Abstract
The tolerance against malodors in industrialized societies decreases. Thus, it is necessary to develop new and more powerful technologies for exhaust air purification. To reduce concentrations below the odor threshold, selective adsorption processes with on-site regeneration of the adsorbents are very promising. To regenerate adsorbents new and more cost sensitive methods are needed. The development of four innovative methods based on microwave, ultrasound, ultrasound with water, and water desorption for the regeneration of adsorbents is reported. Different odorous lead compounds such as acetic acid and triethylamine were desorbed. The investigations were performed with various adsorbents such as activated carbon, silica gel, aluminum oxide, and a modified bentonite, covering a wide range of typical materials used in industry. The examination by microwave desorption was successful. After 20 min of microwave radiation bentonite had a residual load of less than 10% of the original load. Desorption by ultrasound gave satisfactory results only when using water as a transmitter. Moreover, the results with water strongly depend on the odor compound to be desorbed. In the case of a highly soluble adsorptive in water the results are promising but, because odor compounds are often sparingly soluble in water, the yields decrease. Among the four examined desorption methods microwave desorption and ultrasonic-water desorption offer the best results. From among the adsorbents the modified bentonite provides the best adsorption properties with the best regeneration performance.
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