What Is Filter Paper

Most filter papers are made of cotton fibers and are made in different ways according to different uses. Because its material is made of fiber, there are countless small holes on its surface for liquid particles to pass through, but larger solid particles cannot pass through. This property allows the separation of liquid and solid materials that are mixed together.

Filter paper can generally be divided into two types: qualitative and quantitative. In the application of analytical chemistry, when the inorganic compound is filtered to separate the precipitate, the residue collected on the filter paper can be used to calculate the loss rate during the experiment. Qualitative filter paper has more cotton fibers after filtration, so it is only suitable for qualitative analysis; quantitative filter paper, especially ash-free filter paper through special treatment procedures, can more effectively resist chemical reactions, so the generated There are few impurities and can be used for quantitative analysis. In addition to the filter paper used in general laboratories, there are also many applications of filter paper in daily life and engineering. Coffee filter paper is one of the widely used filter papers, and the filter paper on the outer layer of the tea bag provides high softness and high wet strength. Others use air filter paper for testing suspended particles in the air, and fiber filter paper for different industrial applications.

Choosing the right filter paper can be determined by considering the following four factors.

Hardness: The filter paper will become wet during filtration. For some long-term filtration experiments, you should consider using filter paper that is tougher after wet water.

Filtration efficiency: The density and size of the water seepage pores on the filter paper affect its filtration efficiency. The high-efficiency filter paper has fast filtration speed and high resolution.

Capacity: The solid particles accumulated during filtration may block the pores on the filter paper. Therefore, the denser the water seepage pores, the higher the capacity and the more filter that is allowed to filter.

Applicability: Some filter papers are made by special manufacturing steps. For example, they are used to determine the nitrogen content in blood in laboratory medicine, and nitrogen-free filter paper must be used.