Process configuration and product selection standard for new ultra-pure water machine
The ultra-pure water machine adopts pretreatment, reverse osmosis technology, ultra-purification treatment and post-treatment to remove the conductive medium in water almost completely, and removes the colloidal substances, gases and organic substances that are not dissociated in the water to a very low level. Water treatment equipment.
Laboratory ultrapure water machine
The laboratory ultra-pure water machine is roughly divided into four units: pretreatment, reverse osmosis, ultra-purification, and terminal ultrafiltration. The tap water first passes through the pretreatment unit to remove larger particles, suspended solids and some organic matter in the water. Then enter the reverse osmosis unit to remove the ionic substances and macromolecular substances (such as viruses, microorganisms, etc.) in the water. After purification and ultra-purification, the micro-ion remaining after membrane removal is purified and ultra-purified to reduce the ion content in the water to trace levels. Finally, through UV, ultrafiltration and other technologies to ensure that micro-organisms, organic matter and pyrogens in ultra-pure water meet the needs of various experimental applications.
Application field
1, electronics, electricity, electroplating, lighting appliances, laboratories, food, paper, daily chemicals, building materials, paint, batteries, laboratory, biological, pharmaceutical, petroleum, chemical, steel, glass and other fields.
2. Pure water for chemical process water, chemical agents, cosmetics, etc.
3, single crystal silicon, semiconductor wafer cutting manufacturing, semiconductor chips, semiconductor packaging, lead frame, integrated circuits, liquid crystal displays, conductive glass, picture tubes, circuit boards, optical communications, computer components, capacitors clean products and various components, etc. The production process uses pure water.
4, pure water equipment, reverse osmosis equipment, boiler softened water equipment, industrial softened water equipment, food industry softened water equipment, household water softener
Industrial pure water machine
The industrial pure water machine consists of three parts: pretreatment system, finishing system and post-processing system. After the raw water passes through the pretreatment system such as quartz sand unit, activated carbon unit and water softener unit, the content of suspended solids (particulate matter), colloid, organic matter, hardness and microorganisms in the water is greatly reduced to reduce the subsequent reverse osmosis and electric elimination. The processing load of the salt and other finishing systems prolongs the service life.
Technical principle
The ion exchange of an ultrapure water machine is a special solid adsorption process which is carried out in an electrolyte solution of an ion exchanger. A typical ion exchanger is a solid particulate material that is insoluble in water, i.e., an ion exchange resin. It can extract a certain cation or anion from the electrolyte solution, and exchanges another ion with the same charge symbol contained in its own equivalent amount and releases it into the solution. This is called ion exchange. Depending on the type of ion exchanged, the ion exchanger can be divided into two major categories: cation exchangers and anion exchangers.
Various types of water quality
1. Distilled Water
One of the most commonly used pure waters in laboratories, although inexpensive, is extremely energy intensive and costly and slow, and applications are gradually reduced. Distilled water removes most of the contaminants in tap water, but volatile impurities cannot be removed, such as carbon dioxide, ammonia, silica, and some organic matter. Fresh distilled water is sterile, but the bacteria are easy to reproduce after storage. In addition, the storage container is also very particular. If it is a non-inert substance, the ions and the shaped material of the container will precipitate to cause secondary pollution.
2, deionized water (Deionized Water)
Ion exchange resin is used to remove anions and cations from water, but there are still soluble organic substances in the water, which can contaminate the ion exchange column and reduce its efficiency. It can also cause bacterial growth after deionized water storage.
3. Reverse osmosis Water
The principle of the formation is that under the action of pressure, the water molecules become pure water through the reverse osmosis membrane, and the impurities in the water are intercepted and discharged by the reverse osmosis membrane. Reverse osmosis water overcomes many shortcomings of distilled water and deionized water. Reverse osmosis technology can effectively remove dissolved salts, colloids, bacteria, viruses, bacterial endotoxins and most organic substances in water, but reverse osmosis membranes produced by different manufacturers. It has a great influence on the quality of reverse osmosis water.
4, ultra-pure grade water (Ultra-pure grade water)
The standard is that the water resistivity is greater than 10 MΩ-cm. However, ultrapure water is not the same in terms of TOC, bacteria, endotoxin and other indicators. It should be determined according to the requirements of the experiment. For example, cell culture requires bacteria and endotoxin, while HPLC requires low TOC.
