TWI401215B - Separation and recovery of metal ions - Google Patents

Description

Method for separating and recovering metal ions

The invention relates to a method for separating and recovering metal ions, in particular to a method for separating and recovering metal ions by magnetic separation principle, the method of the invention can be applied to treating heavy metals in a pollution source or recovering precious metals from a source to be treated. .

Metal pollution in soil and groundwater, as well as metal waste liquid discharged from factories, is a common and difficult environmental problem in Taiwan, because metals are not like organic substances that can be degraded into simpler substances to effectively reduce their concentration. Fixing metal or removing it from contaminated areas is one of the most important environmental issues. Conventional metal pollution treatment technologies include methods such as leaching and pickling. Although these methods can effectively remove metals from contaminated areas using specific treatment agents, they meet regulatory standards, but it is not easy to recycle them. Since the metal ions are separated from the treating agent, metal ions cannot be efficiently recovered, and the treating agent cannot be reused.

On the other hand, because Taiwan is a country with highly developed industries and extremely scarce resources, it is of great environmental significance to effectively recycle high-value precious metals from industrial processes or resource-recovered products. For example, in the waste liquid produced by the electroplating industry in the process, there are many recyclable substances. In addition, waste electronic parts, waste integrated circuits, waste printed circuit boards, etc. also contain gold, silver, palladium and the like. A precious metal such as platinum. Zhang Jiayuan et al., in the paper of the 29th issue of the Journal of the South China Journal of the Republic of China (pp. 236-247 ) , pointed out that "the potassium cyanide is often used as the raw material for the electroplating gold bath in the IC process, and the electroplating aging solution after use. The amount of gold in the cleaning liquid is several tens to several ppm. In addition, the literature also mentions that the use of ion exchange resin to recover precious metals in the waste liquid still has the following problems: (1) although the electroplating waste liquid has been It is filtered through the membrane first, but it contains citric acid, which is easy to breed microorganisms, and causes the resin tank to be easily blocked, which seriously affects the performance of the ion exchange resin. (2) After the precious metal is recovered by the resin, the recovery of the precious metal is found through the subsequent refining process. The rate is not high. Therefore, in recent years, new technologies for separating and recycling metals have been continuously developed.

Magnetic Nano-Particle (MNP) is one of the emerging materials for removing contaminants from water, because when the magnetic substance is converted into nano-particles, it has a small volume (about 10 nm or less) and a high ratio. The surface area (up to 97m ² /g) and magnetic properties can also play the role of nuclear species and accelerate the sedimentation of suspended solids. Moreover, the preparation of magnetic nanoparticles is simple, with the most common ferroferrite. For example, the rice granules can be prepared by using a mixed solution of a divalent iron metal and a trivalent iron metal and adjusting the pH in an alkaline environment. Therefore, some domestic scholars have used magnetic nanoparticles to adsorb chemically mechanically ground suspended particles in wastewater, but the magnetic nanoparticles can no longer be used, or the ability to be reused is poor, and it is not economical. Foreign studies have also pointed out that nano magnetic particles can be used to adsorb heavy metals, but the desorption effect after adsorption is not good and cannot be reused.

The research team of the inventor of the present case disclosed in the paper "Discussion on the Catalytic Properties of Nanocomposite Metals" in the first seminar on soil and groundwater treatment technology (2003), which uses a self-made nano-zero-valent iron metal ( ZVI) test to remove metal in water, and found that the adsorption amount is 30 to 60 times that of non-nano-grade iron metal, and in this removal study, it is also found that the zero-valent iron metal can effectively reduce and degrade the chlorine-containing organic matter (ie, In addition to carbon tetrachloride, metals such as pentavalent arsenic, hexavalent chromium, divalent lead and divalent copper can be removed, but the metal is not easily desorbed after being adsorbed on zero-valent iron metal, so it will be reused. The disadvantage of poor sex.

In addition, Dendrimer has the advantages of low viscosity, low toxicity, high dispersibility, high reactivity and high load capacity, and has been applied to metals adsorbing water and soil, such as: Xu and Zhao, in Environmental Science and Technology , Vol. 39, pp. 2369-2375, used a dendrimer of different generations and terminal functional groups to adsorb metal copper, and found that dendrimers can be fast and It effectively adsorbs metals and has excellent desorption ability under acidic solutions. However, since the current technology for recovering dendrimers is to utilize an ultrafine filtration membrane with an expensive unit price, it is not feasible to apply it to a large amount of metal waste liquid in consideration of economic efficiency.

Therefore, there is still a need to develop a method for separating and recovering metal ions which is low in cost, high in metal recovery rate, and excellent in recyclability of a treating agent.

In view of the existing methods for separating and recovering metal ions by using magnetic nano particles, there is a disadvantage that it is not easy to desorb metal ions that have been adsorbed thereon, and the inventors of the present invention have thought that the surface of the magnetic nanoparticles can be changed. The structure solves this problem, and it is thought that a tree-like polymer having a good adsorption and desorption ability can be bonded to the surface of the existing magnetic nanoparticle, thereby improving the metal recovery rate.

Accordingly, an object of the present invention is to provide a method for separating and recovering metal ions which is low in cost, high in metal recovery rate, and excellent in recyclability of a treating agent.

The method for separating and recovering metal ions of the present invention comprises the steps of: (a) providing a dendrimer-like composite magnetic metal particle comprising a core composed of a magnetic metal oxide, and at least one on the surface of the core a metal oxide-bonded dendrimer; (b) placing the dendrimer-composite magnetic metal particles of the step (a) in a source to be treated containing at least one metal ion to cause the metal ion and the tree The polymer-like magnetic metal particles are combined to obtain a dendrimer-like composite magnetic metal particle to which a metal ion is combined; and (c) the dendrimer-like composite magnetic metal particle to which the metal ion is bonded is used by magnetic separation Separated from the source to be processed.

