CN112662875A - Method for recovering precious metal silver in wastewater - Google Patents
Method for recovering precious metal silver in wastewater Download PDFInfo
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- CN112662875A CN112662875A CN201910983422.8A CN201910983422A CN112662875A CN 112662875 A CN112662875 A CN 112662875A CN 201910983422 A CN201910983422 A CN 201910983422A CN 112662875 A CN112662875 A CN 112662875A
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Abstract
The invention provides a method for recovering precious metal silver in wastewater, which comprises the following steps: s1, adding an MOF adsorption material into silver-containing wastewater to adsorb silver in the wastewater; s2, recovering the MOF adsorption material adsorbing silver; and S3, optionally, carrying out desorption treatment on the MOF adsorption material adsorbed with the silver to obtain a regenerated MOF adsorption material. The MOF adsorbing material used in the method has excellent performance, stable structure and good silver ion removing effect, the adsorption capacity is higher than that of the traditional adsorbing material reported at home and abroad, and the MOF adsorbing material can be recycled for many times after simple desorption treatment, and can be applied to treatment of various sewage such as lakes, reservoirs, underground water, industrial wastewater and the like.
Description
Technical Field
The invention relates to a method for recovering noble metal silver in wastewater, belonging to the technical field of environmental protection and the field of new material application.
Background
Silver is a precious metal resource, has excellent physical and chemical properties, and is widely applied to various fields of electronics, electroplating, photosensitive materials, chemical industry and the like. At the same time, silver is also a highly toxic heavy metal contaminant. Silver ions in the silver-containing wastewater have high cytotoxicity, and if the silver ions are directly discharged without effective treatment, the ecological environment is seriously polluted, and the resource waste is caused. Currently, the related industry standards require that the total silver of the discharged water body is lower than 0.1 mg/L; and the silver ion concentration of the water quality reaching the standard specified by the national drinking water health standard is not higher than 0.05 mg/L. Therefore, the recovery of the noble metal silver in the wastewater, particularly the industrial wastewater, has important significance for protecting the ecological environment, promoting the resource recovery and saving the economic cost.
At present, the treatment technology of silver-containing wastewater generally has the problems of high energy consumption, low recovery rate, unobvious removal effect, easy secondary pollution and the like, and the high-efficiency cyclic utilization of resources is difficult to realize; and the silver is recovered by an electrolytic reduction mode, so that the requirement on equipment is high and the operation cost is high. Therefore, it is necessary to develop a new technology for advanced treatment of silver-containing wastewater, so as to realize effective removal of silver ions in wastewater and recycling of precious metal resources.
Metal-Organic Framework (MOF) is a porous crystalline material obtained by coordination self-assembly of inorganic Metal nodes and Organic bridging ligands, and has the characteristics of large specific surface area, high porosity, ordered structure, controllable pore size and the like. The nano-carbon nano-particle has great application potential in the fields of adsorption, separation, catalysis, gas storage, photoelectric sensing, medical diagnosis and the like, and is particularly considered to be an almost ideal adsorption material.
The invention develops a method for recovering noble metal silver from silver-containing wastewater by utilizing a high-performance water-stable MOF material aiming at the silver-containing wastewater with different concentrations. The technology can provide a more green and efficient solution for the advanced treatment of the silver-containing wastewater.
Disclosure of Invention
The invention aims to solve the problems of high energy consumption, low recovery rate, unobvious removal effect, easy secondary pollution, difficult realization of high-efficiency resource recycling and the like in the prior art, and provides a method for recovering precious metal silver in wastewater.
According to one aspect of the present invention, there is provided a method for recovering noble metal silver from wastewater, comprising the steps of:
s1, adding an MOF adsorption material into silver-containing wastewater to adsorb silver in the wastewater;
s2, recovering the MOF adsorption material adsorbing silver;
and S3, optionally, carrying out desorption treatment on the MOF adsorption material adsorbed with the silver to obtain a regenerated MOF adsorption material.
According to some embodiments of the invention, the MOF adsorbing material is prepared by a method comprising the steps of:
(1) preparing a mixed solution containing nitroterephthalic acid, zirconium tetrachloride, an organic solvent and water;
(2) heating the mixed solution to react to prepare a matrix MOF material;
(3) and (3) carrying out defect treatment on the parent MOF material prepared in the step (2) to obtain the MOF adsorption material.
