KR0125587B1 - Methed for the disposal of used ion-exchangers and/or absorber resins - Google Patents

Abstract

The present invention relates to a process for treating used synthetic resin ion exchangers, which are mostly in the form of granules, comprising carbonizing the ion exchangers in a substantially inert atmosphere at temperatures between 300 ° C. and 900 ° C., followed by carbonization of the ion exchangers. It consists of activating the same in an oxidizing atmosphere to convert to activated carbon granules.

Description

Treatment method of used ion exchanger

The present invention relates to a method for treating used synthetic resin ion exchangers which are mostly in the form of granules.

Synthetic resin ion exchangers are porous polymers having numerous chemical groups with exchangeable ions. Generally it consists of a copolymer skeleton of styrene and divinylbenzene or styrene and acrylic acid, which have an acid group, in particular a sulfonic acid group, in the cation-exchange and a basic group (amine) in the anion-exchange. Depending on its functional group, it may be present as a cation- or anion-exchange resin, or may be present as an adsorbent, and may be a polymer selected from the group consisting mainly of polystyrene resins, polyacrylic resins, polyalkylamine resins or phenol-formaldehyde resins. Organic ion-exchangers of the kind having resin matrices are described in Ullmann's Encyclopedia df Industrial Chemistry, Fifth Edition, Volume A 14, VCH- Verlagsgesellschaft mbH, Ion exchanger chapters in Weinheim, Germany 1989, in particular on page 394-398. , Dowex, Kastel, Diaion, Relite, Purolite, Amberlite, Duolite, Imac, Ionac, Wofatit. Numerous applications of ion exchange resins are also described on pages 399-448 of the chapter cited above.

The main purpose of using ion exchangers is to exchange undesirable ions present in water with less harmful ions and to remove ions completely. Ions that generate hardness—basically, Ca ²⁺ and Mg ²⁺ are exchanged with Na + ions for hard water. Removal of cations and anions results in deionized water. Soft water is required, for example, in the textile industry and deionized water is needed in steam generation, especially in high pressure boilers.

In general, ion exchangers are not effective because their pores are blocked by obstacles, i.e., inorganic particles such as suspended particles or iron compounds. The latter is washed off regularly, but over time more holes are gradually blocked, eventually replacing the bed. At this point, processing problems occur. As long as there are no ions polluting the environment, the used ion exchangers can be disposed of in the waste heap.

Inert particulate organic ion-exchanger resins are contaminated with large amounts of inorganic or organic external substances such as all kinds of suspended particles, sludges, microorganisms, algae and various cations such as sodium, potassium, iron, and calcium ions. The amount of these impurities usually amounts to 20% by weight based on dry matter. Particulate ion exchange resins to be treated have a water content which can reach up to 50% by weight in most cases.

The subject matter of the present invention is a method of treating the used particulate organic ion exchanger of the kind mentioned above, which is mainly carbonized at a temperature of 300 ° C. to 900 ° C. in an inert atmosphere and then activated in an oxidizing atmosphere, and thus the ion exchange. Converting the sieve to activated carbon spherulet.

Specifically defined and polysulfonated macroporous cross-linked vinylaromatic polymers are known (US-PS 4,957,897). Sulphonic acid groups are released during pyrolysis and radical sites are produced which lead to a strongly cross-linked structure that is insoluble and contains almost no volatile carbon.

It is surprising, however, that high quality wear-resistant activated carbon granules can be produced by pyrolysis from heavily contaminated used resin ion exchangers and that various foreign materials do not impair the quality and stability of the adsorbent. Surprisingly enough, the macro- and mesoporous structure of the feedstock is maintained during the decomposition and carbonization of the impurities. Accumulated organic and biological products are destroyed or disappear without forming any significant carbon residues, especially if carbonization is carried out in a weak oxidizing atmosphere.

In the cation-exchange resins used, cations are usually bound to sulfonic acid groups and are essentially transferred to sulfuric acid at temperatures up to 400 ° C. At higher temperatures they are reduced by carbon to a significant amount of sulfides. Therefore, it is useful to first convert the cation-exchange resin into H + form before carbonization. This is preferably done by washing the acidic wetted material before drying.

As already mentioned, it is recommended to dry the used particulate resin which is treated in order to remove water content which can be up to 50% of the particulate organic ion-exchange resin, preferably in a tumble dryer or in a fluidized bed. Before reaching the softening point and usually after drying, the resin ion-exchanger is preferably powdered with an inert inorganic powder, preferably carbon powder, thereby preventing agglomeration and maintaining the particulate structure during the entire treatment. .

To temperatures up to 400 ° C., preferably from about 300 ° C. to 350 ° C., the inert atmosphere of the carbonization step may comprise 0.2 to 4 volume percent oxygen. The oxygen content is preferably controlled by the addition of air. This pre-oxidation differs in terms of destruction of organic impurities, as well as in terms of reduction of volatile carbon by oxygen bridges and radical sites with powdering and / or slow temperature rise, and melting or together Recommended in preventing sticking. Particular oxidation is very important when the resin does not contain sulfonic acid groups such as anion-exchange resins or adsorbent resins. It is recommended to treat this resin type with a cation-exchange resin containing sulfonic acid groups.

