FR2693383A1 - Regenerating adsorbents using electrical field - in which adsorbents are in open-ended column treating liq. flow and electrical field is generated between two electrodes - Google Patents

Regenerating adsorbents using electrical field - in which adsorbents are in open-ended column treating liq. flow and electrical field is generated between two electrodes Download PDF

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FR2693383A1
FR2693383A1 FR9207732A FR9207732A FR2693383A1 FR 2693383 A1 FR2693383 A1 FR 2693383A1 FR 9207732 A FR9207732 A FR 9207732A FR 9207732 A FR9207732 A FR 9207732A FR 2693383 A1 FR2693383 A1 FR 2693383A1
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electrodes
absorbent
characterized
method according
regeneration
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FR9207732A
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FR2693383B1 (en
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Flork Michel
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Flork Michel
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01JCHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/30Processes for preparing, regenerating, or reactivating
    • B01J20/34Regenerating or reactivating
    • B01J20/3441Regeneration or reactivation by electric current, ultrasound or irradiation, e.g. electromagnetic radiation such as X-rays, UV, light, microwaves
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01JCHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J49/00Regeneration or reactivation of ion-exchangers; Apparatus therefor
    • B01J49/30Electrical regeneration

Abstract

Process is for the regeneration or elution (washing) of adsorbents (I) in adsorption columns in which a liquid flow is treated. After adsorption, the adsorbents are submitted to an electric field applied by an anode and a cathode (8, 9). Appts. for the process, comprises an elongated receiver with two open ends (12, 13). The major part between these cpds. contains an adsorbent and has two electrodes arranged opposite each other so they can generate an electric field in most of the adsorbent. The electrical field is perpendicular to the flow (F, F1) of the liquid to be treated. At least one electrode is separated from the adsorbent by a membrane (2, 3) permeable to ions. A potential difference of between 1 and 1000 volts is applied between the electrodes. The adsorbent is an ion-exchanging resin, or a mixture of cationic, anionic and nonionic resins. The electrodes are parallel plates. USE - The regeneration or elution of an adsorbent (claimed), in particular anionic, cationic or nonionic resins or a mixture of these. Also used for the demineralisation of water, the extraction of nitrates and nitrites and the separation of amino acids.

Description

 The present application relates to a new process for regenerating or eluting absorbents, and to implementing devices.

 It has long been known to regenerate anionic or cationic resins, that is to say anion or cation exchangers, respectively, with a base or an acid. It is also known to regenerate certain absorbents by modifying the ionic strength or the pH.

 However, if the use of reagents to regenerate was envisaged very early, these processes encountered a certain number of difficulties, which limit their industrial exploitation, or their diffusion to other techniques. The eluates or the regenerates are systematically mixed with the reagents. Handling reagents is dangerous (generally strong acid or base). Wash volumes are important to remove excess reagents.

 In order to simplify the regeneration in the use of resins for water treatment, these resins are usually used in permutation of ions with regeneration with sodium chloride. In this case, for example, the sodium fixed on the resin is gradually replaced by calcium. But the sodium ion pollutes the treated solution, and it takes a very large excess of sodium chloride to shift the balance and regenerate the resin.

 In addition, the chemical regeneration time is long and lasts several hours.

 Finally, it is known that resins in mixed beds are much more effective than anionic or cationic resins because the anions interfere with the fixation of the cations, and the cations those of the anions. In mixed beds, the anions and the cations are fixed simultaneously, which leads to very extensive demineralization of the treated solutions.

 However, all the techniques used have never made it possible to regenerate the resins in mixed beds. Indeed, the regenerating reagent of the first resin is fixed on the second, and that of the second on the first.

 It would therefore be desirable to find a method allowing rapid and efficient regeneration of ion exchange resins, absorbent resins or any absorbent in a heterogeneous medium.

 It would therefore be desirable to find a process allowing the regeneration of ion exchange resins in an anionic-cationic mixed bed.

 This is why the subject of the present invention is a process for the regeneration or the elution of absorbents from absorption columns in which a flow of liquid is treated, characterized in that said absorbents are subjected after absorption to l action of an electric field applied by an anode and a cathode.

In the present invention and in the following
By "regeneration" is meant that the partially or fully saturated absorbent is treated to regain its substantially initial fixing capacity
By "elution" is meant that the elements fixed on the absorbent detach from it, in particular to be recovered.

 By "absorbents" is meant absorbents of any type capable of fixing molecules and ions, in particular granular coals, resins, very particularly ion exchange resins, both anionic, cationic and non-ionic.

