Method for selectively reducing, removing and recovering antimony from acid wastewater containing arsenic and antimony

Abstract

The invention relates to a method for selectively reducing and recovering antimony from acid wastewater containing arsenic and antimony, which comprises the following steps: adding a carboxylic acid compound into the acid wastewater containing arsenic and antimony, uniformly mixing, irradiating the mixed solution under ultraviolet light, and carrying out solid-liquid separation after ultraviolet irradiation to obtain metal antimony and treated wastewater, wherein the molar ratio of antimony to carboxylic acid compounds in the acid wastewater containing arsenic and antimony is 1: (50-150). The principle of the invention is as follows: the carboxylic acid compound is subjected to photolysis by ultraviolet light to generate CO2 <.-> free radicals, the CO2 <.-> free radicals can efficiently reduce Sb (III) and Sb (V) into metal antimony (Sb (0)) in thermodynamics and dynamics, and the reaction rate of the CO2 <.-> free radicals with As (III) and As (V) is very slow and cannot occur in dynamics. The residual concentration of antimony in the treated wastewater is as low as 25 [mu] g / L, and the content of metal antimony in a precipitate is as high as 99.9 wt%.

Description

Technical Field

[0001] The invention relates to the technical field of acidic wastewater treatment and resource recovery, and in particular to a method for selectively reducing, removing and recovering antimony from arsenic-antimony-containing acidic wastewater. Background Art

[0002] In many industrial fields, especially in non-ferrous metal smelting and ore mining, acidic wastewater containing high concentrations of arsenic and antimony is inevitably produced. Arsenic and antimony in acidic wastewater mainly exist in dissolved forms of As(III), As(V) and Sb(III), Sb(V), which are highly toxic and carcinogenic and are listed as priority pollutants by the International Agency for Research on Cancer and many governments. If such wastewater is not properly treated and discharged into the environment, it will cause great harm to the surrounding ecological environment and human health. Therefore, it is urgent to effectively treat acidic wastewater containing arsenic and antimony.

[0003] Traditional arsenic and antimony removal technologies in water treatment processes, such as adsorption, ion exchange, membrane filtration and other methods, usually concentrate or enrich arsenic and antimony in wastewater, and transfer arsenic and antimony from wastewater to waste residues and high-concentration brine. These waste residues and brine are classified as hazardous wastes because they contain extremely high content / concentration of arsenic and antimony, and their environmental risks cannot be completely eliminated. For example, CN110642324A discloses a method for removing antimony from wastewater, using primary secondary iron oxide as an adsorbent to remove antimony. However, due to the complex composition of wastewater, the adsorption of the adsorbent is not selective, and arsenic and antimony are adsorbed by the adsorbent together to form arsenic-antimony mixed waste residue.

[0004] Antimony resources are extremely scarce. Based on the strategy of achieving harmlessness through resource utilization, selective recovery of antimony from acidic wastewater and resource utilization in the form of metallic antimony is a potential and feasible treatment strategy. This strategy can prevent the generation of hazardous mixed waste slag and realize resource utilization of antimony.

[0005] Photochemical reduction is a green wastewater in-situ treatment technology. It has been proven that the reducing free radicals generated under ultraviolet irradiation have hydrated electrons (e aq - ), hydrogen radical (H · ), sulfite radical (SO2 ·- ) and carbon dioxide radicals (CO2 ·- ), etc. The standard redox potential of these free radicals is very low, such as e aq - , H · and CO2 ·- The standard redox potentials of Sb(V)(E 0(Sb(V) / Sb(III))=0.363V), Sb(III)(E 0 (Sb(III) / Sb(0))=0.204V) is reduced to metallic antimony (Sb(0)). Therefore, based on the thermodynamic and kinetic differences in the reduction process of arsenic and antimony, a reducing active species system is constructed to reduce antimony to its elemental state without reducing arsenic, thereby achieving the selective removal and recovery of antimony in acidic wastewater, which has significant environmental and economic benefits. Summary of the invention

[0006] In order to solve one or more of the technical problems existing in the prior art, the present invention provides a method for selectively reducing, removing and recovering antimony from arsenic-antimony acidic wastewater, using ultraviolet light to photolyze carboxylic acid compounds to produce CO2 ·- The high selectivity of free radicals for antimony reduction enables the selective reduction and recovery of antimony in arsenic-containing antimony acidic wastewater.

