Preparation method and application of loofah sponge adsorbent for efficiently recovering gold (III) in electronic waste

Abstract

The invention discloses a preparation method and application of a loofah sponge adsorbent for efficiently recovering gold (III) in electronic waste, and belongs to the technical field of hydrometallurgy and precious metal recoverability. The method specifically comprises the steps that loofah sponge is weighed, washed with deionized water and dried; 0.1 g of loofah sponge is placed in a 0.05-1 g / L modification solution to be soaked and modified at the normal temperature; washing, filtering and drying to obtain modified loofah sponge; a preparation method of the modified solution comprises the step of dissolving 0.05 to 1g of pyridine-2-azo p-dimethylaniline into 1L of an ethanol solution. The method can rapidly and effectively adsorb gold (III) in the waste circuit board leachate, and has the advantages of being easy to operate, rapid, efficient, environmentally friendly, high in loading capacity, low in price and the like.

Description

Technical Field

[0001] The invention discloses a preparation method of a loofah adsorbent for efficiently recovering gold (III) in electronic waste and application thereof, belonging to the technical field of hydrometallurgy and precious metal recovery. Background Art

[0002] As a precious metal with unique physical and chemical properties, gold is widely used in jewelry, electronic equipment, financial investment and other fields; however, with the continuous exploitation of gold resources, gold reserves and grades are decreasing year by year, and the degree of dispersion and difficulty of ore processing are also increasing; in order to meet the sustainable development of various industries in society, the industry has gradually focused on a renewable secondary gold resource: electronic waste; common electronic waste includes mobile phone circuit boards, computer circuit boards, computer CPUs, etc. The gold grade in this type of solid waste is much higher than that in natural deposits. Studies have shown that the gold grade in computer components is as high as 900 grams per ton, and the gold grade in mobile phone printed circuit boards is as high as 1,200 grams per ton, while the current high-grade gold mine is only about 10 grams per ton; and with the advancement of science and technology, the consumption of electronic products is increasing day by day, and the speed of updates and iterations is accelerating, which has caused tremendous pressure on environmental protection, but also provided us with a stable and sustainable way to recycle precious metals.

[0003] At present, the main methods for recycling gold from circuit boards include cyanide method, thiourea method, halogen method, thiosulfate method, etc. Among the many gold recovery methods, although the cyanide method has the advantages of high gold leaching efficiency and good economic benefits, the cyanide used in this method is a highly toxic reagent. After gold leaching, a large amount of cyanide-containing waste and wastewater will be produced, posing a threat to the environment and human life safety; although the thiourea method and thiosulfate method have certain advantages in safety performance and leaching efficiency, both methods have the disadvantages of large reagent consumption and high cost, and cannot be promoted in actual production; considering the raw material cost and leaching efficiency comprehensively, the halogen method stands out and is considered to be the most effective gold leaching method.

[0004] After leaching, it is necessary to select a suitable method to separate and recover the gold element from the leaching solution; researchers have determined that in the halogen leaching solution, gold is separated as Au 3+ The ion form coexists stably with other metal ions in the leachate. Therefore, finding an effective gold recovery method is of great significance for the recovery of gold in electronic waste; among various separation and enrichment methods such as electrodeposition, extraction, metal replacement, and adsorption, the adsorption method is widely used because of its simple operation, environmental friendliness, high efficiency, and reusability; in the field of gold recovery, traditional adsorbents such as activated carbon, mesoporous silicon, and resin are commonly used, but the adsorption capacity of activated carbon is poor and the cost is expensive; mesoporous silicon mostly exists in powder form, and although functionalized mesoporous silicon has good adsorption effect, it is affected by its morphology and is difficult to achieve industrial application; and the resin is expensive, has poor selectivity, and has strict requirements on elution conditions.