 The process according to the invention can be implemented on resins of the same ionicity or also as a mixture, in particular anionic and cationic, in all proportions.

 By "absorption columns" is meant a container of any suitable shape, in particular of cylindrical section (columns stricto sensa) or parallelepiped (section column) containing an amount of absorbent contained in. The columns are preparative columns, opposite the columns and analytical plates of small dimensions and / or flow.

 The electric field is applied using at least two electrodes: an anode and a cathode, therefore using direct current.

 The voltage and amperage used can vary widely, however it is desirable to avoid increasing their values too much to avoid unwanted heating.

 Very suitable values for the intensity are for example less than 1 mA for an element of 100 cm 2 of surface per electrode and of a thickness of resin separating planar electrodes of 1 cm, and of approximately 1 mA for an element of 400 cm2 of surface per electrode and of the same thickness. Depending on the case, the intensity can go up to 10 amps.

 In these conditions a voltage of 20 to 200 volts is quite suitable, but values of 1 volt and less to 1000 volts and more are also usable.

 The electrodes can be of any suitable nature, but metal electrodes, in particular platinum or stainless steel, as well as carbon, for example braided carbon, or graphite, electrodes are preferred.

 The present invention also relates to a device designed for the implementation of the method described above.

 This device comprises a container provided with two open ends of which a part capable of receiving an absorbent included between said ends is provided with at least two electrodes opposite one another arranged so as to be able to generate an electric field on the major part of the absorbent.

 The present invention also relates to such devices containing at least one absorbent, in particular a resin, particularly an ion exchange resin, very particularly in mixed beds.

 In its simplest forms, such a device is for example constituted by two parallel rectangular or square current-carrying plates constituting the electrodes, connected to each other by electrically insulating rectilinear walls, thus constituting a sort of tube of rectangular or square cross section. open at two opposite ends, one used for the arrival of the liquid to be treated and the other for the exit of the treated liquid.

 The space between the plates can be completely or partially filled with an absorbent, for example with an ion exchange resin retained at least at its lower part if the outlet orifice is located at the bottom of the device by a screen or filter .

 The electrodes can be connected to a direct current generator.

 The arrangement of the electrodes is such that preferably all of the absorbent is subjected to the electric field when current flows through the circuit.

 It is for example made up of a cylindrical tube, for example made of glass, comprising inside electrodes having for example the shape of two half-tubes of smaller diameter to match the shape of the external tube, without however being in direct contact with one or the other, the space between the electrodes can thus be filled with absorbent.

 However, under preferential conditions, at least one and preferably two electrodes are not in direct contact with the absorbent.

 They are separated from the absorbent by an ion-permeable membrane, for example made of woven synthetic fabric and are contained in a compartment itself provided at two ends, preferably opposite, with liquid inlet and outlet ports; the circulation of liquid in the compartment of an electrode makes it possible to wash the electrode concerned, and thus to recover the ions fixed on it. We can thus recover on the one hand the anions, on the other hand the cations and proceed to the elution and regeneration of the column.

 Indeed, once the column is conventionally used, for example to demineralize water or to make it drinkable, to regenerate the column, it suffices to send the direct current, for example 20 to 30 seconds, and the column is regenerated.

 In the case of a simple installation, one can, while keeping the current connected, empty the column and place the regenerated resin in another column.

 In the case of the use of permeable membranes to separate the electrodes from the absorbent, it is not necessary to change the absorbent from the column; direct current is sent, the electrodes are rinsed by circulation of liquid such as demineralized or ordinary water while maintaining the electric field to prevent the return of the ions towards the absorbent, then the liquid to be treated can again be sent to the regenerated column, after having cut the current.

 The implementation of the method and the device according to the present invention provide remarkable advantages; in particular, they allow the regeneration of mixed anionic-cationic columns.

 They allow a very rapid complete regeneration, without manipulation of regeneration liquids, of the absorbent column. The duration of a regeneration can range from 10 seconds to 30 minutes, and preferably from 30 to 60 seconds.

 They allow cycles of use of the column at very close intervals, even in the case of resins.

 They make it possible to avoid the use of polluting and caustic regenerating reagents such as strong bases (NaOH, KOH, etc.) and strong acids (HCl, H2SO4, etc.).

 The elution phase which is necessary to displace the products fixed on the absorbent is unnecessary. The regeneration according to the invention also makes it possible to separate the anions from the cations.

