A method for recovering a nickel-cobalt catalyst

Abstract

The application discloses a recycling method of a nickel-cobalt catalyst, and comprises the following steps: S1, soaking waste catalyst containing nickel and cobalt by using sulfuric acid to obtain a liquid containing nickel ions and cobalt ions; S2, adding chitosan-graphene porous adsorption material into the liquid obtained in S1; S3, stirring for 5 to 8 hours, and adsorbing the nickel ions and the cobalt ions by the amino groups of the chitosan-graphene porous adsorption material; and S4, heating the mixed system in S3 to 55 DEG C to 65 DEG C, and competitively adsorbing the nickel ions and the cobalt ions adsorbed on the chitosan-graphene porous adsorption material to selectively separate the nickel ions and the cobalt ions in the liquid phase. 2+ The application has selective adsorption of chitosan on Ni 2+ And Co 2+ The application can efficiently separate the miscible Ni 2+ And Co The application can be repeatedly performed, and is beneficial to the enrichment of the two materials in the solid phase and the liquid phase respectively.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of catalyst recovery, in particular to a recovery method of a nickel-cobalt catalyst. BACKGROUND

[0002] In the separation of waste catalysts containing a mixture of Ni, Al, Mo, V and Co, the prior art first obtains a slurry under the premise of mixing NaOH through ball milling, pressure cooking and filtering to obtain a liquid phase containing Mo and V and a residue phase containing Ni, Co and Al; for the liquid phase, Mo is converted into MOS3 and V is recovered as V2O5; for the residue phase, Al is separated in the form of a sodium metaaluminate solution by pressure cooking after adding NaOH, and the solid phase obtained is a mixture of Ni and Co. Since Ni and Co are extremely similar in physical and chemical properties, separation is difficult. The main methods for separating Ni and Co include chemical precipitation and solvent extraction. The solvent extraction method is widely used in the hydrometallurgical industry, and phosphonic acid extractant P204 is often used for the separation of Ni, Co, Mn and Fe, and P507 and Cyanex272 are often used for the separation of Ni and Co in sulfuric acid and chloride systems. The main process method for separating Ni and Co by solvent extraction has the advantages of good selectivity, high recovery rate and simple operation, but also has its own disadvantages, such as solvent volatilization inherent in extraction, emulsification in the extraction process, and extractant loss, which leads to high extraction process costs. SUMMARY

[0003] The present application aims to provide a recovery method of a nickel-cobalt catalyst, which uses chitosan to selectively adsorb Ni 2+ and Co 2+ , and efficiently separates miscible Ni 2+ and Co 2+ .

[0004] To solve this technical problem, the technical solution of the present application is as follows: a recovery method of a nickel-cobalt catalyst, comprising the following steps:

[0005] S1, soaking waste catalysts containing nickel and cobalt with sulfuric acid to obtain a liquid containing nickel ions and cobalt ions;

[0006] S2, adding chitosan-graphene porous adsorbent to the liquid obtained in S1, wherein the mass ratio of chitosan-graphene porous adsorbent to the liquid obtained in S1 is (0.05 to 0.1) : 10;

[0007] S3, stirring for 5 to 8 hours, and the amino groups of the chitosan-graphene porous adsorbent adsorb nickel ions and cobalt ions;

[0008] S4, heating the mixed system of S3 to 55-65 DEG C, nickel ions and cobalt ions adsorbed on the chitosan-graphene porous adsorption material compete, the cobalt ions adsorbed on the chitosan-graphene porous adsorption material are replaced by nickel ions, and the nickel ions and cobalt ions in the liquid phase are selectively separated.

[0009] Preferably, the concentration of sulfuric acid used in acid leaching is 40-45% by mass, and the acid leaching time is 1-3 hours.

[0010] Preferably, the chitosan-graphene porous adsorption material is prepared as follows:

[0011] S21, dispersing chitosan powder in an aqueous citric acid solution and stirring until the chitosan is completely dispersed;

[0012] The molecular chains of the granular chitosan powder intertwine during stirring, and the H + to positively charged chitosan;

[0013] S22, dispersing an aqueous dispersion of graphene oxide in the positively charged chitosan of S21;

[0014] The hydroxyl and carboxyl groups on the surface of the graphene oxide dispersed in the deionized water electrostatically adsorb the positively charged chitosan, and the graphene oxide is loaded with chitosan molecular chains during stirring;

[0015] S23, performing a hydrothermal reaction on the suspension system obtained in S22, and the citric acid reduces the graphene oxide during the hydrothermal reaction;

[0016] S24, freeze-drying the obtained gel composition to obtain a porous structure;

[0017] S25, repeatedly washing the dried porous chitosan-graphene composite with lye and deionized water to eliminate the citric acid in the chitosan-graphene porous adsorption material.

