FI82611C - Ways to reduce hydrocarbon content in air or water - Google Patents

Description

5 8261 1

Method for reducing the hydrocarbon content of air or water Sätt att minska halten kolväten i luft eller vatten

The present invention comprises a method for reducing the content of organic compounds in air or water.

Recently, there has been an equal interest in emissions of organic matter to air and water from 10 different types of industry. These emissions often cause adverse effects on humans and animals, but although not all adverse effects are yet known, there is a desire to reduce the concentration of organic matter in certain types of emissions before they are released into the environment.

15

Examples of organic substances, especially hydrocarbons, which have been shown to be harmful to nature and humans, are various solvents for varnishing and printing processes, chlorinated hydrocarbons used in purification processes, chlorinated compounds obtained as a by-product from various production processes, by-products from various combustion processes and manufacturing processes.

r So far, the most suitable methods are based on adsorption on activated carbon. The air or water is then passed through a filter containing activated carbon. The activated carbon can then be in a layer or attached to a support such as paper or ceramic material. The activated carbon can also be in the form of a fluidized bed, in which case the air or water to be treated forms a fluidizing agent.

30 Activated carbon has been used for a long time and its benefits in air and water purification are well known. Despite the fact that these known methods have evolved over time, the methods still have certain drawbacks which have not been overcome.

35 The efficiency of activated carbon is low when the concentrations of impurities are low. Furthermore, activated carbon is flammable and cannot withstand high temperatures, which is why the regenerability is very limited when 2,82611 high-boiling molecules are adsorbed. It is still a dirty material and therefore the material is somewhat cumbersome to handle.

In addition to the use of activated carbon, the use of various polymers as an adsorbent has long been discussed. Their properties are in many respects similar to those of activated carbon, for example their adsorption capacity and large surface area compared to several other species of adsorbable molecules. However, they have several disadvantages of activated carbon such as temperature sensitivity and flammability.

10 The disadvantages of the adsorbents known so far are very important for their applicability and it is therefore urgent to find new and more efficient methods for purifying air and water from hydrocarbons.

It is therefore an object of the present invention to provide a method for reducing organic compounds from air and water.

The process according to the invention is characterized in that water or air is passed through a filter comprising a hydrophobic zeolite of the formula HAlSi3s072 or HAlSi25052.

The zeolites used in the invention have been rendered hydrophobic by making their Si: Al ratio high either by direct synthesis or by modifying zeolites with a lower Si: Al ratio.

Normal zeolite is hydrophilic in nature and adsorbs water vapor before organic molecules. By direct synthesis or chemically modifying existing zeolites, zeolites that are hydrophobic or lipophilic can be obtained, thereby increasing their tendency to adsorb organic molecules. Due to their crystal structures, these zeolites can selectively adsorb substances such as phenols, guaiacols, various solvents, degreasers, products from biochemical processes, etc. from air or water.

35 In this case, the dimensions of the crystal structures determine the selective properties, mainly the size of the molecules to be adsorbed.

li 3 82611

The zeolites used in the invention are a crystalline material consisting of silicon, aluminum and oxygen and possibly simple cations such as sodium or hydrogen ions. They are non-flammable and 5 withstand heating to 800-900 ° C. They can thus be subjected to the harsh conditions of regeneration processes. Furthermore, hydrophobic zeo attachments can be treated with mineral acids and thus released from the particles.

Because the crystal structures accurately determine pore sizes and pore openings, they are selective for the molecules to be adsorbed. They act like inverted screens, i.e. they adsorb molecules up to a certain size, which is determined by the crystal structure at the time, while allowing larger molecules to pass through.

Zeolites can be rendered hydrophobic gradually, from fully hydrophilic to fully hydrophobic, allowing the hydrophobicity to be set to a value appropriate to the species of molecule being adsorbed.

Zeolites suitable for use as hydrophobics for use in the invention include heulandite, mordenite, phillipsite, cabazite, natrolite, analyte, clinoptilolite, gmelinite and / or fauiacite.

Among the zeolites which have so far been found to be functional are those with a Si: Al ratio of more than 15: 1, and in particular HA1Si35072 and HAlSijjO0.

The present invention can be applied in various contexts, such as in the separation of relatively small concentrations of toxic substances, especially organic substances, from water. Furthermore, it can be used to separate toxic substances, especially those formed during the combustion of fuels, from the air that is discharged into motor vehicles, boats or buildings. The method can also be used to reduce toxic substances from air discharged into the area of agglomerations 35.

4,82611

Filters can be arranged in the inlet * and outflow channels in different ways. For example, a plurality of filter cartridges may be provided in a collection box to purify dirty water. When the filters are more or less saturated with impurities, they are regenerated by letting in warm air or inert gas. After this regeneration, the solvents can be recovered by condensation.

The filtration can also be arranged in such a way that there are two parallel filter systems at the same time, whereby one is used alternately for filtration while the other is regenerated.

The invention is further illustrated by the following examples, which in no way limit the invention.

15 EXAMPLE 1

Butanol was produced by a continuous chemical fermentation process. When the butanol content had risen to 2.8 percent, the process was interrupted because the alcohol content became too high for the microorganisms. Allowing the process water to pass through the hydrophobic zeolite having a composition of HAlSi35072 reduced the alcohol content and could be kept at a constant level of 0.2%. Butanol was continuously adsorbed on the zeolite and the process solution did not reach the butanol concentrations that are rayr-rich for microorganisms. After the zeolite was saturated with butanol, it was replaced with a new batch of zeolite and the butanol was recovered from the saturated zeolite.

EXAMPLE 2 30 Industrial wastewater with a phenol content of 3% was passed through a regenerable filter. The filter consisted of a hydrophobic zeolite with the composition HAlSi25052. In this way, the phenol content was reduced to 0.01%.

35 5 82611 EXAMPLE 3

The effluent from the pulp alkaline bleaching, which contained low concentrations of chlorophenols and chloroglycols and high concentrations of S in methanol and formic acid, was treated with a hydrophobic zeolite having the composition HAlSi35072 after pH adjustment. The amount of chlorophenols and chloroglycols was reduced to 35%, which means the proportion of compounds with a kinetic diameter of less than about 8 Å.

10 EXAMPLE 4

The effluent from the pulp bleaching, which contained low concentrations of chlorophenols and chloroglycols and high concentrations of formic acid and methanol, was treated directly with a hydrophobic zeolite having the composition HAlSi35072. Concentration of chlorophenols and chloroglycols to about 30%, which means the proportion of compounds with a kinetic diameter of about 8 A.

20 EXAMPLE 5

Exhaust air from the spray varnish chamber containing 200 mg of solvent per cubic meter, mainly xylene and white benzene, was treated with a hydrophobic zeolite having the composition HAlSi35072. The concentration of solvent-25 decreased to 1 mg per cubic meter of air. The adsobed solvent was then distilled off and recovered from the zeolite.

EXAMPLE 6 30

The exhaust air from the spray varnish chamber containing 2800 mg of solvent per cubic meter was treated with a hydrophobic zeolite having the composition HAlSi35072. The solvent content of the treated air decreased to about 1.5 mg per cubic meter. The adsobed amount was distilled and recovered from 35 zeolites.

Claims (1)

A method for reducing the content of organic compounds in air and water, characterized in that air or water is passed through a filter comprising a hydrophobic zeolite of the formula HAlSi35072 or HAlSi25052. To 1 82611 For the reduction of an organic organic compound or a water, a mixture of the air or a water ring 5 passes the genome and the filter or hydrophobic zeolite with the formula HAlSi35072 or HAlSi25052.