A quantitative electrodialysis separation method for dissolved inorganic arsenic forms in water

Abstract

The present application discloses a quantitative electrodialysis separation method for inorganic arsenic forms dissolved in water. The quantitative electrodialysis separation method is to perform electrodialysis on a water sample containing inorganic arsenic forms, so that arsenic (V) migrates to the anode chamber through the diaphragm in an ionic manner, while arsenic (III) does not migrate in the water sample chamber, thereby achieving the separation of arsenic (V) and arsenic (III). The arsenic (V) is then detected by constant volume in the anode chamber solution, and the total arsenic in the filtered water sample is detected. The arsenic (III) content is calculated by subtraction or the arsenic (III) content in the water sample chamber is directly detected by constant volume. The outstanding features of this method are: it realizes the automated separation of different forms of arsenic, the method is simple, economical and environmentally friendly, and the analysis time is short.

Description

Technical Field

[0001] The present application relates to the technical field of arsenic separation, and in particular to a quantitative electrodialysis separation method for inorganic arsenic forms dissolved in water. Background Art

[0002] Arsenic in natural water bodies (such as seawater, groundwater, and tailings water) primarily exists in an inorganic form. This inorganic form is further divided into dissolved and particulate forms. Particulate arsenic can be removed by suction or filtration, leaving the filtered water primarily composed of soluble arsenic (V) and arsenic (III). Liquid chromatography coupled with atomic fluorescence or ICP-MS is currently commonly used for separation and detection of arsenic (V) and arsenic (III). The chromatographic column performs the separation function, while the atomic fluorescence detector or ICP-MS performs the detection function. Liquid chromatography offers unparalleled advantages in separating organic arsenic. However, if used solely for the separation of soluble arsenic (V) and arsenic (III), the column mobile phase requires chromatographically pure organic reagents and inorganic solutions, resulting in expensive instrumentation and high testing costs. This has limited the widespread application of speciation analysis for arsenic (V) and arsenic (III) in water. The cost of submitting a single speciation for testing is significantly higher than the cost of single-component analysis using atomic fluorescence or ICP-MS. Some studies have used ion exchange separation and detection, but this is highly complex. Summary of the Invention

[0003] In view of this, the present application provides an electrodialysis separation and quantitative method for the forms of dissolved inorganic arsenic in water, which can realize the automated separation of different forms of arsenic. The method is simple, economical, and environmentally friendly, with a short analysis time and high sensitivity and accuracy.

[0004] The present application provides a method for the electrodialysis separation and quantitative determination of inorganic arsenic forms dissolved in water, specifically comprising: subjecting a water sample containing dissolved inorganic arsenic forms to electrodialysis;

[0005] Wherein, the inorganic arsenic forms contain at least trivalent arsenic and pentavalent arsenic forms;

[0006] For the electrodialysis, a membrane for blocking molecules is arranged in the ion migration path leading to the anode, and the ions targeted by the ion migration path are derived from the inorganic arsenic.

[0007] As used herein, the term "ion migration path" refers to the path taken by ions from the water sample that move directional toward the anode. It should be understood that the ion migration path corresponds to the region between the boundary formed when the water sample is added to the electrolytic solution of electrodialysis and the anode.

[0008] As used herein, the term "molecular barrier membrane" refers to a membrane capable of blocking molecular-sized particles, with the only limitation being the pore size of the membrane. In this application, a molecular barrier membrane effectively blocks trivalent arsenic from entering the anode compartment, allowing for rapid and quantitative separation of pentavalent arsenic. Furthermore, its molecular barrier function ensures that the amount of water passing through the sample and anode compartments remains essentially constant.

[0009] As a reference implementation method, the diaphragm is a hydrophilic polytetrafluoroethylene membrane with 50-200 nm nano-scale micropores.

[0010] As a reference implementation method, the pH of the water sample is 3-6, and the voltage of the electrodialysis is 5-60V.

[0011] As a reference implementation method, the electrodialysis adopts a direct current voltage method.

