FR3031739A1 - PROCESS FOR TREATING AN AQUEOUS SOLUTION CONTAINING METALLIC IONS - Google Patents

Abstract

The present invention relates to a method of treating an aqueous solution SA1 containing metal ions, comprising the steps of: (a) preparing particles by functionalization of polyurea particles with 8-hydroxyquinoline or a derivative thereof; (b) dispersing these particles in the SA1 aqueous solution; (c) complexing the metal ions of the SA1 solution by forming bonds between the metal ions and the particles; (d) separating the particles and the aqueous solution SA1.

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a process for extracting the metal ions contained in an aqueous solution, by using functionalized polyurea particles.

The field of use of the present invention relates in particular to the treatment of wastewater. PRIOR STATE OF THE ART For environmental reasons, the treatment of wastewater presents a major challenge for the future. In fact, these wastewaters, which often come from industrial sites, can contain significant quantities of metals. The recovery of these metals is of interest in view of their potential harmfulness to health and their value. For this reason, many methods have been developed to treat wastewater by metal removal. These methods use various techniques and include in particular: neutralization processes with alkalis which make it possible to recover the metals by complexation; processes for forming insoluble salts which precipitate metal compounds; ion exchange processes which remain complicated to implement on an industrial scale.

For example, US 2014/0295162 discloses a device for collecting metals using a textile based on organic polymer fibers. This polymer includes functions for chelating metal ions.

Be that as it may, these processes are not satisfactory in terms of cost and / or yield.

The Applicant has developed a process in which particles based on polyurea make it possible to extract the dissolved metals in water. This is a simple process to implement and inexpensive, in which particles bind by complexing the dissolved metals in water.

SUMMARY OF THE INVENTION The present invention relates to a method for removing at least a portion of the metal ions contained in an aqueous solution by means of water insoluble particles. This process is particularly suitable for the treatment of wastewater which may contain heavy metals, and more generally any kind of dissolved metal ions.

More specifically, the present invention relates to a method of treating an aqueous solution SA1 containing metal ions, comprising the following steps: (a) preparation of particles by functionalization of polyurea particles with 8-hydroxyquinoline or one of its derivatives; (b) dispersing these particles in the SA1 aqueous solution; (c) complexing the metal ions of the SA1 solution by forming bonds between the metal ions and the particles; (d) separating the particles and the aqueous solution SA1. In general, the metal ions are metal cations. This process uses specifically functionalized polyurea particles to be able to complex metal ions. In general, the metal ions may be ions of a metal selected from the group consisting of alkaline earths; lanthanides; actinides; and transition metals, especially copper; Mercury ; manganese; money; the iron ; chromium; vanadium; nickel; aluminum; europium; or arsenic. These metal ions can be in various degrees of oxidation.

Preferably, the polyurea particles are in spherical form. Their diameter is advantageously between 0.1 and 20 microns, more advantageously between 1 and 10 microns, and even more advantageously between 2 and 10 microns. By way of example, the polyurea particles may correspond to the compound whose CAS number is 37955-36-5. Typically, the polyurea corresponds to the formula (NH-C (= O) NH-R1-NH-C (= O) NHR1). in which n is an integer advantageously between 1 and 500. The R 1 group is advantageously a hydrocarbon chain, preferably C 1 -C 12, or a phenyl group. According to one particular embodiment, the group R1 may comprise branching and / or unsaturations and / or heteroatoms. It may be a long chain aliphatic, with or without branching (s), but also a cyclohexane heterocycle, or phenyl. Advantageously, the entirety of the metal ions contained in the SA1 aqueous solution is trapped by complexation with the particles.

The complexation of the metal ions corresponds to the formation of a coordination compound between a metal ion and an organic compound comprising groups capable of forming bonds with the metal ion. In the present case, the OH group (or the oxygen atom) at the 8-position and the nitrogen atom of the quinoline group allow the complexation, the quinoline group (I) being the following: (I) hydroxyquinoline corresponds to the following formula (II): OH The 8-hydroxyquinoline derivatives correspond to the substitution of the quinoline group (I) in the 2-position preferentially. The substituents may in particular be alkyl, hydroxyl or amino groups.

