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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. [ABSTRACT FROM AUTHOR]

Abstract: The intention of this work is to offer, within the shortest time, an appropriate sorption separation process for almost any odour problem. The development is based on the preparation and characterisation of new adsorbents, the strategy for the selection of the best adsorbent, the process engineering and the choice of a suitable regeneration procedure. In this context a new method for the characterisation of the adsorbents – the adsorption profile analysis – was developed. The classification of the adsorbents was carried out by means of a cluster analysis, which simplifies the selection of the most suitable adsorbent for a particular problem. The physical and chemical behaviour of silica-adsorbents could be tailored by silanisation of the surfaces. Methods for the determination of process engineering parameters were developed, established and used. Adsorption kinetics and isotherms were determined with a magnetic adsorption balance. In a laboratory-scale fixed bed adsorber, breakthrough curves of different support materials were investigated and compared. For the investigations of different regeneration procedures, four innovative methods were employed: microwave desorption, ultrasonic desorption, ultrasonic-water desorption and extraction with water. Of the four desorption methods examined, microwave desorption and ultrasonic-water desorption demonstrated the best results. [Copyright &y& Elsevier]

Abstract: The potential of natural clay as adsorbent for biotechnology processes was systematically investigated. Adsorption isotherms for several substrates and products of an alcohol dehydrogenase catalysed reaction were determined by static experiments. A distinct selective adsorption behaviour of natural kerolite clay was proven for aromatic ketones and alcohols in particular for acetophenone and phenylethanol. In aqueous media high adsorbed amounts (q) were stated for those molecules to be adsorbed (adsorptive) which possess both a carbonyl and a phenyl group. This led to an adsorbed amount of 17% (w/w) for acetophenone on kerolite clay. [Copyright &y& Elsevier]