[0018] The present application uses citric acid to provide hydrogen ions to improve the solubility of chitosan, and the citric acid dispersed between chitosan and graphene oxide acts as a reducing agent for graphene oxide during the hydrothermal reaction. The hydroxyl groups and the remaining free amino groups of chitosan form intramolecular and intermolecular hydrogen bonds again with the dispersion and electrostatic adsorption of chitosan and graphene oxide, thereby forming a chitosan molecular chain surrounding graphene oxide and constructing a dispersed distribution of chitosan. With the hydrothermal reaction and subsequent alkaline washing and water washing, the dispersed citric acid in the gel product is removed, the looseness of the internal structure of the gel is strengthened, and the use as a selective adsorption material is facilitated.

[0019] The mass ratio of the chitosan powder, the citric acid and the graphene oxide in S22 is preferably (1 to 5) : (1 to 5) : (1 to 2). In the present application, in order to promote the improvement of the solubility of the chitosan powder, the chitosan and the citric acid are used in equal mass, while the graphene oxide is used to effectively load the ionized chitosan by electrostatic adsorption, so as to improve the specific surface area of the chitosan and increase the -NH2 and Ni 2+ and Co 2+ The contact possibility of the chitosan adsorption is ensured.

[0020] The conditions of the hydrothermal reaction in S23 are preferably as follows:

[0021] 120℃ to 160℃, and the reaction time is 4 to 6 hours. The sufficient consumption of the citric acid and the effective reduction of the graphene oxide are ensured.

[0022] The process conditions of the freeze-drying in S24 are preferably as follows:

[0023] After the gel composition obtained through the hydrothermal reaction is pre-frozen to form a solidified state in an environment of -18℃ to -25℃, the gel composition is placed in a vacuum freeze-drying machine for freeze-drying for 50 to 60 hours, so as to obtain the porous composite adsorption material.

[0024] The present application uses the freeze-drying to maintain the uniformity of the spatial mutual dispersion of the chitosan and the graphene, which is beneficial to the exposure of the free amino groups of the chitosan, and promotes the adsorption of the nickel ions and the cobalt ions.

[0025] Preferably, the gel composition is pressed into a sheet structure in a mold. By setting the chitosan-graphene porous adsorption material into a sheet structure, the adsorption path of the chitosan to the nickel ions and the cobalt ions is relatively uniform, which is convenient for the rapid adsorption and the realization of the selective adsorption.

[0026] Preferably, the cobalt ions selectively distributed in the liquid phase are precipitated or crystallized and purified from the liquid phase.

[0027] Preferably, the chitosan-graphene porous adsorption material adsorbed with the nickel ions is heated to 800℃ to 850℃ and calcined under inert gas, so as to obtain a graphene-loaded carbon-nickel oxide composite material.

[0028] The nickel oxide is converted into nickel ions dispersed in the liquid phase and separated from the carbon material by pickling;

[0029] The nickel ion solution is filtered, and the nickel is precipitated or crystallized and purified.

[0030] By adopting the above technical solutions, the present application has the following beneficial effects:

[0031] The present application firstly dissolves the nickel and the cobalt in the liquid phase by using the acid, and the chitosan is provided with H +The part of -NH2 of the chitosan molecular chain is converted into -NH + 3, the graphene oxide dispersed in deionized water is electro-negative in the aqueous solution due to the rich hydroxyl and carboxyl groups on the surface, and the chitosan is positively charged, so the chitosan is uniformly electrostatically adsorbed with the electro-negative chitosan; the part of -NH2 of the chitosan molecular chain is converted into -NH + 3, the intermolecular and intramolecular hydrogen bonds formed between the surface aminos are reduced, thereby promoting the dissolution of the chitosan in the aqueous phase, and the graphene oxide is uniformly dispersed between the chitosan under the action of electrostatic adsorption, forming a uniform dispersion of the graphene oxide and the chitosan; the -NH2 of the chitosan molecular chain is effectively contacted with the liquid phase, and the free amino groups of the chitosan are combined with the nickel ions and the cobalt ions; after the nickel ions and the cobalt ions are sufficiently combined, the chitosan-graphene porous adsorption material is added and heated, the nickel ions and the cobalt ions adsorbed on the chitosan-graphene porous adsorption material compete for adsorption, under the condition of heating, the cobalt ions adsorbed on the chitosan-graphene porous adsorption material are replaced by the nickel ions, realizing the selective separation of the nickel ions and the cobalt ions in the liquid phase, that is, the nickel ions are adsorbed on the chitosan-graphene porous adsorption material, and the cobalt ions are left in the liquid phase, thereby realizing the effective separation of the nickel ions and the cobalt ions;