According to a preferred embodiment of the present invention, the molar ratio of nitroterephthalic acid, zirconium tetrachloride, organic solvent and water is (1-100): (1-100): (10-5000): (0.1-10), preferably (1-10): (1-10): (10-5000): (0.1-10).
According to some embodiments of the invention, in step (1), the organic solvent is N, N-dimethylformamide.
According to some embodiments of the present invention, in the step (1), the p-nitrobenzoic acid, the zirconium tetrachloride, the organic solvent and the water are mixed, and stirred at the speed of 200-300rpm for 20-60min to obtain a mixed solution; preferably the stirring speed is 220rpm, and the preferred stirring time is 30 min; the stirring is preferably mechanical stirring.
According to some embodiments of the invention, the step (2) comprises:
(2A) heating the mixed solution for reaction to obtain a solid-liquid mixture;
(2B) and carrying out solid-liquid separation on the solid-liquid mixture, and washing, activating and drying the obtained solid to obtain the matrix MOF material.
According to a preferred embodiment of the present invention, in the step (2A), the reaction temperature is 100-; the reaction time is 24-72h, preferably 24-48 h.
According to some embodiments of the invention, in the step (2B), the separation is centrifugal separation at 10000-; the single centrifugation time is 10-20min, preferably 15 min; the washing is carried out by adopting an organic solvent, and the organic solvent is preferably ethanol; the washing times are 6-10 times; the drying is vacuum drying, and the drying temperature is 25-35 ℃, preferably 30 ℃; the drying time is 10-30h, preferably 24 h.
According to some embodiments of the invention, the defect treatment in step (3) is a treatment in which the parent MOF material produced in step (2) is added to a lye with slow stirring.
According to a preferred embodiment of the invention, the pH of the lye in step (3) is ≥ 13; the alkali liquor is preferably NaOH solution; the concentration of the alkali liquor is 0.1-2%, preferably 1%; the stirring conditions are preferably mechanical stirring, with a stirring speed of 100 and 150rpm, preferably 100 rpm.
According to a preferred embodiment of the invention, after the reaction in step (3) is finished, the improved MOF adsorbing material is obtained by centrifuging, washing and drying.
According to a preferred embodiment of the present invention, the reaction time in the step (3) is 10 to 30min, preferably 15 min; the centrifugal speed is 10000-15000rpm, preferably 15000 rpm; the single centrifugation time is 10-20min, preferably 15 min; washing with deionized water; the washing times are 6-8 times; the drying is vacuum drying, and the drying temperature is 25-35 ℃, preferably 30 ℃; the drying time is 10-30h, preferably 24 h.
According to some embodiments of the present invention, the particle size of the MOF adsorbing material prepared in step (3) is 100-600nm, preferably 300-400 nm; the specific surface area is 500-1000m2G, preferably 600-700m2(ii) in terms of/g. The particle size prepared by the invention is adjustable and has good stability.
According to some embodiments of the present invention, the concentration of silver ions in the silver-containing wastewater is 1 to 100mg/L, preferably 20 mg/L; the pH value of the silver-containing wastewater is 1-7, and the preferable pH value is 2.
According to some embodiments of the invention, the MOF adsorbing material is added in an amount of 0.1-1g/L, preferably 0.5g/L, in the silver-containing wastewater.
According to some embodiments of the invention, in the step S1, the MOF adsorbing material is added into the silver-containing wastewater and stirred at 100-300rpm for 30-120min to be fully mixed; the stirring is preferably mechanical stirring, preferably at a speed of 200rpm, preferably for a period of 60 min.
According to some embodiments of the present invention, in the step S1, after the adsorption is completed, the concentration of silver ions in the produced water is less than 0.1mg/L, preferably less than 0.05mg/L
According to some embodiments of the invention, the MOF adsorbent material having adsorbed silver is recovered in said step S2 by a combination of one or more of precipitation, media filtration or membrane filtration.