[0007] The technical solution of the present invention to solve the above technical problems is as follows: A method for selectively reducing, removing and recovering antimony from arsenic-antimony acidic wastewater, comprising the following steps: adding a carboxylic acid compound to the arsenic-antimony acidic wastewater, mixing the mixture evenly, irradiating the mixture under ultraviolet light, and performing solid-liquid separation after ultraviolet irradiation to obtain metallic antimony and treated wastewater, such as Figure 1 As shown; wherein, the molar ratio of antimony to carboxylic acid compounds in the acidic wastewater containing arsenic and antimony is 1: (50-150).

[0008] The beneficial effects of the present invention are as follows: the method for selectively reducing, removing and recovering antimony from acidic wastewater containing arsenic and antimony utilizes ultraviolet light to photolyze carboxylic acid compounds to generate CO2 ·- The high selectivity of free radicals for antimony reduction enables the reduction and recovery of antimony in acidic wastewater containing arsenic and antimony. The specific principle is that CO2 ·- The free radicals can reduce Sb(III) and Sb(V) efficiently both thermodynamically and kinetically; although CO2 ·- Free radicals can thermodynamically reduce As(III) and As(V), but the reaction rate between them and As(III) and As(V) is extremely slow, which makes the reaction kinetically impossible. Based on this difference, the efficient and selective removal and recovery of antimony in arsenic-antimony acidic wastewater is achieved. The present invention can efficiently and selectively reduce, remove and recover antimony in acidic wastewater, so that the residual concentration of antimony in the wastewater is as low as 25μg / L ( Figure 2 ) and obtain high purity metal antimony (>99.9wt%) products ( Figure 3 and Figure 4 ), which has the advantages of fast and simple operation and strong selectivity for antimony reduction.

[0009] Based on the above technical solution, the present invention can also be improved as follows.

[0010] Furthermore, the acidic wastewater containing arsenic and antimony includes a mixture of one or more acidic wastewaters generated in the process of smelting, mining and beneficiation of non-ferrous metals.

[0011] Furthermore, the concentrations of arsenic and antimony in the acidic wastewater containing arsenic and antimony are 0.1 mg / L to 200.5 mg / L, respectively. The concentrations of arsenic and antimony in the acidic wastewater containing arsenic and antimony can be selected as 0.1 mg / L, 1 mg / L, 5 mg / L, 10 mg / L, 20 mg / L, 30 mg / L, 50 mg / L, 60 mg / L, 80 mg / L, 100 mg / L, 120 mg / L, 140 mg / L, 150 mg / L, 160 mg / L, 180 mg / L, and 200 mg / L, respectively.

[0012] Furthermore, the carboxylic acid compound includes one or a mixture of two or more organic compounds containing carboxyl groups or carboxylate ions.

[0013] Furthermore, the carboxylic acid compound includes one or a mixture of two or more of tartaric acid, lactic acid, citric acid, potassium oxalate, ethylenediaminetetraacetic acid, ethyl trifluoroacetate, trimellitic acid, oxalic acid, terephthalic acid, and pyromellitic acid.

[0014] Furthermore, the ultraviolet light includes single-wavelength, multi-wavelength or continuous-wavelength ultraviolet light with an effective wavelength in the range of 190 to 900 nm, and the optional wavelengths are 190 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, 550 nm, 600 nm, 650 nm, 700 nm, 750 nm, 800 nm, 850 nm, and 900 nm.

[0015] The beneficial effect of adopting the above further scheme is: exciting the carboxylic acid compound to decompose it into CO2 ·- Free radicals.

[0016] Furthermore, the irradiation time of the ultraviolet light is 1h to 2.5h.

[0017] Furthermore, the carboxylic acid compound is directly added to the acidic wastewater containing arsenic and antimony, or the carboxylic acid compound is configured into a concentrated solution and added to the acidic wastewater containing arsenic and antimony.

[0018] Furthermore, after adding the carboxylic acid compound into the acidic wastewater containing arsenic and antimony, the mixture is evenly mixed by shaking, stirring or oscillating.

