Method for intensifying dissolution of arsenic-lead-containing solid solution through electric field and application

Abstract

The invention discloses a method for intensifying dissolution of arsenic lead ore solid solution through an electric field and application. The method comprises the following steps: preparing a mixed solution from a sodium arsenate solution and a sodium chloride solution in proportion, and preparing an arsenite solid solution by taking a lead acetate solution as a basic solution; different electrolytes are selected at the temperature of 25 DEG C according to the dissolving-out speed and concentration requirements of arsenic ions and lead ions, an arsenite solid solution is subjected to electric field strengthening rapid dissolution, and the technology provides technical support for electrokinetic remediation of soil polluted by arsenic and lead and resource utilization of tailings containing arsenic and lead.

Description

Technical Field

[0001] The present invention belongs to the field of environmental safety and technology, and relates to a method and application of rapidly dissolving arsenic (As) lead (Pb) ore using electrical enhancement technology, providing technical support for the electric remediation of arsenic-lead contaminated soil and the resource utilization of arsenic-lead tailings. Background Art

[0002] Arsenic is a metalloid element that is widely present in rocks, soil, water and the atmosphere in nature. The global soil arsenic concentration is 6 mg / kg, while the soil arsenic concentration in my country is 11.2 mg / kg, almost twice the global soil arsenic concentration. Arsenic pollution comes from a wide range of sources. Natural sources are mainly due to crustal movement, volcanic eruptions, rock weathering, soil erosion, etc., which produce arsenic substances; while anthropogenic sources are mainly pollution caused by human production activities, which can be divided into agricultural pollution and industrial pollution. These activities allow arsenic to enter the environment in the form of smoke, wastewater, waste gas and waste residue, causing pollution to the soil, water and atmosphere, and thus posing huge health risks to humans. Studies have shown that trace amounts of arsenic can also be detected in normal humans. Reasonable arsenic is beneficial to human metabolism. The maximum arsenic intake of the human body per day is about 0.1 mg, but when the human body ingests a large amount of arsenic-containing substances, it will cause organ failure, damage to the nervous system and cancer. When the arsenic content in the human body reaches 10-50 mg, it will cause arsenic poisoning, and when it reaches 60-300 mg, it will cause death.

[0003] The remediation of arsenic pollution has always attracted the attention of many scientific researchers. At present, traditional physical and chemical remediation technologies have achieved certain results and formed some mature process flows. For arsenic pollution in water bodies, membrane separation, ion exchange, coagulation and precipitation are mainly used for remediation, while the traditional methods for remediation of arsenic pollution in soil mainly include physical remediation, chemical remediation, biological remediation, etc. In general, the selection of appropriate remediation technology is determined based on the depth of contaminated soil, metal concentration, type of pollutants and geological characteristics of the contaminated site. These factors make it possible to choose a method that is environmentally friendly, convenient, effective, stable, low-cost and easy to operate.

[0004] As one of the end-member components of the arsenite family of solid solutions, arsenite is the most common and stable mineral among arsenate minerals. 2+ 、AsO4 3- , Cl -When the arsenic and lead ions dissolved in the aqueous solution are fixed, the arsenic and lead ions will be quickly precipitated in the form of white and stable Pb5(AsO4)3Cl crystals. By utilizing this mechanism, the arsenic and lead ions dissolved in the aqueous solution can be fixed. The present invention provides a method for rapidly dissolving an arsenic-lead solid solution, which uses an electric field to enhance the rapid dissolution of arsenic and lead in the arsenic-lead solid solution, and provides a new method for the electric remediation of arsenic-lead contaminated soil and the resource utilization of arsenic-lead tailings. Summary of the invention

[0005] The purpose of the present invention is to provide a method for rapid dissolution of arsenic-lead ore solid solution. The prepared solid solution and the dissolved solid solution are subjected to infrared absorption spectroscopy (FT-IR), X-ray diffraction (XRD), and scanning electron microscopy (SEM) solid phase characterization, the dissolution concentrations of Pb and As under the conditions of no power supply and power supply dissolution using different electrolytes are tested, and the solubility and stability are subjected to detailed experimental analysis, which provides technical support for the remediation of arsenic-lead contaminated soil and the resource utilization of arsenic and lead in tailings.

