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Filter paper filter difference

Time:2018-04-24 19:33:55 Source: TianJinSheng

Quantitative filter paper
In the manufacturing process of quantitative filter paper, the pulp is treated with hydrochloric acid and hydrofluoric acid and washed with distilled water to remove most of the impurities in the paper fiber. Therefore, the residual ash content after ignition is small, and there is little impact on the analysis results. It is suitable for Precision quantitative analysis. The amount of ash produced after ashing does not exceed 0.0009%.
The current domestic production of quantitative analysis of filter paper, divided into three types of fast, medium and slow, in the filter box with leucorrhea (fast), blue band (medium speed), red band (slow) as a sign of classification. The shape of the filter paper has two kinds of circles and squares. The specifications of the circular fixed paper are divided into several types according to the diameter: D7cm, D9cm, D11cm, D12.5cm, D15cm and D18cm. Square quantitative filter paper 60cm × 60cm and 30cm × 30cm.
Quantitative filter paper is mainly used for ashing weighing analysis after filtration, that is, gravimetric analysis test and corresponding analysis test in quantitative chemical analysis. The weight of ash after each filter paper is a fixed value; qualitative filter paper is used for general Filtration, qualitative chemical analysis and corresponding filtration separation. The difference between quantitative filter paper and qualitative filter paper mainly lies in the amount of ash produced after ashing: qualitative filter paper does not exceed 0.13%, and quantitative filter paper does not exceed 0.0009%.
Ashless filter paper It is a quantitative filter paper with an ash content of less than 0.1 mg. This weight is negligible on analytical balances. Note that both the concept of quantitative filter paper and qualitative filter paper are unique to cellulose filter paper and do not apply to other types of filter paper such as glass microfiber filter paper. Filter paper aperture
Fast: 80 to 120 micron pore size Medium speed: 30 to 50 micron pore size Slow speed: 1 to 3 micron pore size
Qualitative filter paper
7, 9, 11, 12.5, 15cm
Qualitative filter paper When referring to "qualitative analysis of filter paper," qualitative analysis of filter paper is relative to quantitative analysis of filter paper and chromatographic qualitative analysis of filter paper.
Filter paper is a kind of paper with good filtration performance, loose paper, strong absorption of liquid. Analytical laboratories use filter paper as a filter medium to separate the solution from the solids. Qualitative analysis of filter paper:
Qualitative analysis of filter paper generally has more residual ash. It is used only for general qualitative analysis and for filtering sediments or suspensions in solution. It cannot be used for quality analysis.
Qualitative analysis of filter paper types and specifications is basically the same as quantitative analysis of filter paper, indicating fast, medium, and slow speeds, but printing on fast, medium, and slow speeds. However, when using a quantitative and qualitative filter paper filter sediment on the filter paper box, pay attention to:
1 General use of natural filtration, the use of filter paper and the ability to retain solid particles, so that liquid and solid separation; 2 due to the filter paper mechanical strength and toughness are less than the use of suction filtration methods, such as the need to speed up the filtration rate, to prevent wear Filtration results in failure of filtration. When the air pump is filtered, 2 or 3 layers of filter paper can be stacked in the funnel according to the size of the pumping force. When vacuum filtration is used, the filter should be drained. First, a layer of dense filter cloth should be placed, and then the filter paper should be placed. ; 3 filter paper is best not to filter hot concentrated sulfuric acid or nitric acid solution. 3. Qualitative analysis of filter paper
Chromatographic qualitative analysis of filter paper is mainly used as a support in paper chromatography analysis, qualitative analysis of the sample to be analyzed chromatographic Qualitative analysis of filter paper are No. 1 and No. 3, each is divided into fast, medium and slow speed Three kinds.
Microporous membrane application should pay attention to the following points
1 The determination of the bubble point should be made: The determination of the bubble point pressure can reflect the pore size of the microporous membrane, which is closely related to the quality of the filtered liquid, and is also an important means to ensure the quality of the microporous membrane. The microporous membrane used should be soaked in water for injection at about 70°C for 1 h. The water was poured out and soaked in warm water for overnight use. Take it out when it is in use, rinse it with water for injection, and put it into the filter for use and installation. Prevents the filter membrane from leaking.
2 In order to protect the service life of the filter, the same size of filter paper or silk cloth (it should be boiled with 20 g·L -1 sodium sulfonate solution for about 30 min before cleaning with water for injection) Place it on the filter to prevent it from cracking. 3 The pore size of the microporous membrane is cone-shaped, and the smooth one has a small pore size. The coarse one has a large pore size. When installed, the surface should be face down, and the reverse surface should be upward. Otherwise, the pore size will be blocked by impurities and affect the filtration rate. . When the temperature is low, the treated membrane should be placed in the water for injection with the same temperature as the liquid temperature for 5 to 10 minutes so as to avoid the cracking phenomenon caused by the decrease in the tensile strength of the membrane due to the temperature difference.
4 On the filter head of the exhaust pipe of the filter frame, fix a 16-gauge infusion needle and use a water stop clamp to prevent the filter from bursting due to the exhaust pressure and speed.
5 Do not sterilize the filter holder together with the filter, otherwise the filter membrane will be brittle due to thermal expansion and contraction.
6 After use, the microporous membrane is placed in water for injection to prevent drying, but it should not be soaked for too long. It cannot be used for dried membranes that have lost water.
7 According to the concentration and viscosity of the liquid, microporous membranes with different pore sizes should be used.
8 If it is found that the microporous membrane has small holes or small cracks, it can be washed and dried after the original filter membrane is not used, then shredded and placed in a small amount of acetone in a small cup, stir into a paste of mucus, the mucus Dropping in the small holes or small cracks in the flat membrane should not be too much, and the mucus can be covered slightly, and after being dried, it can continue to be used without affecting it.
9 Infiltration Filtration When a multi-stage filtration device is used after fine filtration after fine filtration, a microporous membrane may be used for the final fine filtration, and compression, decompression, and azimuth static pressure filtration methods may be used.
The PTFE membrane is completely made of natural, permanently hydrophobic PTFE material. Even at very low differential pressures, moist air or other gases can pass through without being blocked, and aqueous solutions cannot. Its performance is exactly the opposite of hydrophilic membranes. PTFE membranes are extremely chemically compatible and can handle almost all organic solvents and strong corrosive chemicals. When the PTFE membrane must be used to filter the aqueous solution, it must be presoaked with ethanol or isopropyl alcohol before the aqueous solution can be filtered.

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