PAN fiber-based gold adsorption material and its manufacturing method and gold recovery method using the same

Abstract

The present invention relates to a PAN fiber-based gold adsorption material capable of realizing excellent gold adsorption characteristics, excellent durability, excellent ease of manufacturing, and excellent usability through a structure in which an alkylamine compound is fixed to a polyacrylonitrile (PAN) fiber, a method for manufacturing the same, and a method for recovering gold using the same. The PAN fiber-based gold adsorption material according to the present invention is intended to adsorb gold ions in water and is characterized by having a structure in which an alkylamine compound is fixed to the surface of a PAN fiber.

Description

Technology Field

[0001] The present invention relates to a PAN fiber-based gold adsorption material, a method for manufacturing the same, and a method for recovering gold using the same. More specifically, the invention relates to a PAN fiber-based gold adsorption material and a method for manufacturing the same and a method for recovering gold using the same, which can achieve excellent gold adsorption characteristics, excellent durability, excellent ease of manufacturing, and excellent usability through a structure in which an alkylamine compound is immobilized on a polyacrylonitrile (PAN) fiber. Background Technology

[0002] Adsorption materials are used to recover gold from industrial waste, such as electrical and electronic waste. To maximize the specific surface area and increase recovery efficiency, the diameter of the adsorption materials is being reduced to hundreds of micrometers to several nanometers. While reducing the diameter of the adsorption materials improves gold recovery efficiency, it is difficult to recover the materials after use due to their small size, and it is less economical because it causes a high pressure drop during the gold recovery process.

[0003] On the other hand, if the diameter of the gold adsorption material is in the mm range, no pressure drop occurs during the gold recovery process; however, there is a problem in that the adsorption efficiency of the adsorption material is reduced because the pores of the adsorption material are clogged by suspended solids.

[0004] In addition, the adsorption selectivity for gold ions (Au ions) must be considered during the gold recovery process using adsorption materials. During the gold recovery process, various metallic ions other than gold ions are present, and it is known that up to 14 types of metallic ions, including copper (Cu), nickel (Ni), cobalt (Co), and zinc (Zn), can coexist with gold ions. Since these metallic ions act as factors that reduce the adsorption efficiency of gold adsorption materials by blocking their pores, it is required of gold adsorption materials to selectively adsorb only gold ions in an environment where these metallic ions are present.

[0005] Korean Patent Publication No. 2284087 presents a porous adsorption material for adsorbing gold ions with a diameter of 1 to 100 μm, in which a polyphenol-based compound is coated on the surface of porous polymer particles. However, due to the small size, difficulties in recovering the adsorption material are anticipated, and conditions requiring irradiation with a light source of a specific wavelength are essential for the adsorption of gold ions. In addition, there is a risk that the pores of the adsorption material may become clogged by various suspended solids during the gold recovery process.

[0006] US Patent Publication No. 10301180 presents a method for regenerating activated carbon used in a gold recovery process, but it does not present a configuration for recovering the activated carbon used in the gold recovery process, so difficulties as described above are expected in the recovery of gold adsorption materials.

[0007] Mesoporous Silica Derived from Municipal Solid Waste Incinerator (MSWI) Ash Slag: Synthesis, Characterization and Use as Supports for Au(III) Recovery, Yosep Hand, etc., 2021, Materials, 14, 6894 presents a technique for adsorbing gold ions by manufacturing silica particles with a porous structure, but the recovery of silica particles is not easy, and the problem of the pores of the silica particles being clogged by metallic ions that may coexist during the gold recovery process is not considered.

[0008] In addition, International Patent Publication WO2019-131946 discloses a technology for recovering gold from a solution containing a gold cyano complex using a crosslinking resin containing vinyl amine units, and U.S. Patent Publication US 4723998 presents a technology for recovering gold from carbonate minerals using an ion exchange resin.

[0009] Meanwhile, various alkylamines have been proposed as gold adsorption materials based on their excellent adsorption and reduction capabilities (see Non-patent Literature 2). However, alkylamines have the characteristic of dissolving easily in aqueous solutions due to their strong hydrophilicity, making them difficult to apply as gold adsorption materials.

[0010] To solve the problem of high water solubility of alkylamines, the applicant and inventors proposed a "gold adsorption material with a core-shell structure having a three-dimensional radial pore structure" as disclosed in Korean Patent Publication No. 2023-0148067 (Patent Document 5). The gold adsorption material disclosed in Patent Document 5 forms a three-dimensional radial pore structure inside a gold adsorption material made of polyacrylonitrile (PAN) and immobilizes amine functional groups within the pores, thereby suppressing the dissolution of amine functional groups in an aqueous solution. Prior art literature

[0011] Korean Patent Publication No. 2284087 (Published Aug. 2, 2021) US Patent Publication US 10301180 (Published May 28, 2019) International Patent Publication WO2019-131946 (Published July 4, 2019) US Patent Publication US 4723998 (Published Feb. 9, 1988) Korean Published Patent Publication No. 2023-0148067 (Published Oct. 24, 2023) International Patent Publication WO2023-001810 (Published Jan. 26, 2023)

[0012] Mesoporous Silica Derived from Municipal Solid Waste Incinerator (MSWI) Ash Slag: Synthesis, Characterization and Use as Supports for Au(III) Recovery , Yosep Hand, etc., 2021, Materials, 14, 6894Gold(III) recovery using synthetic chelating resins with amine, thio and amine / mercaptan functionalities, AM Donia, AA Atia , KZ Elwakeel, Separation and Purification Technology, Volume 42, Issue 2, 15 March 2005, Pages 111-116 The problem to be solved

[0013] The present invention was devised to solve the above-mentioned problems, and aims to provide a PAN fiber-based gold adsorption material that can improve the durability of the gold adsorption material through a structure in which an alkylamine compound is immobilized on a polyacrylonitrile (PAN) fiber.

[0014] In addition, another objective of the present invention is to provide a technology that improves the ease of recovery of the gold adsorption material by implementing a PAN fiber-based gold adsorption material having a diameter of μm, and can also suppress the pressure drop phenomenon caused by the gold adsorption material during the gold recovery process.

