What problems should be precautions for filtration when using qualitative filter paper?
Precautions in filtration experiment. Qualitative filter paper is a kind of paper with good filtering performance. Qualitative filter paper is loose and has a strong liquid absorption performance. Analytical laboratories often use filter paper as a filter medium to separate the solution from the solid.
Due to the characteristics of qualitative filter paper, qualitative filter paper is used in some filtration in laboratories, hospitals, factories, and other industries. It is also because of this that the output of qualitative filter paper has risen linearly.
Precautions for filtration in the filtering process of qualitative filter paper. Under normal circumstances, qualitative filter paper will not be used for filtering at high temperatures. This temperature has a limit as long as it does not exceed it. Don’t filter hot concentrated sulfuric acid or nitric acid. The hot acidity of the solution can destroy the filtering effect of the qualitative filter paper.
Natural filtration is generally used, and the filter paper body and the ability to trap solid particles are used to separate the liquid from the solid; With the use of qualitative filter paper in the filter machine, the mechanical strength and toughness of the filter paper are less than the use of suction filtration. If the filtration speed must be accelerated, in order to prevent filtration failure caused by the filtration, the air pump can be filtered according to the suction force. Size: stack 2 to 3 layers of filter paper in the funnel. When vacuum filtration is used, it is leaking. Put a layer of dense filter cloth first, and then put filter paper on it to filter;
Precautions in filtration experiment
Matters Needing Attention On Filter Paper
a. Experimental Suggestions
When using quantitative and qualitative analysis filter paper to filter precipitation, there are some suggestions about precautions in filtration experiments:
1. Natural filtration is generally used to separate liquids and solid particles by using a filter paper body and the ability to intercept solid particles;
2. Because the mechanical strength and toughness of the filter paper are as little as possible, if the filtration speed must be accelerated, in order to prevent filtration failure, layers of filter paper can be stacked in the funnel according to the pumping force, and when vacuum filtration is used, the filter paper can be stacked in the funnel according to the pumping force.
3. Do not filter hot concentrated sulfuric acid or nitric acid solution. The square qualitative filter paper is 60cm × 60cm and 30cm × 30cm.
b. Replacement Time
Filter paper replacement time is depending on the number of impurities, you can regularly check the filter paper adsorption of impurities in the filtration process, and look at the flow rate of the import and export samples if more and more slowly indicates that more and more impurities adsorption needs to be replaced in time.
c. Operational Procedure for Filter Paper
The use of filter paper in the experiment is mostly used with a filter funnel and Brinell funnel and other instruments. The filter paper can be folded into a needed shape before putting into operation. The common folding method is to fold the filter paper into a flower-like shape. The higher the folding degree of the filter paper, the higher the surface area it can provide, and the better the filtration effect is, but be careful not to overfold and cause the filter paper to break. Place the drained glass rod on the multi-layer filter paper and force it evenly to avoid damage to the filter paper.
d. Material Property for Filter Paper
At present, the filter paper used for industrial liquid filtration is mainly made of PPP material. However, if different materials are used or different processing conditions, even if the unit weight of the filter paper, the filtering accuracy expressed will also differ greatly. Most filter paper is made of fiber, and there are countless holes in its surface for liquid particles to pass through, while larger solid particles cannot pass through. This property allows for the separation of liquid and solid substances mixed together.
The aperture of Qualitative Filter Paper
The pore size of the qualitative filter paper is irregular, usually, the pore size of the qualitative filter paper is large, and the quantitative one is small. The filter paper filter speed is different, the aperture is also different. Generally speaking, the pore size of the qualitative filter paper is large and there is no very strict regulation. The quantitative filter paper is divided into three types: fast, medium, and slow. The aperture of the filter paper is about 80 μ 120 μm, 30 μ 50 μm, and 1 μ 3 μm, respectively.
The aperture of Quantitative Filter Paper
At present, the quantitative analysis filter paper produced in Hawach is divided into three categories: fast, medium, and slow. White belt (fast), blue belt (medium speed), and red belt (slow speed) are used as the symbol classification on the filter carton. The shape of the filter paper is round and square. According to the diameter of circular fixed paper, it is divided into D7cm, D9cm, D11cm, D12.5cm, D15cm, and D18cm. The square quantitative filter paper is 60cm × 60cm and 30cm × 30cm.