Voltammetric detection of heavy metals in soil using two-step electrodeposition and stripping steps

A stripping voltammetry and detection method technology, which is applied in the detection field, can solve the problems of high detection sensitivity and anti-interference requirements, complex soil components, and difficult detection, and achieves wide detection range, high degree of portability, and easy detection. carrying effect

Active Publication Date: 2019-05-21
CHINA AGRI UNIV
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  • Description
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  • Application Information

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Problems solved by technology

[0003] However, due to the complex soil components, there are great differences between the laboratory testing environment and the actual measurement environment of soil samples. The detection sensitivity and anti-interference requirements of the method are relatively high
Conventional anodic stripping voltammetry consists of four processes of deposition, standing, stripping, and cleaning. Due to the complexity of the detection of heavy metals in soil, there are still certain problems in the application of conventional stripping voltammetry to the detection of heavy metals in soil. Its application in the detection of heavy metals in soil

Method used

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  • Voltammetric detection of heavy metals in soil using two-step electrodeposition and stripping steps
  • Voltammetric detection of heavy metals in soil using two-step electrodeposition and stripping steps
  • Voltammetric detection of heavy metals in soil using two-step electrodeposition and stripping steps

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0037] Embodiment 1, the preparation of carbon paste electrode

[0038] ① Mix graphite powder and paraffin oil into the mortar

[0039] ② After fully grinding, put the mixture into the cavity 5 of polytetrafluoroethylene material with a diameter of 10 mm, compact and form it, and use the copper pillar as the wire at the rear end to conduct with the carbon paste.

[0040] ③ Grind the surface of the carbon paste electrode with weighing paper to obtain a smooth electrode surface.

[0041] Such as figure 2 Shown is a three-electrode sensor structure composed of graphite powder-paraffin oil carbon paste electrode, a composite electrode structure diagram composed of Ag / AgCl reference electrode 8 and platinum wire electrode, Ag / AgCl reference electrode 8, carbon paste electrode 9, platinum wire electrode The wire counter electrode 10 is combined and inserted into a composite electrode carrier 11 made of polytetrafluoroethylene.

Embodiment 2

[0042] Embodiment 2, the preparation of soil extract and blank soil extract

[0043] Pre-treatment of the collected soil. Weigh 12.5g of soil, place the soil in a constant temperature drying box, and dry the soil at a constant temperature of 100°C for 10 minutes, transfer the dried soil to a beaker, then add 500mL of acetic acid-sodium acetate buffer solution with pH5.0, and use ultrasonic The processor performs ultrasonic treatment on 500mL soil extract solution for 10 minutes, and rests for 10 minutes until the soil settles to the bottom of the bottle.

[0044] The supernatant after ultrasonic treatment was preliminarily filtered on the soil with filter paper, and then the soil extract after preliminary filtration was manually filtered through a combination of a disposable syringe and a water filter to obtain a soil extract.

[0045] Through the electrodeposition function of stripping voltammetry, the three-electrode sensor composed of graphite powder-paraffin oil carbon pa...

Embodiment 3

[0046] Embodiment 3 Modification of glassy carbon electrode and glassy carbon three-electrode sensor

[0047] The preparation process of multi-walled carbon nanotube-Nafion modified glassy carbon electrode is as follows:

[0048] ① Put 1 mg of multi-walled carbon nanotubes into 4 mL of DMF solution.

[0049] ② Use a mixer to mix the multi-walled carbon nanotube dispersion.

[0050] ③ Add 500 μL of 1% Nafion solution to the multi-walled carbon nanotube dispersion and place it in an ultrasonic processor for ultrasonic treatment.

[0051] ④ Centrifuge the mixed solution after ultrasonic treatment.

[0052] ⑤Use a pipette gun to draw 6 μL of the upper layer solution, and drop-coat it on the surface of the polished glassy carbon electrode. The glassy carbon electrode has a diameter of 3 mm.

[0053] ⑥ Place the modified electrode under an infrared drying lamp for drying.

[0054] ⑦ After drying, place the electrode in the air to cool down to room temperature naturally.

[005...

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Abstract

The invention provides a soil heavy metal volt-ampere detection method adopting two steps of electric deposition and dissolution. The method comprises the following steps: (1) adding bismuth ions into a soil leaching liquor, and by taking a graphite powder-paraffin oil carbon paste electrode as a working electrode, plating a bismuth film on the electrode by adopting an in-situ film plating method; (2) forming a carbon paste three-electrode sensor through the graphite powder-paraffin oil carbon paste electrode, and performing primary deposition on heavy metals in the soil leaching liquor to be detected through a dissolution volt-ampere method for 500 to 1,000 seconds; (3) dissolving out the heavy metals deposited on the surface of the electrode into an electrolytic tank through the dissolution volt-ampere method; (4) placing a glass-carbon three-electrode sensor consisting of a multi-wall carbon nano tube-Nafion modified glass-carbon electrode into the electrolytic tank, and performing secondary deposition and dissolving out on heavy metal ions in the electrolytic tank, thus obtaining a heavy metal dissolution volt-ampere signal. The soil heavy metal volt-ampere detection method is high in portability, easy to carry and operate, low in cost and wide in detection range, and can be widely applied to actual detection of all fields.

Description

technical field [0001] The invention belongs to the technical field of detection, and in particular relates to a detection method of heavy metal ions in soil. Background technique [0002] With the continuous development of my country's industrialization process, heavy metal pollution has become one of the most harmful environmental problems. Among them, heavy metal pollution in soil has a strong enrichment property, can be enriched in organisms through the food chain, and is not easy to find in a short period of time. greater harm to human health. Therefore, it is of great significance to establish a rapid and reliable detection method for trace heavy metal ions in food, medicine and environmental monitoring. Compared with the detection method of large-scale spectral equipment in the laboratory, anodic stripping voltammetry has always been considered as an effective method for the determination of trace heavy metal ions. This method has the advantages of convenient operatio...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01N27/48
CPCG01N27/48
Inventor 刘刚赵国王辉
Owner CHINA AGRI UNIV
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