[0006] Method for synthesizing arsenite solid solution:

[0007] (1) Prepare fresh ultrapure water, weigh appropriate amounts of lead acetate, sodium arsenate and sodium chloride solids, and prepare 0.5 mol / L solutions for later use.

[0008] (2) In a clean polyethylene bottle, mix the prepared 0.5 mol / L lead acetate solution, sodium arsenate solution and sodium chloride solution in a ratio of 5:3:1.

[0009] (3) Before the proportioning in step (2), 100 mL of 0.5 mol / L lead acetate solution is taken into a 250 mL polyethylene bottle at room temperature, and placed in an intelligent magnetic stirrer. The temperature is controlled at 25°C and the stirring is continued at a speed of 300 r / min. During the process, the bottle mouth is sealed with plastic wrap and aerated with nitrogen.

[0010] (4) In the proportioning of step (2), 80 mL of 0.5 mol / L sodium arsenate solution and 0.5 mol / L sodium chloride solution were slowly added to the 250 mL polyethylene bottle solution obtained in step (3) to obtain a uniform solution, and the mixture was added to the polyethylene bottle at a rate of 10 mL / min. The reaction time was 10 min, and stirring was stopped.

[0011] (5) The polyethylene bottled solution system obtained in step (4) was placed in a constant temperature water bath at 25°C for aging for 24 hours, followed by solid-liquid separation, and the obtained solid precipitate was washed with ultrapure water for 3-5 times.

[0012] (6) The washed solid precipitate is placed in a 90°C forced air drying oven and dried for 24 h to obtain an arsenic lead ore solid solution.

[0013] The dissolution effect of the arsenic lead ore solid solution is different under different electrolyte conditions when electricity is applied, and the specific steps are as follows:

[0014] (1) An experimental device for electric field enhanced dissolution of arsenic-lead ore solid solution is set up, which mainly consists of a DC power supply, a cathode chamber, an anode chamber, electrodes, and an electrolyte.

[0015] (2) The DC power supply is connected to the electrodes by a pure copper power line, and the non-active electrode part is sealed with ceramic to isolate it from contact with the electrolyte.

[0016] (3) Both the cathode chamber and the anode chamber are made of plexiglass. A circular connecting port about 2 cm long and 1 cm in diameter is set between the two chambers. The proton membrane is placed in the middle of the connecting port and fixed with a fixing clamp. After the cathode chamber, anode chamber and connecting port are fixed, they form an H shape.

[0017] (4) Weigh 1 g of ground arsenite solid solution that has been passed through a 100-mesh sieve and place it into the anode chamber of a 1000 mL H-type plexiglass reactor.

[0018] (5) Add 500 mL of electrolyte to the cathode and anode chambers of the H-type organic glass reactor respectively. Preferably, the electrolyte can be 0.1 mol / L KNO3, Na2SO4 and NaCl solution.

[0019] (6) Using electric field electrodes as the anode and cathode of the H-type organic glass reactor, preferably, the electric field electrodes are titanium ruthenium electrodes.

[0020] (7) The cathode chamber and anode chamber of the experimental device were covered and sealed, and then a DC power supply was used to apply a constant current of 0.1 A to perform electric field enhanced dissolution at room temperature.

[0021] (8) During the electric field enhanced dissolution process, a certain volume of supernatant samples were collected at 1, 3, 5, 10, 20, 40, 60, 90, 120, 180, 360, 720, 1440, 2880, 4320, and 5760 min, respectively, and filtered through a 0.22 μm membrane filter into a centrifuge tube.

[0022] (9) For the sample in step (8), use ICP-OES instrument to analyze and determine Pb 2+ The concentration of As was measured by atomic fluorescence spectrophotometer 5+ The concentration of lead and arsenic is obtained respectively.