[0015] In addition, the present invention has another objective of providing a PAN fiber-based gold adsorption material that exhibits the highest level of gold adsorption characteristics compared to known gold adsorption materials, including nanometer (nm) sized gold adsorption materials.

[0016] In addition, the present invention has another objective of providing a PAN fiber-based gold adsorption material that exhibits high gold recovery efficiency even in an environment where various metallic ions coexist. means of solving the problem

[0017] The PAN fiber-based gold adsorption material according to the present invention for achieving the above objective is intended to adsorb gold ions in water and is characterized by having a structure in which an alkylamine compound is fixed to the surface of the PAN fiber.

[0018] The maximum gold adsorption capacity of the PAN fiber-based gold adsorption material is 600 mg / g or more.

[0019] The molecular weight of the alkylamine compound is 25,000 g / mol or more.

[0020] The alkylamine compound is fixed by the amination reaction between the alkylamine compound and the PAN fiber, and the number of grafted molecules of the alkylamine compound at the time the amination reaction is terminated is less than 1 mmol / g.

[0021] Alkylamine compounds are branched alkylamine compounds.

[0022] The branched alkylamine compound is any one of bPEI (branched poly(ethyleneimine)), iso-butylamine, sec-butylamine, iso-amylamine, PEA (phosphoethanolamine), trimethylamine, and isopropylamine, or a combination thereof.

[0023] The method for manufacturing a PAN fiber-based gold adsorption material according to the present invention is characterized by introducing a PAN fiber into an aqueous solution of an alkylamine compound to fix an alkylamine compound on the surface of the PAN fiber through an amination reaction, and the moles of grafted molecules of the alkylamine compound at the time when the amination reaction is terminated being less than 1 mmol / g.

[0024] The maximum gold adsorption capacity of the manufactured PAN fiber-based gold adsorption material is 600 mg / g or more.

[0025] A method for recovering gold using a PAN fiber-based gold adsorption material according to the present invention comprises the steps of: acidifying a treatment target solution containing gold ions; and introducing a PAN fiber-based gold adsorption material into the treatment target solution under acidic conditions; wherein when the gold adsorption material is introduced into the treatment target solution under acidic conditions, the amine functional group provided in the alkylamine compound [subjects] hydrogen ions (H + It is characterized by the fact that it combines with ) to form an electrical (+) electrode state, the gold ion combines with an anion to form a (-) electrode state, other metallic ions present in the solution to be treated maintain a cation state, the gold ion in the (-) electrode state is adsorbed to the amine functional group in the (+) electrode state, and other metallic ions maintaining a cation state are not adsorbed to the amine functional group in the (+) electrode state. Effects of the invention

[0026] The PAN fiber-based gold adsorption material according to the present invention, the method for manufacturing the same, and the method for recovering gold using the same have the following effects.

[0027] The maximum adsorption capacity of gold ions is 1,463 mg / g, which is significantly superior to µm-sized and millimeter (mm)-sized gold adsorption materials. Furthermore, it exhibits the highest level of gold adsorption characteristics even when compared to nano-sized (nm) gold adsorption materials.

[0028] In addition, as high molecular weight alkylamine compounds are immobilized on the PAN surface at a low introduction density, the reduction in crystallinity and strength of the PAN fiber is suppressed, and gold adsorption characteristics are improved. Along with this, by acidifying the solution to be treated to enable the selective adsorption of only anionic gold ions, the adsorption selectivity for gold ions is excellent. Brief explanation of the drawing

[0029] FIG. 1 is a schematic diagram of a PAN fiber-based gold adsorption material according to one embodiment of the present invention. Figure 2 is a schematic diagram showing alkylamine compounds of various molecular weights immobilized on the surface of PAN fibers. Figure 3 is a schematic diagram showing the introduction of bPEI onto the surface of PAN fibers by an amination reaction. Figure 4a shows the FT-IR analysis results of gold adsorption materials immobilized with DETA, TETA, TEPA, and bPEI, respectively, prepared according to Experimental Example 1. Figure 4b shows the number of moles of grafted molecules, respectively, of DETA, TETA, TEPA, and bPEI, in the gold adsorption material prepared according to Experimental Example 1. Figure 4c shows the weight of the gold adsorption material with DETA, TETA, TEPA, and bPEI immobilized, respectively, prepared according to Experimental Example 1. Figure 4d shows the XRD analysis results of gold adsorption materials immobilized with DETA, TETA, TEPA, and bPEI, respectively, prepared according to Experimental Example 1. Figure 4e shows the tensile strength characteristics of gold adsorption materials with DETA, TETA, TEPA, and bPEI immobilized, respectively, prepared according to Experimental Example 1. Figure 4f shows the results of measuring the maximum adsorption capacity of gold adsorption materials immobilized with DETA, TETA, TEPA, and bPEI, respectively, prepared according to Experimental Example 1. Figures 5a to 5d are experimental results showing the changes in characteristics of the gold adsorption material according to the amination reaction time. Figures 6a to 6c are experimental results showing the gold recovery rate according to the pH of a solution containing gold ions. Figures 7a to 7c are experimental results showing the gold recovery rate according to gold ion concentration. Fig. 7d Ci This is the result of the isothermal adsorption experiment of the gold adsorption material according to FIG. 7e is a schematic diagram summarizing the maximum adsorption capacity results of the gold adsorption material according to the present invention and a known gold adsorption material. Figure 8 shows the experimental results of gold recovery characteristics in an environment where gold ions and 14 types of metallic ions coexist. Figure 9 is an experimental result showing the regeneration characteristics of the gold adsorption material according to the present invention. Figure 10a is an experimental result showing the pressure drop characteristics of the gold adsorption material according to the present invention. FIG. 10b is a photograph showing a gold adsorption material according to the present invention woven into an arbitrary shape. Figure 11 is a microscopic image of gold adsorption materials immobilized with bPEI having molecular weights of 10,000, 25,000, and 70,000 g / mol, respectively. Specific details for implementing the invention

[0030] Hereinafter, a PAN fiber-based gold adsorption material according to one embodiment of the present invention, a method for manufacturing the same, and a method for recovering gold using the same will be described in detail with reference to the drawings.