[0005] In recent years, domestic and foreign research teams have also developed a series of new adsorbents, including MOFs materials and various types of nano-adsorbents, but most of these adsorbents are not suitable for acidic solutions, and the preparation process is complicated, the cost is high, and it is difficult to apply them on a large scale. In addition, the reagents used in the existing precious metal recovery methods almost all contain sulfur and phosphorus. After gold leaching, a large amount of sulfur- and phosphorus-containing waste liquid, solid waste, and waste gas are generated, which poses risks to the environment and organisms. Based on the above, in order to achieve effective recovery of gold in electronic waste, it is still necessary to find an adsorbent that is fast, efficient, green, low-cost, has a large load capacity, and has good adsorption performance. Summary of the invention

[0006] The object of the present invention is to provide a preparation method of a loofah adsorbent, wherein pyridine-2-azo-p-dimethylaniline is used as a modifier to modify the loofah, and the modified loofah can significantly improve the adsorption efficiency of gold, and provide a green, renewable, rapid, efficient, large adsorption capacity, and low-cost adsorption method, which specifically comprises the following steps:

[0007] (1) Weigh a loofah, wash off the surface dust with deionized water, filter, and dry;

[0008] (2) placing the loofah obtained in step (1) in an ethanol solution of pyridine-2-azo-p-dimethylaniline, soaking and modifying the loofah at room temperature, washing, filtering and drying to obtain a modified loofah.

[0009] Preferably, the concentration of the pyridine-2-azo-p-dimethylaniline in the ethanol solution of the present invention is 0.05-1 g / L.

[0010] Preferably, the soaking modification time of the present invention is 4 to 20 hours.

[0011] Another object of the present invention is to provide an application of the loofah adsorbent prepared by the method in the recovery of gold (III) from electronic waste, wherein the loofah is modified to adsorb gold (III) from the leaching solution of waste circuit boards, thereby not only realizing the performance reconstruction of the loofah, but also having great significance for the environmentally friendly recovery of circuit boards, and specifically comprising the following steps:

[0012] (1) Take the waste circuit board, add 1:1 aqua regia and heat on a hot plate to dissolve, cool and filter, take the filtrate and set aside.

[0013] (2) Add loofah sponge adsorbent to the filtrate, and the solid-liquid ratio of loofah sponge to modified solution is 1:100 to 2:100, unit: g:mL.

[0014] The electronic waste described in the present invention includes but is not limited to computer CPUs, circuit boards of mobile phones and other electronic products, etc.

[0015] The beneficial effects of the present invention are:

[0016] (1) The modified loofah can significantly improve the adsorption rate and efficiency of gold (III). It can quickly adsorb gold under acidic conditions and has a large adsorption capacity.

[0017] (2) The modified loofah of the present invention is easy to prepare, and the reagents used are harmless to the environment and organisms. The recovery of gold (III) by using the modified loofah is environmentally friendly and has good industrial application prospects.

[0018] (3) The modified loofah sponge of the present invention is a renewable natural agricultural waste with a wide source of raw materials and low cost, which is of great significance to the environmentally friendly recycling of electronic waste. DETAILED DESCRIPTION

[0019] The present invention is further described in detail below in conjunction with specific embodiments, but the protection scope of the present invention is not limited to the described contents.

[0020] Example 1

[0021] This embodiment uses 0.05g of modifier-modified loofah to adsorb gold (III) in waste circuit boards, comprising the following steps:

[0022] (1) Take 2 pieces of waste circuit boards, add 40 mL of 1:1 aqua regia and heat on a 400°C hot plate for 20 minutes. After cooling, filter and dilute to a 500 mL volumetric flask for later use.

[0023] (2) Weigh two portions of 0.1 g of untreated loofah in parallel, wash with deionized water, filter, and dry at 80 °C for 4 h.

[0024] (3) placing one portion of the loofah obtained in step (2) in the modified solution at a solid-liquid ratio of 1:100 for 8 h at room temperature, washing it with deionized water for 3 times and filtering it, and drying it at 60° C. for 4 h to obtain the modified loofah, and the other portion is the original loofah.

[0025] The modified solution is prepared by dissolving 0.05 g of pyridine-2-azo-p-dimethylaniline in 1 L of ethanol solution.

[0026] (4) The modified loofah obtained in step (3) and the original loofah are respectively placed in 100 mL of the solution obtained in step (1) at pH = 2, and stirred for adsorption at the same room temperature; the concentration of gold (III) is 25 mg / L; after adsorption for 5 hours, the adsorption rate of gold (III) by the modified loofah reaches 100%, and the loading capacity is 25 kg / t; the gold remaining in the original loofah solution is 20 mg / L.