According to some embodiments of the invention, the step S3 includes:
adding the MOF adsorbing material adsorbed with silver into a desorption agent for desorption and desorption treatment, and then carrying out solid-liquid separation to respectively obtain a regenerated MOF adsorbing material and desorption liquid containing silver ions; the desorption agent is preferably 5-25 wt% of ammonia water, and is preferably 20 wt% of ammonia water; the desorption treatment is carried out for 10-60min, preferably 30 min.
According to some embodiments of the present invention, the method for recovering noble metal silver from wastewater further comprises the steps of:
and S4, adding a reducing agent into the desorption solution to reduce silver ions in the desorption solution into a silver simple substance, and then recovering.
According to some embodiments of the invention, the reducing agent is an aldehyde, preferably acetaldehyde and/or glucose; and/or the molar ratio of the silver ions to the reducing agent in the desorption solution is 1: (0.5-1), preferably 1: 1.
According to some embodiments of the present invention, when the content of silver ions in the desorption solution reaches 100-1000mg/L, the elemental silver is recovered, and the recovery rate of the elemental silver is 85-95%; preferably, the content of silver ions in the desorption solution reaches 800mg/L, and the recovery rate of the simple substance silver is preferably 90%.
Compared with the prior art, the method for recovering the noble metal silver in the wastewater provided by the invention has the following advantages:
(1) the preparation method of the material used in the method is simple, the cost is controllable, no virulent chemical reagent and harsh reaction conditions of high temperature and high pressure are needed, and the method is easy to realize.
(2) The material used in the method has excellent performance, stable structure and good silver ion removal effect, the adsorption capacity is higher than that of the traditional adsorption material reported at home and abroad, and the material can be recycled for multiple times after simple desorption treatment.
(3) The method is suitable for the silver-containing wastewater with the pH value of 1-7, can realize high-efficiency adsorption under the acidic condition, and does not need to repeatedly adjust the pH value in the process.
(4) The method has simple application process and direct process, and does not need a special reactor or a reaction device; can be applied to the high-efficiency removal, advanced treatment and recycling of silver ions in various sewage such as lakes, reservoirs, underground water, industrial wastewater and the like.
Drawings
FIG. 1 is a scanning electron micrograph of a MOF material prepared according to example 1 of the present invention.
FIG. 2 is a graph of the adsorption capacity of MOF materials prepared in example 1 of the present invention at various pH conditions.
Detailed Description
The present invention will be further illustrated by the following examples, but is not limited to these examples.
[ example 1 ]
(1) Preparation of precursor solution of MOF material: zirconium tetrachloride, nitroterephthalic acid, trace deionized water and N, N-dimethylformamide are mixed according to the weight ratio of 10: 10: 1: 4800 mixing, mechanically stirring at 220rpm for 30min to obtain a mixture, i.e. MOF material precursor solution.
(2) Preparation of parent MOF material:
(2A) and (3) reacting 24 the precursor solution of the MOF material in the step (1) at the temperature of 100 ℃.
(2B) After the reaction is finished, centrifuging for 15min at the rotating speed of 15000 rpm; washing with ethanol for 6 times; subsequent drying at 30 ℃ for 24h under vacuum provided the parent MOF material.
(3) Defect treatment: adding the matrix MOF material in the step (2) into NaOH alkali liquor with the concentration of 1% under the condition of slow mechanical stirring for reaction for 15min, and after the reaction is finished, performing centrifugal separation for 15min at the rotating speed of 15000 rpm; washing with ethanol for 6 times; then drying for 24h at 30 ℃ under vacuum condition to finally obtain the MOF adsorbing material with the particle size of 300nm and the specific surface area of 660m2/g。
[ example 2 ]
Silver-containing sewage, wherein the concentration of silver ions is 5mg/L, and the pH value is 6; adding the MOF adsorbing material prepared in the embodiment 1 of the invention into the sewage, wherein the adding amount is 0.5 g/L; the mixture was thoroughly mixed under mechanical stirring (paddle speed 200rpm) for a reaction time of 60 min. And after the reaction is finished, the produced water and solid particles are separated by standing and precipitating, and the concentration of silver ions in the produced water is less than 0.05mg/L, so that the wastewater discharge standard of related industries is met.
And putting the separated MOF material into 20 wt% ammonia water for reaction for 30min, washing the MOF material with deionized water and ethanol after desorption, and collecting and drying the MOF material for recycling.