[0031] PAN fiber-based gold adsorption material

[0032] The present invention provides a technology that not only achieves excellent gold recovery characteristics by utilizing the gold adsorption characteristics of alkylamines but also improves the durability of gold adsorption materials by suppressing the high water solubility of alkylamines.

[0033] As described above in 'Technical Background of the Invention,' the excellent gold adsorption properties of alkylamines are known (see Non-Patent Literature 2), and how to limit the high water solubility of alkylamines is a key factor in their utilization as gold adsorption materials. As one method to limit the high water solubility of alkylamines, the inventors have presented the technology disclosed in Patent Literature 5.

[0034] The inventors have developed a gold adsorption material having a simpler manufacturing method, superior gold adsorption characteristics, superior durability, and superior usability as an extension of the research on the technology disclosed in Patent Document 5.

[0035] While the maximum adsorption capacity of the gold adsorption material disclosed in Patent Document 5 (see FIG. 9a and FIG. 9b of Patent Document 5) is less than 600 mg / g, the maximum adsorption capacity of the gold adsorption material according to the present invention is 1463 mg / g, which is more than twice as excellent (see Experimental Example 4 described later). The maximum adsorption capacity of the gold adsorption material according to the present invention can be considered to be of the highest level of gold adsorption characteristics, not only compared to fibrous gold adsorption materials but also compared to nanometer (nm) sized gold adsorption materials that exhibit relatively excellent gold adsorption characteristics based on a high specific surface area (see Experimental Example 4 and Table 2 described later). Furthermore, while the gold adsorption material of Patent Document 5 is a millimeter (mm) sized granular material, the gold adsorption material according to the present invention is fibrous with a diameter of μm, so it can be woven into various shapes such as pellets, thereby expanding its usability. Above all, Patent Document 5 presents a structure in which radial pores are formed inside a gold adsorption material to suppress the water solubility of amine functional groups and the amine functional groups are immobilized in the pores, but the present invention can be considered an advanced technology in that it can effectively suppress the water solubility of alkylamines while manufacturing a gold adsorption material in a very simple way.

[0036] The gold adsorption material according to the present invention has a structure in which an alkylamine compound is immobilized on the surface of a polyacrylonitrile fiber (hereinafter referred to as 'PAN fiber') having a diameter of μm (see FIG. 1). The alkylamine compound immobilized on the surface of the PAN fiber contains a rich variety of amine functional groups such as primary amines, secondary amines, and tertiary amines, thereby exhibiting excellent gold adsorption characteristics. Furthermore, as the alkylamine compound is immobilized on the PAN fiber without damaging the crystallinity of the PAN fiber, the water solubility of the alkylamine compound is suppressed.

[0037] The technology of immobilizing amine functional groups on the surface of PAN is a known technology, and PAN with immobilized amine functional groups is used as an adsorption material for various applications. Representatively, as disclosed in Patent Document 6, PAN with immobilized amine functional groups is utilized for carbon dioxide capture.

[0038] The technical reason why the gold adsorption material according to the present invention has an advanced design compared to the known technology, even though it has a structure in which an alkylamine compound is immobilized on a PAN fiber similar to the known technology, is that it has a structure in which the water solubility of the alkylamine is suppressed and has high gold adsorption characteristics.

[0039] In the case of the known PAN technology with fixed amine functional groups, as described in Patent Document 6, the adsorption material is exposed to an atmospheric environment, and therefore, the high water solubility of alkylamine is not a characteristic that needs to be considered when manufacturing the adsorption material. That is, as the adsorption material is exposed to an atmospheric environment and carbon dioxide is captured by alkylamine, the high water solubility of alkylamine does not affect the characteristics as a carbon dioxide adsorption material.

[0040] On the other hand, when PAN with immobilized alkylamine compounds is used as a gold adsorbent material to adsorb gold ions in water, the high water solubility of the alkylamine has a very significant impact on whether it can be utilized as a gold adsorbent material. In order to suppress the high water solubility of the alkylamine, the alkylamine must be stably immobilized on the support. For example, PAN and the alkylamine must form a stable chemical bond.

[0041] In this way, it is possible to suppress the high water solubility of alkylamine through the stable chemical bonding between PAN and alkylamine, and the high water solubility of alkylamine is closely related to the crystallinity of PAN. That is, even if PAN and alkylamine form a stable chemical bond, if the crystallinity of PAN is compromised due to the bonding between PAN and alkylamine, mechanical strength such as tensile strength decreases, and the gold adsorption material is bound to dissolve in a strongly acidic environment.

[0042] Therefore, chemical bonding between PAN and alkylamine must be induced within a range where the crystallinity of PAN is minimized so that the high water solubility of alkylamine is suppressed and the dissolution of the gold adsorption material can be prevented.

[0043] Nitrile groups (-C≡N) are distributed at a uniform density on the surface of PAN fibers. Alkylamine compounds are grafted onto PAN fibers in a form where the amine functional groups of the alkylamine compounds substitute for the nitrile groups (-C≡N). The crystallinity of PAN fibers is determined by the degree of substitution of nitrile groups (-C≡N) with alkylamine compounds. In other words, as the proportion of nitrile groups (-C≡N) on the surface of PAN fibers that are substituted with alkylamine compounds increases, the crystallinity of PAN decreases. In other words, as the graft density of alkylamine compounds increases, the crystallinity of PAN decreases. Therefore, it is necessary to lower the graft density of alkylamine compounds to suppress the water solubility of alkylamine compounds.

[0044] Meanwhile, by lowering the introduction density of alkylamine compounds, the decrease in crystallinity of PAN can be mitigated and the high water solubility of alkylamine compounds can be suppressed; however, if the introduction density of alkylamine compounds is lowered, the number of amine functional groups capable of adsorbing gold ions in water decreases, and thus the gold adsorption characteristics are bound to deteriorate.

[0045] As a solution to this, the present invention enables the introduction of a high molecular weight alkylamine compound with a molecular weight of 25,000 g / mol or more that can cause steric hindrance, thereby lowering the density of the alkylamine compound introduction while simultaneously enabling the expression of excellent gold adsorption characteristics. Referring to Table 1 of Experimental Example 3 described below, when an alkylamine compound with a molecular weight of less than 25,000 g / mol is applied, the strength characteristics are poor and excellent gold adsorption characteristics cannot be expected.

