Desorption of a fixed-bed adsorber by ultrasound.

Adsorption processes offer the possibility to remove trace impurities of liquid process streams. An important step in adsorption processes is the regeneration of the adsorbent as it does not only affect the adsorption-desorption cycle but also the expenses of the following process steps. In this study, various desorption experiments of a loaded polymeric resin have been conducted. They were performed with cold and hot water as well as with ultrasound at different frequencies and intensities. The results indicate, that an important factor of ultrasound enhanced desorption is the temperature rise due to ultrasonication. But as regeneration is more effective at higher frequencies even though temperatures inside the column are lower, another ultrasonic effect occurs during ultrasonic desorption.

Influence of ultrasound on adsorption processes.

One of the most popular means for removal of organic water pollutants found in small concentrations is by adsorption. An important step in adsorption processes is the regeneration of the adsorbent as it does not only affect the adsorption-desorption cycle but also the expenses of the following process steps. State of the art regeneration of adsorbent resins is done by chemical methods. These require the use of organic solvents or inorganic chemicals and involve a difficult secondary separation step. Therefore, industry seeks for alternative methods to regenerate exhausted adsorbents. One of the discussed regeneration methods is desorption by ultrasound. Ultrasound does not only promote desorption but also enhances the mass transfer of sorption processes. We discuss the arising problems and basic effects when applying ultrasound during sorption processes in order to show the potentials of this desorption process. The focus is laid in particular on the influence of ultrasound frequency and intensity.