The desorption solution can be used for a plurality of times until the content of silver ions reaches 100mg/L, and the silver simple substance is generated after adding acetaldehyde or glucose, thereby completing the recovery of the noble metal silver (the recovery rate is about 90 percent).
[ example 3 ]
Silver-containing wastewater, wherein the concentration of silver ions is 50mg/L, and the pH value is 1; adding the MOF adsorbing material prepared in the embodiment 1 of the invention into the wastewater, wherein the adding amount is 1 g/L; the mixture was thoroughly mixed under mechanical stirring (paddle speed 200rpm) for a reaction time of 60 min. And after the reaction is finished, the produced water and solid particles are separated by standing and precipitating, and the concentration of silver ions in the produced water is less than 0.1mg/L, so that the wastewater discharge standard of related industries is met.
And putting the separated MOF material into 20 wt% ammonia water for reaction for 30min, washing the MOF material with deionized water and ethanol after desorption, and collecting and drying the MOF material for recycling.
The desorption solution can be used for a plurality of times until the content of silver ions reaches 500mg/L, and the silver simple substance is generated after acetaldehyde or glucose is added, so that the recovery of the noble metal silver is finished (the recovery rate is about 90 percent).
[ example 4 ]
Silver-containing wastewater, wherein the silver ion concentration is 20mg/L, the pH is 2, and the wastewater also contains sodium (Na) with the concentration of 20mg/L respectively+) Potassium (K)+) Magnesium (Mg)2+) Calcium (Ca)2+) Ions; adding the MOF adsorbing material prepared in the embodiment 1 of the invention into the wastewater, wherein the adding amount is 0.5 g/L; the mixture was thoroughly mixed under mechanical stirring (paddle speed 200rpm) for a reaction time of 60 min. And after the reaction is finished, filtering the water body by utilizing a flat ceramic ultrafiltration membrane dead-end separation mode. The concentration of the residual silver ions in the filtered product water is less than 0.1mg/L, and the wastewater discharge standard of related industries is met.
The MOF material intercepted by the flat ceramic membrane is collected by backwashing with ammonia water with the concentration of 20 wt%, then is repeatedly cleaned and activated by deionized water and ethanol for many times, is fully dried under the vacuum condition of 30 ℃, and can be continuously recycled.
The desorption solution can be used for a plurality of times until the content of silver ions reaches 200mg/L, and the silver simple substance is generated after acetaldehyde or glucose is added, so that the recovery of the noble metal silver is finished (the recovery rate is about 90 percent).
[ example 5 ]
The same as example 2, except that the amount of the MOF adsorbing material prepared in example 1 of the present invention was 0.1 g/L. After the adsorption and separation steps are finished, the concentration of silver ions in the filtered produced water is 0.25mg/L, and the silver ions do not meet the wastewater discharge standard of related industries.
[ example 6 ]
The same as example 2, except that the amount of the MOF adsorbing material prepared in example 1 of the present invention was 0.2 g/L. After the adsorption and separation steps are finished, the concentration of silver ions in the filtered produced water is 0.10mg/L, and the wastewater discharge standard of related industries is basically met.
[ example 7 ]
The same as example 2, except that the amount of the MOF adsorbing material prepared in example 1 of the present invention was 1 g/L. After the adsorption and separation steps are finished, the concentration of silver ions in the filtered produced water is less than 0.05mg/L, which is similar to the result in the embodiment 2, and the silver ion concentration meets the wastewater discharge standard of related industries.
From fig. 2, we can see that the MOF adsorbing materials prepared by the present invention all have higher adsorption capacity in silver-containing wastewater with pH 1-7, and the effect is best at pH 2. The invention can realize high-efficiency adsorption under acidic condition without repeatedly adjusting pH value in the process.
It should be noted that the above-mentioned embodiments are only for explaining the present invention, and do not constitute any limitation to the present invention. The present invention has been described with reference to exemplary embodiments, but the words which have been used herein are words of description and illustration, rather than words of limitation. The invention can be modified, as prescribed, within the scope of the claims and without departing from the scope and spirit of the invention. Although the invention has been described herein with reference to particular means, materials and embodiments, the invention is not intended to be limited to the particulars disclosed herein, but rather extends to all other methods and applications having the same functionality.
