DE4026373A1 - Extn. of heavy metals and toxic organic substances - using a mixt. of low aliphatic mono:carboxylic acid and butyl acetate - Google Patents

Abstract

A mixt. of low aliphatic carboxylic acids with up to 7C with butyl acetate, esp. sec. butyl acetate of isobutyl acetate, is used for leaching out of heavy metals together with toxic organic cpds. form contaminated substrates. USE/ADVANTAGE - The addn. of butyl acetates to low aliphatic monobasic acids such as formic acid, acetic acid and propionic acid as used for extn. of heavy metals from contaminated substrates such as soils, sludges and dusts as described in DE3716646, allows simultaneous extn. of toxic organic substances such as organic halides, polychlorinated biphenyls, chlorodioxines and furans. The extn. can be carried out at reflux using the butyl acetate also for azeotropic removal of water from the substrate, with return of the butyl acetate to the medium after condensn. and sepn. of the water. (2pp Dwg.No.0/0)

Description

According to DE 37 16 646.8, it is already known to use heavy metals from earth, sludge and dust monobasic organic acids such as methane, ethane and Propionic acid pure or in mixtures of different Solve composition and the dissolved heavy metals from separate the remaining inert substances. Now in the in most cases not only to clean heavy metals in the earth, mud and dust. Almost always fin which are also more or less organic compounds, such as the organic halides called EOX, polychlo biphenyls (PCB) and especially chlorine dioxins and fu rane in the material to be cleaned.

While some of these toxic substances are named according to the above mentioned publication removed, there remain but possibly more than the permissible quantities treatment for inert substances.

Experiments have now shown that one can be trusted at the same time sig Remove heavy metals and organic compounds can if you have more or less small amounts of esters which adds ethanoic acid to the acids or their mixtures. However, not all esters have the desired effect. It it was found that only those esters which are not used Transesterification tend to be and a complete solubility in the used acids or mixtures thereof.

It is also advantageous that the boiling points of the esters and the ethanoic acid are approximately the same, since then also at the boiling points can be extracted.  

This fact is given when the butyl esters are the vinegar acid can be used. It can all with the same effect Butyl esters used in any ratio with each other will.

The following example shows an execution of the procedure explained, but without the method of working on it lay.

example 1

A 1000 g sample taken from heavy metals and oily mud contaminated soil from a former Ze The area around Völklingen is divided equally. It 500 g for experiment I are only made with an acid mixture Set methane and ethanoic acid. Experiment II became the Acid mixture, while maintaining the total quantity ratio ses, sec. Butyl acetate added.

The leach was under at a temperature of 85-90 ° C Reflux was carried out for 40 minutes.

After cooling and filtration, the filtrates from I and II steamed dry. The residue from experiment I was made of 9% heavy metals and 2.2% tarry substance.

The residue from experiment II was 9% heavy metal and 11.9% tarry substance. Checking the inert residue on volatile substances by heating to 600 ° C gave at I a loss of 9.7%, while there was no loss in II.

The result of experiment II thus confirms that all orga niche substances were extracted.  

Another advantage of adding butyl acetate to the ent removal of heavy metals and toxic organic ver Binding is that of the earth to be treated moisture or other materials the evaporation of the leachate filtrate as an azeotrope with the Butyl acetate to be removed. This way is always ensures that the concentration of acid used mixture remains constant, what a perfect and he required extraction of heavy metals and toxic organic compounds is necessary.

During evaporation, e.g. B. in experiment II of the example, evaporate 100 ml of butyl acetate. With a composition of the butyl acetate / water azeotrope (bp 90.2 ° C) of 73.3 to So 26.7, about 36.4 ml of water are discharged. At con densation form two phases, of which the aqueous phase separated and the butyl acetate phase is returned. The Acid / butyl acetate mixture can therefore be replaced by the for the heavy metal acetates formed consumed acid in the desired original concentration be det.

The addition of an auxiliary component to the azeotropic Distillation avoided, which simplifies the process Procedure leads.

The addition of butyl acetate, especially sec. Butyl acetate and iso-butyl acetate to lower organic carboxylic acids offers two advantages. First is the perfect extract on of organic components possible, secondly omitted the time-consuming concentration of the acetic acid used water introduced by the substances to be treated remove.

Claims (3)

1. Addition of butyl acetate, especially sec. Butyl acetate and iso-butyl acetate, to lower aliphatic carboxylic acid with up to 7 carbon atoms in the molecular chain simultaneous, complete leaching of heavy metals and toxic organic compounds. 2. The method according to claim 1, wherein butyl acetate as an adjuvant for azeotropic distillation for, by the to be treated Water introduced into the material to be discharged is used. 3. Return of the butyl acetate after condensation and separation of water in the process.