[0046] When introducing high molecular weight alkylamine compounds, the large molecular size of the alkylamine compounds causes repulsion—that is, steric hindrance—between adjacent alkylamine compounds during the reaction between the nitrile groups (-C≡N) on the PAN surface and the alkylamine compounds. Consequently, the alkylamine compounds ultimately immobilized on the PAN surface form a structure spaced apart from one another. In other words, nitrile groups (-C≡N) not bonded to the alkylamine compounds exist between the alkylamine compounds immobilized on the PAN surface, which implies a lower introduction density of the alkylamine compounds. Referring to the schematic diagram in Fig. 2, when introducing DETA, a low molecular weight alkylamine compound (see (a)), DETA is immobilized on the PAN surface with a high introduction density in a form that matches the nitrile groups (-C≡N) on the PAN surface in a 1:1 ratio; whereas, as illustrated in Fig. 2 (b) to (d), as the molecular weight of the alkylamine compound increases (TETA <TEPA<bPEI) 알킬아민 분자간 입체장애로 인해 알킬아민 화합물의 도입밀도가 낮아지게 된다.

[0047] Meanwhile, high molecular weight alkylamine compounds have a significantly larger number of amine functional groups compared to low molecular weight alkylamine compounds. Therefore, by introducing high molecular weight alkylamine compounds, it is possible to lower the density of alkylamine compound introduction while simultaneously improving gold adsorption characteristics.

[0048] A branched alkylamine compound may be used as an alkylamine compound with a molecular weight of 25,000 g / mol or more. Additionally, the branched alkylamine compound may be any one of bPEI (branched poly(ethyleneimine)), iso-butylamine, sec-butylamine, iso-amylamine, PEA (phosphoethanolamine), trimethylamine, and isopropylamine, or a combination thereof.

[0049] PAN fibers with immobilized alkylamine compounds are obtained by the polymerization of acrylonitrile and the spinning of polyacrylonitrile obtained by polymerization, and all PAN fibers produced by such a process are applicable to the present invention. In addition, the diameter of the PAN fibers to which the present invention is applied is not numerically limited, but in one example, it may have a diameter of 1 to 500 μm. For reference, in Experimental Examples 1 to 5 described below, PAN fibers with a diameter of 50 μm were used.

[0050] Method for manufacturing PAN fiber-based gold adsorption material

[0051] An aqueous alkylamine solution in which an alkylamine compound is dissolved is prepared, and PAN fibers are mixed with the aqueous alkylamine solution to induce an amination reaction. Through the amination reaction, the alkylamine compound is immobilized on the surface of the PAN fibers in a form in which the nitrile groups (-C≡N) on the surface of the PAN fibers are substituted with the amine functional groups of the alkylamine compound. That is, an alkylamine compound layer of a certain thickness is formed on the surface of the PAN fibers through the amination reaction.

[0052] The amine functional group of an alkylamine compound encompasses various functional groups including an amine group (-NH2), and, for example, may refer to any one of primary amines, secondary amines, tertiary amines, quaternary amines, or a combination thereof.

[0053] To promote the amination reaction, a non-metallic Lewis acid catalyst or a metallic Lewis acid catalyst may be added to an aqueous alkylamine solution. Any one of BF3·2H2O, acetic acid, or hydrochloric acid may be used as the non-metallic Lewis acid catalyst, and AlCl3·6H2O may be used as the metallic Lewis acid catalyst.

[0054] The amination reaction can be achieved by mixing PAN fibers with an aqueous alkylamine solution, and hydrothermal synthesis can be induced by heating to a certain temperature to promote the amination reaction. In one example, a mixed solution of an aqueous alkylamine solution and PAN fibers can be loaded into an autoclave to induce the amination reaction through hydrothermal synthesis.

[0055] When an alkylamine compound is immobilized on the surface of a PAN fiber by an amination reaction, the unreacted alkylamine compound on the surface of the PAN fiber is removed using ultrapure water and chemicals, thereby completing the method for manufacturing a PAN fiber-based gold adsorption material according to one embodiment of the present invention. FIG. 3 is a schematic diagram showing bPEI introduced onto the surface of a PAN fiber by an amination reaction.

[0056] Gold recovery method using PAN fiber-based gold adsorption material

[0057] First, the solution to be treated containing gold ions is acidified.

[0058] Referring to Experimental Example 4 described below, the gold recovery efficiency increases as the acidity of the solution to be treated increases, and preferably, the pH of the solution to be treated should be maintained at 4 or lower. The acidification of the solution to be treated can be controlled by adding a weak acid or a strong acid to the solution to be treated. In addition to gold ions, up to 14 types of metallic ions, including copper (Cu), nickel (Ni), cobalt (Co), and zinc (Zn), may coexist with gold ions in the solution to be treated.

[0059] Next, a PAN fiber-based gold adsorption material according to the present invention is introduced into a solution to be treated under acidic conditions to adsorb gold ions present in the solution to be treated onto the gold adsorption material.

[0060] When the gold adsorption material of the present invention is introduced into a treatment solution under acidic conditions, the amine functional groups present in the alkylamine compound [add] hydrogen ions (H + It combines with ) to form an electrically (+) pole state, and gold ions are anions, for example, chloride ions (Cl - It combines with ) to form a (-) electrode state. Meanwhile, other metallic ions present in the solution to be treated, such as copper (Cu), nickel (Ni), cobalt (Co), and zinc (Zn), maintain a cation state even under acidic conditions.

[0061] Accordingly, gold ions in the negative electrode state are adsorbed onto the amine functional group in the positive electrode state, while other metallic ions maintaining a cationic state are not adsorbed onto the amine functional group in the positive electrode state. Furthermore, the gold ions in the negative electrode state adsorbed onto the amine functional group in the positive electrode state are converted into a metallic form (Au) through a reduction reaction. 0 It crystallizes and grows into ). Referring to Experimental Example 4 described below, in the form of metal (Au 0 Gold reduced by ) crystallizes on the surface of PAN fibers in a brick-by-brick form.