[0032] The application uses the chitosan dispersed with graphene to effectively adsorb the nickel ions and the cobalt ions between the solid phase and the liquid phase, and uses the adsorption difference under heating to effectively selectively enrich the chitosan of the solid phase, and then directly separates the nickel ions adsorbed on the solid phase from the cobalt ions in the liquid phase. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 It is the infrared spectrum of the chitosan, the graphene oxide and the porous adsorption material used in the embodiment 4 of the application. DETAILED DESCRIPTION

[0034] In order to further explain the technical scheme of the application, the application will be described in detail below through specific embodiments.

[0035] Embodiment 1

[0036] The embodiment discloses a method for recycling a nickel-cobalt catalyst, comprising the following steps:

[0037] S1, the waste catalyst containing nickel and cobalt is soaked with sulfuric acid to obtain a liquid containing nickel ions and cobalt ions, and the volume of the liquid is 50 ml; the concentration of the nickel ions and the cobalt ions in the solution is 1.0 g / L respectively.

[0038] The concentration of the sulfuric acid used for acid leaching is 40% by mass fraction, and the acid leaching time is 1 hour.

[0039] S2, adding chitosan-graphene porous adsorbent material to the liquid obtained in S1, wherein the mass ratio of chitosan-graphene porous adsorbent material to the liquid obtained in S1 is 0.05:10;

[0040] The preparation method of chitosan-graphene porous adsorbent material is as follows:

[0041] S21, dispersing chitosan powder in a citric acid aqueous solution and stirring until the chitosan is completely dispersed;

[0042] The molecular chains of the granular chitosan powder intertwine with each other during stirring, and the H + to positively charged chitosan;

[0043] S22, dispersing the aqueous dispersion of graphene oxide in the positively charged chitosan of S21;

[0044] The hydroxyl and carboxyl groups on the surface of graphene oxide dispersed in deionized water electrostatically adsorb the positively charged chitosan, and with stirring, the graphene oxide is loaded with chitosan molecular chains;

[0045] The mass ratio of chitosan powder, citric acid and graphene oxide in S22 is 1:1:2;

[0046] S23, performing a hydrothermal reaction on the suspension system obtained in S22, and during the hydrothermal reaction, the citric acid reduces the graphene oxide;

[0047] The conditions for the hydrothermal reaction in S23 are 110°C and a reaction time of 6 hours.

[0048] S24, freeze-drying the obtained gel composition to obtain a porous structure;

[0049] The process conditions for freeze-drying in S24 are:

[0050] The gel composition obtained after the hydrothermal reaction is placed in a -18°C environment to pre-freeze and form a solidified state, and is placed in a vacuum freeze dryer for freeze-drying for 50 hours to obtain a porous composite adsorbent material.

[0051] S25, repeatedly washing the dried porous chitosan-graphene composite with lye and deionized water to eliminate the citric acid in the chitosan-graphene porous adsorbent material.

[0052] S3, stirring for 8 hours, and the amino groups of the chitosan-graphene porous adsorbent material adsorb nickel ions and cobalt ions;

[0053] S4, heating the mixed system of S3 at 55℃ for 3 hours, nickel ions and cobalt ions adsorbed on the chitosan-graphene porous adsorption material compete with each other, the cobalt ions adsorbed on the chitosan-graphene porous adsorption material are replaced by nickel ions, and the nickel ions and the cobalt ions in the liquid phase are selectively separated.

[0054] The gel composition is pressed into a sheet structure in a mold.

[0055] The cobalt ions selectively distributed in the liquid phase are precipitated or crystallized from the liquid phase.