[0027] Example 2

[0028] This embodiment uses 0.5g of modifier-modified loofah to adsorb gold (III) in waste circuit boards, comprising the following steps:

[0029] (1) Take a piece of waste circuit board, add 30 mL of 1:1 aqua regia and heat on a 400°C hot plate for 20 minutes. After cooling, filter and dilute to a 500 mL volumetric flask for later use.

[0030] (2) Weigh two portions of 0.1 g of untreated loofah in parallel, wash with deionized water, filter, and dry at 80 °C for 4 h.

[0031] (3) One portion of the loofah obtained in step (2) is placed in the modified solution at a solid-liquid ratio of 2:100 and soaked at room temperature for 8 hours, washed with deionized water three times and then filtered, and dried at 60° C. for 4 hours to obtain the modified loofah, and the other portion is the original loofah.

[0032] The modified solution is prepared by dissolving 0.5 g of pyridine-2-azo-p-dimethylaniline in 1 L of ethanol solution.

[0033] (4) The modified loofah obtained in step (3) and the original loofah are respectively placed in 100 mL of the solution obtained in step (1) at pH = 2, and stirred for adsorption at the same room temperature; the concentration of gold (III) is 10 mg / L; after 2 hours of adsorption, the adsorption rate of gold (III) by the modified loofah reaches 91%, and the loading capacity is 9.1 kg / t; the gold remaining in the original loofah solution is 8.11 mg / L.

[0034] Example 3

[0035] This embodiment uses 1g of modifier-modified loofah to adsorb gold (III) in waste circuit boards, comprising the following steps:

[0036] (1) Take 2 pieces of waste circuit boards, add 40 mL of 1:1 aqua regia and heat on a 400°C hot plate for 20 minutes. After cooling, filter and dilute to a 500 mL volumetric flask for later use.

[0037] (2) Weigh two portions of 0.1 g of untreated loofah in parallel, wash with deionized water, filter, and dry at 80 °C for 4 h.

[0038] (3) placing one portion of the loofah obtained in step (2) in the modified solution at a solid-liquid ratio of 1.5:100 at room temperature for 20 hours of soaking, washing with deionized water three times and then filtering, and drying at 60° C. for 4 hours to obtain the modified loofah, and the other portion is the original loofah.

[0039] The modified solution preparation method is as follows: 1 g of pyridine-2-azo-p-dimethylaniline is dissolved in 1 L of ethanol solution.

[0040] (4) The modified loofah obtained in step (3) and the original loofah are respectively placed in 100 mL of the solution obtained in step (1) at pH = 2, and stirred for adsorption at the same room temperature; the concentration of gold (III) is 25 mg / L; after adsorption for 3 hours, the adsorption rate of gold (III) by the modified loofah reaches 88%, and the loading capacity is 22 kg / t; the gold remaining in the original loofah solution is 22.07 mg / L.

[0041] Example 4

[0042] This embodiment uses 0.75g of modifier-modified loofah to adsorb gold (III) in waste circuit boards, comprising the following steps:

[0043] (1) Take 5 pieces of waste circuit boards, add 80 mL of 1:1 aqua regia and heat on a 400°C hot plate for 40 minutes. After cooling, filter and dilute to a 500 mL volumetric flask for later use.

[0044] (2) Weigh two portions of 0.1 g of untreated loofah in parallel, wash with deionized water, filter, and dry at 80 °C for 4 h.

[0045] (3) placing one portion of the loofah obtained in step (2) in the modified solution at a solid-liquid ratio of 1:100 for 16 hours at room temperature, washing it with deionized water three times and filtering it, and drying it at 60° C. for 4 hours to obtain the modified loofah, and the other portion is the original loofah.

[0046] The modified solution is prepared by dissolving 0.75 g of pyridine-2-azo-p-dimethylaniline in 1 L of ethanol solution.

[0047] (4) The modified loofah obtained in step (3) and the original loofah are respectively placed in 100 mL of the solution obtained in step (1) at pH = 2, and stirred for adsorption at the same room temperature; the concentration of gold (III) is 73 mg / L; after adsorption for 3 hours, the adsorption rate of gold (III) by the modified loofah reaches 81%, and the loading capacity is 59 kg / t; the gold remaining in the original loofah solution is 65.35 mg / L.