[0023] The above-mentioned technical comparison shows that the dissolution concentrations of arsenic and lead ions in different processes at the same time are quite different: when 0.1 mol / L KNO3 solution is used as the electrolyte, the lead ion leaching concentration is the highest, and it can be dissolved quickly and has the best effect when the power is turned on; when 0.1 mol / L NaCl solution is used as the electrolyte, the effect is second; when 0.1 mol / L Na2SO4 solution is used as the electrolyte, it is not conducive to the dissolution of lead ions, and its effect is even worse than the natural dissolution effect without power, and it is almost insoluble. When 0.1 mol / L Na2SO4 solution is used as the electrolyte, arsenic ions are rapidly dissolved, and its dissolution concentration shows a trend of first rising and then falling (using this special change trend, arsenic ion resource utilization can be achieved by controlling the electric field action time); the electrolyte using 0.1 mol / L KNO3, Na2SO4 and NaCl solutions can achieve the enhanced dissolution of arsenic ions in arsenic lead ore, and the final dissolved arsenic ion concentration is not much different, while when no power is turned on, arsenic ions are almost not dissolved. It can be inferred from this that under the action of different electrolytes and electric fields, arsenic ions and lead ions can be quickly dissolved in the solid solution of arsenic-lead ore, thereby realizing the resource utilization of arsenic-lead ore by utilizing the characteristics of different electrolyte types and different power-on times.

[0024] The present invention utilizes arsenate, lead ions and chloride ions to react and synthesize end-member components of arsenopyrite family minerals. Compared with arsenic and lead-containing minerals synthesized by the traditional coprecipitation method, the arsenopyrite series solid solution synthesized by the water bath co-heating method has the characteristics of easy process control, purer solid products, high yield and high crystallinity. Moreover, under the condition of different electrolytes being energized, the dissolution concentrations of arsenic and lead ions of the minerals are rapidly dissolved. In a 0.1 mol / L KNO3 solution, the highest lead ion concentration is 3.9 times that of the dissolution under no-electricity conditions, and under all energization conditions, the dissolution concentration of arsenic ions is several orders of magnitude higher than that of the dissolution without electricity. Therefore, the present invention can realize the resource utilization of arsenic and lead ions of arsenopyrite under different electrolyte types and different time conditions of energization dissolution. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a series of XRD diagrams of the arsenite solid solution prepared in Example 1 of the present invention, wherein the arsenite standard card is PDF#01-80-2103.

[0026] Figure 2 This is a scanning electron microscope image (SEM) of the arsenite solid solution prepared in Example 1 of the present invention.

[0027] Figure 3 A diagram of an H-type reactor device for dissolution experiments designed for the present invention.

[0028] Figure 4This is a comparison diagram of the XRD of the arsenite solid solution before and after dissolution of Example 1 and Examples 2-6 of the present invention.

[0029] Figure 5 This is a scanning electron microscope (SEM) image of the arsenic lead ore solid solution after dissolution in Example 2-6 of the present invention.

[0030] Figure 6 FT-IR comparison diagram of the arsenite solid solution before and after dissolution of Example 1 and Examples 2-6 of the present invention.

[0031] Figure 7 This is a graph showing the change in lead ion concentration during the dissolution of the arsenic lead ore solid solution in Example 2-6 of the present invention.

[0032] Figure 8 This is a graph showing the change in arsenic ion concentration during the dissolution of the arsenic lead ore solid solution in Example 2-6 of the present invention. DETAILED DESCRIPTION

[0033] Example 1

[0034] At room temperature, 100 mL of 0.5 mol / L lead acetate solution was placed in a 250 mL polyethylene bottle, and an intelligent magnetic stirrer was placed. The temperature was controlled at 25 ° C, and the stirring was continued at a speed of 300 r / min. During the process, the bottle mouth was sealed with a plastic wrap, and nitrogen was used to aerate it to remove impurities in the water and air. 80 mL of 0.5 mol / L sodium arsenate solution and 0.5 mol / L sodium chloride solution were slowly added in a ratio of 3:1. The solution was evenly mixed and added to the polyethylene bottle at a speed of 10 mL / min. The reaction time was 10 min, and the stirring was stopped. Then, the solution was placed in a 25 ° C constant temperature water bath for aging for 24 h. After aging for 24 h, solid-liquid separation was performed, and the obtained solid phase precipitate was washed with ultrapure water for multiple times. The washed solid phase precipitate was placed in a 90 ° C blast drying oven for 24 h to obtain an arsenic lead ore solid solution.