[0056] The chitosan-graphene porous adsorption material adsorbed with nickel ions is calcined at 800℃ under inert gas to obtain a graphene-loaded carbon-nickel oxide composite material;

[0057] The nickel oxide is converted into nickel ions dispersed in the liquid phase and separated from the carbon material by pickling;

[0058] The nickel ion solution is filtered, and the nickel is precipitated or crystallized.

[0059] The chitosan-graphene composite in the liquid is filtered, and the contents of the nickel ions and the cobalt ions in the solution are measured respectively, and the specific values C0 and C1 are shown in Table 1.

[0060] The present application utilizes the selective adsorption of chitosan to Ni 2+ and Co 2+ , and efficiently separates the miscible Ni 2+ and Co 2+ .

[0061] Example 2

[0062] The present application discloses a method for recycling a nickel-cobalt catalyst, comprising the following steps:

[0063] S1, the waste catalyst containing nickel and cobalt is soaked with sulfuric acid to obtain a liquid containing nickel ions and cobalt ions, 50ml; the concentrations of the nickel ions and the cobalt ions are 1.0g / L respectively.

[0064] The concentration of sulfuric acid used for pickling is 40% by mass, and the pickling time is 1 hour.

[0065] S2, adding chitosan-graphene porous adsorption material to the liquid obtained in S1, wherein the mass ratio of the chitosan-graphene porous adsorption material to the liquid obtained in S1 is 0.08:10;

[0066] The preparation method of the chitosan-graphene porous adsorption material is as follows:

[0067] S21, dispersing chitosan powder in a citric acid aqueous solution and stirring until the chitosan is completely dispersed;

[0068] The molecular chains of the granular chitosan powder intertwine with each other during stirring, and the H + to be converted into positively charged chitosan;

[0069] S22, dispersing the aqueous dispersion of graphene oxide into the positively charged chitosan of S21;

[0070] The hydroxyl and carboxyl groups on the surface of the graphene oxide dispersed in the deionized water electrostatically adsorb the positively charged chitosan, and with stirring, the graphene oxide is loaded with the molecular chains of chitosan;

[0071] The mass ratio of chitosan powder, citric acid and graphene oxide in S22 is 5:5:1;

[0072] S23, subjecting the suspension system obtained in S22 to a hydrothermal reaction, and in the process of the hydrothermal reaction, the citric acid reduces the graphene oxide;

[0073] The conditions for the hydrothermal reaction in S23 are: 120°C, and a reaction time of 5 hours.

[0074] S24, freeze-drying the obtained gel composition to obtain a porous structure;

[0075] The process conditions for freeze-drying in S24 are:

[0076] The gel composition obtained through the hydrothermal reaction is pre-frozen to form a solidified state in an environment of -22°C, and is freeze-dried in a vacuum freeze-drying machine for 60 hours to obtain a porous composite adsorption material.

[0077] S25, repeatedly washing the dried porous chitosan-graphene composite with lye and deionized water to eliminate the citric acid in the chitosan-graphene porous adsorption material.

[0078] S3, stirring for 8 hours, and the amino groups of the chitosan-graphene porous adsorption material adsorb the nickel ions and cobalt ions;

[0079] S4, heating the mixed system of S3 to 60°C for 3 hours, and the nickel ions and cobalt ions adsorbed on the chitosan-graphene porous adsorption material undergo competitive adsorption, the cobalt ions adsorbed on the chitosan-graphene porous adsorption material are replaced by the nickel ions, and the nickel ions and cobalt ions in the liquid phase are selectively separated.

[0080] The gel composition is pressed into a sheet structure in a mold.

[0081] The cobalt ions selectively distributed in the liquid phase are precipitated or crystallized from the liquid phase.

[0082] The chitosan-graphene porous adsorption material adsorbing nickel ions is calcined under inert gas at 850 DEG C to obtain a graphene loaded carbon-nickel oxide composite material;

[0083] The nickel oxide is converted into nickel ions dispersed in liquid phase and separated from the carbon material by acid immersion;

[0084] The nickel ion solution is filtered, and the nickel is precipitated or crystallized and purified.

[0085] The chitosan-graphene composite in the liquid is filtered, and the contents of nickel ions and cobalt ions in the solution are measured respectively, and the specific values C0 and C1 are shown in Table 1.

