Pretreatment of natural clinoptilolite in a laboratory-scale ion exchange packed bed.

The impact of the operational and chemical conditions of pretreatment upon the effective capacity of clinoptilolite has been investigated. Pretreatment tests have been performed in an ion exchange packed bed. The parameters examined for the pretreatment solution were the volumetric flow rate, the concentration, the total volume and the pH; and for washing after pretreatment the volume of washing water used. An optimal flow rate and a minimum concentration were determined, for a pretreatment that leads to a high effective capacity of the material, while pH adjustment did not result in a higher effective capacity and one washing (10 bed volumes) after pretreatment was found to be sufficient. Furthermore, the water quality (use of tap water) as well as the surface dust of the original material (about 5% w/w) did not alter its effective capacity.