FILTER PAPER: CHARACTERISTICS AND TYPES - CHEMISTRY - 2025

The filter paper is a paper having as purpose purifying liquids and air. It is made from cellulose derivatives, which is a substance found in the membrane of plant cells.

Depending on the use that the paper will have, its texture and diameter will be different. Its components make it a strong enough paper to allow the passage of a solution and isolate the insoluble, which in this case would be impurities. Therefore, it is a semi-permeable paper.

Besides being able to withstand any type of substance, it can also withstand high and low temperatures.

This type of paper is commonly used in analytical laboratories in order to distill liquid substances and obtain a clean substance separated from the contaminated remains.

However, it is not the only filter paper that exists. The design of this paper varies depending on what you need to filter.

In this sense, you can find filter papers for professional use such as that used in a chemical laboratory, and for personal use, such as preparing coffee at home in a filter coffee maker.

Types of filter paper

As mentioned above, the proportions, size and roughness of the various filter papers are different and this difference is created out of necessity.

There is a type of filter for each use. In some cases, the choice of filter paper to be used has to be made based on the components to be analyzed and the components that make up the filter paper.

In other cases, it will depend on which device or mechanism needs a filter paper for its proper functioning.

Some of the most common types of filter paper are:

Qualitative filter paper

This type of filter paper is used to perform a qualitative analysis, which serves to identify the particles present in the filtered solution.

It is made with 100% cellulose and is designed to tolerate a pH of 0 to 12. Furthermore, it is capable of withstanding a temperature of up to 120 ºC.

There are 13 different grades of qualitative filter paper. The largest is grade 4 and the smallest is grade 602 h. Also, there are different diameters.

Quantitative filter paper

The quantitative filter paper is made of 100% cellulose cotton and contains 0.01% ash.

It is used to perform gravimetry analysis and monitor the environment. The goal is that by separating the substances present, a quantitative analysis can be performed.

Therefore, the characteristic for which this filter paper stands out is that it does not have among its components those substances to be analyzed.

Like qualitative filter paper, quantitative filter also has different grades and diameters.

Chromatographic filter paper

This filter paper is used by chemists to separate components, a technique known as electrophoresis. It is also functional to perform a qualitative and quantitative analysis.

It is characterized by having a specific water flow rate and rapid absorption, which provides an accurate analysis.

Fiber filter paper

The fiber filter paper can be glass fiber or quartz fiber. This trait allows it to withstand high temperatures, so it can be used for gravimetric analysis. Also, the filter life will be longer and filter sterilization is easy.

There are seven different types of fiberglass filter paper, and one notable difference between these types is the thickness. On the other hand, the fiberglass filter is recommended for highly contaminated substances and for substances that are difficult to dilute.

For its part, a characteristic of quartz fiber filter paper is its great resistance to high levels of chemicals.

Also, this filter is not affected by humidity, so it is used to analyze the level of contamination in the air and water.

Oil filter paper

Many man-made machinery such as automobiles require the engine to be kept lubricated. This is done automatically and constantly with oil when the engine is running.

However, although the oil is purchased in a store after being manufactured by a company that met the required hygiene conditions, it will never be 100% pure.

Therefore, the machinery is built with a filter paper, known as an oil filter, which must be renewed from time to time. This is done so that the engine receives purified oil.

This type of filter is designed with a different shape. The paper is folded in many folds and both ends of the paper are joined, forming a circle.

The ends have caps with a side and side hole that allows the entry, purification and exit of the oil.

Since this lubrication occurs only when the vehicle is running, the oil filter is manufactured to withstand high temperatures.

Air filter paper

Air conditioners are also human inventions and they are not exempt from needing a filter.

The operation of an air consists of providing air at different temperatures. However, this air is drawn from the air in the environment, which is polluted.

To prevent the passage of impure particles into a closed space, the airs are made of filter paper that must have a high number of pores and a specific weight. Likewise, its characteristics include resisting different types of temperatures.

Like the oil filters, although these are not visible, they must be renewed depending on the use that is given to the device.

Coffee filter paper

Filter paper today is a material that is used in many aspects of life to purify or dilute a substance.

In this case, like infusion teas, the coffee filter paper works to extract the flavor and color of the ground coffee through hot water. In this way, the liquid substance is separated from the powder that is not consumed.

Since these infusions can only be obtained by passing them through hot water, the filter paper for coffee and tea are resistant to high temperatures.

References

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7. Scraba, W. Different types of oil filters and how they work. Retrieved on September 12, 2017, from mobiloil.com.