[0012] In view of the predictability of the structure of the electrodialysis device, this application does not list the specific structures of the electrodialysis device that can implement the embodiment of this application. As a reference implementation method, the electrodialysis device for implementing the electrodialysis includes an anode chamber, a cathode chamber, and a water sample chamber located between the anode chamber and the cathode chamber and used to accommodate the water sample, and the diaphragm is arranged between the water sample chamber and the anode chamber.

[0013] Of course, as another method, the diaphragm can also be arranged in the water sample chamber or the anode chamber, for example, close to the edge of the anode chamber, or close to the edge of the water sample chamber.

[0014] As a reference implementation method, the pH values of the anode chamber and the water sample chamber are the same.

[0015] As a reference implementation, the anode chamber is in a sealed state.

[0016] The electrodialysis separation and quantitative analysis method provided above separates arsenic (V) and arsenic (III) by subjecting a water sample containing dissolved inorganic arsenic forms to electrodialysis. This allows arsenic (V) to migrate ionically through the diaphragm to the anode chamber, while arsenic (III) does not migrate in the water sample chamber. Arsenic (V) is then detected by constant volume in the anode chamber solution, and the total arsenic in the filtered water sample is detected. The arsenic (III) content is calculated by subtraction or directly detected in the water sample chamber by constant volume. This method features automated separation of different arsenic forms, a simple, economical, and environmentally friendly method, and a short analysis time. DETAILED DESCRIPTION

[0017] The following will be combined with the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the embodiments described are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative efforts are within the scope of protection of this application.

[0018] In the description of this application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the described features. In the description of this application, "plurality" means two or more, unless otherwise specifically defined.

[0019] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections, electrical connections, or mutual communication; they can refer to direct connections or indirect connections through an intermediate medium; they can refer to internal communication between two components or the interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0020] The disclosure below provides many different embodiments or examples for realizing different structures of the present application. In order to simplify the disclosure of the present application, the components and settings of specific examples are described below. Of course, they are merely examples and are not intended to limit the present application. In addition, the present application may repeat reference numbers and / or reference letters in different examples, and such repetition is for the purpose of simplicity and clarity, and does not itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present application provides examples of various specific processes and materials, but those of ordinary skill in the art will appreciate the application of other processes and / or the use of other materials.

[0021] Example 1

[0022] A groundwater sample, measured using HY / T152, contained 98.0 ppb and 130 ppb of dissolved inorganic arsenic (V) and 130 ppb of arsenic (III), respectively, for a total dissolved inorganic arsenic content of 228 ppb. Adjust the water sample's pH to 3.7, connect the three-chamber, two-membrane electrodialysis device, and tighten the device to ensure it is leak-proof. Add 30 mL of water sample to the middle water sample chamber, add a solution with the same pH as the water sample chamber to the anode chamber, and add a NaCl solution to the cathode chamber. Insert platinum electrodes into the cathode and anode chambers, respectively, and connect them to the negative and positive poles of a DC regulated power supply. Turn on the power switch, set the operating voltage to 30 V, and perform electrodialysis using a constant voltage mode. After the electrodialysis, the anode chamber solution was collected and fixed to volume. After mixing evenly, the arsenic (V) in the anode chamber was determined using the standard arsenic analysis method GB / T 6730.72 ICP-MS. The arsenic (V) content in the original water sample was calculated based on the diluted volume to be 92.6 ppb, with a recovery rate of 94.5%. The arsenic (III) content was calculated by subtraction to be 135 ppb.