[0086] Example 3

[0087] The embodiment discloses a method for recycling a nickel-cobalt catalyst, comprising the following steps:

[0088] S1, the waste catalyst containing nickel and cobalt is soaked with sulfuric acid to obtain a liquid 50ml containing nickel ions and cobalt ions; the concentrations of the nickel ions and the cobalt ions are 1.0g / L respectively.

[0089] The concentration of sulfuric acid used in acid immersion is 40% by mass fraction, and the acid immersion time is 1 hour.

[0090] S2, chitosan-graphene porous adsorption material is added to the liquid obtained in S1, wherein the mass ratio of the chitosan-graphene porous adsorption material to the liquid obtained in S1 is 0.10:10;

[0091] The preparation method of the chitosan-graphene porous adsorption material is as follows:

[0092] S21, chitosan powder is dispersed in a citric acid aqueous solution, and stirring is performed until the chitosan is completely dispersed;

[0093] The molecular chains of the granular chitosan powder intertwine with each other during stirring, and the H + The chitosan is converted into positively charged chitosan;

[0094] S22, an aqueous dispersion of graphene oxide is dispersed in the positively charged chitosan obtained in S21;

[0095] The hydroxyl and carboxyl groups on the surface of the graphene oxide dispersed in the deionized water electrostatically adsorb the positively charged chitosan, and the graphene oxide is loaded with chitosan molecular chains during stirring;

[0096] The mass ratio of the chitosan powder, the citric acid and the graphene oxide in S22 is 3:3:2;

[0097] S23, the suspension system obtained in S22 is subjected to a hydrothermal reaction, and the citric acid reduces the graphene oxide during the hydrothermal reaction;

[0098] The hydrothermal reaction condition in S23 is 130℃, and the reaction time is 4 hours.

[0099] S24, freeze-drying the obtained gel composition to obtain a porous structure;

[0100] The process condition of freeze-drying in S24 is as follows:

[0101] The gel composition obtained through the hydrothermal reaction is pre-frozen to form a solidified state in an environment of-25℃, and then freeze-dried in a vacuum freeze dryer for 50 hours to obtain a porous composite adsorption material.

[0102] S25, repeatedly washing the dried porous chitosan-graphene composite with alkaline solution and deionized water to eliminate citric acid in the chitosan-graphene porous adsorption material.

[0103] S3, stirring for 8 hours to adsorb nickel ions and cobalt ions on the amino groups of the chitosan-graphene porous adsorption material;

[0104] S4, heating the mixed system of S3 at 60℃ for 3 hours, and nickel ions replace cobalt ions adsorbed on the chitosan-graphene porous adsorption material to selectively separate nickel ions and cobalt ions in the liquid phase.

[0105] The gel composition is pressed into a sheet structure in a mold.

[0106] The cobalt ions selectively distributed in the liquid phase are precipitated or crystallized from the liquid phase.

[0107] The chitosan-graphene porous adsorption material adsorbing nickel ions is calcined at 800℃ under inert gas to obtain a graphene-loaded carbon-nickel oxide composite material;

[0108] The nickel oxide is converted into nickel ions dispersed in the liquid phase by acid immersion, and separated from the carbon material;

[0109] The nickel ion solution is filtered, and nickel is precipitated or crystallized.

[0110] The chitosan-graphene composite in the liquid is filtered, and the contents of nickel ions and cobalt ions in the solution are measured respectively. The specific values C0 and C1 are shown in Table 1.

[0111] Example 4

[0112] The embodiment discloses a method for recycling a nickel-cobalt catalyst, comprising the following steps:

[0113] S1, the waste catalyst containing nickel and cobalt is soaked with sulfuric acid to obtain a liquid containing nickel ions and cobalt ions, 50 ml; the concentrations of the nickel ions and the cobalt ions are 1.0 g / L respectively.

[0114] The concentration of sulfuric acid used in the acid leaching is 40% by mass, and the acid leaching time is 1 hour.

