Composite electrode for heavy metal ion detection and preparation method thereof

Abstract

The invention discloses a composite electrode for heavy metal ion detection. The composite electrode is prepared by taking bismuth composite vermiculite loaded carbonized polyaniline as a modifier andmodified sodium alginate as a film-forming agent to perform surface modification on a glassy carbon electrode. The preparation method specifically comprises the following steps: (1) adsorbing bismuthions by vermiculite under a physical adsorption effect, then carrying out in-situ polymerization on polyaniline on the surface of vermiculite, and carrying out gradient heating and roasting to prepare bismuth composite vermiculite loaded carbonized polyaniline; (2) dispersing bismuth composite vermiculite loaded carbonized polyaniline into the modified sodium alginate dispersion liquid, and coating the surface of a polished glassy carbon electrode with the dispersion liquid to prepare the composite electrode; the composite electrode serves as a working electrode and can be used for electrochemical detection of heavy metal lead and cadmium ions, the solution containing the heavy metal ions serves as a working solution, and the concentration of the heavy metal ions is tested through anodicstripping voltammetry. The concentrations of lead ions and cadmium ions can be detected at the same time, and relatively high sensitivity, a wide detection range and a relatively low detection limit are shown.

Description

technical field [0001] The invention relates to the field of electrode material preparation, in particular to a composite electrode for detecting heavy metal ions and a preparation method. Background technique [0002] Due to their concealment, non-degradability and long-term accumulation, heavy metals pose a major threat to human health and survival invisibly. The detection of heavy metals in drinking water, food, medicine, etc. has attracted widespread attention. At present, the detection methods of heavy metals mainly include atomic Absorption, atomic fluorescence, and inductively coupled plasma-mass spectrometry, etc., but these methods often require the use of sophisticated large-scale instruments and cumbersome operations such as special treatment of samples, resulting in high costs, and cannot be conveniently and quickly detected in real-time and on-site; electrochemical The detection is popular because of its advantages of convenient operation, high detection sensiti...

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Problems solved by technology

[0002] Due to their concealment, non-degradability and long-term accumulation, heavy metals pose a major threat to human health and survival invisibly. The detection of heavy metals in drinking water, food, medicine, etc. has attracted extensive attention. At present, the detection methods of heavy metals mainly include atomic Absorption, atomic fluorescence, and inductively coupled plasma-mass spectrometry, etc., but these methods often require the use of sophisticated large-scale instruments and cumbersome operations such as special treatment of samples, resulting in high costs, and cannot be conveniently and quickly detected in real-time and on-site; electrochemical The detection is popular because of its advantages of convenient operation, high detection sensitivity and rapid detection; the choice of electrodes in electrochemical detection will significantly affect the detection sensitivity and the enrichment of heavy metals, which will affect the detection limit; currently used for heavy metal detection The working electrode of the electrochemical sensor is often a glassy carbon electrode, but its sensitivity is not high. With the continuous maturity of the chemically modified electrode technology, the surface modification of the glassy carbon electrode is usually used to obtain high detection sensitivity and low detection. Electrodes with limited and wide application range;

[0003] Due to its special physical and chemical properties, bismuth-based electrodes have attracted extensive attention in the field of heavy metal detection. At present, most of the preparation methods of bismuth-based electrodes are in the form of in-situ or ex-situ deposition of bismuth films or bismuth oxides on the electrode surface. Film deposition needs to strictly control the concentration of bismuth ions, solution pH, deposition potential and other conditions during deposition, which makes the deposition process of bismuth film complicated, resulting in cumbersome electrode preparation process; If it is too thick, the detection sensitivity and the utilization rate of the bismuth film will be reduced; at the same time, there will be problems of poor stability and low reproducibility of the electrode caused by the shedding of the bismuth film;

[0004] At present, with the increasing maturity of electrochemical sensor technology, electrochemical sensors for heavy metal detection have been extensively studied; however, the preparation process of traditional electrochemical sensors for heavy metal detection is cumbersome, the detection sensitivity is low, and the surface of the sensor is modified. Substances can only generate specific signals for specific molecules, and cannot simultaneously detect multiple heavy metal ions. Therefore, it is urgent to research and develop electrochemical sensor working electrodes capable of detecting multiple heavy metals.

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