[0035] Example 2

[0036] The synthesized arsenite solid solution was ground into powder using an agate mortar, and an appropriate amount of solid solution was weighed for natural dissolution. 1 g of the solid solution that was ground and passed through a 100-mesh sieve was weighed and placed in a 1000 mL polyethylene terephthalate (PET) bottle, and then 1000 mL of ultrapure water was added. All bottles were capped and placed at room temperature for dissolution (air conditioning at 25°C). Pb was analyzed and determined using an ICP-OES instrument. 2+ The concentration of As was measured by atomic fluorescence spectrophotometer 5+ The concentration of

[0037] That is, the lead leaching concentration is 0.1473295 mmol / L;

[0038] Arsenic leaching concentration: 0.000011 mmol / L.

[0039] Example 3

[0040] The synthesized arsenic lead ore solid solution was ground into powder using an agate mortar, and an appropriate amount of solid solution was weighed for anode dissolution. 1g of the ground solid solution was weighed and passed through a 100-mesh sieve and placed in the anode chamber of a 1000 mL H-type organic glass reactor. 500 mL of ultrapure water was added to the cathode and cathode chambers respectively. A titanium ruthenium electrode was used, and a constant current of 0.1A was applied. All bottles were capped and placed at room temperature for dissolution (air conditioning 25°C). Pb was analyzed and determined using an ICP-OES instrument. 2+ The concentration of As was measured by atomic fluorescence spectrophotometer 5+ concentration.

[0041] That is, the lead leaching concentration is 0.0153089 mmol / L;

[0042] Arsenic leaching concentration: 0.0025976 mmol / L.

[0043] Example 4

[0044] The synthesized arsenic lead ore solid solution was ground into powder using an agate mortar, and an appropriate amount of solid solution was weighed for anode dissolution. 1g of the ground solid solution was weighed and passed through a 100-mesh sieve and placed in the anode chamber of a 1000 mL H-type organic glass reactor. 500 mL of 0.1 mol / L KNO3 solution was added to the cathode and cathode chambers, respectively. A titanium ruthenium electrode was used, and a constant current of 0.1A was applied. All bottles were capped and placed at room temperature for dissolution (air conditioning 25°C). Pb was analyzed and determined using an ICP-OES instrument. 2+ The concentration of As was measured by atomic fluorescence spectrophotometer 5+ concentration.

[0045] That is, the lead leaching concentration is 0.6030405 mmol / L;

[0046] Arsenic leaching concentration: 0.0270226 mmol / L.

[0047] Example 5

[0048] The synthesized arsenic lead ore solid solution was ground into powder using an agate mortar, and an appropriate amount of solid solution was weighed for cathode dissolution. 1g of the ground solid solution was weighed and passed through a 100-mesh sieve and placed in the cathode chamber of a 1000 mL H-type organic glass reactor, and 500 mL of 0.1 mol / L Na2SO4 solution was added to the anode and cathode chambers, respectively. A titanium ruthenium electrode was used, and a constant current of 0.1A was applied. All bottles were capped and placed at room temperature for dissolution (air conditioning 25°C). Pb was analyzed and determined using an ICP-OES instrument. 2+ The concentration of As was measured by atomic fluorescence spectrophotometer 5+ concentration.

[0049] That is, the lead leaching concentration is 0.0079319 mmol / L;

[0050] Arsenic leaching concentration: 0.025012 mmol / L.

[0051] Example 6

[0052] The synthesized arsenic lead ore solid solution was ground into powder using an agate mortar, and an appropriate amount of solid solution was weighed for anode dissolution. 1g of the solid solution that was ground and passed through a 100-mesh sieve was weighed and placed in the anode chamber of a 1000 mL H-type organic glass reactor, and 500 mL of 0.1 mol / L NaCl solution was added to the cathode and cathode chambers, respectively. A titanium ruthenium electrode was used, and a constant current of 0.1A was applied. All bottles were capped and placed at room temperature for dissolution (air conditioning 25°C). Pb was analyzed and determined using an ICP-OES instrument. 2+ The concentration of As was measured by atomic fluorescence spectrophotometer 5+ concentration.

[0053] That is, the lead leaching concentration is 0.1967664 mmol / L;

[0054] Arsenic leaching concentration: 0.0254426 mmol / L.