[0023] Example 2

[0024] The total inorganic arsenic content of an antimony tailings water sample after adjusting the pH to 4.7 and quantitative dilution was 388 ppb. The arsenic (III) content was determined to be 176 ppb using HY / T152, and the corresponding arsenic (V) content was 212 ppb. Connect the three-chamber two-membrane electrodialysis device and tighten the device to ensure that it is leak-proof. Add 30 mL of water sample to the middle water sample chamber, add a solution with the same pH as the water sample chamber to the anode chamber, and add NaCl solution to the cathode chamber. Insert platinum electrodes into the cathode chamber and the anode chamber respectively, and connect them to the negative and positive poles of the DC regulated power supply respectively. Turn on the power switch, set the operating voltage to 50 V, and perform electrodialysis using constant voltage. After the electrodialysis, the anode chamber solution was collected and fixed to volume. After mixing evenly, the arsenic (V) in the anode chamber was determined using the standard arsenic analysis method GB / T 6730.72 ICP-MS. The arsenic (V) content in the original water sample was converted to 204 ppb based on the dilution volume, with a recovery rate of 96.2%. The arsenic (III) content was calculated to be 184 ppb using the difference subtraction method.

[0025] Example 3

[0026] A water sample with a pH of 5.3, prepared with trivalent and pentavalent arsenic salts, contains 300 ppb of inorganic arsenic (V) and 300 ppb of arsenic (III), respectively, and 600 ppb of total arsenic. Connect the three-chamber, two-membrane electrodialysis apparatus and tighten the system to ensure it is leak-proof. Add 30 mL of water sample to the middle chamber, a solution with the same pH as the chamber in the anode chamber, and a NaCl solution to the cathode chamber. Insert platinum electrodes into the cathode and anode chambers, respectively, and connect them to the negative and positive poles of a DC regulated power supply. Turn on the power switch, set the operating voltage to 60 V, and perform electrodialysis using constant voltage. After the electrodialysis, the anode chamber solution was collected and fixed to volume. After mixing evenly, the arsenic (V) in the anode chamber was determined using the standard arsenic analysis method GB / T 6730.72 ICP-MS. The arsenic (V) content in the self-prepared water sample calculated based on the dilution volume was 291 ppb, with a recovery rate of 97.0%. The arsenic (III) content was calculated by subtraction and was 309 ppb.

[0027] The above is only a preferred specific implementation method of the present application, but the scope of protection of the present application is not limited thereto. Any changes or replacements that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed in this application should be covered by the scope of protection of the present application.

Claims

1. A method for the quantitative separation of dissolved inorganic arsenic forms in water by electrodialysis, characterized in that: Specifically: electrodialysis is performed on water samples containing dissolved inorganic arsenic forms; Wherein, the inorganic arsenic forms contain at least trivalent arsenic and pentavalent arsenic forms; For the electrodialysis, a membrane for blocking molecules is arranged in the ion migration path leading to the anode, wherein the ions targeted by the ion migration path are derived from the inorganic arsenic; The pH of the water sample is 3-6, and the diaphragm is a hydrophilic polytetrafluoroethylene membrane with 50-200 nm nano-scale micropores; By subjecting water samples containing dissolved inorganic arsenic forms to electrodialysis, arsenic (V) is allowed to migrate through the diaphragm to the anode chamber in an ionic form, while arsenic (III) does not migrate in the water sample chamber, thereby achieving separation of arsenic (V) and arsenic (III). Then, the anodic chamber solution is fixed to detect arsenic (V), and the total arsenic in the filtered water sample is detected. The arsenic (III) content is calculated by subtraction or the arsenic (III) content in the water sample chamber is directly detected by fixed volume.

2. The electrodialysis separation quantitative method according to claim 1, wherein The voltage of electrodialysis is 5-60V.

3. The electrodialysis separation quantitative method according to claim 1, wherein The electrodialysis adopts a direct current voltage mode.

4. The electrodialysis separation quantitative method according to claim 1, wherein The electrodialysis device for implementing the electrodialysis comprises an anode chamber, a cathode chamber and a water sample chamber located between the anode chamber and the cathode chamber and used to accommodate the water sample. The diaphragm is arranged between the water sample chamber and the anode chamber.

5. The electrodialysis separation quantitative method according to claim 4, characterized in that: The pH values of the anode chamber and the water sample chamber are the same.

6. The electrodialysis separation quantitative method according to claim 4, characterized in that: The anode chamber is in a sealed state.