[0048] Example 5

[0049] This embodiment uses 0.25g of modifier-modified loofah to adsorb gold (III) in waste circuit boards, comprising the following steps:

[0050] (1) Take 3 pieces of waste circuit boards, add 50 mL of 1:1 aqua regia and heat on a 400°C hot plate for 30 minutes. After cooling, filter and dilute to a 500 mL volumetric flask for later use.

[0051] (2) Weigh two portions of 0.1 g of untreated loofah in parallel, wash with deionized water, filter, and dry at 80 °C for 4 h.

[0052] (3) One portion of the loofah obtained in step (2) is placed in the modified solution at a solid-liquid ratio of 2:100 and is soaked at room temperature for 12 hours for modification, washed three times with deionized water and then filtered, and dried at 60° C. for 4 hours to obtain the modified loofah, and the other portion is the original loofah.

[0053] The modified solution is prepared by dissolving 0.25 g of pyridine-2-azo-p-dimethylaniline in 1 L of ethanol solution.

[0054] (4) The modified loofah obtained in step (3) and the original loofah are respectively placed in 100 mL of the solution obtained in step (1) at pH = 1, and stirred for adsorption at the same room temperature; the concentration of gold (III) is 42 mg / L; after 2 hours of adsorption, the adsorption rate of gold (III) by the modified loofah reaches 55%, and the loading capacity is 23 kg / t; the gold remaining in the original loofah solution is 37.83 mg / L.

[0055] Example 6

[0056] This embodiment uses 0.1g of modifier-modified loofah to adsorb gold (III) in waste circuit boards, comprising the following steps:

[0057] (1) Take 4 pieces of waste circuit boards, add 50 mL of 1:1 aqua regia and heat on a 400°C hot plate for 30 minutes. After cooling, filter and dilute to a 500 mL volumetric flask for later use.

[0058] (2) Weigh two portions of 0.1 g of untreated loofah in parallel, wash with deionized water, filter, and dry at 80 °C for 4 h.

[0059] (3) placing one portion of the loofah obtained in step (2) in the modified solution at a solid-liquid ratio of 2:100 for 20 hours at room temperature, washing it with deionized water for 3 times, filtering it, and drying it at 60° C. for 4 hours to obtain the modified loofah, and the other portion is the original loofah; the modified solution is prepared by: dissolving 0.1 g of pyridine-2-azodimethylaniline in 1 L of ethanol solution.

[0060] (4) The modified loofah obtained in step (3) and the original loofah are respectively placed in 100 mL of the solution obtained in step (1) at pH = 1, and stirred for adsorption at the same room temperature; the concentration of gold (III) is 48 mg / L; after 4 hours of adsorption, the adsorption rate of gold (III) by the modified loofah reaches 76%, and the loading capacity is 36 kg / t; the gold remaining in the original loofah solution is 40.25 mg / L.

[0061] The specific implementation modes of the present invention are described in detail above, but the present invention is not limited to the above implementation modes, and various changes can be made within the knowledge scope of ordinary technicians in this field without departing from the purpose of the present invention.

Claims

1. A method for preparing a loofah adsorbent, characterized in that, The specific steps include: (1) Weigh a loofah, wash off the surface dust with deionized water, filter, and dry; (2) placing the loofah obtained in step (1) in an ethanol solution of pyridine-2-azo-p-dimethylaniline, soaking and modifying the loofah at room temperature, washing, filtering and drying to obtain a modified loofah.

2. according to the preparation method of the described loofah adsorbent of claim 1, it is characterized in that: The concentration of the ethanol solution of pyridine-2-azo-p-dimethylaniline is 0.05-1 g / L.

3. according to the preparation method of the described loofah adsorbent of claim 1, it is characterized in that: The soaking modification time is 4 to 20 hours.

4. Application of the loofah adsorbent prepared by the method of claim 1 or 2 in recycling gold (III) from electronic waste.

5. The application according to claim 3, characterized in that: The specific steps include: (1) Take the waste circuit board, add 1:1 aqua regia, heat and dissolve on a hot plate, cool and filter, take the filtrate and set aside; (2) Add loofah sponge adsorbent to the filtrate, and the solid-liquid ratio of loofah sponge to modified solution is 1:100 to 2:100, unit: g:mL.