Today, physical, chemical and biological refinement methods are commonly used. The most common one amongst harmful material removing methods is that the organic compounds adhesion on the solid absorbers. The adsorption process being economical depends on the availability and the cheapness of the solid which is used. Active carbon had an important role in waste water treatment until recently. Due to the micro-pores which the active carbon has, it has very large surface area; its surface area is approximately 200-1200m2/g. Since the openings of this porous structure are in various dimensions, any kind of molecule can easily hold onto these surfaces. Despite the fact that active carbon has large surface area, the examiners have headed to different adsorbents (silica gel, fly ash, bentonite, etc.) since the active carbon is high cost and it regeneration is difficult.
In examinations performed on bentonites, it was found that natural bentonite is effective in adsorption of organic contaminants in waste water due to its having large surface area. In order to acquire more efficiency from the bentonites, activations studies have been performed such as modification of surface properties of bentonite with organic cations, and organobentonites are synthesized. Therefore the surface property of natural bentonite which is hydrophilic is made organophilic (hydrophobic).