[0115] S2, adding chitosan-graphene porous adsorption material to the liquid obtained in S1, wherein the mass ratio of the chitosan-graphene porous adsorption material to the liquid obtained in S1 is 0.06:10;

[0116] The preparation method of the chitosan-graphene porous adsorption material is as follows:

[0117] S21, dispersing chitosan powder in a citric acid aqueous solution and stirring until the chitosan is completely dispersed;

[0118] The molecular chains of the granular chitosan powder intertwine with each other during stirring, and the H + to positively charged chitosan;

[0119] S22, dispersing an aqueous dispersion of graphene oxide in the positively charged chitosan of S21;

[0120] The hydroxyl and carboxyl groups on the surface of the graphene oxide dispersed in the deionized water electrostatically adsorb the positively charged chitosan, and with stirring, the graphene oxide is loaded with chitosan molecular chains;

[0121] The mass ratio of chitosan powder, citric acid and graphene oxide in S22 is 4:1:1;

[0122] S23, performing a hydrothermal reaction on the suspension system obtained in S22, and in the process of the hydrothermal reaction, the citric acid reduces the graphene oxide;

[0123] The conditions of the hydrothermal reaction in S23 are: 120°C, and the reaction time is 5 hours.

[0124] S24, freeze-drying the obtained gel composition to obtain a porous structure;

[0125] The process conditions of the freeze-drying in S24 are:

[0126] The gel composition obtained by the hydrothermal reaction is placed in an environment of -25°C to pre-freeze and form a solidified state, and is placed in a vacuum freeze dryer to freeze-dry for 60 hours to obtain a porous composite adsorption material.

[0127] S25, repeatedly washing the dried porous chitosan-graphene composite with lye and deionized water to eliminate the citric acid in the chitosan-graphene porous adsorption material.

[0128] S3, stirring for 8 hours, the amino group of the chitosan-graphene porous adsorption material adsorbs nickel ions and cobalt ions;

[0129] S4, heating the mixed system of S3 at 60℃ for 3 hours, nickel ions and cobalt ions adsorbed on the chitosan-graphene porous adsorption material compete for adsorption, the cobalt ions adsorbed on the chitosan-graphene porous adsorption material are replaced by nickel ions, and nickel ions and cobalt ions in the liquid phase are selectively separated.

[0130] The gel composition is pressed into a sheet-shaped structure in a mold.

[0131] The cobalt ions selectively distributed in the liquid phase are precipitated or crystallized from the liquid phase.

[0132] The chitosan-graphene porous adsorption material adsorbed with nickel ions is calcined at 850℃ under inert gas to obtain a graphene-loaded carbon-nickel oxide composite material;

[0133] The nickel oxide is converted into nickel ions dispersed in the liquid phase and separated from the carbon material by pickling;

[0134] The nickel ion solution is filtered, and nickel is precipitated or crystallized.

[0135] The chitosan-graphene composite in the liquid is filtered, and the contents of nickel ions and cobalt ions in the solution are measured respectively, and the specific values C0 and C1 are shown in Table 1.

[0136] Example 5

[0137] The embodiment discloses a method for recycling a nickel-cobalt catalyst, comprising the following steps:

[0138] S1, the waste catalyst containing nickel and cobalt is soaked with sulfuric acid to obtain a liquid 50ml containing nickel ions and cobalt ions; the concentrations of nickel ions and cobalt ions are 1.0g / L respectively.

[0139] The concentration of sulfuric acid used for acid pickling is 40% by mass, and the acid pickling time is 1 hour.

[0140] S2, chitosan-graphene porous adsorption material is added to the liquid obtained in S1, wherein the mass ratio of chitosan-graphene porous adsorption material to the liquid obtained in S1 is 0.08:10;

[0141] The preparation method of the chitosan-graphene porous adsorption material is as follows:

[0142] S21, disperse the chitosan powder in the aqueous citric acid solution, and stir until the chitosan is completely dispersed;

[0143] The molecular chains of the granular chitosan powder intertwine with each other during stirring, and the H +transformed into positively charged chitosan;

[0144] S22, dispersing the aqueous dispersion of graphene oxide into the positively charged chitosan of S21;

[0145] The hydroxyl and carboxyl groups on the surface of graphene oxide dispersed in deionized water electrostatically adsorb the positively charged chitosan, and with stirring, the graphene oxide is loaded with chitosan molecular chains;

[0146] The mass ratio of chitosan powder, citric acid and graphene oxide in S22 is 2:2:2;

[0147] S23, the suspension system obtained in S22 is subjected to hydrothermal reaction, and the citric acid reduces the graphene oxide during the hydrothermal reaction;

[0148] The conditions for the hydrothermal reaction in S23 are: 110°C, and the reaction time is 6 hours.

