Filter Paper Story
Filter paper is used for the separation of liquid and solid substances mixed together. Because it is made of fiber, the surface has numerous holes through which liquid particles can pass, while larger solid particles cannot. Most filter paper is made of cotton fibers and is made in different ways for different purposes. The filter paper will become wet during filtration, and some of the experimental steps of long-time filtration should consider using the filter paper stronger after wet water.
Quantitative filter paper
Filter paper can be divided into qualitative and quantitative two kinds. In the field of applied analytical chemistry, residues collected on filter paper after inorganic compounds have been filtered out of sediments that can be used to calculate the loss rate during the experiment. Qualitative filter paper after filtration more cotton fiber generation, so only suitable for qualitative analysis; The quantitative filter paper, especially the non-ash filter paper, can resist the chemical reaction more effectively after special processing procedures, so the generated impurities are less, which can be used for quantitative analysis. In addition to the general laboratory application of filter paper, life and engineering applications are also many. Coffee filter paper is a widely used filter paper, while the tea bag filter paper provides high softness and high wet strength. Other air filters used to test suspended particles in the air and fiber filters for different industrial applications.
In the process of making 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, so there is little residual ash after burning, which has little impact on the analysis results and is suitable for precise quantitative analysis. And the proportion of ash generated after ashing is less than 0.0009%.
The domestic production of quantitative analysis filter paper, divided into fast, medium and slow three types, in the filter box with white (fast), blue (medium), red (slow) as the logo classification. The shape of the filter paper is circular and square, and the size of circular paper can be divided into D7cm, D9cm, D11cm, d12.5cm, D15cm and D18cm according to the diameter. Square quantitative filter paper is 60cm×60cm and 30cm×30cm.
The difference between the two series filter paper mainly lies in the amount of ash generated after ashing: qualitative filter paper does not exceed 0.13%, and the quantitative filter paper does not exceed 0.0009%.
Ash-less filter paper is a quantitative filter paper with ash content less than 0.1mg, which is negligible in the analytical balance.
Note that the concepts of quantitative filter paper and qualitative filter paper are only for cellulose filter paper and are not applicable to other types of filter paper such as glass microfiber filter paper.
The aperture of the filter paper
Fast: aperture of 80 to 120 microns
Medium speed: aperture 30 to 50 microns
Slow speed: aperture 1 ~ 3 microns
Qualitative filter paper property: also known as qualitative analysis filter paper. It is a kind of filter paper used in chemical laboratories to filter precipitation and suspended matter. Silicon content is higher than the quantitative filter paper, burning after a certain amount of ash.
Because the size of the filter paper aperture is different, it is divided into fast, medium and slow three kinds. Outer packing marked white, blue and red, respectively. It should be used according to different types of precipitation. Using cotton pulp or refined sulfate wood pulp as raw materials, after the free beating, then with hydroelectric acid impregnated fiber purification treatment, in the long net paper machine under low pressure.
How to use filter paper: Before daily use, the filter paper should be folded into some shapes, the common way is to fold into the shape of flowers. The use of filter membrane device does not require chemical treatment of matriculation, nor does it require evaporation separation, only pressure to separate solid from liquid in water, which is a major feature of filter membrane treatment. But be careful not to destroy the filter paper after multiple folds. After placing the glass rod used for drainage on the mulch-layer filter paper, evenly apply force to avoid the filter paper being destroyed. Place the glass rod of drainage on the mulch-layer filter paper, force evenly to avoid the damage of the filter paper.
Specific operation process:
1. Fold the filter paper in half and fold it into a 90° central Angle shape for two consecutive times.
2. Fold the filter paper into a funnel and open it in three layers on one side and one on the other.
3. Put the filter paper into the funnel. The edge of the filter paper should be lower than the edge of the funnel.
4. Place the filter paper funnel on the filter funnel frame (such as the ring on the iron frame), lower the beaker or test tube to receive the filtrate at the funnel neck, and make the tip of the funnel neck rest on the wall of the receiving container.
5. Injection of the need to filter the liquid into the funnel, right-hand hold drip beaker, left hand holding a glass rod, glass rod bottom on tight funnel three-layer on the low side, make close to the glass rod at the top, to filtrate body along the flow at the top, and then tilt the glass rod, then flows into the funnel, flow to the liquid in the funnel, the liquid level should not exceed the height of the filter paper funnel.
6. When the liquid passes through the filter paper and flows down the neck of the funnel, check to see if the liquid flows directly down the side of the cup and into the bottom of the cup at one time. Otherwise, move the breaker or turn the funnel so that the tip of the funnel is pressed against the side of the burner so that the liquid can flow down the side of the burner.