell, and not under the influence of the so-called vital force.
B.’s work, “On Alcoholic Fermentation without Yeast Cells,” published in 1897, caused controversy among his fellow scientists, and in subsequent years, B. spent a lot of time collecting facts to support his theories. In 1902, he published another 15-page article in which he explained and defended this work, as well as several others, where he outlined the results of his research on the chemical effect of yeast on milk sugar.
In 1907, B. was awarded the Nobel Prize in Chemistry “for his research work in biological chemistry and the discovery of extracellular fermentation.” Due to the death of King Oscar II of Sweden, the award ceremony was postponed, but in a written presentation on behalf of the Royal Swedish Academy of Sciences, K. A. H. Mörner summarized the conflicting views on the fermentation process that B.'s research put an end to. “As long as fermentation was considered as an expression of life,” wrote Merner, “there was little hope of being able to penetrate more deeply into the problem of the course of this process.” That is why “a sensation occurred when B. was able to show that alcoholic fermentation can be caused by juice isolated from yeast cells that do not contain living cells... Areas inaccessible until that time now became the object of chemical research, and new ones opened up for chemical science, previously unseen prospects.”
In his Nobel lecture, B. described his discoveries and paid tribute to his predecessors and colleagues. “We are increasingly convinced that plant and animal cells are like chemical factories,” he said, “where different products are produced in different workshops. Enzymes in them act as controllers. Our knowledge of these most important parts of living matter is constantly increasing. And although we may still have a long way to go, we are getting closer to it step by step.”
Two years after receiving the Nobel Prize, B. went to work at the university in Breslau (now Wroclaw, Poland), where he became head of the department of physiological chemistry. His last academic appointment was to the University of Würzburg in 1911. With the outbreak of the First World War, B. voluntarily entered military service. In 1917, while working as a medical major in a field hospital in Romania, he was wounded by shrapnel and died in Focsani on August 13, outliving his wife Lota (Stahl) Buchner, the daughter of a mathematician from Tübingen. From this marriage, concluded in 1900, they had two sons and a daughter.
Edward Buchner(1860-1917) began research into the process of alcoholic fermentation under the guidance of his scientist brother, Hans Buchner.
In 1885 he published his the first article on the effect of oxygen on the fermentation process. Done E. Bukhner experiments refuted the prevailing point of view at that time, which was held by Louis Pasteur that fermentation cannot take place in the presence of oxygen.
In 1893, when Edward Buchner began the search for active substances that promote fermentation, two competing theories of fermentation prevailed. According to mechanistic theory, yeast, constantly decomposing into a liquid state, creates a chemical stress that causes the sugar molecules to decompose. In accordance with this point of view, alcoholic fermentation was, although complex, but, in general, a common chemical reaction. This theory was objected to by vitalists who, like Louis Pasteur, believed that living cells contained a certain vital substance, which was “responsible” for fermentation. In their opinion, without some “vital”, although as yet undiscovered, component in living cells, chemical substances alone could not cause the fermentation process. Although proponents of the mechanistic theory have shown that substances found in living cells can be synthesized, no one has yet been able to isolate the substance that promotes fermentation or induce this process in non-living substances.
Encouraged by his brother, Edward Buchner decided to find the active substance by obtaining pure samples of the internal fluid of yeast cells. Using the method suggested by his brother's assistant Martin Gan, he crushed yeast in a mortar along with sand and earth, thus avoiding the destructive effects of high temperatures and without using solvents that distorted the results obtained by his predecessors. The cellular substance squeezed out in gauze under pressure released liquid. He suggested that this liquid could cause fermentation. Later, however, when he and his assistant Martin Gan I tried to preserve this liquid by adding a concentrated solution of sucrose, carbon dioxide was released. This was astonishing, for even though the yeast cells were dead, it was clear that something in the fluid they secreted had caused 
fermentation. Edward Buchner hypothesized that the active substance was an enzyme, or enzyme, which he called in winter. His discovery meant that fermentation occurs as a result of the chemical activity of the enzyme both inside and outside the yeast cell, and not under the influence of the so-called vital force.
Published in 1897, the work “ About alcoholic fermentation without the participation of yeast cells"caused controversy among his fellow scientists, and in subsequent years Edward Buchner spent a lot of time collecting facts to support his theory.
In 1902, he published another 15-page article in which he explained and defended this work, as well as several others, where he outlined the results of his research on the chemical effect of yeast on milk sugar.
In 1907 Edward Buchner was awarded Nobel Prize in Chemistry"for his research work in biological chemistry and his discovery of extracellular fermentation."
Due to the death of King Oscar II of Sweden, the award ceremony was postponed, however, in a written submission on behalf of the Royal Swedish Academy of Sciences, K. A. X. Merner summarized the conflicting views on the fermentation process, which were put to an end by the Buchner research. “As long as fermentation was considered an expression of life,” wrote Merner“There was little hope of being able to penetrate more deeply into the problem of how this process is proceeding.” That's why "there was a sensation when Buchner it was possible to show that alcoholic fermentation can be caused by juice isolated from yeast cells that do not contain living cells... Areas inaccessible until that time have now become the object of chemical research, and new, previously unprecedented prospects have opened up for chemical science.”
In the Nobel lecture Edward Buchner described his discoveries and paid tribute to his predecessors and colleagues. “We are increasingly convinced that plant and animal cells are like chemical factories,” he said, “where different products are produced in different workshops. Enzymes in them act as controllers. Our knowledge of these most important parts of living matter is constantly increasing. And although we may still have a long way to go, we are getting closer to it step by step.”
Further development of the experiments of the Buchner brothers led to the study of the fermentation process by an English chemist Arthur Garden.
Some scientists still believed that fermentation resulted from the action of a mysterious "vital force" on the living cell, but by 1904 A. Gardena It became obvious that fermentation is a set of chemical processes. To confirm his hypothesis, he prepared a zymase preparation and filtered it under high pressure through porous porcelain impregnated with gelatin. He discovered that the enzyme zymase consists of two components, one of which passes through such a filter, and the other does not. Arthur Garden also found that fermentation stopped when he removed any component from the yeast extract. This was the first evidence that one enzyme component required the presence of a second to function effectively. He left the name “zymase” for one component, and began to call the other component (or coenzyme) cosimase. Subsequently, he discovered that zymase is a protein, while cosimase is not a protein (a substance of non-protein nature).
In 1905 Arthur Garden made his second fundamental discovery: the fermentation process requires the presence of phosphate, consisting of one phosphorus atom and four oxygen atoms. He noted that the rate of breakdown of the sugar molecule and the formation of carbon dioxide and alcohol slowly decreases over time. However, when he added phosphate to the solution, fermentation activity increased dramatically. Based on these observations, Garden concluded that phosphate molecules bind to sugar molecules, creating the conditions for enzymatic induction of fermentation. Moreover, he discovered that phosphate, separated from the reaction products, remains free as a result of a complex chain of transformations.
In 1929 Arthur Garden together with Hans von Euler-Helpin was awarded Nobel Prize in Chemistry « for his research into the fermentation of sugar and fermentation enzymes."