The effect of the present invention: in the present case, when the metal ions are separated and recovered by combining the treatment agent formed by the magnetic nanoparticles and the dendrimer, the magnetic properties of the tree-like polymer are not only improved by the good adsorption and desorption ability, but also the magnetic properties alone. Nanoparticles have the problem of poor recyclability. At the same time, because of the magnetic properties of magnetic nanoparticles, the use of dendrimers alone can have the disadvantage of excessive recycling costs and economic benefits. From the point of view of the treatment source, the method has good metal ion removal efficiency and is suitable for treating heavy metals in pollution sources. From the viewpoint of recovering metal ions, the method has good metal recovery rate and is suitable for metal recovery. In particular, precious metals are indeed capable of achieving the objects of the present invention.

The inventor of this case thought about the combination of magnetic nano-particles and dendrimers, and searched for this concept, and found Pan et al. on J. Colloid Interface Sci. 284, p.1-5 . The published paper reveals a magnetic nanoparticle with a dendrimer bonded to the surface (hereinafter referred to as MNP-Gn), and the protein is immobilized by MNP-Gn to further purify the protein, which utilizes protein to The terminal functional group bond of the dendrimer immobilizes the protein on its surface, and further separates the MNP-Gn from the impurities by magnetic separation principle, but this application belongs to the field of biomedicine, and The purified protein is also very different from the nature of the metal to be separated and recovered in this case.

The method for separating and recovering metal ions of the present invention comprises the steps of: (a) providing a dendrimer-like composite magnetic metal particle comprising a core composed of a magnetic metal oxide, and at least one metal with the core surface An oxide-bonded dendrimer; (b) placing the dendrimer-like composite magnetic metal particles of the step (a) in a source to be treated containing at least one metal ion, and causing the metal ion to form the tree The polymer composite magnetic metal particles are combined to obtain a dendrimer composite magnetic metal particle combined with metal ions; and (c) the dendritic polymer composite magnetic metal particles combined with the metal ion are used by magnetic separation Separated from the processing source.

Preferably, the step (a) further applies a pickling treatment to the dendrimer composite magnetic metal particles.

Preferably, the step (a) is a pickling treatment by contacting the dendrimer-composite magnetic metal particles with an acidic solvent selected from the group consisting of concentrated hydrochloric acid (HCl) and concentrated sulfuric acid (H). ₂ SO ₄ ), concentrated nitric acid (HNO ₃ ) or concentrated phosphoric acid (H ₃ PO ₄ ). However, it should not be limited to the above acidic solvent, as long as it can be applied in this field to remove surface impurities.

In a specific embodiment of the present invention, the step of pickling is to first add the dendrimer composite magnetic metal particles to 10 mL of water and stir, and slowly drop a few drops of concentrated hydrochloric acid to make the pH value in the water reach 3.0. The mixture was stirred for 5 minutes and subjected to solid-liquid separation, and the dendrimer-type composite magnetic metal particles were washed with deionized water to obtain a acid-treated dendritic polymer composite magnetic metal particle.

Note that the above pickling treatment mainly removes a solvent such as methanol remaining when the dendrimer-composite magnetic metal particles are previously prepared.

Preferably, the magnetic metal oxide in the step (a) is selected from the group consisting of iron oxide, cobalt oxide or nickel oxide. More preferably, the magnetic metal oxide in the step (a) is iron oxide.

Preferably, the terminal group of the dendrimer in the step (a) can form a mismatched structure with the metal ion of the step (b).

Preferably, the dendrimer in the step (a) can be combined with the metal ion of the step (b) by an electrostatic force.

Preferably, the dendrimer in the step (a) has pores capable of trapping the metal ions of the step (b) therein.

The "combination" of the metal ion and the dendrimer-composite magnetic metal particle mentioned in the step (b) may be combined by chemical bonding or by a force between the two. Bonding, or bonding due to the intercalation of metal ions in the dendrimer.

The present invention is mainly prepared by the method described in Enzel et al., J. Chem. Educ. 76, pp. 943 (1999) and Mehta et al., Biotechnol. Tech. 77, pp. 493-496 (1997) . The ferroferric oxide magnetic nanoparticles are first prepared with an aqueous solution of Fe ³⁺ and Fe ²⁺ molar ratio of 2:1, and then added with a strong aqueous alkali solution (NaOH or NH ₄ OH) to adjust the pH to about 10, And mixing and stirring at a constant temperature of 80 ° C for 30 minutes and then cooling, a triiron tetroxide colloidal material is obtained, and then the colloidal material is washed several times with deionized water and ethanol, and the colloidal material is subjected to anaerobic environment. Air-dried to obtain a ferroferric oxide nano-nanoparticle.

Preferably, the dendrimer-composite magnetic metal particles are bonded to the magnetic metal oxide on the surface of the magnetic nanoparticle by first bonding at least one compound containing a ruthenium oxygen bond, and then sequentially added according to the chemical dose. The amount of methyl acrylate and ethylenediamine is obtained by forming at least one dendrimer on the surface of the magnetic nanoparticles by a convergence method.

In a specific embodiment of the present invention, the oxime bond-containing compound is 3-aminopropyl-trimethoxysiliane (ATPS), the magnetic metal oxide is iron oxide, and the ruthenium containing ruthenium The oxygen-bonded compound and the atom bound to the magnetic metal oxide are oxygen, and the bonding condition is as shown in the following formula (I):

Preferably, the particle size of the dendrimer-composite magnetic metal particles in the step (a) is between 10 nm and 5000 nm. More preferably, the particle size of the dendrimer-composite magnetic metal particles in the step (a) is between 10 nm and 100 nm.

Preferably, the source to be treated in the step (b) is a solution or a soil. In particular, the method for separating and recovering metal ions based on the present invention may be used to treat wastewater or contaminated soil, but may also be used to recover or concentrate metals, especially high-priced precious metals, so the above The source to be treated is not limited to metal contamination sources.

Therefore, the metal ion in the step (b) is a heavy metal ion or a noble metal ion.

Preferably, the heavy metal ion is selected from the group consisting of copper ions, zinc ions, nickel ions, manganese ions, cadmium ions, mercury ions, lead ions, chromium ions, arsenic ions, or a combination thereof.