[0149] S24, the obtained gel composition is freeze-dried to obtain a porous structure;

[0150] The process conditions for freeze-drying in S24 are:

[0151] The gel composition obtained by hydrothermal reaction is placed in an environment of -22°C to pre-freeze into a solid state, and is placed in a vacuum freeze dryer for freeze-drying for 50 hours to obtain a porous composite adsorption material.

[0152] S25, the dried porous chitosan-graphene composite is repeatedly washed with lye and deionized water to eliminate the citric acid in the chitosan-graphene porous adsorption material.

[0153] S3, stirring for 8 hours, the amino groups of the chitosan-graphene porous adsorption material adsorb nickel ions and cobalt ions;

[0154] S4, heating the mixed system of S3 to 65°C for 3 hours, the nickel ions and cobalt ions adsorbed on the chitosan-graphene porous adsorption material undergo competitive adsorption, the cobalt ions adsorbed on the chitosan-graphene porous adsorption material are replaced by nickel ions, and the nickel ions and cobalt ions in the liquid phase are selectively separated.

[0155] The gel composition is pressed into a sheet structure in a mold.

[0156] The cobalt ions selectively distributed in the liquid phase are precipitated or crystallized from the liquid phase.

[0157] The chitosan-graphene porous adsorption material adsorbed with nickel ions is calcined at 800°C under inert gas to obtain a graphene-loaded carbon-nickel oxide composite material;

[0158] The nickel oxide is converted into nickel ions by pickling, which are dispersed in the liquid phase and separated from the carbon material.

[0159] The nickel ion solution is filtered, and the nickel is purified by precipitation or crystallization.

[0160] The chitosan-graphene composite in the liquid is filtered, and the contents of the nickel ions and the cobalt ions in the solution are measured respectively. The specific values C0 and C1 are shown in Table 1.

[0161] Comparative Example

[0162] In the comparative example, a solution of 50 ml with the concentrations of nickel ions and cobalt ions of 1.0 g / L is prepared as in Example 1. Chitosan particles with a D50 of 60 microns are added to the solution, and the nickel ions and the cobalt ions are adsorbed at room temperature for 11 hours. After the adsorption, the chitosan in the liquid is filtered, and the contents of the nickel ions and the cobalt ions in the solution are measured respectively. The specific value C0 is shown in Table 1.

[0163] C0 and C1 are the concentrations of Ni 2+ and Co 2+ in the liquid environment after S3 and S4, respectively.

[0164] Table 1: Separation of nickel and cobalt in Examples 1 to 5 and the comparative example

[0165]

[0166]

[0167] The porous composite adsorption materials prepared in Examples 1 to 5 are crushed into particles with a D50 of 60 microns after S25, and the specific surface areas of the chitosan in the comparative example are tested. The specific data are shown in Table 2.

[0168] Table 2: Specific surface areas of the porous adsorption materials obtained in Examples 1 to 5 and the chitosan particles in the comparative example

[0169] Item Specific surface area (m 2 / g) Example 1 326.25 Example 2 189.56 Example 3 266.93 Example 4 205.38 Example 5 286.77 Comparative Example 72.68

[0170] Graphene is mainly used for adsorbing organic matters and inorganic anions in aqueous solutions. In the present application, graphene oxide and chitosan with free amino groups are electrostatically adsorbed, i.e., physical adsorption between molecules. In the present application, uniform distribution exists between chitosan and graphene. The present application realizes electrostatic adsorption of chitosan and graphene oxide by using citric acid. Then, the hydrothermal reaction is used to consume the citric acid, and the alkaline solution is used to remove the citric acid. Meanwhile, the loading of graphene on chitosan effectively improves the reduction of the formation of hydrogen bonds in chitosan. As shown in Table 2, the spatial blocking effect of graphene is used to improve the dispersion of chitosan, so that more amino groups are exposed to participate in the combination with nickel ions and cobalt ions. Meanwhile, the competitive adsorption of nickel ions and cobalt ions with amino groups under heating conditions is further used to effectively realize the selective adsorption of cobalt and nickel.Figure 1 The infrared spectrum of the porous adsorption material obtained in Example 4 is given, chitosan and hydrothermally reacted graphene oxide are combined to form the porous adsorption material, and further combined with nickel ions and cobalt ions to realize the selective separation of nickel ions and cobalt ions by the difference in the binding kinetics of the amino groups. Further combining Examples 1 to 5, it can be known that, by repeating the above separation process, the effective separation of nickel and cobalt, i.e. the separate enrichment of nickel and cobalt, can be further realized. Further comparing Examples 2 and 4, it can be known that, if chitosan cannot be effectively dispersed by graphene oxide, the amino groups cannot be effectively exposed, and the binding effect on nickel ions and cobalt ions is relatively poor compared with Examples 3, 5 and 1. The comparative examples are compared with Examples 2 and 4, and chitosan loaded with graphene oxide or graphene is obtained, the dispersibility is significantly improved, the hydrogen bonds are reduced, and the ability to bind cobalt ions and nickel ions is enhanced.