Process configuration standard
1. Pretreatment system → reverse osmosis system → intermediate water tank → coarse mixed bed → fine mixed bed → pure water tank → pure water pump → ultraviolet sterilizer → polishing mixed bed → precision filter → water object (≥18MΩ.CM) (traditional Process)
2. Pretreatment→Reverse Osmosis→Intermediate Water Tank→Water Pump→EDI Device→Purification Water Tank→Pure Water Pump→UV Sterilizer→Polishing Mixed Bed→0.2 or 0.5μm Precision Filter→Water Object (≥18MΩ.CM) (Latest Process)
3. Pretreatment → first-stage reverse osmosis → dosing machine (pH adjustment) → intermediate water tank → second-stage reverse osmosis (positive charge reverse osmosis membrane) → pure water tank → pure water pump → EDI device → ultraviolet sterilizer → 0.2 or 0.5μm precision filter → water object (≥17MΩ.CM) (latest process)
4. Pretreatment→Reverse Osmosis→Intermediate Water Tank→Water Pump→EDI Device→Pure Water Tank→Pure Water Pump→UV Sterilizer→0.2 or 0.5μm Precision Filter→Water Object (≥15MΩ.CM) (Latest Process)
5. Pretreatment system → reverse osmosis system → intermediate water tank → pure water pump → coarse mixed bed → fine mixed bed → ultraviolet sterilizer → precision filter → water object (≥15MΩ.CM) (traditional process)
product keeper
First of all, simply understand the laboratory ultra-pure water machine, the tap water is pre-treated through the precision filter element and the activated carbon filter element, filtering the sediment and other particulate matter and adsorbing the odor, so that the tap water becomes cleaner, and then the water is purified and desalted by the reverse osmosis device. The purified water is stored in the storage tank, and the water quality can reach the national three-level water standard, and the wastewater produced by the reverse osmosis device (also called "concentrated water") is discharged. The reverse osmosis pure water is subjected to deep desalting treatment through the purification column to obtain first-grade water or ultra-pure water. Finally, if the user has special requirements, ultraviolet sterilizing or microfiltration, ultrafiltration and the like are added after the ultrapure water to remove residual water. Bacteria, particles, heat sources, etc.
Precision filter element, activated carbon filter element, reverse osmosis membrane and purification column are all materials with relative life. The precision filter element and activated carbon filter element are actually the protection of reverse osmosis membrane. If they fail, the load of reverse osmosis membrane will be aggravated and the service life will be reduced. If the water is turned on, the quality of the pure water produced will decrease, which will increase the burden on the purification column, and the life of the purification column will be shortened. The end result is an increase in the cost of using ultrapure water machines. Therefore, in the use of laboratory ultra-pure water machines, there are the following aspects that need attention.
Activated carbon filter
The activated carbon filter is made of high-quality shell carbon and coal-based activated carbon, supplemented by food-grade binders. It is processed by special technology using high-tech technology. It integrates adsorption, filtration, interception and catalysis. Effectively remove organic matter, residual chlorine and other radioactive substances in water, and have the effect of discoloration and odor removal. It is an ideal new generation product in the liquid and air purification industry. Type: white head sintered activated carbon filter, black head with skeleton, sintered activated carbon filter, granular activated carbon filter. There is no intuitive change in the surface of the activated carbon filter. According to experience, it is generally saturated in a year or so and needs to be replaced.
Reverse osmosis membrane
Reverse osmosis membrane is an important part of ultrapure water machine. Its pore size is very small. Therefore, microscopic substances such as bacteria are often deposited on the surface during use. Generally, the pure water machine of each manufacturer has a backwash function. Wash off the contaminants. The water consumption can be washed 3-5 times within 10 liters/day. If it exceeds 10 liters, it should be washed several times. If it is not used for a long time (such as more than 1 month), it needs to be taken out and immersed in the disinfectant to avoid the breeding of bacteria. However, the process is troublesome. It is recommended that even if it is not used, it is often turned on with a small amount of water to allow the inside of the machine. Water forms a circulation, minimizing the deposition time of stagnant water. The life of the reverse osmosis membrane is 2-3 years, which is mainly determined by the amount of water used. Therefore, it is necessary to select the matching specifications when selecting.