Claims

1. A method for electric field intensification of the dissolution of arsenite solid solution, characterized in that The specific steps are: (1) Method for synthesizing arsenite solid solution: prepare fresh ultrapure water, weigh appropriate amounts of lead acetate, sodium arsenate and sodium chloride solids, and prepare 0.5 mol / L solutions for later use; in a clean polyethylene bottle, mix the prepared 0.5 mol / L lead acetate solution, sodium arsenate solution and sodium chloride solution in a ratio of 5:3:1; Before proportioning, 0.5mol / L sodium arsenate solution and sodium chloride solution are mixed evenly in a ratio of 3:1; at room temperature, 100mL of 0.5mol / L lead acetate solution is taken into a 250mL polyethylene bottle, and an intelligent magnetic stirrer is placed, the temperature is controlled to be 25°C, and stirring is continued at a speed of 300r / min. During the process, the bottle mouth is sealed with a plastic wrap, and nitrogen is aerated to remove impurities in water and air, and 80mL of 0.5mol / L sodium arsenate solution and 0.5mol / L sodium chloride solution are slowly added in a ratio of 3:

1. The solution is evenly mixed and added to the polyethylene bottle at a speed of 10mL / min. The reaction time is 10min, and stirring is stopped. Then, the solution is placed in a constant temperature water bath at 25°C for aging for 24h; after aging for 24h, solid-liquid separation is performed, and the obtained solid phase precipitate is washed with ultrapure water for multiple times. The washed solid phase precipitate is placed in a 90°C blast drying oven for drying for 24h to obtain an arsenic lead ore solid solution; (2) Setting up an experimental device for electric field enhanced dissolution of arsenic lead ore solid solution, which mainly consists of a DC power supply, a cathode chamber, an anode chamber, electrodes, and an electrolyte; (3) The DC power supply is connected to the electrodes by a pure copper power line, and the non-active electrode part is sealed with ceramic to isolate it from contact with the electrolyte; (4) Both the cathode chamber and the anode chamber are made of plexiglass. A circular connection port about 2 cm long and 1 cm in diameter is set between the two chambers. The proton membrane is placed in the middle of the connection port and fixed with a fixing clip. After the cathode chamber, anode chamber and connection port are fixed, they form an H shape; (5) In step (4), the proton membrane uses a commercial PFSA proton exchange membrane; (6) Weigh 1 g of ground arsenite solid solution that has passed through a 100-mesh sieve and place it into the anode chamber of a 1000 mL H-type plexiglass reactor; (7) Add 500 mL of electrolyte to the cathode and anode chambers of the H-type organic glass reactor respectively. Preferably, the electrolyte can be 0.1 mol / L KNO3, Na2SO4 and NaCl solution; (8) Using electric field electrodes as the cathode and anode of the H-type organic glass reactor, preferably, the electric field electrodes are titanium ruthenium electrodes; (9) The cathode chamber and anode chamber of the experimental device were covered and sealed, and then a DC power supply was used to apply a constant current of 0.1 A to perform electric field enhanced dissolution at room temperature; (10) During the electric field enhanced dissolution process, a certain volume of supernatant samples were taken at 1, 3, 5, 10, 20, 40, 60, 90, 120, 180, 360, 720, 1440, 2880, 4320, and 5760 min, respectively, and filtered into a centrifuge tube through a 0.22 μm membrane filter; (11) The sample obtained in step (10) was analyzed and determined by ICP-OES instrument. 2+ The concentration of As was measured by atomic fluorescence spectrophotometer 5+ The concentration of lead and arsenic is obtained respectively.

2. The method for electric field enhanced dissolution of arsenite solid solution according to claim 1, characterized in that The positive and negative electrodes in step (2) are both titanium ruthenium electrodes; the H-type connection in step (4); the PFSA proton exchange membrane in step (5); and the electrolyte in step (7) is 0.1 mol / L KNO3, Na2SO4 and NaCl solution.

3. An application of the method for electric field enhanced dissolution of arsenite solid solution as claimed in claims 1 and 2, characterized in that By applying appropriate voltage, the electric field acts on the arsenic-lead ore solid solution to enhance the selective rapid dissolution effect of the arsenic-lead ore solid solution, which is applied to the remediation of arsenic-lead contaminated soil and the resource utilization of arsenic and lead in tailings.

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