[0171] Meanwhile, the present application uses citric acid as an intermediate substance for compounding graphene oxide and loading chitosan, and removes it in the process of preparing the porous adsorption material, uses graphene oxide to increase the dispersibility of chitosan, and uses graphene to enhance the solid characteristics of the porous adsorption material, facilitating the effective separation from the solution and the selective separation of nickel ions and cobalt ions.

Claims

1. A method for recovering a nickel-cobalt catalyst, characterized in that: The following steps are involved: S1. Soaking the waste catalyst containing nickel and cobalt in sulfuric acid to obtain a liquid containing nickel ions and cobalt ions; S2. Adding chitosan-graphene porous adsorption material to the liquid obtained in S1, wherein the mass ratio of chitosan-graphene porous adsorption material to the liquid obtained in S1 is (0.05 to 0.1):10; The preparation method of chitosan-graphene porous adsorption material is as follows: S21, dispersing chitosan powder in citric acid aqueous solution, and stirring until the chitosan is completely dispersed; The molecular chains of the granular chitosan powder are entangled with each other during the stirring process due to the H provided by citric acid. + Converted into positively charged chitosan; S22, dispersing the aqueous dispersion of graphene oxide in the positively charged chitosan of S21; The hydroxyl and carboxyl groups on the surface of graphene oxide dispersed in deionized water undergo electrostatic adsorption with the positively charged chitosan. With stirring, the graphene oxide loads the chitosan molecular chains. The mass ratio of chitosan powder, citric acid, and graphene oxide in S22 is 1:1:(1 to 2); S23, subjecting the suspension system obtained in S22 to a hydrothermal reaction, wherein citric acid reduces graphene oxide during the hydrothermal reaction; S24, freeze-drying the obtained gel composition to obtain a porous structure; S25, repeatedly washing the dried porous chitosan-graphene composite with alkaline solution and deionized water to eliminate citric acid in the porous chitosan-graphene adsorption material; S3, stirring for 5 to 8 hours, so that the amino groups of the chitosan-graphene porous adsorption material adsorb nickel ions and cobalt ions; S4, heating the mixed system of S3 to 55° C. to 65° C., so that the nickel ions and cobalt ions adsorbed on the chitosan-graphene porous adsorption material undergo competitive adsorption, and the cobalt ions adsorbed on the chitosan-graphene porous adsorption material are replaced by nickel ions, thereby selectively separating the nickel ions and cobalt ions in the liquid phase; The cobalt ions selected to be distributed in the liquid phase are precipitated or crystallized from the liquid phase for purification; The chitosan-graphene porous adsorption material adsorbed with nickel ions is heated to 800° C. to 850° C. and calcined under inert gas to obtain a graphene-supported carbon-nickel oxide composite material; Acid immersion converts nickel oxide into nickel ions which are dispersed in the liquid phase and separated from the carbon material; The nickel ion solution is filtered and the nickel is purified by precipitation or crystallization.

2. A method for recovering a nickel-cobalt catalyst according to claim 1, characterized in that: The concentration of sulfuric acid used in acid leaching is 40% to 45% by mass.

3. A method for recovering a nickel-cobalt catalyst according to claim 1, characterized in that: The conditions for the hydrothermal reaction in S23 are: 110℃ to 130℃, reaction time 4 to 6 hours.

4. The method for recovering a nickel-cobalt catalyst according to claim 1, wherein: The process conditions for freeze drying in S24 are: The gel composition obtained by the hydrothermal reaction is placed in an environment of -18°C to -25°C for pre-freezing to form a solidified state, and is placed in a vacuum freeze dryer for freeze drying for 50 to 60 hours to obtain a porous composite adsorption material.

5. The method for recovering a nickel-cobalt catalyst according to claim 1, wherein: The gel composition is pressed into a sheet-like structure in a mold.

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