By way of example, the 8-hydroxyquinoline derivatives (CAS No. 148-24-3) may especially include the following compounds: - 2,8-quinolinediol (CAS No. 15450-76-7); 2-amino-8-quinolinol (CAS number 70125-16-5); and 8-hydroxy-2-quinoline carboxamide (CAS No. 6759-79-1). Thus, the functionalized polyurea particles make it possible to ensure a surface interaction with the metal ions by virtue of the presence of the 8-hydroxyquinoline compound or its derivatives. . Although the polyurea particles are insoluble in water, the functional group (8-hydroxyquinoline or its derivatives) can ionize in water and thus allow the complexation of metal ions. Functionalization of the polyurea particles is advantageously carried out by formation of azo bonds (N = N) between the polyurea and the planar group consisting of the quinoline group. This type of bond is not rigid and is very prone to isomerize. It provides flexibility properties of the connection, and therefore a better complexation in three dimensions. Once grafted onto the polyurea, the 8-hydroxyquinoline compound, or one of its derivatives, always has an OH group at the 8-position of the quinoline group.

The grafting is advantageously carried out at the carbon at the 5-position of the quinoline group (I). As already indicated, the 8-hydroxyquinoline compound and its derivatives make it possible to complex the metal ions by virtue of their chelating properties originating from the nitrogen atom on the heterocycle and the OH group (or the oxygen atom) in According to a particular embodiment, the functionalization of the polyurea particles (step (a)) can comprise the following steps: (i) preparation of an aqueous suspension of polyurea particles; (ii) forming a diazonium salt on at least one NH group of the polyurea; (iii) functionalizing the polyurea particles by adding, to the aqueous suspension containing the diazonium salt, 8-hydroxyquinoline or a derivative thereof.

Step (ii) is advantageously carried out by adding, to the suspension Si, at least one nitrosating agent and at least one acid. Step (ii) is even more advantageously carried out by adding, to the Si suspension, an aqueous solution S2 comprising at least one nitrosating agent and at least one acid. In this case, step (iii) uses a mixture S1 + S2. The nitrosating agent is advantageously sodium nitrite NaNO 2. The acid is advantageously hydrochloric acid HCl or sulfuric acid H 2 SO 4. During step (ii), the suspension Si is advantageously at a temperature between -5 and 5 ° C., more advantageously between 0 and 5 ° C. Further, in step (ii), the solution S2 is preferably at a temperature of -5 to 5 ° C, more preferably 0 to 5 ° C. The mixture S 1 + S 2 corresponds to an aqueous suspension of polyurea particles of which at least one NH group forms a diazonium group. This mixture is advantageously stirred, for example by mechanical stirring, at a temperature between -5 and 5 ° C, for a period of time ranging from 0 to 5 minutes. In step (iii), the suspension (preferably S1 + S2) is advantageously at a temperature between 0 and 5 ° C prior to the introduction of the compound 8-hydroxyquinoline or a derivative thereof. The compound 8-hydroxyquinoline or a derivative thereof is advantageously introduced in the form of a solution S3 based on an organic solvent. The organic solvent of the solution S3 may especially be chosen from the group comprising ethanol; THF tetrahydrofuran; and acetone.

Solution S3 is added to the suspension resulting from step (ii), for example S1 + S2. The addition can be carried out drop by drop. During step (iii), the solution S3 is advantageously at a temperature between 0 and 5 ° C. Once the 8-hydroxyquinoline compound or one of its derivatives is introduced into the suspension resulting from stage (ii) (for example S1 + S2), the resulting suspension (for example S1 + S2 + S3) is advantageously stirred, for example by mechanical stirring, at a temperature between 0 and 5 ° C, for a period of between 30 and 120 minutes. Typically, the aqueous solutions and suspensions used in the invention are advantageously produced from deionized water.

At the end of step (iii), functionalized polyurea particles are obtained and separated from the reaction medium. They can then be washed and / or dried. Functionalization of the polyurea particles may thus further comprise the following steps: (iv) optionally washing the functionalized polyurea particles; advantageously with ethanol and then with water; (v) drying the functionalized polyurea particles, advantageously in an oven.

Step (d) of the process consists in separating the particles and the SA1 aqueous solution. It can be carried out according to conventional techniques known to those skilled in the art, in particular by filtration.

Typically, the functionalization does not significantly change the shape of the particles and their diameter. Thus, the functionalized polyurea particles are advantageously in spherical form. Their diameter is advantageously between 0.1 and 20 microns, more advantageously between 1 and 10 microns, and still advantageously between 2 and 10 microns.

The amount of 8-hydroxyquinoline or its derivatives used to functionalize the polyurea particles is advantageously between 0.1 and 1.5 grams per gram of polyurea particles, more advantageously between 0.5 and 1 gram.