Preferably, the noble metal ion is selected from the group consisting of silver ions, gold ions, palladium ions, platinum ions, or a combination thereof.

The magnetic separation mode in the step (c) is a principle of attracting a magnetic metal by the magnetic force of a magnet, that is, a tree-shaped polymer composite magnetic metal particle to which metal ions are bound is separated from the source to be treated by using a magnet.

In the present case, a magnet is brought into contact with or contacted with a wall of a container containing a plurality of dendritic polymer composite magnetic metal particles combined with metal ions, so as to make the dendrimer complex in the source to be treated. The magnetic metal is attracted by the magnet. At this time, the solution in the source to be treated is discharged until the liquid is no longer present in the container, and the magnet remains, and the substance remaining in the container is a tree-shaped metal ion. Polymer composite magnetic metal particles.

The above method is mainly for the small-scale experiment in the laboratory. In practice, the electromagnet can be used to control the magnetism and directly applied to the reaction tank without the need to carry out the outer wall of the container.

Preferably, the method further comprises a step (d) after the step (c), wherein the metal ion-bound dendrimer composite magnetic metal particles are contacted with a desorbent to separate the metal Ions and the dendrimer-like composite magnetic metal particles.

When the dendrimer-containing composite magnetic metal particles combined with the metal ions are in contact with the desorbing agent, the metal ions are desorbed from the dendrimer-composite magnetic metal particles and dissolved in the desorbing agent. Further, the effect of separating from the dendrimer-composite magnetic metal particles is achieved.

Preferably, the desorbent is an acidic solvent. More preferably, the acidic solvent is hydrochloric acid.

Preferably, the concentration of the acidic solvent is between 0.005 M and 0.1 M.

Preferably, the step (d) further separates the dendrimer-composite magnetic metal particles from the desorbent by magnetic separation. The magnetic separation mode in this step is the same as the magnetic separation method in the above step (c), except that the dendrimer hybrid magnetic metal particles are separated from the deionization agent in which the metal ions are dissolved.

Example

The invention is further described in the following examples, but it should be understood that these examples are for illustrative purposes only and are not to be construed as limiting.

[chemical source]

1. Zinc chloride, chemical formula: ZnCl ₂ , Mw: 136.3, purity: 98%, label: Riedel-dehaen.

2. Copper (II) Sulfate, chemical formula: CuSO ₄ , MW: 159.61, purity: 97.5%, label: SHOWA.

3. Sodium Arsenate, chemical formula: Na ₂ HA ₂ O ₄ , MW: 312.01, purity: 99.0%, label: JT Baker.

4. Cobalt(II) chloride hexahydrate, chemical formula: CoCl ₂ , MW: 237.93, purity: 99%, label: SCHARLAU.

5. Nickel (II) sulfate hexahydrate, chemical formula: NiSO ₄ ‧6H ₂ O, MW: 262.85, purity: 99%, label: SHOWA.

6. Lithium chloride, chemical formula: LiCl, MW: 42.39, purity: 99%, label: Alfa Aesar.

7. Silver chloride, chemical formula: AgCl, MW: 143.32, purity: 99%, label: Alfa Aesar.

[instrument]

1. Transmissive Electron Microscope (TEM): In this case, the surface morphology of the sample was observed by the Field Emission electron microscope with the model Hitachi Model HF-2000, and the energy dispersion was used. Spectrometers (EDX) perform qualitative and semi-quantitative analysis of chemical elements. The test sample is dried and ground into a powder by nitrogen, placed in an aqueous solution and sampled with a carbon-coated copper mesh for subsequent instrumental observation.

2. X-ray Diffraction (XRD): In this case, X-ray powder diffractometer model Hitachi Model HF-2000 was used to perform magnetic nanoparticle and dendrimer composite magnetic metal colloid. Analysis of composition of ingredients. Before the test, the test sample will be dried with nitrogen and filtered with a No. 200 sieve. During the test, the scanning angle (2θ) is set to 20 to 80 degrees, and it is scanned at two degrees per minute. The measured spectrum is then compared with the JCPDS standard. The map database is compared to confirm the composition of the test sample.

3. Fourier Transform Infrared Spectrometer (FT-IR): This method uses the FT-IR model Perkin Elmer Spestrum GX to detect magnetic nanoparticles and dendrimers in dendrimer composite magnetic metal particles. Whether the polymers do have bonds together. Before the test, the prepared nanometer-shaped polymer composite magnetic metal particles were blown dry with nitrogen and dried together with potassium bromide (KBr) in an oven at 100 ° C. Thereafter, KBr: dendrimer The composite magnetic metal particles were mixed at a ratio of 100:1, and then ground to a fine powder by an agate burr and pressed into a transparent tablet for measurement.

4. Inductively coupled plasma spectrometer (ICP): This case is based on the model of Perkin Elmer, Optima 2000DV ICP, and reference to the Environmental Protection Agency "amethysts for the detection of metals and trace elements in water - inductively coupled plasma mass spectrometry" In the operation step, the diluted analyte is filtered through a 0.2 μm filter paper, and the actual concentration of the metal in the analyte is converted according to the dilution factor.

<Preparation process> [Preparation of metal stock solution]

The inventors first placed an appropriate amount of AgCl, KCl, LiCl, ZnCl ₂ , CuSO ₄ , CoCl ₂ , NiSO ₄ ‧6H ₂ O, MnSO ₄ , Na ₂ HAsO ₄ and Al ₂ (SO ₄ ) ₃ into different 165 mL In the serum bottle, the amount of deionized water is quantified to 100 mL, so as to obtain ten kinds of sequentially containing Ag ⁺ , K ⁺ , Li ⁺ , Zn ²⁺ , Cu ²⁺ , Co ²⁺ , Ni ²⁺ , Mn ²⁺ , As ⁵⁺ and Al ³⁺ metal stock solution, and the metal ion concentration is 1000mg / L, and sealed with a Teflom-containing gasket and aluminum cap and placed at constant temperature Store in a 4°C refrigerator.

