The Composition and Application of Filter Paper

What is filter paper made of

Most filter papers are made of cotton fibers and are made in different ways for different purposes. The key composition of filter paper is cellulose. The pigments are a capillary function of cellulose.

The liquid rises along with the filter paper and shows very significant color bands: green is chlorophyll, yellow is lutein, and orange is carotene. Filter paper filtration is actually a chromatographic function. In experiments, uses of filter paper together with the filter funnel and Brinell funnel.

filter paper composition

Because filter paper composition is fibers, there are numerous holes on its surface for liquid particles to pass through, while larger solid particles can not pass through. This property allows the separation of liquid and solid materials mixed together. The laboratory filter has good filtration and absorption performance and high compressive strength. Hawach provided Qualitative 20 Micron Filter Paper Grade: BIO-4, Quantitative Ashless Filter Paper Grade: BIO-41, and Quantitative Laboratory Filter Paper Grade: BIO-42 for your choice.

Ash content of filter paper

The residual ash content of the filter media (such as cotton cellulose qualitative filter paper) after burning at 900 ° C in air. “Ashes” is essential for gravimetric experiments. The smaller the ash content of the filter media, the lower the impurity background, which also contributes to the cleanliness of conventional samples. The essential difference between qualitative filter paper and quantitative filter paper (including ashless filter paper) is the size of the ash value.

Hawach cotton fiber filter paper

What is filter paper made of? Hawach qualitative and quantitative filter paper composition of high-quality cotton cellulose. These cotton fibers are specially treated to ensure that the α-cellulose content is above 98%. The cellulose filter paper is suitable for conventional filtration, particle retention up to 30um, minimum to 2μm, divided into multiple flow rate levels, and a variety of cut-off particle size/flow rate combinations to meet laboratory application needs.

Hawach ashless quantitative filter papers have an unparalleled high purity and are suitable for chemical analysis and specific gravity. This type of filter paper has the smallest metal background. Other cellulose such as lignocellulose, sheepskin fiber, and other metal backgrounds will be slightly higher, and some varieties add wet strength agents in order to increase the strength of the filter paper.

Therefore, when choosing any kind of filter media (not only cellulose filter media), we must not only choose the “chemical compatibility table of the media and the outer casing”, but also must consider the material of the filter media, and the purity of the material. How, because it affects the integrity of the physicochemical information of the sample you are analyzing.

Proper selection of a properly functional filter medium or filter not only ensures the integrity of the sample preparation process, but also facilitates accurate and reliable experimental results, and is more conducive to accelerating the development process, creating benefits and saving costs.

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Application of Filter Paper

Filter paper is a versatile laboratory tool used for various filtration and separation applications. Here are some common applications of filter paper:

  1. Gravity Filtration:
    • Used in conjunction with a filter funnel and vacuum flask, filter paper allows for the separation of solid particles from a liquid phase under the influence of gravity.
  2. Vacuum Filtration:
    • Filter paper is an essential component of vacuum filtration setups, aiding in the efficient separation of solids from liquids under reduced pressure.
  3. Qualitative Analysis:
    • Filter paper is used in qualitative chemical analysis techniques to separate and identify specific ions or compounds in a mixture.
  4. Quantitative Analysis:
    • Filter paper may be used in quantitative analysis methods to measure the concentration of a specific substance in a solution.
  5. Microbiology and Sterilization:
    • Filter paper discs are used in microbiology for techniques like bacterial filtration, and they are also used in autoclaves for sterilization.
  6. Chromatography:
    • Filter paper can be used as a stationary phase in paper chromatography, where it separates components of a mixture based on their affinity for the paper.
  7. HPLC Sample Preparation:
    • Filter paper is employed to remove particulates from samples before injection into a High-Performance Liquid Chromatography (HPLC) system.
  8. Air and Environmental Monitoring:
    • Filter paper is used in air sampling devices to capture airborne particles for subsequent analysis.
  9. Food and Beverage Industry:
    • Filter paper is utilized in processes like coffee filtration and the removal of sediments from beverages.
  10. Pharmaceutical Industry:
    • Filter paper plays a crucial role in various pharmaceutical processes, including the filtration of drug formulations and quality control testing.
  11. Oil and Petrochemical Industry:
    • Filter paper is used to separate impurities from oil and other petrochemical products.
  12. Laboratory Experiments and Demonstrations:
    • Filter paper is a fundamental material used in various laboratory experiments to demonstrate principles of filtration and separation.
  13. Water and Wastewater Treatment:
    • Filter paper is employed in water treatment plants and laboratories for the analysis and purification of water samples.
  14. Medical and Healthcare Settings:
    • Filter paper is used in medical applications such as blood typing, where it helps separate blood components.
  15. Environmental Science:
    • Filter paper is used to collect and analyze particulate matter in air and water samples for environmental monitoring.
  16. Agricultural and Soil Testing:
    • Filter paper is used in agriculture for soil testing and analysis, allowing researchers to separate soil particles for various tests.

The diverse range of applications for filter paper makes it an indispensable tool in laboratories across various scientific disciplines and industries. Its ability to effectively separate solids from liquids is crucial for a wide array of analytical, research, and industrial processes.

Technical index of filter paper

The technical indicators of cellulose filter papers can be divided into two aspects, one is the filtration characteristics of the filter paper, and the other is the physical characteristics. Filtration characteristics include air permeability, air resistance, maximum pore size, and average pore size. Physical properties include quantitative, thickness, stiffness, corrugation depth, burst resistance, resin content, etc.

Quantitative: refers to the quality of filter paper per square meter, unit: g/m2.

Thickness: refers to the thickness of filter paper, excluding corrugated depth. Unit: mm.

Air resistance: the resistance of the filter paper to airflow. Use 100cm2 filter paper to pass 85 liters of air in one minute to express the pressure drop value. The unit is mbar or the height of the water column (mm).

Corrugated depth: the depth of the grooves suppressed to strengthen the longitudinal stiffness of the filter paper, in mm. Under normal circumstances, its value is 0.2mm.

Air permeability: The amount of air passing through the filter paper per unit time under a certain area and pressure (20 mm water column). The unit is L/m2·s.

Stiffness: the ability of filter paper to resist deformation. Unit: mg.

Resin content: percentage of resin in the weight of the filter paper. Generally 10%~30%.

Nominal filtration accuracy: refers to the retention capacity of the filter paper for particles of a certain size, and the particle size of the tiny spheres at 50% that can be retained or filtered out shall prevail. Unit: μm.

Maximum pore size: because of cellulose filter paper composition, the size of the gap is calculated by the pressure when the first bubble emerges on the filter paper sample during the test. Unit: μm.

Average pore diameter: The pore diameter calculated by the pressure during “dense” bubbling is called the average pore diameter. The unit is: μm.

Bursting resistance: the maximum pressure that the filter paper can withstand per unit area. Unit: kPa.

At present, the filter paper is mainly used in petroleum, pharmaceutical, industrial oil, and industrial organic suspension to separate solid and semi-solid impurities. The filter paper is mainly used in the ashing weighing analysis test after filtration. The ash weight of each filter paper after ashing is a fixed value, while the qualitative filter paper is used in the general filtering function.

Know more about filter paper, please see the Precautions When Using Qualitative and Quantitative Filter Paper