At the end of the functionalization, the functionalized polyurea particles have a degree of functionalization advantageously comprised between 10 and 90% relative to the number of nitrogen atoms of the polyurea, more advantageously between 40 and 50%.

Typically, this degree of functionalization generally allows 5 to 10 grams of particles to complex 1 to 20 grams of metal ions. The complexation of the metal ions is advantageously carried out at a temperature of between 15 and 30 ° C.

The aqueous solution containing metal ions advantageously consists of wastewater. Once the metal ions complexed, the particles can be separated from the aqueous solution SA1, in particular by filtration. The present invention also relates to a wastewater treatment process using the polyurea particles described above.

The polyurea particle according to the invention comprises at least one of the nitrogen atoms forming an azo -N = N- bond between said polyurea and a molecule of 8-hydroxyquinoline or one of its derivatives. As already stated, the number of nitrogen atoms of the polyurea forming an azo bond between the polyurea and a molecule of 8-hydroxyquinoline or one of its derivatives advantageously represents 10 to 90% relative to the number of atoms. nitrogen of the polyurea. The invention and the advantages thereof will appear more clearly from the following figures and examples, given to illustrate the invention, in a nonlimiting manner.

BRIEF DESCRIPTION OF THE FIGURES FIG. 1 illustrates the reaction scheme of the functionalization of polyurea particles according to a particular embodiment of the present invention.

FIG. 2 illustrates the principle of interactions between functionalized polyurea (MP) particles according to the invention and a metal ion. Figure 3 illustrates functionalized polyurea particles according to a particular embodiment of the present invention.

FIG. 1 illustrates a particular embodiment making it possible to prepare the functionalized polyurea particles used in the process that is the subject of the present invention. The polyurea particle having NH 2 groups is first treated in aqueous solution to form a particle having diazonium groups. These are steps (i) and (ii) described in the description. The formation of a diazonium salt on at least one NH group of the polyurea is carried out in the presence of a nitrosating agent, advantageously sodium nitrite, and of an acid such as hydrochloric acid. Functionalization of the polyurea particles is then carried out by adding, to the aqueous suspension containing the diazonium salt, 8-hydroxyquinoline or one of its derivatives. This is the step (iii) described in the description.

The group "N = NR" in FIG. 1 denotes the functionalizing group of the particle in which R denotes the grafted 8-hydroxyquinoline or one of its derivatives and in which the nitrogen atom having no bond with R is derived from polyurea.

As already indicated, according to an advantageous embodiment, 10 to 90% of the nitrogen atoms of the polyurea are functionalized. In other words, the number of nitrogen atoms of the polyurea being linked by an azo bond N = N with a molecule of 8-hydroxyquinoline or a derivative thereof, advantageously represents 10 to 90% relative to the number of nitrogen atoms of the polyurea. This functionalization is preferably carried out at the level of the carbon atom at the 5-position of the quinoline group.

Once prepared, the functionalized particle according to the invention can be used to trap metal ions, usually cations. The interactions between the functionalized particle (MP) and the metal cation Mx + are illustrated in FIG. 2. It is these interactions that make it possible to extract the metal ions from the treated aqueous solution. The nitrogen atom and the OH group of the grafted 8-hydroxyquinoline (or a derivative thereof) make it possible to complex the metal ion by forming bonds.

As already indicated, according to this advantageous embodiment, the presence of the N = N bond between the polyurea particle and the grafted 8-hydroxyquinoline (or a derivative thereof) provides flexibility and improves the complexation of the metal ions. EXAMPLES OF CARRYING OUT THE INVENTION Functionalization of Polyurea Particles: Polyurea particles were functionalized following this protocol: Preparation of a first Si solution by dispersion of polyurea particles (100 mg) in deionized water ionized (5 mL); cooling to 0 ° C. of Si; preparation of a second solution S2 containing sodium nitrite (100 mg, NaNO2), hydrochloric acid HCl (828 μL, ie 2M in the final volume of the second solution) and deionized water ( 5 mL); - cooling of S2 to 0 ° C; addition of S 2 dropwise to Si at 0 ° C .; stirring of the mixture S1 + S2 for 30 minutes at 0 ° C .; - preparation of a third solution S3 containing 8-hydroxyquinoline (CAS No. 148-24-3, 80 mg) and ethanol (5 mL); cooling and stirring of S3 at 0 ° C. for 5 minutes; addition of S3 dropwise to the mixture S1 + S2 at 0 ° C .; stirring of the mixture S1 + S2 + S3 for 30 minutes at 0 ° C. and then for 2 hours at room temperature; obtaining polyurized particles functionalized with 8-hydroxyquinoline; centrifugation of these particles at 5000 rpm for 10 minutes; washing these particles with ethanol and then with water at room temperature; drying these particles in an oven at 80 ° C. for 30 minutes.