[0062] Referring to Experimental Example 4 described below, even when 0.5 g / L of the PAN fiber-based gold adsorption material according to the present invention is introduced into an environment containing gold ions at a concentration of 0.1 ppm, it exhibits a gold recovery efficiency close to 100%. This result is a result in which the gold recovery characteristics are significantly improved compared to the gold adsorption material of Patent Document 5, which exhibited a gold recovery efficiency of about 80% when 1 g / L of the gold adsorption material was introduced into an environment containing gold ions at a concentration of 0.1 ppm.

[0063] In addition, the maximum adsorption capacity of the gold adsorption material according to the present invention was 1,463 mg / g. This result is more than twice as excellent as the maximum adsorption capacity (less than 600 mg / g) of the gold adsorption material in Patent Document 5, which exhibits the best gold adsorption characteristics among millimeter (mm) sized gold adsorption materials, and represents the highest level of gold adsorption characteristics even when compared to nanometer sized gold adsorption materials. Furthermore, in an environment where gold ions and 14 types of metallic ions coexist, even when the concentration of the 14 types of metallic ions is 100 times higher than the concentration of gold ions, the gold adsorption material of the present invention exhibits a gold recovery efficiency of 99.4% or higher.

[0064] Meanwhile, the PAN fiber-based gold adsorption material of the present invention, in which gold ions have been adsorbed, can be regenerated by being introduced into an aqueous solution mixed with thiourea and HCl. When the gold adsorption material with adsorbed gold ions is introduced into an aqueous solution mixed with thiourea and HCl, gold is leached out, and then the gold adsorption material is washed with NaOH or the like to complete the regeneration of the gold adsorption material.

[0065] The PAN fiber-based gold adsorption material according to the present invention exhibits a gold recovery efficiency of 90% or more even when the adsorption and regeneration of gold ions are repeated. Referring to Experimental Example 4 described below, when the adsorption and regeneration of gold ions are repeated 5 times, a gold recovery efficiency close to 100% is maintained, and even when repeated 10 times, a gold recovery efficiency of 90% or more is exhibited.

[0066] Above, a PAN fiber-based gold adsorption material according to one embodiment of the present invention, a method for manufacturing the same, and a method for recovering gold using the same have been described. Below, the present invention will be explained in more detail through experimental examples.

[0067] Experimental Example 1: Preparation of PAN fiber-based gold adsorption material

[0068] Various alkylamine compounds, namely DETA (99%, Sigma Aldrich), TETA (97%, Sigma Aldrich), TEPA (technical grade, Sigma Aldrich), and bPEI (molecular weight 70,000 g / mol, 30% aqueous solution, Alfa Aesar), were each dissolved in aqueous alkylamine solutions at a concentration of 10 wt% to prepare aqueous alkylamine solutions. Subsequently, 5 g of PAN fiber was added to 70 ml of each aqueous alkylamine solution and swollen for 1 hour. The fiber was then transferred to a 100 ml high-pressure autoclave, and BF3·2H2O, an amination reaction catalyst, was added. The mixture was then left at 160°C for 6 hours. After the reaction was complete, the PAN fiber was washed sequentially with ultrapure water, 1 M HCl solution, NaOH solution, and ultrapure water to remove unreacted alkylamine molecules, and then dried at 80°C for 24 hours.

[0069] Experimental Example 2: Analysis of Crystallinity and Strength Characteristics of PAN Fiber-Based Gold Adsorption Material

[0070] The effects of the molecular weight of the alkylamine compound and the introduction density of the alkylamine compound on the crystallinity and strength characteristics of the PAN fiber-based gold adsorption material were analyzed.

[0071] Figure 4a shows the FT-IR analysis results of gold adsorption materials with DETA, TETA, TEPA, and bPEI immobilized, prepared according to Experimental Example 1; Figure 4b shows the number of moles of grafted molecules of DETA, TETA, TEPA, and bPEI, prepared according to Experimental Example 1; and Figure 4c shows the weight of gold adsorption materials with DETA, TETA, TEPA, and bPEI immobilized, prepared according to Experimental Example 1. In addition, Fig. 4d shows the XRD analysis results of gold adsorption materials with DETA, TETA, TEPA, and bPEI immobilized, prepared according to Experimental Example 1; Fig. 4e shows the tensile strength characteristics of gold adsorption materials with DETA, TETA, TEPA, and bPEI immobilized, prepared according to Experimental Example 1; and Fig. 4f shows the results of measuring the maximum adsorption capacity of gold adsorption materials with DETA, TETA, TEPA, and bPEI immobilized, prepared according to Experimental Example 1.

[0072] Referring to Fig. 4a, in the case of the gold adsorption material with immobilized DETA (DETA@PANF), 1590 cm⁻¹, corresponding to the primary amine (-NH2), -1 It can be seen that a peak is observed. This is a result of the relatively short and linear primary amine (-NH2) being easily immobilized on the surface of the PAN fiber. On the other hand, in the case of gold adsorption materials (TETA@PANF, TEPA@PANF, bPEI@PANF) immobilized with TETA, TEPA, and bPEI, which have molecular weights greater than DETA, the 1650 cm⁻¹ peak corresponds to the secondary amine (-NH-). -1 Peak and 1570cm -1 A peak was observed. The predominant observation of secondary amines (-NH-) indicates that high molecular weight alkylamines and branched alkylamines are immobilized on the PAN fibers, which means that the incorporation density of TETA, TEPA, and bPEI is lower than that of DETA.

[0073] This trend in graft density is more clearly confirmed through the measurement results of the moles (mmol / g) of grafted molecules in Fig. 4b. Referring to Fig. 4b, as the molecular weight of the alkylamine compound immobilized on the gold adsorption material increases (DETA <TETA<TEPA<bPEI) PAN 섬유 표면에 도입된 알킬아민 화합물의 도입분자 몰수의 감소됨을 확인할 수 있다. 특히, bPEI가 도입된 금 흡착소재의 경우, 도입분자 몰수의 0에 수렴되는 결과를 나타내었는데 이는 bPEI의 분자량(70,000g / mol)이 DETA, TETA 그리고 TEPA 보다 월등히 크기 때문이다. 이러한 결과를 도 4c의 금 흡착소재의 무게측정결과와 함께 보면, 도 4c에 알킬아민 화합물의 증가할수록 금 흡착소재의 무게가 증가하는 경향을 나타내고 있는데, 이는 bPEI의 도입밀도가 낮음에도 불구하고 즉, bPEI의 도입분자 몰수가 작음에도 불구하고 bPEI의 분자량이 커 bPEI가 도입된 금 흡착소재의 무게가 가장 큼을 의미한다.