[Preparation of ferroferric oxide (Fe) ₃ O ₄ Magnetic nanoparticles (MNP)

The steps for preparing the ferroferric oxide magnetic nanoparticles in this case are as follows:

1. 2.7 g of FeSO ₄ ‧7H ₂ O and 5.7 g of FeCl ₃ ‧6H ₂ O powder were respectively weighed in 100 ml of deionized water, and then mixed and stirred to obtain an aqueous solution containing Fe ³⁺ and Fe ²⁺ . The pH of the aqueous solution at this time was measured to be 1.6.

2. While stirring the aqueous solution of Step 1, an appropriate amount of aqueous ammonia (NH ₄ OH) was added to the aqueous solution until the pH of the aqueous solution became 10.

3. Place the aqueous solution prepared in Step 2 on a heating stirrer and maintain the temperature at 80 ° C for 30 minutes.

4. After the stirred aqueous solution of step 3 is allowed to stand for cooling, a triiron tetroxide colloidal material is obtained, and the colloidal material is washed several times with deionized water and ethanol to have a pH of about 8.9.

5. Finally, the colloidal material is air-dried in an anaerobic environment to obtain a ferroferric oxide nanoparticle (hereinafter referred to as MNP).

[Preparation of dendrimer-like composite magnetic metal particles]

The steps of preparing the first generation (G ₁ ) dendrimer composite magnetic metal in this embodiment are as follows:

1. 2.5 g of the MNP of Preparation Example 1 was taken up to 200 ml with ethanol, and 10 ml of 3-aminopropyltrimethoxydecane was added to obtain a first mixed liquid.

2. Using a magnet stirrer and a condenser, the first mixture of step 1 is stirred at 60 ° C for 7 hours, and completely dispersed in ethanol. After completion, it is washed with methanol several times to obtain zero generation (G ₀ ). Composite magnetic metal particles (hereinafter referred to as MNP-G ₀ ), which were then blown dry with nitrogen for subsequent quantitative use.

3. The zero-generation (G ₀ ) composite magnetic metal particles prepared in step 2 were quantified into 50 ml of methanol and 20 ml of methyl acrylate was added, and the mixture was shaken for 7 hours with ultrasonic waves to completely mix and react uniformly. After completion, the mixture was washed with methanol. Several times, a half-generation (G _0.5n ) dendrimer composite magnetic metal particle (hereinafter referred to as MNP-G _0.5 ) can be obtained.

4. The half-generation (G _0.5n ) dendrimer composite magnetic metal particles prepared in step 3 were quantified to 20 ml of methanol and 10 ml of ethylenediamine was added _thereto , and the mixture was shaken for 3 hours by ultrasonic _wave , and then washed several times with methanol after completion. The first generation (G ₁ ) dendrimer composite magnetic metal particles (hereinafter referred to as MNP-G ₁ ) can be obtained.

In Examples 2 to 5, the second-generation to fifth-generation (G ₂ to G ₅ ) dendrimer-composite magnetic metal particles (hereinafter abbreviated as MNP-G ₂ , MNP, respectively) were prepared in the same manner as in Example 1. -G ₃ , MNP-G ₄ and MNP-G ₅ ), except that the number of times of steps 3 and 4 is repeated in Examples 2 to 5.

<TEM observation and EDX analysis results>

The inventors of the present invention made the MNP of Preparation Example 1, the MNP-G ₀ , MNP-G _0.5 , MNP-G ₁ of Example _1, and the dendrimer composite magnetic metal particles of Examples 2 to 5 as test samples of TEM, respectively. The surface morphology of these test samples was observed by TEM, and it was found that the simple ferroferric oxide magnetic nanoparticles have weak magnetic properties, so although it can be seen that the spherical particles are in a pellet shape, there is agglomeration. As for the zero-generation, half-generation and first-generation dendrimer-composite magnetic metal particles, since the polymer material itself has a dispersing effect, the agglomeration phenomenon between each other is effectively reduced. In addition, the average particle diameter of the self-synthesized dendrimer composite magnetic metal colloid can be measured by the TEM image to be about 10 nm, which is similar to the average particle size of the simple ferroferric oxide magnetic nanoparticles.

In addition, the characteristic peaks of O, Cu and Fe appear in the EDX analysis results of magnetic nanoparticle (MNP), wherein the component Cu should be caused by the carbon-coated copper mesh, and O and Fe are characteristic peaks of triiron tetroxide; In addition to the characteristic peaks of Fe and O, the EDX analysis results of the zero-generation composite magnetic metal colloid also have the characteristic peak of Si, which is one of the components of ATPS.

<XRD analysis result>

The inventors of the present invention also made the MNP of Preparation Example 1, the MNP-G ₀ , MNP-G _0.5 , MNP-G ₁ of Example _1, and the dendrimer composite magnetic metal particles of Examples 2 to 5 into XRD test samples. And XRD analysis, and from the XRD analysis of the test sample in this case, it can be found that characteristic peaks appear at the characteristic peaks of the standard map corresponding to Fe ₃ O ₄ , and the signal intensity also approaches Fe ₃ O. ₄ standard map, it can be seen that in the process of synthesizing different generations, it does not cause the modification of magnetic nanoparticles.

In addition, in the XRD analysis of the samples of the zero-generation and half-generation dendrimer-composite magnetic metal particles, a characteristic peak representing Si-O appears at a wavelength of 995-1300 cm- ¹ , demonstrating magnetic nano-particles. The surface of the particle does have an attached precursor (ATPS). Further, the dendrimer-composite magnetic metal particles of the first to fifth generations of Examples 1 to 5 (i.e., MNP-G ₁ , MNP-G ₂ , MNP-G ₃ , MNP-G _{4 ,} and MNP-G) XRD analysis pattern ₅₎ in the test sample, the other at a wavelength of stretching at 1200cm ^-1 with a tertiary amine vibration peaks at 2943cm ^-1 there is -CH ₂ - characteristic absorption peaks at 1645 cm ^-1 characteristic bands have -CONH- There are -NH ₂ functional peaks at 1558 cm ^-1 and 3412 cm ^-1 .