[0019] Furthermore, the solid-liquid separation includes a combination of one or more of centrifugation, filter press and membrane filtration. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The present invention is a flow chart of the method for selectively reducing, removing and recovering antimony from arsenic-antimony-containing acidic wastewater;

[0021] Figure 2 The residual concentrations of arsenic and antimony in the wastewater after treatment in Example 3;

[0022] Figure 3 The X-ray diffraction (XRD) pattern of the precipitate was obtained for Example 3;

[0023] Figure 4 An energy dispersive X-ray spectroscopy (EDS) pattern of the precipitate was obtained for Example 3. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present invention will be described in detail and completely. It is worth noting that the embodiments mentioned are only a part of the many examples of the present invention, not all of them. Based on the embodiments given in the present invention, those skilled in the art can derive all other possible implementation methods without creative work, and these derived embodiments are also regarded as the protection scope of the present invention.

[0025] Example 1

[0026] The weighed potassium oxalate solid was added to the acidic wastewater containing arsenic and antimony concentrations of 1.5 mg / L and 10.2 mg / L respectively, so that the molar ratio of antimony to potassium oxalate reached 1:50, and uniform stirring was achieved by a magnetic stirrer. A high-pressure mercury lamp with a power of 1000W was used, and the wavelength range of the light emitted by the high-pressure mercury lamp was 190-900nm. After irradiation for 10 minutes, particles were precipitated. After continuous irradiation for 1 hour, a 0.45μM filter membrane was used for filtration to separate the precipitated particles and the treated wastewater. In this process, the concentrations of arsenic and antimony ions in the treated wastewater were measured by atomic fluorescence spectrometer (AFS), and it was found that the arsenic concentration was basically unchanged, while the antimony concentration gradually decreased, and its concentration was less than 50μg / L at the end of the reaction. The XRD analysis results showed that the obtained precipitate was metal antimony, and EDS analysis found that the content of metal antimony in the precipitate was 99.97wt%.

[0027] Example 2

[0028] The weighed trimellitic acid solid was added to the acidic wastewater containing arsenic and antimony concentrations of 200.5mg / L and 100.2mg / L respectively, so that the molar ratio of antimony to trimellitic acid reached 1:150, and uniform stirring was achieved by a mechanical stirrer. A high-pressure mercury lamp with a power of 1000W was used, and the wavelength range of the light emitted by the high-pressure mercury lamp was 190-900nm. The formation of particle precipitation was observed after irradiation for 10min. After continuous irradiation for 1h, the precipitation particles and the treated wastewater were separated by filtering through a 0.45μM filter membrane. In this process, the concentrations of arsenic and antimony ions in the treated wastewater were determined by atomic fluorescence spectrometer (AFS), and it was found that the arsenic concentration was basically unchanged, while the antimony concentration gradually decreased. At the end of the reaction, its concentration was less than 30μg / L. The XRD analysis results showed that the obtained precipitate was metallic antimony, and EDS analysis found that the content of metallic antimony in the precipitate was 99.91wt%.

[0029] Example 3

[0030] Oxalic acid solution was added to acidic wastewater containing arsenic and antimony concentrations of 23.5 mg / L and 14.2 mg / L, respectively, so that the molar ratio of antimony to oxalic acid reached 1:140, and uniform stirring was achieved by a magnetic stirrer. A low-pressure mercury lamp with a power of 32W was used, and the wavelength of light emitted by the low-pressure mercury lamp was 253.7nm. After irradiation for 15 minutes, the formation of particle precipitation was observed. After continuous irradiation for 2.5 hours, centrifugal separation was performed to separate the precipitated particles and the treated wastewater. In this process, the concentrations of arsenic and antimony ions in the treated wastewater were measured by atomic fluorescence spectrometry (AFS). It was found that the arsenic concentration remained basically unchanged during the reaction, while the antimony concentration gradually decreased. At the end of the 2.5-hour reaction, its concentration was less than 25μg / L. The XRD analysis results showed that the diffraction peaks of the obtained precipitate were consistent with those of Sb(0)(PDF#35-0732) ( Figure 3 ), indicating that the precipitate is mainly Sb(0). EDS analysis found that the content of Sb(0) in the precipitate is 99.98wt% ( Figure 4 ).