[0074] The molecular weight and introduction density of the alkylamine compound described above have a direct effect on the crystallinity and strength characteristics of the gold adsorption material.

[0075] Looking at the XRD analysis results in Fig. 4d, it can be seen that in the case of gold adsorption materials with DETA, TETA, and TEPA introduced (DETA@PANF, TETA@PANF, TEPA@PANF), the 16.8 and 29.2 peaks, which are the intrinsic peaks of the PAN fiber, disappear or are diluted due to the introduction of alkylamine compounds. On the other hand, in the case of the gold adsorption material with bPEI introduced (bPEI@PANF), the intrinsic peaks of the PAN fiber are maintained. These results indicate that as the density of alkylamine compound introduction increases and the substitution rate of nitrile groups (-C≡N) on the surface of the PAN fiber increases, the crystallinity of the PAN fiber decreases. Furthermore, as the density of alkylamine compound introduction decreases, the decrease in the crystallinity of the PAN fiber is suppressed.

[0076] The crystallinity of the PAN fiber is directly related to the strength characteristics of the gold adsorption material, which can be confirmed through the tensile strength characteristics shown in Fig. 4e. As shown in Fig. 4e, it can be seen that the tensile strength of the gold adsorption material increases as the molecular weight of the alkylamine compound increases, that is, as the density of the alkylamine compound introduced decreases. In particular, the gold adsorption material with introduced bPEI exhibits a tensile strength of 150 MPa at a strain of about 8%, indicating that it exhibits significantly superior tensile strength characteristics compared to other gold adsorption materials.

[0077] Based on the above analysis results, it can be seen that as the molecular weight of the alkylamine compound increases and the density of the alkylamine compound introduced decreases, the crystallinity and strength characteristics of the gold adsorption material are excellent.

[0078] Furthermore, the crystallinity and strength characteristics of the gold adsorption material have the same trend as the gold adsorption characteristics of the gold adsorption material. Referring to Figure 4f, it can be seen that the maximum adsorption capacity of the gold adsorption material increases as the density of the alkyl amanide compound introduced decreases, consistent with the trend of the crystallinity and strength characteristics of the gold adsorption material. In particular, the gold adsorption material with bPEI introduced exhibits a maximum adsorption capacity of 1463 mg / g.

[0079] Experimental Example 3: Gold Adsorption Characteristics of Gold Adsorption Material According to the Amount of bPEI Introduced

[0080] Through Experimental Example 2, it was confirmed that as the molecular weight of the alkylamine compound increases, the density of the alkylamine compound introduced decreases, and as the density of the alkylamine compound introduced decreases, the decrease in crystallinity of the PAN fiber is suppressed, thereby securing excellent strength characteristics of the gold adsorption material, and through this, the gold adsorption characteristics of the gold adsorption material introduced with bPEI showed the best results.

[0081] In Experimental Example 3, an experiment was conducted to examine the optimal conditions for introducing bPEI. In Experimental Example 1, the amination reaction was carried out by leaving it at 160°C for 6 hours; the results were examined by applying an amination reaction time of 0 to 8 hours under the same temperature conditions. Other experimental conditions were applied identically to those in Experimental Example 1.

[0082] Figure 5a shows the change in weight of the gold adsorbent material according to the amination reaction time, Figure 5b shows the change in density of the gold adsorbent material according to the amination reaction time, Figure 5c shows the change in strength of the gold adsorbent material according to the amination reaction time, and Figure 5d shows the change in maximum adsorption capacity of the gold adsorbent material according to the amination reaction time.

[0083] Referring to Figures 5a and 5b, it can be seen that the weight and density of the gold adsorption material increase as the amination reaction time increases. Additionally, as shown in Figure 5c, the strength of the gold adsorption material also showed a tendency to increase as the amination reaction time increased; however, there was no change in strength after 6 hours of amination reaction time. Regarding the gold adsorption characteristics, as shown in Figure 5d, the maximum adsorption capacity of the gold adsorption material showed a tendency to increase as the amination reaction time increased, and equilibrium was reached after 7 hours of amination reaction time. This means that the amination reaction between the PAN fibers of bPEI is terminated at the point where 7 hours have elapsed.

[0084] When comparing the results of Figures 5c and 5d with the measurement results of the number of grafted molecules in Figure 4b, it can be seen that at the end of the amination reaction, the gold adsorbent material with DETA, TETA, and TEPA each immobilized shows a result of having a number of grafted molecules exceeding 1.75 mmol / g, whereas the gold adsorbent material with bPEI immobilized shows a number of grafted molecules less than 1 mmol / g, or more precisely, a number of grafted molecules converging to 0.

[0085] From the experimental results above, it can be seen that as the molecular weight of the alkylamine compound fixed to the surface of the PAN fiber increases, the number of moles of the introduced alkylamine compound decreases, and excellent crystallinity and strength characteristics are exhibited, thereby improving gold adsorption characteristics. It was confirmed that the gold adsorption material with bPEI fixed to the PAN fiber with a molecular weight of 70,000 g / mol corresponds to this experimental example.

[0086] Meanwhile, to confirm the effect of the molecular weight of the alkylamine compound on the gold adsorption material, the strength characteristics of the gold adsorption material according to the molecular weight of bPEI were analyzed. As described above, the strength characteristics of the gold adsorption material are directly related to the number of moles of the alkylamine compound introduced, the crystallinity of the gold adsorption material, and the gold adsorption characteristics; therefore, through the analysis of the strength characteristics of the gold adsorption material according to the molecular weight of bPEI, changes in the various characteristics of the gold adsorption material according to the molecular weight of bPEI can be inferred.

[0087] Table 1 below shows the density, force at break, and elongation at break of gold adsorbent materials in which bPEI with different molecular weights was immobilized on PAN fibers. In this case, the method of manufacturing the gold adsorbent material followed the method of Experimental Example 1, and the amination reaction conditions were applied at 160°C for 6 hours.