Claims (10)
1. A method for recovering precious metal silver in wastewater comprises the following steps:
s1, adding an MOF adsorption material into silver-containing wastewater to adsorb silver in the wastewater;
s2, recovering the MOF adsorption material adsorbing silver;
and S3, optionally, carrying out desorption treatment on the MOF adsorption material adsorbed with the silver to obtain a regenerated MOF adsorption material.
2. The method of claim 1, wherein the MOF adsorbing material is prepared by a method comprising:
(1) preparing a mixed solution containing nitroterephthalic acid, zirconium tetrachloride, an organic solvent and water;
(2) heating the mixed solution to react to prepare a matrix MOF material;
(3) and (3) carrying out defect treatment on the parent MOF material prepared in the step (2) to obtain the MOF adsorption material.
3. The process according to claim 1 or 2, characterized in that the molar ratio of nitroterephthalic acid, zirconium tetrachloride, organic solvent and water is (1-100): (1-100): (10-5000): (0.1-10).
4. A process according to any one of claims 1 to 3, characterised in that the organic solvent is N, N-dimethylformamide.
5. The method according to any one of claims 1-4, wherein the step (2) comprises:
(2A) heating the mixed solution for reaction to obtain a solid-liquid mixture;
(2B) and carrying out solid-liquid separation on the solid-liquid mixture, and washing, activating and drying the obtained solid to obtain the matrix MOF material.
6. The method according to any one of claims 1 to 5, wherein the concentration of silver ions in the silver-containing wastewater is 1 to 100 mg/L; the pH value of the silver-containing wastewater is 1-7; and/or the dosage of the MOF adsorption material in the silver-containing wastewater is 0.1-1 g/L.
7. The method of any of claims 1 to 6, wherein the MOF adsorbent material having adsorbed silver is recovered in step S2 by a combination of one or more of precipitation, media filtration or membrane filtration.
8. The method according to any one of claims 1 to 7, wherein the step S3 includes:
adding the MOF adsorbing material adsorbed with silver into a desorption agent for desorption and desorption treatment, and then carrying out solid-liquid separation to respectively obtain a regenerated MOF adsorbing material and desorption liquid containing silver ions; the desorption agent is preferably 5-25 wt% of ammonia water.
9. The method according to any one of claims 1-8, further comprising the step of:
and S4, adding a reducing agent into the desorption solution to reduce silver ions in the desorption solution into a silver simple substance, and then recovering.
10. The method according to claim 9, characterized in that the reducing agent is an aldehyde, preferably acetaldehyde and/or glucose; the molar ratio of the silver ions to the reducing agent in the desorption solution is 1: (0.5-1).
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103305700A (en) * | 2013-06-27 | 2013-09-18 | 江苏省环境科学研究院 | Method for recovering silver from silver-containing wastewater |
| US20140319058A1 (en) * | 2013-04-01 | 2014-10-30 | Kathryn M.L. Taylor-Pashow | Metal-organic framework templated synthesis of porous inorganic materials as novel sorbents |
| WO2017210874A1 (en) * | 2016-06-08 | 2017-12-14 | Xia, Ling | Imperfect mofs (imofs) material, preparation and use in catalysis, sorption and separation |
| CN109876774A (en) * | 2017-12-06 | 2019-06-14 | 中国石油化工股份有限公司 | A kind of adsorbent material and preparation method thereof handling dye wastewater |
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- 2019-10-16 CN CN201910983422.8A patent/CN112662875A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20140319058A1 (en) * | 2013-04-01 | 2014-10-30 | Kathryn M.L. Taylor-Pashow | Metal-organic framework templated synthesis of porous inorganic materials as novel sorbents |
| CN103305700A (en) * | 2013-06-27 | 2013-09-18 | 江苏省环境科学研究院 | Method for recovering silver from silver-containing wastewater |
| WO2017210874A1 (en) * | 2016-06-08 | 2017-12-14 | Xia, Ling | Imperfect mofs (imofs) material, preparation and use in catalysis, sorption and separation |
| CN109876774A (en) * | 2017-12-06 | 2019-06-14 | 中国石油化工股份有限公司 | A kind of adsorbent material and preparation method thereof handling dye wastewater |
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