Classifications and Operation Process of Filter Paper

Qualitative filter paper chemistry lab is generally used to filter solutions for qualitative tests that do not require the calculation of values for chlorides, sulfates, etc.; quantitative filter paper is used to filter for precise calculation of values, such as the determination of residues, insoluble, etc. After filtration, there is no need to enter a high-temperature furnace for treatment.

1. Quantitative analysis filter paper
In the manufacturing process, treat the pulp with hydrochloric acid and hydrofluoric acid, and wash it with distilled water in order to remove most of the impurities in the paper fiber, so there is little residual ash after burning, and the analysis results are almost not influenced. It is suitable for precise quantitative analysis.

Usually, the quantitative analysis filter paper is divided into three categories based on the filtering speed: fast, medium, and slow. The filter boxes are classified with white belt (fast), blue belt (medium speed), and red belt (slow speed) respectively.

It could be round or square and for the square ones, there are two specifications available, 30cm×30cm and 60cm×60cm. The specifications of the round paper are divided into d9cm, dllcm, d12.5cm, d15cm, and d18cm according to the diameter.

2. Qualitative analysis of filter paper
Compared with the quantitative analysis filter paper, the qualitative ones have more residual ash, making it suitable for precipitation or suspension filtration in solution, not for quality analysis. There are filter papers of the fast, medium, and slow speeds available. However, if the quantitative and qualitative analysis filter paper is not described on the packing box, please should pay attention to:
①Natural 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;
②Due to the small mechanical properties of the filter paper, both the strength and toughness, try to filter by suction as little as possible. To achieve accelerated filtering speed and to prevent filtration failure, two or three layers of the filter paper can be stacked in the funnel, based on the suction force, when the air pump is filtered. For filter paper, when vacuum filtration is used, put a layer of dense filter cloth on the funnel, and then put filter paper on it to filter;
③It’s better not to filter nitric acid or sulfuric acid.

3. Chromatographic qualitative analysis filter paper
Chromatographic qualitative analysis filter paper is mainly used as a support in paper chromatographic analysis to carry out the qualitative separation of the analyte. There are two types of chromatographic qualitative analysis filter paper, and each is divided into fast, medium, and slow speeds.

Operation process of filtr paper

1. Fold the filter paper twice in a row to form a 90-degree central angle;
2. Form a funnel by pressing the folded one into 3-layer on one side and opening one layer on the other side;
3. Put it into the funnel. Place the filter paper funnel on the funnel rack for filtering, and place the beaker or test tube under the funnel neck, and the tip of the funnel neck is against the wall of the receiving container;
4. When the liquid to be filtered is injected into the funnel, use your right hand to hold the liquid beaker and hold the glass rod in your left hand. Make the mouth of the cup close to the glass rod. When the filtered liquid flows out along the mouth of the cup, it will flow into the funnel by tilting it along the glass rod. The liquid level of the liquid flowing into the funnel should not exceed the height of the filter paper in the funnel.