Gas purification techniques

Alkaline oxidating scrubber

Alkaline oxidating scrubbing is specially used for fragrance purification. The organic odor-components in alkaline environment are being oxidized at pH 7 - 10.
Some examples which can be used as strong oxidans are sodium hypochlorite (NaOCl), potassium permanganate (KMnO₄) or hydrogen peroxide (H₂O₂). With potassium permanganate MnO₂ is formed that has to be removed periodical from the washing liquid. With the use hypochlorite are chlorides formed and with hydrogen peroxides no by-products are formed. Hydrogen peroxide is however a less strong oxidant than hypochlorite or permanganate.
Since fragrance disposal can be relative complex concerning the
composition of the fragrance components, it's suitable to carry out with preceding pilot-tests to stipulate the specific disposal efficiency.
If amines are present in the off gases, it is preferably to firstly carry out a
acidous scrubber to avoid the forming of chlorine amines.

Components which cause odor-problems frequently have a rather low odor threshold. The concentrations of the components to remove are frequently on the sub-ppm the ppb level. For components with an extremely low odor threshold like e.g. mercaptants, it's difficult to bring the rest-concentration under the odor threshold.
The removal output depends on the oxidating capacity of the components and the stay time in the scrubber. An increase of the stay time requires a larger installation and higher investment costs.

De advantages of the scrubber is:

Capable of a removal efficiency of 95%

The disadvantages are:

Use of strong oxidating reagents asks the necessary safety measures and a special design of the installation

The application of these type of odor removing installations are mainly used at the food industry, fertilizer producers, slaughterhouses, odor production and textile industry.

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