The polyurea particles thus functionalized were then used to remove metal ions contained in an aqueous solution. Treatment of an aqueous solution containing metal ions according to the invention: Several aqueous solutions containing metal ions were treated according to this protocol: preparation of a dispersion of functionalized polyurea particles (8-hydroxyquinoline) in water of ionized (20 mg of particles in 5 ml of water); addition of a solution (5 mL) containing 10 mg of metal ions to this dispersion. Four different solutions were tested. They were prepared from: CuSO4 for copper; HgC12 for mercury; MnCl2 for manganese; AgNO3 for the money.

In general, the discoloration of the solution containing the metal ions is observed. This discoloration corresponds to the absorption of the metal ions and complexation of the latter with the functionalized and reactive surface of the particles of the invention.

Complexation of metal ions is confirmed by X-ray diffraction (XRD) analysis. The XRD analysis shows that the functionalized polyurea particles contain the metals initially present in the treated solutions.

Claims (4)

REVENDICATIONS1. A method of treating an aqueous solution SA1 containing metal ions, comprising the steps of: (a) preparing particles by functionalizing polyurea particles with 8-hydroxyquinoline or a derivative thereof; (b) dispersing these particles in the SA1 aqueous solution; (c) complexing the metal ions of the SA1 solution by forming bonds between the metal ions and the particles; (d) separating the particles and the aqueous solution SA1. Process according to claim 1, characterized in that the metal ions are ions of a metal selected from the group consisting of alkaline earths; lanthanides; actinides; and transition metals, preferably copper; Mercury ; manganese; money; the iron ; chromium; vanadium; nickel; aluminum; europium; or arsenic. Process according to claim 1 or 2, characterized in that the polyurea particles are functionalized according to the following steps: (i) preparation of an aqueous Si suspension of polyurea particles; (ii) forming a diazonium salt on at least one NH group of the polyurea; (iii) functionalizing the polyurea particles by adding, to the aqueous suspension containing the diazonium salt, 8-hydroxyquinoline or a derivative thereof. Process according to Claim 3, characterized in that step (ii) is carried out by adding, to the Si suspension, an aqueous solution S2 comprising at least one nitrosating agent and at least one acid. Process according to Claim 4, characterized in that the nitrosating agent is sodium nitrite NaNO 2; and in that the acid is hydrochloric acid HC1 or sulfuric acid H2SO4. 10 2. 15 3. 20 25 4. Process according to claim 4 or 5, characterized in that, in step (ii), the Si suspension is at a temperature between -5 and 5 ° C; and solution S2 is at a temperature between -5 and 5 ° C. Process according to one of Claims 3 to 6, characterized in that it further comprises the following steps: (iv) washing of the functionalized polyurea particles; advantageously with ethanol and then with water; (v) drying the functionalized polyurea particles; advantageously in an oven. Process according to one of Claims 1 to 7, characterized in that the functionalized polyurea particles are in spherical form and have a diameter of between 0.1 and 20 microns, advantageously between 1 and 10 microns. Process according to one of Claims 1 to 8, characterized in that the functionalized polyurea particles have a degree of functionalization of between 10 and 90% relative to the number of nitrogen atoms of the polyurea. Process according to one of Claims 1 to 9, characterized in that the SA1 aqueous solution consists of wastewater. Process according to one of Claims 1 to 10, characterized in that the 8-hydroxyquinoline derivatives are chosen from the group comprising: - 2,8-quinolinediol; 2-amino-8-quinolinol; and - 8-hydroxy-2-quinoline carboxamide. Polyurea particle of which at least one of the nitrogen atoms forms an azo -N = N- bond between said polyurea and a molecule of 8-hydroxyquinoline or a derivative thereof. Particle according to Claim 12, characterized in that the number of nitrogen atoms of the polyurea forming an azo bond between the polyurea and a molecule of 8-hydroxyquinoline or one of its derivatives represents 10 to 90% relative to the number of nitrogen atoms of the polyurea.