<Specific surface area and pore volume analysis>

In this case, the MNP of Preparation Example 1, the MNP-G ₀ prepared in Step 2 of Example 1, and the specific surface area and pore volume of MNP-G ₅ of Example 5 were respectively determined by a COULTER SA3100 specific surface area analyzer, wherein the instrument setting parameters were used. The degassing time was 60 min, the degassing temperature was 120 ° C, and the weighing was 0.2 g each time. The results were as follows: (1) specific surface area: MNP was 97.41 m ² /g, and MNP-G ₀ was 68.89 m. ² / g, MNP-G ₅ was 56.96 m ² /g; (2) Pore volume: MNP was 0.24 ml/g, MNP-G ₀ was 0.21 ml/g, and MNP-G ₅ was 0.16 ml/g.

From this test, it is known that when the algebra of the dendrimer is high, the specific surface area is low, but the dendrimer is compared with the specific surface area of the magnetic metal particles (ie, MNP) which are not combined with the dendrimer. The effect of algebraic contrast surface area is not large.

<Measurement of Zeta Potential>

In this case, the surface electrical properties of the MNP of Preparation Example 1, the MNP-G ₃ of Example _3, and the MNP-G ₅ of Example 5 were measured using a Zeta Potential Analyzer (ZPC; abbreviated as ZPC; available from Brookhaven Instruments Corporation). First, 0.03g of the test substance is quantified into 100ml of deionized water (0.3mg/ml), and ultrasonically oscillated for 30min, so that it is completely mixed uniformly, and then the pH value of the test sample is adjusted by using HCl and NaOH. To obtain test samples with different pH values and analyze them by instrument, the results are shown in Figure 1.

Figure 1 shows the boundary potentials of MNP, MNP-G ₀ and MNP-G ₅ in different pH environments, and the equipotential points are: MNP is 7.0mV; MNP-G ₀ is 6.9mV; MNP -G ₅ is 6.7 mV, and the result of the MNP of Preparation Example 1 is represented by a circular mark; the result of MNP-G ₃ of Example 3 is represented by a triangular mark; and MNP-G ₅ of Example 5 The result is indicated by a diamond mark.

<Simulated Zn ²⁺ and Ag ⁺ saturated adsorption capacity and adsorption capacity index>

The inventors of the stock solution containing Zn ²⁺ Zn ²⁺ content is formulated as 30mg / L and 50mg / L of the plurality of sets of the test solution at pH 7, respectively, at 25 ℃, respectively, different doses of MNP-G ₃ (0.025g~0.5g), and measure the Zn ²⁺ content by ICP at regular intervals, and then simulate the isotherm adsorption curve by using two adsorption equations, namely Langmuir adsorption equation and Freundlich adsorption equation. Using Langmuir adsorption equation simulation, the maximum saturated adsorption amount (q _max ) of MNP-G ₃ to Zn ²⁺ is about 24.30 mg/g, b value is 0.09, and R ² value is 0.96. The Freundlich adsorption equation is simulated and The calculated adsorption capacity index (K _f ) of MNP-G ₃ to Zn ²⁺ was 3.49, the 1/n value was 0.47, and the R ² was 0.95. Therefore, from the above equation, MNP-G ₃ has a good adsorption effect on Zn ²⁺ .

The inventors tested the saturated adsorption capacity and adsorption capacity of Ag ⁺ in the same manner. The simulation results of the Langmuir adsorption equation showed that the maximum saturated adsorption amount (q _max ) of MNP-G ₃ to Ag ⁺ was about 58.8 mg/g. The b value is 0.249 and the R ² value is 0.99. The simulation results of the Freundlich adsorption equation are as follows: the adsorption capacity index (K _f ) of MNP-G ₃ to Ag ⁺ is 2.44, the 1/n value is 0.39, and the R ² is 0.79. Therefore, MNP-G ₃ also has a good adsorption effect on Ag ⁺ .

<Test for removing metal ions> [Experiment 1: Removal of Zn using different treatment agents ²⁺ Comparison]

The inventors first prepared a Zn ^{2+ -containing} stock solution into 3 parts of a test solution having a Zn ²⁺ content of 50 mg/L and a pH of 7, and obtained the MNP of Preparation Example 1 and Example 3 at 25 ° C, respectively. MNP-G ₃ and 0.5 g of MNP-G ₅ of Example 5 were placed in different test solutions, and the Zn ²⁺ content thereof was measured by ICP at regular intervals, thereby obtaining the remaining percentage of Zn ²⁺ in a test solution. graph showing changes over time, the results shown in Figure 2, in which the ordinate is a percentage of the Zn ²⁺ remaining in the test solution, i.e., the amount of Zn ²⁺ remaining in the test solution with Zn ²⁺ in the test solution The ratio of the initial amount, and the result of the MNP of Preparation Example 1 is represented by a circular mark; the result of MNP-G ₃ of Example 3 is represented by a diamond mark; and the result of MNP-G ₅ of Example 5 It is represented by a square mark.

As can be seen from FIG. 2, when the concentration of Zn ²⁺ is 50 mg/L, the removal efficiency of MNP-G ₃ of Example ₃ and MNP-G ₅ of Example 5 can reach 80%, and the reaction is all in a short time (about 1hr) has an excellent effect. Although the MNP of the pure preparation example 1 can also have a removal effect in a short time, the removal efficiency is only about 30%, and the removal ability is obviously inferior to that of MNP-G ₃ and MNP-G ₅ .

