Filter paper

November 1, 2021

Filter paper is the instrument used to perform the separation of solid elements in substances. Filtration is a fairly old purification method and is applied in a huge variety of areas; even in everyday life where you have surely seen yourself at some point in need of filtering something.

In fact, it is extremely common to have water filters to ensure that the same comes without impurities; filtration processes are so useful that their use clearly goes beyond domestic use; having relevance within the processes carried out in the laboratory. Because even being a simple procedure it is necessary when working with substances.

What is Filter Paper?

Filter paper is just as the name suggests, a paper used for filtering. This is circular and is made of cellulose derivatives , like the rest of the papers and fabrics. This being a membrane found in plant cells; paper is usually made from cellulose that is extracted from wood.

Filter paper is made in a circular way and that used in laboratories is usually linked to the use of the funnel; which is where the paper is placed to perform the filtration. The color of this is commonly somewhat opaque white and its diameter and length vary depending on the type of paper.

Filtration is a process in which solid elements are separated from a liquid ; they can be large or difficult to perceive. The filter paper is made in such a way that it is resistant to substances, that is, it will not fall apart as it happens with other types of paper when faced with a liquid.

Therefore, the filter paper needs to be strong enough to withstand the liquid passing through it; retaining solid elements but allowing the substance to pass through.

What is Filter Paper for?

The filter paper fulfills the function of being used for filtration. Both in gravity filtration, which is the common type of filtration in which you pour the liquid to be filtered, both in vacuum filtration, in which the liquid is sucked by vacuum pressure; filter paper is also used.

In fact, even funnels that are themselves designed to allow filtration are used with filter paper, but why? Simply because the porosity of the filter paper makes the filtering process reliable .

Even if another instrument has screens, or holes that appear to be suitable for filtration, it is likely that their surface is not capable of efficiently retaining small solid elements.

Uses of Filter Paper

Filter paper has the most diverse uses, being used even in making coffee. But for now let’s focus on professional uses. One of the procedures in which the filter plays a central role is qualitative analysis . Which is done to identify the particles that make up a substance.

The gravimetric analysis also makes use of the filter paper, this is the determination of the proportion of an element. Carrying out electrophoresis, a procedure to separate molecules, also requires a filter under certain conditions.

In general, in many laboratory procedures the use of the filter is established, especially in analytical chemistry. Although it is also used occasionally, as situations in which it is required to use filter paper are recurrent. Even many times it is detached from its function and is used to place solid samples.

The industrial sector also makes use of different types of filter paper, either in the production of its products, or as part of the product itself. A clear example is automobiles, which have internal filters for oil processing.

Knowing the uses of each of the measurement instruments that are frequently used can be of great help in obtaining the best results in terms of measurement and investigations.

Filter Paper Types

As you could see earlier, there are many different uses for filter paper. But it is not the same type of filter paper that is used for everything; Although a filter paper can be used for different types of applications; there are substances that need somewhat different surfaces to carry out a good filtration process.

  • Quantitative filter paper

Composed of cotton liners and cellulose fibers. This type is used for the filtration of substances that require that the paper does not have any of its elements in its components.

  • Qualitative filter paper

This paper is quite resistant, being able to perceive substances with a pH of 0 to 12 and 120 ° C. Its main use is qualitative analysis. It has a good filtration speed and is made with cotton and other cellulose derivatives.

  • Chromatographic filter paper

Used to do chromatography; which is a method of separating elements. There are several ways to do chromatography and one of these is with filter paper, but this must have specific characteristics, such as rapid absorption of the liquid.

  • Fiber filter paper

These are made of fiberglass or quartz, which gives them the quality of being resistant to very high temperatures. Something necessary for certain procedures where you work with substances at a high temperature.

  • Other types

As stated at the beginning, the use of the filter extends beyond the laboratory. So there are also oil filters, air filters and the common ones used in the kitchen area; each with their respective qualities.

There are several types of filter paper for different uses, although some are extended to be used in various procedures, such as chromatographic filter paper, which is equally applicable in qualitative analysis. To know which one you should use it is necessary that you know the types of filter and the nature of the substance with which you will work.

Filter Paper Features

The filter paper has its variations depending on the type, both in composition, material, and size; however, there are qualities that they must share in order to make the filtration process possible through them. Among its main features you can find:

  • Dimensions

Although this point varies, the most common ones have an area of ​​10 cm² and a weight of approximately 80 to 130 g / m².

  • Porosity

The surface of the filter paper must be porous, that is, it must have a good volume of holes in which to retain the solid remains of the substance to be filtered. The diameters of the pores vary depending on the type of paper.

  • Semipermeabilidad

This is a determining factor for filtering, since it is the quality that allows to maintain the integrity of the filter paper and the passage of the liquid through the material at the same time.

  • Thermal resistance

Fiberglass filter papers are stronger at this point, but all filter papers must have good heat resistance to deal with substances.

  • Chemical resistance

Filter papers do not resist the impregnation of a substance, because for this they should be waterproof and would not work for filtering. But they must have a good level of resistance to corrosion and erosion caused by a substance so as not to affect the filtering process.

To know how to use filter paper properly it is important to know its characteristics; This will allow you to determine in which procedures and with substances to apply its use. In itself it is very simple to use and you must remember that it is used together with the funnel and a container to contain the substance, usually a flask.

Importance of Filter Paper

Filter paper is used in many areas and is a procedure that has been used for a long time to free impurity substances, even being required to clean the air. Although professional filtration processes began to be applied in the 20th century, filtration is a fairly old method.

Without the filter paper, making filtrations where all the solid elements are extracted would be difficult, having a wider margin of error. Its importance derives from its usefulness, which is unquestionable.

Dr. Loony Davis5
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Born and raised in Brussels in an English family, I have always lived in a multicultural environment. After several work experiences in marketing and communication, I came to Smart Water Magazine, which I describe as the most exciting challenge of my career.
I am a person with great restlessness and curiosity to learn, discover what I do not know, as well as reinvent myself daily, someone who is curious about life and wants to know. I enjoy sharing knowledge.
This is my personal project but I also collaborate in other blogs, it is the case, the most important web on water currently exists in the US, if you are interested you can read my articles here.

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