The applications of the present application are numerous, there may be mentioned in particular - the regeneration of absorbents, in particular - the regeneration of anionic resins, - the regeneration of cationic resins - the regeneration of nonionic resins - the regeneration of resins in mixed beds - regeneration of absorbents and resins in mixed beds - demineralization of water with resins in beds
mixed regenerated by electric field - elimination of nitrites, nitrates and other pollutants
by resin in mixed beds regenerated by electric field - the depollution of water by absorbent resins in beds
mixed, regenerated by electric field - separation of amino acids on exchange resins
of ions with desorption by electric field.

 Figure 1 shows schematically a column according to the invention seen in longitudinal section in elevation.

 Figure 2 is a section along XX 'of Figure 1 but with the electrodes attached to the outer wall.

 The view in FIG. 1 is analogous whether the column is a column with parallel plates, or whether the column is cylindrical (section made at the level of a diameter); on the other hand, a section along an axis perpendicular thereto would in the first case be a rectangle (see FIG. 2), in the second substantially cylindrical case.

 We place ourselves below in the first case.

 There is an absorbent 1, for example an ion-exchange resin in anionic-cationic mixed beds held between two walls 2, 3 permeable to ions. These walls 2, 3 constitute, with more external walls 4, 5 of the device, compartments 6, 7 containing electrodes 8, 9 for example made of braided carbon or graphite. The electrodes 8, 9 can be attached to the outermost wall 4, 5, or not as shown.

 The absorbent is held by sieves 10, 11 allowing total retention of the absorbent while being a minimum obstacle to the circulation of the flow of liquid to be treated F, and of the treated liquid F1.

 When it is estimated that the absorbent is starting to lose its efficiency, regeneration can be carried out by applying for example for 45 seconds an electric field, by establishing a potential difference of 20 volts between the electrodes 8, 9. The ions fixed on the absorbent 1 then migrate to the electrodes 8, 9, and maintaining the field we send in R a rinsing liquid making it possible to recover in R1 separately the anions and the cations.

 The above device is shown vertically but can also be used if desired horizontally.

 Instead of using two electrodes, one could obviously put for example two anodes, for example with a surface half that of a single cathode, and a cathode, or two surface cathodes of each.

 An identity of the electrode surfaces, although preferred, is no more critical.

 In FIG. 2, a distinction is made between the walls 12, 13 which have the mechanical function of maintaining and constituting the enclosures 6, 7 containing the electrodes 8, 9. It can be seen that the electrodes are here substantially flat and parallel.

The examples which follow illustrate the present invention without however limiting it.
EXAMPLE 1
A sodium chloride solution is percolated on a plate column containing a 50/50 mixture of anionic Duolite A 101 (R5hm and Haas) and cationic resins
Duolite C 20 (Rahm and Haas). The water after percolation is completely deionized. A DC voltage of 24 volts is applied between the two 10 x 10 cm carbon electrodes 1 cm apart. The chloride ions are moved to the anode and the sodium ions to the cathode.

EXAMPLE 2
Hard water of 25 TH is percolated on a plate column containing a 50/50 mixture of anionic and cationic resins. As above, the water after percolation is completely deionized. A voltage of 200 volts DC is applied between the two electrodes, in graphite of 20 cm by 20, for 20 seconds.

 The electrodes are washed simultaneously with a low water flow, perpendicular to the field. The calcium and carbonate ions are displaced and recovered in the electrode washes. It is possible to repeat this cycle a very large number of times, without any alteration in the quality of the water obtained (more than 1000 cycles).

EXAMPLE 3
Water loaded with metallic salts such as waste water from the electroplating industries is percolated on a plate column containing a 50/50 mixture of anionic and cationic resins. As above, the treated water is completely deionized. Metal ions in solution are not detectable. The column is then subjected to an electric field of 20 volts / cm. The regeneration time is less than 2 min. The ions are cadmium and dichromate eliminated 10 cm by 10 by washing the electrodes with a volume of less than 1% of the volume of polluted water treated.

EXAMPLE 4
Water containing mineral salts and ionic and non-ionic organic compounds, namely a liquid discharge from pig farms of chemical oxygen demand (COD) of approximately 5000 mg / l, is percolated on two columns with plates 10 cm by 10.

 The first contains an absorbent support (Ceca charcoal granules), the second a resin of sulfonic type C 20 mixed in equal parts with a quaternary ammonium resin A 101.

 The water leaving the percolation of the two columns is of demineralized quality with a COD <30 mg / l.

 An electric field of 20 volts / cm is applied for 2 min between the electrodes of the two columns, with simultaneous washing of the two electrodes. The set of two columns in series is ready to be reused immediately.

EXAMPLE 5
A mixture of glutamic acid and arginine is percolated on C 20 sulfonic resins and A 101 quaternary ammonium resins in 50/50 mixed beds. The fixation is total.