Product selection standard
We do experiments every day, and the most exposed reagents are water, which usually runs through our entire experimental process. Perhaps because of the universality and availability of water, we often overlook the impact it has on experimental results. Therefore, the correct choice of a laboratory ultra-pure water machine can help researchers avoid many unnecessary troubles. However, there are many brands of ultra-pure water machines in the domestic market, the quality is uneven, and the price disparity is huge. This has caused great confusion to the purchasers who are interested in using ultra-pure water machines. I don’t know which brand to choose, the following combination The actual work experience to talk about how to choose an ultra-pure water machine that suits you. Before we talk about how to choose ultra-pure water machine, we first understand the difference between pure water and ultra-pure water and the current domestic laboratory ultra-pure water machine. Market conditions.
Pure water difference
Before choosing the right laboratory ultrapure water machine, we must have a good understanding of the following concepts: What is pure water? What is ultrapure water? What is the difference between the two?
Pure water, also known as pure water, refers to the seal made by the electrodialyzer method, the ion exchanger method, the reverse osmosis method, the distillation method and other appropriate processing methods, using water that meets the sanitary standard of drinking water as the raw water. In the container, without any additives, colorless and transparent, water that can be directly consumed. The space water and distilled water sold on the market are pure water.
Ultrapure water removes the conductive medium in the water almost completely on the basis of pure water, and removes the colloidal substances, gases and organic substances that are not dissociated in the water to a very low level of water. The resistivity is greater than 18 MΩ*cm, or close to the 18.25 MΩ*cm limit. Ultrapure water is difficult to achieve in general process. Two or more technologies of microfiltration technology, ultrafiltration technology, reverse osmosis technology, EDI technology and ion exchange technology can be designed through reasonable process and equipment selection. In order to produce ultrapure water, the resistivity can reach 18.20MΩ*cm.
The difference between pure water and ultrapure water exists in many aspects. Here are just a few of them, which are summarized as follows:
A, the conductivity is different, the conductivity of pure water is between 2-10us/cm, and the conductivity of ultrapure water is 0.056us/cm;
B. The degree of difficulty in manufacturing is different. The pure water used in the market is basically obtained by reverse osmosis, distillation, etc., and the ultrapure water is subjected to photo-oxidation technology, fine treatment and on the basis of pure water. A series of complicated purification techniques such as polishing treatment.
C, heavy metals, bacteria, particles and other indicators are also very different, pure water impurity content is ppm level, and ultra-pure water is ppb level, simply said that there is no impurity in ultra-pure water, close to the theoretical water.
D, the field of use is also different;
E. The requirements for the material of the conveying pipe are also different. The ultra-pure water requires stricter material for the conveying pipe than the pure water.
The ultrapure water equipment is a preparation device for pure water for laboratory inspection and quarantine. The laboratory ultra-pure water machine is suitable for laboratories of testing centers, research institutes, universities, hospitals and enterprises to provide the required analytical test water, reagent water, laboratory water and analytical instrument water. In inorganic and analytical chemistry experiments, depending on the task and requirements, the purity requirements for water are also different. Pure water is "pure water" and "ultra-pure water".
People generally confuse these two concepts in the process of purchasing ultrapure water equipment, which makes it difficult to select and increase the cost of material supply for no reason. Pay attention to the following points when purchasing ultrapure water equipment:
1. When purchasing ultra-pure water equipment, it is best to choose the type of water according to the nature of your enterprise and the purpose of the experiment, in order to purchase the model according to the previous sales experience;
2, the purchase of ultra-pure water equipment models reference indicators should follow the "high or low" principle;
3, the amount of water is generally calculated according to 8 hours a day, if the ultra-pure water equipment on the model water output is 15L / hour, then its daily water output should be 120L;
Folding ultra pure water machine brand
At present, the domestic ultra-pure water machine market has changed from a situation in the past to a "one big, one hundred schools of thought", domestic ultra-pure water machine manufacturers have made great progress, but the overall technical level is relatively low, truly capable There are still relatively few manufacturers of ultra-pure water. Many manufacturers regard pure water with a resistivity of 18.2 MΩ·cm as ultrapure water. In fact, this is a misunderstanding because many organic molecules, bacteria and particles do not exist in ionic form, so they will not be affected. When the resistivity is measured, the result is that when the resistivity reading is good, there may still be contamination of organic matter, bacteria, etc. in the water. Such water cannot be called ultrapure water, and true ultrapure water contains almost no impurities. Nowadays, the domestic ultra-pure water machine market is gradually prospering, and a large number of manufacturers are working hard to improve the technical level and open up a new world.