[Test 2: Different pH values for Zn ²⁺ Effect of removal efficiency]

The inventors first prepared a Zn ^{2+ -containing} stock solution into four different test solutions each having a Zn ²⁺ content of 10 mg/L, but having pH values of 4, 5, 6, and 7, respectively, and at 25 ° C, 0.1 g of the MNP-G _{3 of} Example 3 was added to the above four test solutions, and the Zn ²⁺ content thereof was measured by ICP at regular intervals, thereby obtaining a curve of the remaining percentage of Zn ²⁺ in the test solution as a function of time. The results are shown in Fig. 3. The ordinate is the remaining percentage of Zn ²⁺ in the test solution, and the result of pH 4 is indicated by a circular mark; the result of pH 5 is a triangle. The mark indicates that the result of pH 6 is indicated by a square mark; and the result of pH 7 is indicated by a diamond mark.

It can be seen from Fig. 3 that when the pH value is 4, the removal efficiency is about 10%; when the pH value is 5, the removal efficiency is increased to 20%, and as the pH is increased, the removal efficiency is also increased (10% improvement). Up to 80%). In addition to the higher pH value of the environment, the removal efficiency of Zn ²⁺ is relatively improved. It can also be inferred that the adsorption and desorption of Zn ²⁺ can be controlled by adjusting the pH.

[Trial 3: MNP-G ₃ Comparison of removal efficiency of different metal ions (pH=4)]

The inventors first formulated six kinds of stock solutions containing K ⁺ , Li ⁺ , Cu ²⁺ , Zn ²⁺ , Al ³⁺ and As ³⁺ into six different contents each having a content of 10 mg/L and a pH of 4. The test solution was prepared, and 0.1 g of the MNP-G _{3 of} Example 3 was added to the above six test solutions at 25 ° C, and the metal ion content thereof was measured by ICP at regular intervals, thereby obtaining metal ions in a test solution. A graph of the remaining percentage as a function of time, the results of which are shown in Figure 4, wherein the ordinate is the remaining percentage of each metal ion in the test solution, and the result of K ⁺ is represented by an inverted triangle; the result of Li ⁺ It is represented by a circular mark; the result of Cu ²⁺ is represented by a hexagonal mark; the result of Zn ²⁺ is represented by a diamond mark; the result of Al ³⁺ is represented by a square mark; and As ³⁺ The result is represented by an equilateral triangle mark.

It can be seen from Fig. 4 that in the environment with pH 4, the removal efficiency of MNP-G ₃ for different metal ions is: As ⁵⁺ >Al ³⁺ >K ⁺ >Zn ²⁺ >Cu ²⁺ >Li ⁺ . Under acidic conditions, the removal efficiency of As ⁵⁺ and Al ³⁺ is significantly higher. The reason for the higher removal efficiency of As ⁵⁺ is that arsenic is a special metal. It is often H ₂ AsO ₄ ^- , HAsO ₄ in the environment. ^2- or AsO ₄ ^3- or the like has a negatively charged state, so it will adsorb to the positively charged MNP-G ₃ under acidic conditions. As for Al ³⁺ , since it exists in a positively charged state in water, under acidic conditions, there should be no reaction of charge attraction, and the high removal efficiency may be due to the mismatch with MNP-G ₃ . . In addition, the reason why MNP-G ₃ has no removal effect on Li ⁺ is that Li ⁺ does not have a low energy orbital domain for the mismatch reaction, while the K ⁺ which belongs to the alkali gold group still has a removal efficiency of 20%. When the potassium atomic form is present, its electronic configuration is 1 s ² 2 s ² 2 p ⁶ 3 s ² 3 p ⁶ 4 s ¹ , and when potassium is in the ionic state, its electronic configuration is 1 s ² 2 s ² 2 p ⁶ 3 s ² 3 p ⁵ 4 s ¹ , ps forms a mixed orbital domain, which can be misaligned with MNP-G ₃ and has a removal effect. The removal efficiency of Zn ²⁺ and Cu ²⁺ is about 20%.

Note that the removal efficiency measured in this test is generally not high, mainly because the dendrimer itself is not conducive to the mismatch reaction at low pH, because its -NH ₂ functional group is in acidic conditions. It is easily protonated into a functional group of -NH ³⁺ . This monofunctional matrix is the main principle of depolymerization of dendrimers at low pH.

[Experiment 4: Adsorption competition of different metal ions (pH=7) test]

The inventors firstly each containing K ^+, Li ^+, Cu ²⁺ and Zn ²⁺ four mixed deployment of a stock solution containing 10mg / L of K ^+, 10mg / L of Li ^+, 10mg / L of Cu ²⁺ And 10 mg/L of Zn ²⁺ and a test solution having a pH of 7, and 0.1 g of the MNP-G _{3 of} Example 3 was added to the test solution at 25 ° C, and the ICP was measured periodically. The metal ion content, which in turn obtains a graph of the remaining percentage of metal ions in a test solution as a function of time, the results of which are shown in Figure 5, wherein the ordinate is the remaining percentage of each metal ion in the test solution, and K ⁺ The results are indicated by circular marks; the result of Li ⁺ is represented by an equilateral triangle; the result of Zn ²⁺ is indicated by an inverted triangle; and the result of Cu ²⁺ is represented by a square mark.

Comparing the results of Fig. 5 and Fig. 3, it can be found that the removal efficiency can reach 80% when Zn ^{2+ is} removed separately, but when the competition test is performed, the removal effect is only 70%, and Cu ²⁺ is also present. The removal efficiency is reduced. Therefore, it is speculated that the removal efficiency of metal is closely related to the amount of MNP-G ₃ used. It is speculated that each unit of dendrimer composite magnetic metal particles has a fixed action position, and it is also found in this test. The removal efficiency and competitiveness of divalent metals will be higher than that of monovalent metals.

[Experiment 5: Effect of pickling treatment on removal efficiency]

In this test, 0.5 g of MNP-G _{3 of} Example 3 was added to 10 mL of water and stirred, and a few drops of concentrated hydrochloric acid were slowly dropped to make the pH of the water reach 3.0, stirred for 5 minutes, and subjected to solid-liquid separation. Wash MNP-G ₃ with deionized water.