[0088] Referring to Table 1, gold adsorbent materials with fixed bPEI with a molecular weight of 700 to 10,000 exhibit characteristics of a breaking strength of 17.5 cN or less and a breaking elongation of 3.26% or less, whereas gold adsorbent materials with bPEI with a molecular weight of 25,000 exhibit a breaking strength of 89.79 cN and a breaking elongation of 12.96%, indicating a significant improvement in strength characteristics. In addition, gold adsorbent materials with bPEI with a molecular weight of 75,000 also show excellent characteristics in terms of breaking strength (90.61 cN) and breaking elongation (13.39%). These results indicate that the strength characteristics of the gold adsorption material can be improved by applying an alkylamine compound with a molecular weight of 25,000 g / mol or more, and furthermore, it can be inferred that the overall characteristics of the gold adsorption material, namely the number of moles of introduced molecules, the crystallinity of the gold adsorption material, and gold adsorption characteristics, can be improved through the application of an alkylamine compound with a molecular weight of 25,000 g / mol or more.

[0089] In addition, Figure 11 shows microscopic images of gold adsorbent materials with fixed bPEI with molecular weights of 10,000 (top), 25,000 (middle), and 70,000 (bottom) g / mol, respectively, and it was confirmed that the gold adsorbent material with fixed bPEI with a molecular weight of 10,000 exhibited a brittle characteristic with low fracture strength and fracture elongation.

[0090] <Strength Characteristics of Gold Adsorption Materials Immobilized with bPEI of Different Molecular Weights> bPEI molecular weight (g / mol) Fiber Density (g cm-3) Force at break (cN) Elongation at break (%) 700 1.28 12.1 0.57 1300 1.27 12.3 1.44 5000 1.28 12.8 1.01 10000 1.27 17.5 3.26 25000 1.27 89.79 12.96 70000 1.28 90.61 13.39

[0091] Experimental Example 4: Gold recovery characteristics of a gold adsorption material with introduced bPEI

[0092] Through Experimental Example 3, it was confirmed that the gold adsorption characteristics of the gold adsorption material to which an amination reaction of 7 hours was applied were excellent, and various gold recovery experiments were conducted using the gold adsorption material prepared under these conditions.

[0093] First, the gold recovery rate according to the pH of a solution containing gold ions was examined. Specifically, the gold recovery rate was measured by adjusting the pH of a solution containing 100 ppm of gold ions in increments of 1 between 1 and 12. At this time, the gold adsorption material was added at a concentration of 0.5 g / L, and the gold adsorption reaction time was applied for 24 hours at room temperature.

[0094] As shown in Fig. 6a, the experimental results showed a gold recovery rate of 100% under conditions of pH 4 or lower. In addition, under conditions of pH greater than 4, the gold recovery rate decreased significantly as the pH increased. SEM analysis (see Fig. 6b) and XRD analysis (see Fig. 6c) were performed on the gold adsorbent material in which gold adsorption proceeded under conditions of pH 1, 4, 8, and 12, and the results confirmed that the adsorbed material was gold (Au).

[0095] The gold recovery rate was examined by varying the concentration of gold ions. Specifically, the gold ion concentration of the solution was set to 0.1, 0.2, 0.5, 1, 2, 5, 10, 100, 500, and 1000 ppm, respectively, and the gold recovery rate was measured along with FESEM and EDS analysis.

[0096] Referring to Fig. 7a, it can be seen that the gold recovery rate reaches 100% even under low gold ion concentration conditions of 10 ppm or less. Fig. 7b is an FESEM image of a gold adsorbent material adsorbed at gold ion concentrations of 0.1, 1, 10, 100, 500, and 1000 ppm, and Fig. 7c is the result of FESEM-EDS analysis of a gold adsorbent material adsorbed at a gold ion concentration of 1000 ppm, indicating that the substance adsorbed on the gold adsorbent material is a gold crystal.

[0097] In addition, isothermal adsorption experiments were conducted to measure the maximum adsorption capacity of the gold adsorption material.

[0098] Fig. 7d Ci As a result of the isothermal adsorption experiment of the gold adsorption material according to, CiAs increases, the adsorption capacity of the gold adsorption material for gold ions at the equilibrium concentration (Ce, mg / L) ( qe It indicates that (mg / g) increases. The isotherm data for gold recovery were fitted using three representative isotherm models: Langmuir, Freundlich, and Sips. The Sips equation agreed well with the isotherm data compared to the Langmuir and Freundlich models, and the coefficient of determination (R²) 2 ) showed a value close to 1 (0.99). When the maximum adsorption capacity of the gold adsorbent material was calculated according to the Sips model, it showed a maximum adsorption capacity of 1463 mg / g (see Table 2 below).

[0099] <Results of Isothermal Adsorption Experiment of Gold Adsorption Material According to the Present Invention> Langmuir Freundlich Sips q m K L R 2 n K F R 2 q m k s N R 2 1068.63 0.0086 0.94 3.21 113.68 0.97 1462.96 0.036 1.73 0.99

[0100] The maximum adsorption capacity of 1463 mg / g of the gold adsorption material according to the present invention is a characteristic that is significantly superior to known µm-sized and millimeter (mm)-sized gold adsorption materials as well as fibrous gold adsorption materials, despite having a relatively low specific surface area compared to nano-sized gold adsorption materials (see FIG. 7e and Table 3), and this can be attributed to the fact that structural stability, such as crystallinity and strength characteristics of the gold adsorption material, is secured as described above.

[0101] In addition, an adsorption selectivity experiment of the gold adsorption material according to the present invention was conducted.

[0102] Considering that other metallic ions are present alongside gold ions during recovery, 14 types of metallic ions capable of coexisting with gold ions were introduced, and gold recovery experiments were conducted using this mixture. The initial concentration of gold ions was 10 mg / L, and the concentrations of the coexisting metallic ions were set to 1 time (10 mg / L), 10 times (100 mg / L), and 100 times (1000 mg / L) of the gold ion concentration, respectively. The adsorption time was carried out for 24 hours at room temperature with stirring at 200 rpm. Additionally, the pH of the solution was set to 1. The 14 types of metallic ions are copper (Cu(II)), chromium (Cr(III)), iron (Fe(III)), aluminum (Al(III)), nickel (Ni(II)), zinc (Zn(II)), cobalt (Co(II)), cadmium (Cd(II)), lead (Pb(II)), manganese (Mn(II)), sodium (Na(I)), potassium (K(I)), magnesium (Mg(II)), and calcium (Ca(II)) ions in the form of nitrates (ACS reagent, Sigma Adrich).

