5 Questions Will Help You Know Filter Paper Better

What is filter paper?

Now the filter paper, as an effective filter medium has been widely applied in many industries. The filter paper’s usage and performance would be different if the fiber that composes the filter paper is different. It can be divided into general filter papers that are frequently used in many experiments, ultra-clean polypropylene ones and glass fiber filter papers used at high temperatures, and so on. For lab experiments, the filter paper usually refers to the qualitative filter paper and quantitative filter paper. The ash content after ashing determines what kind of filter paper is. For the qualitative filter paper, its ash content is less than 0.15%. if the ash content is less than 0.01%, it will be the quantitative filter paper. Both kinds of filter papers can be in slow, medium, and fast flow filter paper. In general, the slow-speed filter paper is used for crystalline precipitation, and the fast ones are suitable for colloidal precipitation.
quantitative-filter-papers-bio-41 hawach-filter-papers-bio-41 filter paper for laboratory use

What are the technical indicators of the filter paper?

There are two kinds of technical indicators of filter paper, one is the filter characteristics, and the other is the physical characteristics. Filtration accuracy is the most important technical indicator of filter paper. The factors that affect the filtration accuracy include the thickness of the fiber, the compactness of the filter paper structure, and the size of the quantitative.
Maximum pore size: the size of the gap calculated by the pressure when the first bubble appeared on the filter paper sample during the test. Unit: μm.

The service life of filter paper is guaranteed by its strength and bulk. It is pointed out that while ensuring that the filter paper has sufficient strength, efforts must be made to increase its bulk. The factors affecting bulk are related to fiber types, fiber morphology (cross-section, fineness, etc.), post-processing conditions, reinforcement methods, papermaking methods, and drying methods.

Several technical indicators define the characteristics of filter paper, and these may vary based on the intended application. Common technical indicators include:

  1. Pore Size:
    • The size of the pores in the filter paper determines the range of particle sizes that can be effectively filtered.
  2. Flow Rate:
    • This indicates the speed at which a liquid can pass through the filter paper. It is influenced by the porosity and thickness of the paper.
  3. Particle Retention:
    • Filter paper is rated for its ability to retain particles of a certain size. This is important for selecting the appropriate filter paper for a specific filtration task.
  4. Basis Weight:
    • The weight of a unit area of the filter paper is known as the basis weight. It is typically measured in grams per square meter (g/m²).
  5. Material Composition:
    • Filter paper is primarily made from cellulose fibers, but variations may exist, and some may include synthetic materials to enhance specific properties.

How to fold filter paper?

The laboratory filter paper is mostly round. Just fold it in half and then fold it in half to make 4 pieces. Use your fingers to separate them, 3 pieces on one side and 1 piece on the other, and you can put them in the funnel. There is also a suction-type funnel (round and flat), this kind of filter paper does not need to be folded and is directly spread on the funnel.

What is the difference between filter paper and ordinary paper, and why can it filter?

The main reason is that most filter papers are made of cotton fibers and are made by different methods for different purposes. Countless small holes are at the surface enabling the liquid particles to pass through, due to the fiber material. While the larger solid particles cannot pass through, which separates the liquid from the mixed together solid materials. Ordinary paper can only absorb 23% of the water and cannot achieve the filtering effect.

How does the filter paper filter the solvent?

In the solution that passes through the filter paper, if the diameter of the substance is larger than the filter diameter of the filter paper, it cannot pass through the filter paper and remains on the filter paper. A substance with a smaller diameter than the filter paper can be added through the filter paper. The colloid can pass through the filter paper but cannot pass through the semi-permeable membrane, the solution can pass through the filter paper or the semi-permeable membrane, the turbid liquid particles larger than 100 nanometers can not pass.

HAWACH is specialized in manufacturing filter paper and other lab consumables. Welcome to contact HAWACH for details.