In addition, the Cu ^{2+ -containing} stock solution was formulated into four test solutions with Cu ²⁺ content of 10 mg/L but pH values of 4, 5, 6 and 7, respectively, at 25 ° C in the test. 0.1 g of the above-mentioned acid-washed MNP-G ₃ was added to the solution, and the metal ion content thereof was measured by ICP at regular intervals, thereby obtaining a graph of the remaining percentage of Cu ²⁺ in the test solution as a function of time. As shown in Fig. 6, the ordinate is the remaining percentage of Cu ²⁺ in the test solution, and the result of pH 4 is represented by a circular mark; the result of pH 5 is represented by an inverted triangle mark. The result with a pH of 6 is indicated by an equilateral triangle; and the result with a pH of 7 is indicated by a square mark.

It can be seen from Fig. 6 that the removal efficiency of Cu ²⁺ by the acid-washed MNP-G ₃ is about 50% at pH 4, and the removal ability increases with the increase of pH (by 50). % rises about 95%). In addition, in the operating environment with a pH of 4, the removal efficiency of Cu ²⁺ by the MNP-G ₃ after pickling treatment was significantly higher (by 20%) compared to the test 3 without acid pickling. Up to 50%), therefore, the operator can further remove the impurities attached to the surface of the MNP-G ₃ by this pickling treatment step to improve the removal efficiency.

[Test 6: MNP-G ₅ For Ag ⁺ Adsorption capacity]

The inventors first formulated a stock solution containing Ag ^{+ to} a test solution having an Ag ⁺ content of 50 mg/L and a pH of 7, and placed 0.5 g of the MNP-G _{5 of} Example 5 at the above test at 25 ° C. In the solution, and periodically measure the Ag ⁺ content by ICP, and then obtain a graph of the residual amount of Ag ⁺ in a test solution with time, the result is shown in Figure 7, wherein the ordinate represents Ag ⁺ in the test solution The remaining amount in .

<Recycling agent treatment test>

In this test example, MNP-G ₃ was firstly subjected to the pickling treatment as described in Test 5, that is, 0.1 g of the MNP-G _{3 of} Example 3 was added to 10 mL of water and stirred, and the concentrated hydrochloric acid was gradually added dropwise. After dropping, the pH of the water was 3.0, stirring for 5 minutes, and performing solid-liquid separation, and then washing the MNP-G ₃ with deionized water. Thereafter, at 25 ° C, MNP-G ₃ and a 100 ml test solution having a Cu ²⁺ content of 10 mg/L and a pH of 7 were placed in a beaker, and after 24 hours, the magnetic separation method was used. The Cu ²⁺ MNP-G ₃ is separated from the water, so that there is no more water in the beaker, and 10 ml of 0.1 M HCl solution is poured into the beaker to dissolve the Cu ²⁺ on the MNP-G ₃ into the HCl solution. At this time, the HCl solution containing Cu ²⁺ (hereinafter referred to as A1 portion) was separated from MNP-G ₃ (hereinafter referred to as B1 portion) by magnetic separation.

Next, the inventors placed the B1 portion with a test solution in which 100 ml of Cu ²⁺ content was 10 mg/L and pH 7 was placed in a beaker, and after 1 hour, the secondary magnetic separation step as described above was repeated. Further, a separated Cu ^{2+ -containing} HCl solution (hereinafter referred to as A2 portion) and MNP-G ₃ (hereinafter referred to as B2 portion) were obtained. The inventors can obtain another four sets of HCl solution containing Cu ²⁺ (hereinafter referred to as A3, A4, A5, A6, A7, A8, A9 and A10, respectively) by repeating the steps described in the preceding paragraph of this paragraph five times. ), and found that MNP-G ₃ after repeated use for 10 times still has a good ability to bind metal ions, and the removal efficiency is still close to 100%.

In addition, for the collected parts A1 to A10, the inventors separately measured the metal ion content in ICP and multiplied by 10 ml (volume of HCl solution) to obtain the total weight of the recovered metal ions, and then divided this value by the initial addition. The total weight of the metal ions (10 mg / L × 100 ml), the metal ion recovery ratio of each stage (ie, part A1 to A10) can be obtained, as shown in Fig. 8, the ordinate is the recovery rate of metal ions ( %), the abscissa is the recycling times, and the average metal ion recovery rate of 10 times is about 95%.

In Test Examples 2 to 5 and Test Comparative Example 1, the treatment agent reuse test was carried out in the same manner as in Test Example 1, except that the type and amount of the treatment agent and the metal ions in the test solution were different. The operating parameters of the type and content, the concentration of HCl, and the number of reuse tests are shown in Table 1 below. In addition, the measured removal efficiency and average metal ion recovery rate are also shown in Table 1 below.

It can be seen from Table 1 that compared with MNP, the metal ion removal efficiency and recovery rate of MNP-G ₃ and MNP-G ₅ in this case are greatly improved, and the effect of using 0.1 M HCl as a desorbent is greatly improved. optimal. It can be seen that the dendrimer composite magnetic metal particles combined with metal ions in the present invention not only have the advantages of simple preparation method and separation by simple magnets, but also the metal ion removal efficiency and recovery rate which are presented are quite good. This is a method that is familiar to those who are not familiar with this technology, let alone expect such a good effect.

In the present case, when a metal ion is separated and/or recovered by a treatment agent formed by combining magnetic nanoparticles and a dendrimer, the advantage of the dendrimer can be exerted on the one hand - having good adsorption and desorption ability, on the one hand The magnetic properties of the magnetic nano particles can be utilized, and the metal ion-containing treatment agent can be separated from the source to be treated by using a simple magnetic separation method, thereby achieving an unexpectedly good metal ion recovery rate, and is suitable for recovering precious metals. When it is applied to the treatment of a source of pollution such as waste water, it can be said that it has a good metal ion removal efficiency, and further, the treatment agent used can be reused and still has a good effect, so that the object of the present invention can be achieved.

The above is only the preferred embodiment of the present invention, and the scope of the invention is not limited thereto, that is, the simple equivalent changes and modifications made by the scope of the invention and the description of the invention are All remain within the scope of the invention patent.

