TABLE OF CONTENTS Nonwoven filter media in their simplest forms are random fiber structures, usually in sheet form, that are used to separate one or more phases from a moving fluid passing through the media. Filtration is generally perceived as the removal of particulate phases from the moving fluid by entrapping the particulate matter in the tortuous structure of the filter medium. However, the discussion to be presented in this book will also include other forms of separation where a nonwoven is used as the separating media. This will include adsorption, absorption, extraction coalescence, electrostatic effects, and antimicrobial activity.
To define the scope of this handbook it is necessary to define filtration and separation, nonwovens, and filter media.
INDA, the Association of the Nonwovens Fabrics Industry (Butler [1]) explains filtration as follows:
"Filtration is a mechanism or device for separating one substance from another. Filtration may be used to separate contaminants from a fluid or separate value-added materials, such as minerals, chemicals, or foodstuffs in a process operation."
Separations can be broadly classified into six categories:
Solids gases separations.
Solids liquids separations.
Solids solids separations.
Liquids liquids separations.
Gas liquid separations.
Gas gas separations.
Except for "solids solids separations" each of these separation processes will be discussed in more detail in later sections of this book. Solid solid separations are achieved by screening larger solid particles from a solid mixture containing smaller particles. In certain cases, the separation can also be achieved by magnetic separation. The author is unaware of any significant use...