Desorption is carried out by an electric field of 20 volts / cm between two electrodes of 10 cm by 10 in braided carbon fiber. Glutamic acid is collected by washing one electrode and arginine on the other.

Claims (12)

 1. Method for the regeneration or elution of absorbents (1) of absorption columns in which a flow of liquid is treated, characterized in that the said absorbents are subjected after absorption to the action of a field electric applied by an anode and a cathode (8, 9).
 2. Method according to claim 1, characterized in that the electric field is substantially perpendicular to the flow (F, F1) of the liquid to be treated.
 3. Method according to claim 1 or 2, characterized in that at least one electrode (8, 9) is separated from the absorbent (1) by a wall (2, 3) permeable to ions.
 4. Method according to one of claims 1 to 3, characterized in that a potential difference of 1 to 1000 volts is applied between the electrodes.
 5. Method according to one of claims 1 to 4, characterized in that the absorbent is an ion exchange resin.
 6. Method according to one of claims 1 to 4, characterized in that the absorbent is a nonionic resin.
 7. Method according to one of claims 1 to 4, characterized in that the absorbent is a mixture of resins chosen from cationic, anionic and nonionic resins.
 8. Device for implementing the method according to one of claims 1 to 7, characterized in that it comprises a container of elongated shape provided with two ends (12, 13) open and of which a major part capable of containing an absorbent included between said ends (12, 13) is provided with at least two electrodes opposite one another arranged so as to be able to generate an electric field over the major part of the absorbent.
 9. Device according to claim 8, characterized in that the electrodes are parallel plates.
 10. Device according to one of claims 8 and 9, characterized in that at least one electrode (8, 9) is separated from the absorbent (1) by a wall (2, 3) permeable to ions.
 11. Device according to one of claims 8, 9 or 10, characterized in that the potential difference applied between the electrodes ranges from 1 to 1000 volts.
 12. Application of the method according to claims 1 to 7 or of the device according to claims 8 to 11 to the regeneration or ltélution of an absorbent.
FR9207732A 1992-06-24 1992-06-24 New process for the regeneration or elution of absorbents, and devices for implementing same. Expired - Fee Related FR2693383B1 (en)

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FR9207732A FR2693383B1 (en) 1992-06-24 1992-06-24 New process for the regeneration or elution of absorbents, and devices for implementing same.

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FR9207732A FR2693383B1 (en) 1992-06-24 1992-06-24 New process for the regeneration or elution of absorbents, and devices for implementing same.

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FR2693383A1 true FR2693383A1 (en) 1994-01-14
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2739693A1 (en) * 1995-10-09 1997-04-11 Korea Electric Power Corp Continuous regeneration cationic column for measuring electrical conductivity of water

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB744059A (en) * 1952-02-23 1956-02-01 Chem Fab Budenheim Ag Method of recovering ammonia from dilute aqueous solutions containing ammonium ions
DE1054419B (en) * 1954-05-07 1959-04-09 Basf Ag A process for the regeneration of ion exchangers
FR1229010A (en) * 1959-03-19 1960-09-02 Commissariat Energie Atomique electrolytic regeneration of an ion exchanger mixed bed used in the deionization water
EP0337050A1 (en) * 1988-03-11 1989-10-18 CILLIT WASSERTECHNIK GMBH &amp; CO. Process and apparatus for the partial or total demineralisation of water
US5078842A (en) * 1990-08-28 1992-01-07 Electric Power Research Institute Process for removing radioactive burden from spent nuclear reactor decontamination solutions using electrochemical ion exchange

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB744059A (en) * 1952-02-23 1956-02-01 Chem Fab Budenheim Ag Method of recovering ammonia from dilute aqueous solutions containing ammonium ions
DE1054419B (en) * 1954-05-07 1959-04-09 Basf Ag A process for the regeneration of ion exchangers
FR1229010A (en) * 1959-03-19 1960-09-02 Commissariat Energie Atomique electrolytic regeneration of an ion exchanger mixed bed used in the deionization water
EP0337050A1 (en) * 1988-03-11 1989-10-18 CILLIT WASSERTECHNIK GMBH &amp; CO. Process and apparatus for the partial or total demineralisation of water
US5078842A (en) * 1990-08-28 1992-01-07 Electric Power Research Institute Process for removing radioactive burden from spent nuclear reactor decontamination solutions using electrochemical ion exchange

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2739693A1 (en) * 1995-10-09 1997-04-11 Korea Electric Power Corp Continuous regeneration cationic column for measuring electrical conductivity of water

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