1 is a graph showing the change of an exponential potential with a pH value to illustrate the boundary potential of different treatment agents in different pH environments, wherein the result of the MNP of Preparation Example 1 is represented by a circular mark; The result of MNP-G ₃ of Example 3 is indicated by a triangular mark; and the result of MNP-G ₅ of Example 5 is represented by a diamond mark;

2 is a graph showing the change of the remaining percentage of Zn ²⁺ with time to show the difference in the removal of Zn ²⁺ using different treating agents, wherein the result of the MNP of Preparation Example 1 is represented by a circular mark; The result of MNP-G ₃ is indicated by a diamond mark; and the result of MNP-G ₅ of Example 5 is represented by a square mark;

Figure 3 is a graph of the residual percentage of Zn ²⁺ as a function of time to show the effect of different pH values on the removal efficiency of Zn ²⁺ , wherein the result of pH 4 is indicated by a circular mark; The result of 5 is indicated by a triangular mark; the result of pH 6 is represented by a square mark; and the result of pH 7 is represented by a diamond mark;

Figure 4 is a graph of the remaining percentage of each metal ion as a function of time to show the removal efficiency of MNP-G3 for different heavy metal ions (at pH = 4), wherein the result of K ⁺ is represented by an inverted triangle mark The result of Li ⁺ is represented by a circular mark; the result of Cu ²⁺ is represented by a hexagonal mark; the result of Zn ²⁺ is represented by a diamond mark; the result of Al ³⁺ is represented by a square mark; And the result of As ³⁺ is represented by an equilateral triangle mark;

Figure 5 is a graph of the residual percentage of each metal ion as a function of time to show the adsorption competition of different metals at pH = 7, wherein the result of K ⁺ is represented by a circular mark; the result of Li ⁺ is It is represented by an equilateral triangle; the result of Zn ²⁺ is represented by an inverted triangle; and the result of Cu ²⁺ is represented by a square mark;

Figure 6 is a graph showing the change of Cu ²⁺ residual percentage with time to show the effect of MNP-G ₃ at pickling on Cu ²⁺ removal efficiency under different pH conditions, wherein pH is 4 The result is indicated by a circular mark; the result with a pH of 5 is indicated by an inverted triangle; the result with a pH of 6 is indicated by an equilateral triangle; and the result with a pH of 7 is represented by a square mark. ;

Figure 7 is a graph showing the change of the residual amount of Ag ⁺ with time to show the adsorption effect of MNP-G ₅ on Ag ⁺ ;

Figure 8 is a graph showing the recovery of a metal ion versus the number of reuses to show the effect of MNP-G ₃ on Cu ²⁺ when MNP-G ₃ is reused.

Claims (16)

A method for separating and recovering metal ions, comprising the steps of: (a) providing a dendrimer-like composite magnetic metal particle comprising a core composed of a magnetic metal oxide, and at least one metal with the core surface An oxide-bonded dendrimer, wherein the magnetic metal oxide is selected from the group consisting of iron oxide, cobalt oxide or nickel oxide; (b) the dendrimer composite magnetic metal particles of the step (a) are placed a source to be treated containing at least one metal ion, the metal ion is combined with the dendrimer-composite magnetic metal particles to obtain a dendrimer-type composite magnetic metal particle to which a metal ion is bonded, wherein the metal ion Is a heavy metal ion or a noble metal ion; and (c) separating the metal ion-bonded dendrimer composite magnetic metal particles from the source to be treated by magnetic separation. The method for separating and recovering metal ions according to claim 1, wherein the step (a) further applies a pickling treatment to the dendrimer composite magnetic metal particles. The method for separating and recovering metal ions according to claim 2, wherein the step (a) is a pickling treatment by contacting the dendrimer-composite magnetic metal particles with an acidic solvent. The acidic solvent is selected from concentrated hydrochloric acid, concentrated sulfuric acid, concentrated nitric acid or concentrated phosphoric acid. The method for separating and recovering metal ions according to claim 1, wherein the magnetic metal oxide in the step (a) is iron oxide. The method for separating and recovering metal ions according to the first aspect of the invention, wherein the terminal group of the dendrimer in the step (a) can form a misaligned structure with the metal ion of the step (b). The method for separating and recovering metal ions according to claim 1, wherein the dendrimer in the step (a) can be combined with the metal ions of the step (b) by an electrostatic force. The method for separating and recovering metal ions according to the first aspect of the invention, wherein the dendrimer in the step (a) has pores capable of trapping the metal ions of the step (b) therein. The method for separating and recovering metal ions according to claim 1, wherein the dendrimer-type composite magnetic metal particles in the step (a) have a particle diameter of between 10 nm and 5000 nm. The method for separating and recovering metal ions according to claim 8, wherein the dendrimer hybrid magnetic metal particles in the step (a) have a particle diameter of between 10 nm and 100 nm. The method for separating and recovering metal ions according to claim 1, wherein the source to be treated in the step (b) is a solution or a soil. The method for separating and recovering metal ions according to claim 1, wherein the heavy metal ions are selected from the group consisting of copper ions, zinc ions, nickel ions, manganese ions, cadmium ions, mercury ions, lead ions, and chromium ions. , arsenic ions, or a combination of these. The method for separating and recovering metal ions according to claim 1, wherein the noble metal ion is selected from the group consisting of silver ions and gold ions. Palladium ion, platinum ion, or a combination of these. The method for separating and recovering metal ions according to claim 1, further comprising a step (d) after the step (c), wherein the dendrimer-containing composite magnetic metal combined with metal ions The particles are contacted with a desorbing agent to separate the metal ions and the dendrimer-composite magnetic metal particles. The method for separating and recovering metal ions according to claim 13, wherein the desorbing agent of the step (d) is an acidic solvent. The method for separating and recovering metal ions according to claim 14, wherein the desorbing agent of the step (d) is hydrochloric acid. The method for separating and recovering metal ions according to claim 13 , wherein the step (d) further separates the dendrimer composite magnetic metal particles from the desorbent by magnetic separation.