Water quality monitoring
In general, pure water is measured by electrical conductivity, and ultrapure water is measured by electrical resistivity. The conductivity is calculated as follows: X is the conductivity, F is the Faraday constant, Ci is the ion concentration, Zi is the charge number of the ion, Ui is the ion mobility, and the formula: X = FΣ CiZiUi theoretically, completely free of ions The ultrapure water has an electrical conductivity of 0.055 μS/cm at 25 °C. The resistance value is the reciprocal of the conductivity. Then R = 1 / X, 1 / 0.055 = 18.1818 is about 18.2 MΩ.cm.
In general, we cannot accurately measure the resistivity or conductivity of ultrapure water under off-line conditions. Because when ultrapure water is exposed to the external environment, it will be polluted by the external environment. The air in the laboratory contains a large amount of ions that can enter ultrapure water, which affects the quality of ultrapure water. In addition, the instruments used to measure conductivity (beakers, resistometers/probes) also carry ionic contaminants. As shown in the calculation formula for conductivity, any increase in ions affects the conductivity value because the type of conductivity ion is proportional to the charge it carries.
Conductivity and resistivity units
Conductivity and resistivity units
Ultrafiltration membrane
The ultrafiltration membrane material is a porous membrane with super "sieving" separation function. Its pore size is only a few nanometers to tens of nanometers, which means that there is only one hair strand of one hair! Applying appropriate pressure on one side of the membrane can screen out solute molecules larger than the pore size to separate molecular weights greater than 500 dols. Particles with a particle size greater than 2-20 nm.
The structure of the ultrafiltration membrane is symmetrical and asymmetrical.
The former is isotropic, has no cortex, and the pores in all directions are the same, belonging to deep filtration; the latter has a dense surface layer and a bottom layer mainly composed of finger structures, and the surface layer thickness is 0.1 micron or less. It has ordered micropores with a thickness of 200~250 microns, which belongs to surface filtration. Ultrafiltration membranes used in industry are generally asymmetric membranes. The membrane materials of ultrafiltration membrane mainly include cellulose and its derivatives, polycarbonate, polyvinyl chloride, polyvinylidene fluoride, polysulfone, polyacrylonitrile, polyamide, polysulfone amide, sulfonated polysulfone, cross-linked Polyvinyl alcohol, modified acrylic polymer, and the like.
Ultrafiltration membrane was one of the earliest developed polymer separation membranes. In the 1960s, ultrafiltration equipment was industrialized. Ultrafiltration membranes are widely used in industrial applications and have become one of the new chemical unit operations. It is used in separation, concentration, purification of biological products and food industry; it is also used in terminal treatment equipment in blood treatment, wastewater treatment and ultrapure water preparation. In China, the ultrafiltration membrane has been successfully used for the concentration and purification of Chinese herbal medicine. With the advancement of technology, ultrafiltration membranes will be improved and strengthened, and their contribution to human society will increase.
Application industry
The application scope of ultra-pure water machine involves hospitals, university research, quality inspection units, chemical plants, pharmaceutical factories, water quality monitoring centers, animal husbandry, water plants, disease control centers, seed monitoring stations, battery factories, LCD screen factories, precision circuit factories. , dust-free production and so on.
Petrochemical industry: such as chemical reaction cooling, chemical agents, fertilizers and precision chemicals, cosmetics manufacturing process using pure water ultra-pure water equipment industrial ultra-pure water equipment.
Electronics, semiconductor industry: the production of electronic industry consumption such as monocrystalline silicon semiconductor integrated circuit blocks, picture tubes, glass bulbs, liquid crystal display and other industrial pure water ultra-pure water machine.
Water for the pharmaceutical industry: pharmaceutical, preparation process water, medical hemodialysis, biochemical analysis, infusion, etc.
Boiler water disposal: oil, chemical, refining, thermal power generation, electric power, heat production, metallurgy, food, paper and other industries in the boiler, plant and mining enterprises high, medium and low pressure boiler water supply required softening water, demineralized pure water.
Beverage industry: drinking pure water, distilled water, natural water, mineral water, mineralized water, alcohol consumption, white wine blending with pure water, beer saccharification feed water and pure draft beer filtration.
Laboratory: Some high-end experiments have harsh requirements on experimental water quality, such as animal and plant cell culture, high performance liquid chromatography, mass spectrometry, plasma coupled spectroscopy, atomic fluorescence, gel analysis, cellular immunity, IVF, genetic experiments, and so on. These experiments not only require the resistivity of water quality, but also have high requirements for organic matter, particulate matter, bacteria and pyrogens in water quality.
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