Small amounts of cations, such as alkali and alkaline earth metal ions, selected from the group consisting of sodium, potassium, or calcium, are already converted to sulfuric acid at the beginning of pyrolysis, which surprisingly enough does not interfere with carbonization and activation and even initiate the activation step. Promote Carbonization at about 700 ° C. is followed by an activation step of the carbonized material. Similar to carbonization it may be carried out in a tumble dryer or more preferably in a fluidized bed. Steam and / or carbon dioxide is added in an amount of 3 to 50, preferably 3 to 15 volume percent, to an essentially inert atmosphere to activate the material. The activation temperature may be up to 900 ° C. In order to save energy, activation can be carried out in the same device after carbonization. However, for specific technical and processing reasons it may be useful to perform the activation in a separate and independent step, which means that the carbonization step up to a temperature of about 500 ° C. has already lost 60 to 90% of the weight loss and significant It is accompanied by contraction. The carbon content of the activated carbon granules after the activation step is 90% by weight or more.

Example 1

1 kg of macroporous ion-exchangers, present in H + form, used for fuel additive (MTBE) synthesis and composed mainly of styrene and divinylbenzene inactivated, were dried in a tumble dryer at 110 ° C. The weight loss caused by the evaporation of hydrocarbons and some moisture was approximately 13%. It was then heated to 300 ° C. in an atmosphere consisting of 80% inert gas and 15% air and maintained for 1 hour. The weight increase was about 8%. There, the temperature increased to 700 ° C. in an inert atmosphere within 3 hours.

5% steam was added in the range of 700 ° C to 900 ° C.

The temperature increase lasted for 30 minutes from 700 ° C. to 820 ° C. and reached 900 ° C. within an additional 10 minutes. The yield was 28% based on the feedstock. Aggregation of the municipalities did not occur at any time. A diameter reduction of 0.6 to 0.7 mm was observed at approximately 0.8 mm. The apparent density of the granules was 1.08 g / cm 3 at a hole volume of 0.9 ml / g or more, of which 0.55 ml / g was micropores. The specific surface of 1088 m 2 / g was determined by the BET method. The 0.5 mm grains can be loaded with a 300 g point load without breaking.

Example 2

1 kg of the gel-type cation exchanger used for softening water and lacking sufficient activity was converted to H + using hydrochloric acid solution. After air drying of the surface, the moisture was 50%. After drying at 110 ° C., it was oxidized at 300 ° C. for 6 hours. The method of Example 1 was then applied. The yield was 31% relative to the feedstock. The granules were partially aggregated.

Example 3

The method of Example 2 was applied to the same feedstock in the same manner. However, after oxidation at 300 ° C., powdering was performed with 5% carbon powder and the temperature was increased to 700 ° C. within 6 hours. Thus, aggregation of the granules and formation of an inflated structure were prevented. The inner surface of the obtained activated carbon particles reached approximately 1000 m 2 / g (BET) and the yield was 40% relative to the feedstock. The average burst pressure was 250 g at a diameter of 0.5 mm. In addition, a large pore adsorbent resin, mainly consisting of divinylbenzene-copolymers, was treated in the same manner, and the resin contained organics that had already been exhausted and subsequently adsorbed. Since these products do not contain any sulfate groups, pre oxidation is particularly important.

Claims (13)

In the method of treating the particulate organic ion-exchanger used, carbonizing the ion-exchange body in a substantially inert atmosphere at a temperature of 300 ° C. to 900 ° C., and then converting the ion-exchange body into activated carbon granules. Activating the same in an oxidizing atmosphere to convert it. The method according to claim 1, wherein the ion-exchanger comprises a cation-exchange, a sulfonated styrene-divinylbenzene copolymer or a styrene-acrylic acid copolymer. The method according to claim 1 or 2, wherein the cation-exchanger used is in the H + form. 2. The method according to claim 1, wherein an ion-exchange resin, an anion-exchange resin, a polyacrylic resin or a polystyrene resin having a tertiary or quaternary amine group is used. The method of claim 1 wherein the ion-exchange resin used is dried prior to carbonization. The method of claim 1 wherein the inert atmosphere during carbonization comprises a temperature of 300 ° C.-400 ° C., 0.2-4% by volume of oxygen. 7. The method of claim 6, wherein the ion-exchange resin is replaced in part or in whole with particulate organic sorbent resin. The process according to claim 1, wherein steam is supplied to a substantially inert atmosphere in an amount of 3 to 50% by volume to activate the carbonized material at 700 ° C to 900 ° C. The method of claim 1 wherein the carbon dioxide is fed to a substantially inert atmosphere at 700 ° C. to 900 ° C. during carbonization. The method of claim 1 wherein the activation is performed in a separate step. 2. A method according to claim 1, wherein the particulate ion-exchange resin is powdered together with the inert powder before reaching the softening point. The method of claim 1 wherein the treatment is performed in a fluidized bed or a tumble dryer. Activated carbon granules of high stability prepared according to claim 1.