Filter paper
Filter paper is a semi-permeable paper barrier placed perpendicular to a liquid or air flow. It is used to separate fine solid particles from liquids or gases.
The raw materials are typically different
Properties
Filter paper has various properties. The important parameters are wet strength, porosity, particle retention, volumetric flow rate, compatibility, efficiency and capacity.
There are two mechanisms of filtration with paper; volume, and surface. By volume filtration, the particles are caught in the bulk of the filter paper. By surface filtration, the particles are caught on the paper surface. Filter paper is mostly used because of the ability of a small piece of filter paper to absorb a significant volume of liquid.
Manufacture
The raw materials are different
Types
Air filters
The main application for air filters are
Coffee and tea
Historically,
Modern coffee filters of paper are made from about 100 g/m2
: 114 Coffee filters are made in different shapes and sizes to fit into different holders. Most notable are the (paper)Important parameters are strength, compatibility, efficiency and capacity.
Tea bags also work as a kind of paper filter. They are made from abacá fibers, a very thin and long fiber manilla hemp. Often the paper is augmented with a minor portion of synthetic fibers. The bag paper is very porous and thin and has high wet strength.[1]: 114
Fuel filters
The paper used for fuel filters is a crêped paper with controlled porosity, which is pleated and wound to cartridges. The raw material for filter paper used in fuel filters are made of a mixture of hardwood and softwood fibres. The basis weight of the paper is 50–80 g/m2.[1]: 114
Horizontal plate filters
Horizontal plate filter paper is commonly utilized in industrial processing. Filter paper typically is designed to fit the manufacturers specifications. Absolute micron retention can range from 1–100 microns but Diatomaceous earth is commonly used with filter paper to obtain sub-micron filtration. Activated carbon or other filter aids can be used with the filter paper to form a filter cake to achieve specific results. Filter paper can be impregnated with DE or activated carbon.
Oil filters
Laboratory-grade paper filters
Filter papers are widely used in laboratory experiments across many different fields, from biology to chemistry. The type of filter used will differ according to the purpose of the procedure and the chemicals involved. Generally, filter papers are used with laboratory techniques such as gravity or vacuum filtration.[4]
Historically, a type of soft, porous paper called charta emporetica was used in pharmacy as a filter and as packing paper.[5]
Qualitative filter paper
Qualitative filter paper is used in qualitative analytical techniques to determine materials. There are different grades of qualitative filter paper according to different pore size. There are total 13 different grades of qualitative filter paper. The largest pore size is grade 4; the smallest pore size is grade 602 h; the most commonly used grades are grade 1 to grade 4.[6]
Grade 1 qualitative filter paper has the pore size of 11 μm. This grade of filter paper is widely used for many different fields in agricultural analysis, air pollution monitoring and other similar experiments.[6]
Grade 2 qualitative filter paper has the pore size of 8 μm. This grade of filter paper requires more filtration time than Grade 1 filter paper. This filter paper is used for monitoring specific contaminants in the atmosphere and soil testing.[6]
Grade 3 qualitative filter paper has the pore size of 6 μm. This grade of filter paper is very suitable for carrying samples after filtration.[6]
Grade 4 qualitative filter paper has the pore size of 20~25 μm. This grade of filter paper has the largest pore size among all standard qualitative filter papers. It is very useful as rapid filter for cleanup of geological fluids or organic extracts during experiment.[6]
Grade 602 h qualitative filter paper has the pore size of 2 μm. This grade of filter paper has the smallest pore size among all standard qualitative filter papers. It is used for collecting or removing fine particles.[6]
Quantitative filter paper
Quantitative filter paper, also called ash-free filter paper, is used for quantitative and gravimetric analysis. During the manufacturing, producers use acid to make the paper ash-less and achieve high purity.[7][8]
Chromatography papers
Chromatography is a method chemists use to separate compounds. This type of filter paper has specific water flow rate and absorption speed to maximize the result of paper chromatography. The absorption speed of this type of filter paper is from 6 cm to 18 cm and the thickness is from 0.17 mm from 0.93 mm.[9]
Extraction thimbles
Extraction thimbles are rod-shape filter paper often used in soxhlet extractors or atomized extractors. It is ideal for very sensitive detection, the performance depends on the thickness of inner diameter. Also, it is usually used in areas of food control and environmental monitoring.[10]
Glass fiber filters
Glass fiber filter has the pore size of 1 μm, it is useful for filtering highly contaminated solutions or difficult-to-filter solution. Also, glass fiber filter has extends filter life, wide range of particulate loads and can prevent sample contamination.[11] In addition, different types of glass fiber filter are suitable for different filtration situation. There are 7 different types of glass fiber filters and the major difference is thickness.
Quartz fiber filter
Quartz fiber filter paper has a high resistance to chemicals, does not absorb NOx and SOx dioxides, is unaffected by humidity and is easily sterilized. Thus, it is mostly used for air pollution analysis.[12]
PTFE filter
See also
References
- ^ ISBN 952-5216-18-7.
- ISBN 978-0-578-24608-6. [1](xvi+249+3 pages)
- ^ "111 Jahre Melitta Zeitstrahl Allgemein" (PDF) (in German). Melitta. Archived (PDF) from the original on 2023-03-10. Retrieved 2023-06-08.
- ^ "Filtration Techniques" (PDF). Filtration Techniques. Archived (PDF) from the original on 2015-05-01. Retrieved 2015-11-21.
- ^ Chambers, Ephraim, ed. (1728). . Cyclopædia, or an Universal Dictionary of Arts and Sciences (1st ed.). James and John Knapton, et al.
- ^ a b c d e f "Filter Papers and Membranes" (PDF). Filter Papers and Membranes. Archived (PDF) from the original on 2015-11-22. Retrieved 2015-11-21.
- ^ "Filter Papers for the Laboratory and Industry" (PDF). Filter Papers for the Laboratory and Industry. Sartorius Stedim. Archived (PDF) from the original on 2015-11-22. Retrieved 2015-11-21.
- ^ "Lab Filtration Papers". Lab Filtration Papers.
- ^ "Laboratory Filter Paper" (PDF). Laboratory Filter Paper. Archived (PDF) from the original on 2016-03-09. Retrieved 2015-11-21.
- ^ "Cellulose extraction thimbles". Hahnemuehle. Archived from the original on 2015-11-22. Retrieved 2015-11-21.
- ^ "Glass Fiber Filters". Glass Fiber Filters. Pall Corporation. Archived from the original on 2015-11-22. Retrieved 2015-11-21.
- ^ a b "Laboratory Filter Paper" (PDF). Laboratory Filter Paper. Archived (PDF) from the original on 2016-03-09. Retrieved 2015-11-21.