[0031] Example 4

[0032] Terephthalic acid solution was added to acidic wastewater containing arsenic and antimony concentrations of 17.6 mg / L and 10.4 mg / L, respectively, so that the molar ratio of antimony to terephthalic acid reached 1:80, and the mixture was stirred evenly by shaking. A medium-pressure mercury lamp with a power of 500 W was used, and the wavelength of light emitted by the medium-pressure mercury lamp was 225-450 nm. The formation of particle precipitation was observed after irradiation for 10 minutes. After continuous irradiation for 1.5 hours, the precipitation particles and the treated wastewater were separated by filtering through a 0.45 μM filter membrane. In this process, the concentrations of arsenic and antimony ions in the treated wastewater were measured by atomic fluorescence spectrometer (AFS), and it was found that the arsenic concentration was basically unchanged, while the antimony concentration gradually decreased, and its concentration was less than 20 μg / L at the end of the reaction. The XRD analysis results showed that the obtained precipitate was metallic antimony, and the EDS analysis found that the content of metallic antimony in the precipitate was 99.93 wt%.

[0033] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0034] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A method for selectively reducing, removing and recovering antimony from arsenic-antimony acidic wastewater, characterized in that: The following steps are involved: A carboxylic acid compound is added to the acidic wastewater containing arsenic and antimony, and the mixed solution is placed under ultraviolet light for irradiation after being evenly mixed. After the ultraviolet light irradiation, solid-liquid separation is performed to obtain metallic antimony and treated wastewater; wherein the molar ratio of antimony to the carboxylic acid compound in the acidic wastewater containing arsenic and antimony is 1:(50-150).

2. A method for selectively reducing, removing and recovering antimony from arsenic-antimony acidic wastewater according to claim 1, characterized in that: The acidic wastewater containing arsenic and antimony includes a mixture of one or more acidic wastewaters generated in the process of smelting, mining and beneficiation of non-ferrous metals.

3. A method for selectively reducing, removing and recovering antimony from arsenic-antimony acidic wastewater according to claim 1, characterized in that: The concentrations of arsenic and antimony in the arsenic-antimony-containing acidic wastewater are 0.1 mg / L to 200.5 mg / L respectively.

4. A method for selectively reducing, removing and recovering antimony from arsenic-antimony acidic wastewater according to claim 1, characterized in that: The carboxylic acid compound includes one or a mixture of two or more organic compounds containing a carboxyl group or a carboxylate ion.

5. A method for selectively reducing, removing and recovering antimony from arsenic-antimony acidic wastewater according to claim 4, characterized in that: The carboxylic acid compound includes one or a mixture of two or more of tartaric acid, lactic acid, citric acid, potassium oxalate, ethylenediaminetetraacetic acid, ethyl trifluoroacetate, trimellitic acid, oxalic acid, terephthalic acid, and pyromellitic acid.

6. A method for selectively reducing, removing and recovering antimony from arsenic-antimony acidic wastewater according to claim 1, characterized in that: The ultraviolet light includes ultraviolet light of single wavelength, multiple wavelengths or continuous wavelengths with an effective wavelength in the range of 190 to 900 nm.

7. A method for selectively reducing, removing and recovering antimony from arsenic-antimony acidic wastewater according to claim 1, characterized in that: The irradiation time of the ultraviolet light is 1h to 2.5h.

8. A method for selectively reducing, removing and recovering antimony from arsenic-antimony acidic wastewater according to claim 1, characterized in that: The carboxylic acid compound is directly added to the acidic wastewater containing arsenic and antimony, or the carboxylic acid compound is configured into a concentrated solution and added to the acidic wastewater containing arsenic and antimony.

9. A method for selectively reducing, removing and recovering antimony from arsenic-antimony acidic wastewater according to claim 1, characterized in that: After adding the carboxylic acid compound into the acidic wastewater containing arsenic and antimony, the mixture is evenly mixed by shaking, stirring or oscillating.

10. A method for selectively reducing, removing and recovering antimony from arsenic-antimony acidic wastewater according to claim 1, characterized in that: The solid-liquid separation includes one or more combinations of centrifugation, filter press and membrane filtration.

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