[0103] As a result of conducting gold recovery experiments in an environment where 14 types of metallic ions coexist with gold ions, as shown in Fig. 8, the gold recovery rate was over 99.9% when the concentration of gold ions and the concentration of the 14 types of metallic ions were the same, and approximately 99.5% when the concentration of the 14 types of metallic ions was 10 times that of gold ions. Furthermore, even when the concentration of the 14 types of metallic ions was 100 times that of gold ions, a gold recovery rate of approximately 99.4% was observed.

[0104] Experimental Example 5: Regeneration characteristics of gold adsorption material with introduced bPEI

[0105] An experiment was conducted to determine whether there was a change in gold adsorption performance when the gold adsorption material used in the gold recovery process was regenerated and applied to the gold recovery process again. Specifically, gold ion adsorption was performed by adding the gold adsorption material prepared according to Experimental Example 3 at a concentration of 0.5 g / L to a 10 ppm gold ion solution, and then the gold adsorption material was regenerated by leaving it for 24 hours in an aqueous solution containing 0.5 mol / L thiourea and 0.1 M HCl simultaneously. This adsorption and regeneration process was repeated 10 times.

[0106] As a result of the experiment, as shown in Figure 9, the gold recovery rate was over 99% even after 10 repetitions of adsorption and regeneration, and the gold adsorption rate was 100% up to 5 repetitions, then gradually decreased to about 91% at 10 repetitions.

[0107] Experimental Example 6: Pressure drop characteristics of gold adsorption material with introduced bPEI

[0108] The gold adsorption material prepared according to Experimental Example 3 was prepared in powder form (ALPP) and pellet form (ALPFt), packed into a column, and the pressure drop was measured. The powder form (ALPP) was obtained by grinding the gold adsorption material prepared according to Experimental Example 3 with a ball mill, and the pellet form (ALPFt) was obtained by needle-punching the gold adsorption material prepared according to Experimental Example 3 to form pellets. 5g each of the powder form (ALPP) and the pellet form (ALPFt) were packed into a column with an inner diameter of 1.5cm and a height of 15cm, and the pressure drop was measured while ultrapure water was passed upward at a rate of 1 to 8 L / min.

[0109] As a result of the experiment, as shown in Fig. 10a, when the powder type (ALPP) was filled, ΔP increased exponentially, whereas when the pellet type (ALPFt) was filled, ΔP was relatively very low. Through these results, it can be seen that the gold recovery process can be carried out efficiently by weaving the gold adsorption material according to the present invention into a pellet type (ALPFt), etc. For reference, Fig. 10b is a photograph showing that the gold adsorption material according to the present invention can be woven into various shapes, and the gold adsorption material is woven into the shape of the letters 'KIST'.

[0110]

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Claims

Claim 1 A PAN fiber-based gold adsorption material for adsorbing gold ions in water, characterized by having a structure in which an alkylamine compound is fixed on the surface of a PAN fiber, wherein the molecular weight of the alkylamine compound is 25,000 g / mol or more, the alkylamine compound is fixed by an amination reaction between the alkylamine compound and the PAN fiber, the number of grafted molecules of the alkylamine compound at the time when the amination reaction is terminated is less than 1 mmol / g, and the diameter of the PAN fiber is 1 to 500 μm. Claim 2 A PAN fiber-based gold adsorption material according to claim 1, characterized by having a maximum gold adsorption capacity of 600 mg / g or more. Claim 3 delete Claim 4 delete Claim 5 A PAN fiber-based gold adsorption material according to claim 1, characterized in that the alkylamine compound is a branched alkylamine compound. Claim 6 A PAN fiber-based gold adsorption material according to claim 5, characterized in that the branched alkylamine compound is any one of bPEI (branched poly(ethyleneimine)), isobutylamine, sec-butylamine, iso-amylamine, PEA (phosphoethanolamine), trimethylamine, and isopropylamine, or a combination thereof. Claim 7 A method for manufacturing a PAN fiber-based gold adsorption material, characterized in that a PAN fiber is introduced into an aqueous solution of an alkylamine compound to fix an alkylamine compound on the surface of the PAN fiber through an amination reaction, wherein at the time the amination reaction is terminated, the number of grafted molecules of the alkylamine compound is less than 1 mmol / g, the molecular weight of the alkylamine compound is 25,000 g / mol or more, and the diameter of the PAN fiber is 1 to 500 μm. Claim 8 delete Claim 9 A method for manufacturing a PAN fiber-based gold adsorption material according to claim 7, characterized in that the maximum gold adsorption capacity of the manufactured PAN fiber-based gold adsorption material is 600 mg / g or more. Claim 10 A method for manufacturing a PAN fiber-based gold adsorption material according to claim 7, wherein the alkylamine compound is any one of bPEI (branched poly(ethyleneimine)), isobutylamine, sec-butylamine, iso-amylamine, PEA (phosphoethanolamine), trimethylamine, and isopropylamine, or a combination thereof. Claim 11 A method for recovering gold using a PAN fiber-based gold adsorption material described in any one of claims 1, 2, 5, and 6 comprises: a step of acidifying a treatment target solution containing gold ions; and a step of introducing a PAN fiber-based gold adsorption material into the treatment target solution under acidic conditions; wherein when the gold adsorption material is introduced into the treatment target solution under acidic conditions, the amine functional group provided in the alkylamine compound [subjects] hydrogen ions (H + A method for recovering gold using a PAN fiber-based gold adsorption material, characterized in that the gold ions combine with an amine functional group to form an electrical (+) electrode state, the gold ions combine with an anion to form a (-) electrode state, other metallic ions present in the solution to be treated maintain a cation state, the gold ions in the (-) electrode state are adsorbed to the amine functional group in the (+) electrode state, and other metallic ions maintaining a cation state are not adsorbed to the amine functional group in the (+) electrode state.

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