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:) Membrane separation is a new separation technology that appeared in the early 20th century and emerged rapidly after the 1960s. Membrane separation technology has the functions of separation, concentration, purification and refining, as well as high efficiency, energy saving, environmental protection, molecular-level filtration and simple filtration process, easy control. Therefore, it has been widely used in food, medicine, biology, environmental protection, chemical industry, metallurgy, energy, petroleum, water treatment, electronics, bionics and other fields. It has produced huge economic and social benefits and has become one of the most important means in today's separation science. Membrane is a material with selective separation function. The process of using the selective separation of membranes to separate, purify and concentrate different components of the feed liquid is called membrane separation. It differs from traditional filtration in that the membrane can separate within the molecular range, and this process is a physical process that does not require phase changes or the addition of additives. The pore size of the membrane is generally micron level. According to the difference in pore size (or molecular weight cutoff), the membrane can be divided into microfiltration membrane, ultrafiltration membrane, nanofiltration membrane and reverse osmosis membrane. According to the different materials, it can be divided into inorganic membrane and organic membrane. Inorganic membranes mainly only have microfiltration level membranes, mainly ceramic membranes and metal membranes. Organic membranes are made of polymer materials, such as cellulose acetate, aromatic polyamide, polyethersulfone, polyfluoropolymer, etc. Advantages of membrane separation: Very little loss of active ingredients at room temperature, especially suitable for the separation and concentration of heat-sensitive substances, such as antibiotics and other medicines, juices, enzymes, and proteins. No phase change to maintain the original flavor, extremely low energy consumption, and its cost is about 1/3-1/8 of evaporation concentration or freeze concentration. ·Typical physical separation process without chemical changes, without chemical reagents and additives, and the product is not contaminated. ·Good selectivity can separate substances at the molecular level, with excellent performance that cannot be replaced by universal filter materials. ·Strong adaptability. The processing scale can be large or small, and can be carried out continuously or intermittently. The process is simple, easy to operate, and easy to automate. Development history and current situation of membrane separation technology·Development history Membranes are widely found in nature, especially in living organisms, but the historical process from our human understanding, utilization, and simulation to artificial synthesis is long and tortuous. The development of membrane science and technology in my country began with the study of ion exchange membranes in 1958. Entered the pioneering stage in the 1960s. The exploration of reverse osmosis began in 1965, and the national seawater desalination campaign began in 1967. * * Promoted the development of membrane technology in my country. Entered the development stage in the 1970s. During this period, various membranes and components such as microfiltration, electrodialysis, reverse osmosis and ultrafiltration were successively researched and developed. In the 1980s, they entered the stage of promotion and application. The 1980s was another stage of development of gas separation and other new membranes. With the development of membrane science and technology in my country, corresponding academic and technical groups have also been established one after another. Their establishment plays a decisive role in standardizing the standards of the membrane industry and promoting the development of the membrane industry. Over the past half century, membrane separation has completed the transformation from laboratory to large-scale industrial application, becoming a new separation technology with high efficiency and energy saving. Since 1925, a new membrane process has been applied in industry almost every decade. Due to the superior performance of membrane separation technology itself, the membrane process has now received widespread attention from countries around the world. Today, with energy shortages, resource shortages, and ecological environment deterioration, the industrial and scientific circles regard the membrane process as an extremely important new technology in the transformation of industrial technology in the 21st century. Some experts have pointed out: Whoever masters membrane technology will master the future of the chemical industry. Since the 1980s, my country's membrane technology has entered the application stage, which is also the development stage of new membrane processes. During this period, membrane technology has been developed and applied on a large scale in the fields of food processing, seawater desalination, pure water, ultrapure water preparation, medicine, biology, environmental protection and other fields. And, during this period, * * Key science and technology projects and natural science funds also have membrane topics. Currently, this emerging industry with huge potential is booming * * Challenging the market has brought significant economic, social and environmental benefits to many companies. Commonly used membrane separation processes · Microfiltration In view of the separation characteristics of microporous filter membranes, the application scope of microporous filter membranes is mainly to intercept particles, bacteria and other pollutants from the gas phase and liquid phase to achieve the purpose of purification, separation, and concentration. The specific areas involved mainly include: Pharmaceutical industry, food industry (gelatin, wine, liquor, juice, milk, etc.), high-purity water, urban sewage, industrial wastewater, drinking water, biotechnology, biological fermentation, etc. ·Ultrafiltration Early industrial ultrafiltration was used in wastewater and sewage treatment. Over the past thirty years, with the development of ultrafiltration technology, ultrafiltration technology has now been involved in many fields such as food processing, beverage industry, pharmaceutical industry, biological preparations, traditional Chinese medicine preparations, clinical medicine, printing and dyeing wastewater, food industry wastewater treatment, resource recovery, environmental engineering, etc. ·The main application areas of nanofiltration involve: Food industry, deep processing of plants, beverage industry, deep processing of agricultural products, biomedicine, biological fermentation, fine chemicals, environmental protection industry... Due to the advanced, efficient and energy-saving characteristics of reverse osmosis separation technology, reverse osmosis has been widely used in various sectors of the national economy. It is mainly used in water treatment and concentration of heat-sensitive substances. The main application areas include the following: Food industry, milk industry, beverage industry, deep processing of plants (agricultural products), biomedicine, biological fermentation, preparation of drinking water, pure water, ultrapure water, seawater, brackish water desalination, electricity, electronics, semiconductor industrial water, pharmaceutical industry process water, preparation water, water for injection, sterile non-pyrogenic pure water, food and beverage industry, chemical and other industrial process water, boiler water, washing water and cooling water. Others In addition to the above four commonly used membrane separation processes, there are also dialysis, controlled release, membrane sensors, membrane gas separation, etc.