Reverse osmosis ultrapure water machine
Release date: November 27, 2019 10:55:05
1. Preparation principle of ultrapure water
Reverse osmosis ultrapure water machine It is usually composed of raw water pretreatment system, reverse osmosis purification system and ultra purification post-treatment system. The purpose of pretreatment is to make raw water meet the requirements of reverse osmosis membrane separation module, and ensure the stable operation of reverse osmosis purification system. Reverse osmosis membrane system is the most economical and efficient purification method to remove more than 98% ions, organic matters and 100% microorganisms (theoretically) in raw water. In order to meet the final water quality requirements of different uses, the ultra purification post-treatment system further removes the impurities such as micro ions and organic matters in reverse osmosis pure water through a variety of integrated technologies.
2. Raw water pretreatment system
The pretreatment system of laboratory reverse osmosis ultrapure water machine usually consists of polypropylene fiber (PP) filter and activated carbon (AC) filter. For raw water with high hardness, softened resin filter should be installed. PP filter core can effectively remove more than 5 μ m mechanical particles impurities, rust and large colloidal substances and other pollutants in raw water, and protect the follow-up filter. Its characteristics are large pollution capacity and low price. AC activated carbon filter core can effectively absorb residual chlorine in raw water, some organic matters and colloids, and protect polyamide reverse osmosis composite membrane from residual chlorine oxidation. The softened resin can remove most of the calcium and magnesium ions in raw water, prevent the subsequent RO membrane surface scaling and blocking, and improve the water recovery rate.
3. Reverse osmosis purification system
Reverse osmosis (RO) is a high-tech membrane separation technology driven by pressure difference. It has the characteristics of high primary separation, no phase change, simple and efficient. The "pore size" of reverse osmosis membrane is as small as nanometer (1nm = 10-9m), and no "filtering" pore can be seen under SEM. Under the operating pressure higher than the osmotic pressure of raw water, water molecules can reverse osmosis through ro semi permeable membrane to produce pure water, and a large number of inorganic ions, organic matters, colloids, microorganisms and pyrogen in raw water are intercepted by RO membrane.
Generally, when the conductivity of raw water is less than 200 μ s / cm, the conductivity of primary RO pure water is less than or equal to 5 μ s / cm, which is in line with the level III water standard of the laboratory. For areas with high conductivity of raw water, in order to save the cost of ion exchange resin replacement in the subsequent mixed bed and improve the quality of pure water, customers can consider choosing a two-stage reverse osmosis purification system. The conductivity of secondary RO pure water is about 1 ~ 5 μ s / cm, which is related to the quality of raw water.
4. Ultra purification post-processing system
(1) mixed bed ion exchange purification column
The mixed bed ion exchange purification column is composed of anion exchange resin and cation exchange resin in proportion. Cation exchange resin uses its H + exchange to remove cations in water, anion exchange resin uses its OH - exchange to remove anions in water. H + and oh - exchanged in mixed bed resin combine to form H2O. Therefore, mixed bed ion exchange purification column can be used to deeply remove the remaining trace ions in RO pure water. Small and medium-sized ion exchange column is usually used in laboratory. The ion exchange purification column of yongjieda mixed bed uses imported nuclear grade mixed bed resin, and its water and electricity resistance can reach 18.2m Ω· cm.
(2) EDI device
Continuous electrodeionization (EDI) is a process in which anion and cation in water are adsorbed by mixed bed ion exchange resin, and these adsorbed ions are continuously removed through anion exchange membrane under the action of DC voltage. This new technology can replace the traditional ion exchange (DI) to produce ultrapure water of more than 10 m Ω· cm. The biggest advantage of EDI deep desalting is that it can operate stably for a long time without the need for acid-base regeneration of anion and anion resin. It is very suitable for the central preparation system of ultra pure water with a water yield of more than 100L / h. The water quality is stable, and the operation cost will be greatly reduced, and the TOC will be lower and more stable. The water resistivity of yongjieda EDI unit is about 15 ~ 18m Ω· cm.
(3) pyrogen removal ultrafiltration membrane
Ultrafiltration has been widely used in modern pharmaceutical industry. The pore size of ultrafiltration (UF) membrane is between reverse osmosis and microfiltration (about 0.01-0.1 μ m), which is usually expressed by the minimum molecular weight. Yongjieda pyrogen removal ultrafiltration membrane adopts polysulfone membrane with a molecular weight of 5000 Dalton, which can completely remove pyrogen (the minimum molecular weight is usually greater than 7000) and various microorganisms in water.
(4) ultraviolet germicidal lamp and TOC ultraviolet digester
Ultraviolet germicidal lamp is a safe and effective sterilization method for air and water because it can effectively destroy DNA molecules of microorganisms and form TT dimer without reproduction. TOC UV digester uses a dual wavelength UV lamp which can produce 185nm / 254nm at the same time. The 185nm ultraviolet light can produce ozone in the air to sterilize and deodorize, and hydrogen oxygen free radicals will be produced in water, which can rapidly oxidize trace organic matter in pure water to CO2, so as to achieve the goal of TOC removal.
(5) terminal filter
The filter can completely remove bacteria, spores and fungi. The terminal filters are hollow fiber type, PP barrel filter, bag filter, needle type filter, etc., and the membrane materials are polypropylene, nylon, polyvinylidene fluoride, etc.
5. Application of ultrapure water machine in laboratory
HPLC, TOC analysis, atomic absorption spectrometry, ion chromatography, mass spectrometry, determination of trace metals, preparation of dissolution for identification, microbiological analysis, tissue culture, sample dilution, washing with glassware for identification, application scope of TCEP and TCEI series, DNA sequencing, PCR and electrophoresis, antibody preparation in tube culture, etc. General qualitative analysis, urine analysis, tissue examination, parasite inspection, glass ware cleaning: laboratory analysis, microbial inspection; analysis water, flushing water, physical and chemical analysis, high-precision instrument cleaning; blood and serum inspection, mass spectrometry analysis, atomic absorption, etc.; AA, ICP cell culture, gas chromatography analysis, tissue culture medium Water for preparation, cell culture in low wavelength HPLC, TOC, IC, GC / MS, IVF, amino acid analysis, molecular biology experiment, PCR, gene research and cell culture.