CN-116297741-B - Method for measuring electron transfer speed of soluble organic matters in soil

CN116297741BCN 116297741 BCN116297741 BCN 116297741BCN-116297741-B

Abstract

The invention discloses a method for measuring the electron transfer rate of a soluble organic matter in soil, which comprises the steps of taking soil from shallow soil of a wetland, taking more than 3 parts of soil samples per 2cm of soil, adding ultrapure water into the soil samples to prepare suspension, oscillating by a shaking table, centrifuging and passing through a membrane, extracting the soluble organic matter in the soil suspension to obtain an organic matter solution, obtaining parameters such as peak current and peak potential by using a three-electrode system and connecting an electrochemical workstation at room temperature through a cyclic voltammetry, calculating an electron transfer rate constant k 0 of the soil samples according to a Butler-Volmer equation, calculating an arithmetic average value of more than 3 electron transfer rate constants k 0 to represent the electron transfer rate of the soluble organic matter in the surface layer of the wetland, and obtaining the electron transfer rate of the soluble organic matter in the shallow soil of the wetland by adopting a three-electrode system and a cyclic voltammetry.

Inventors

SONG SHUANGJIE
ZHANG PENG
LI HAO
WU YUFEI
PAN BO

Assignees

昆明理工大学

Dates

Publication Date: 20260512
Application Date: 20230425

Claims (5)

1. The method for measuring the electron transfer rate of the soluble organic matters in the soil is characterized by comprising the following specific steps of: (1) Taking soil from shallow soil of the wetland, wherein more than 3 soil samples are taken per 2cm of soil; (2) Adding ultrapure water into a soil sample to prepare a suspension, and extracting soluble organic matters in the soil suspension through shaking by a shaking table, centrifuging and membrane passing to obtain an organic matter solution; (3) Taking an Ag/AgCl electrode, a platinum wire and a glassy carbon electrode as reference electrodes, a counter electrode and a working electrode as a three-electrode system respectively, connecting an electrochemical workstation, taking the organic matter solution in the step (2) as electrolyte, setting a scanning voltage window, a scanning speed, a scanning circle number, a scanning time interval and a resting time to obtain a cyclic voltammogram, combining peak current, peak potential, a working electrode surface area, an electron transfer number, a Faraday constant and an organic matter solution concentration, and calculating a soluble organic matter electron transfer rate constant k 0 in a soil sample according to a Butler-Volmer equation: Wherein intersept is the Intercept of linear fitting of natural logarithm of absolute value of peak current and overpotential under different scanning speeds, the overpotential is the difference value of peak potential and form potential, and the form potential is the average value of oxidation peak potential and reduction peak potential; n is the electron transfer number, n=2; f is Faraday constant; A is the surface area of a working electrode, and the unit is m 2 ; C is the concentration of an organic matter solution, and the unit is mol/L; and calculating an arithmetic average value of the soil samples k 0 with more than 3 layers, and quantifying the electron transfer speed of the soluble organic matters in the shallow soil of the wetland.
2. The method for measuring the electron transfer rate of a soluble organic substance in soil according to claim 1, wherein the mixing ratio of the soil and the ultrapure water in the step (2) is 1:3 to 1:10 g/mL.
3. The method for measuring the electron transfer rate of the soluble organic matters in the soil according to claim 1, wherein the temperature of the shaking table in the step (2) is 25-30 ℃, the shaking speed is 100-200 rpm, and the time is 12-48 h.
4. The method for measuring the electron transfer rate of the soluble organic matters in the soil according to claim 1, wherein the centrifugal speed in the step (2) is 2000-4000 r/min, the centrifugal time is 15-30 min, and the pore diameter of the filter membrane is 0.45 μm when the filter membrane is used for membrane filtration.
5. The method for measuring the electron transfer rate of the soluble organic matters in the soil according to claim 1, wherein the voltage window in the step (3) is-2V, the scanning speed is 10-160 mV/s, the number of scanning turns is 2-6, the time interval is 0.001-0.1 s, and the rest time is 1-30 s.

Description

Method for measuring electron transfer speed of soluble organic matters in soil Technical Field The invention relates to a method for measuring the electron transfer speed of a soluble organic matter in soil, and belongs to the technical field of electrochemistry. Background In recent years, the rising of greenhouse gas emission amount poses a great threat to human living environment and earth health year by year, wetland soil is concerned as an important source of greenhouse gas, in addition, wetlands such as swamps, shovels, lakesides and the like are important natural ecosystems and natural resources, and have various environmental functions such as flood regulation, climate regulation, water conservation, water purification, biological diversity maintenance and the like, but the pollution problem of the wetland is more and more serious recently, and the two environmental problems are worth noting that both environmental problems relate to an electron transfer link of a bio-geochemical circulation process, but the participation degree of soluble organic matters in the shallow soil of the wetland is still unclear, so that the method has been widely discussed. It is currently known that soil soluble organic matter is involved in electron transfer processes by virtue of its active components as electron shuttles, and that quinones, humic acids, cysteines and other sulfur-containing molecules are well known as typical exogenous shuttles. However, the electron transfer ability of the soluble organic matter in the soil lacks experimental means for characterizing quantification. Disclosure of Invention Aiming at the problems in the prior art, the invention provides a simple and direct calculation method for measuring the electron transfer speed of the soluble organic matters in the soil. The technical scheme of the invention is as follows: A method for measuring the electron transfer rate of a soluble organic matter in soil comprises the following specific steps: (1) Soil sample acquisition, namely, using a needle tube soil sampler to take more than 3 soil samples per 2cm of soil in the shallow soil of the wetland; (2) Preparing a soluble organic matter solution in soil, namely adding a soil sample into ultrapure water according to a certain water-soil ratio to prepare a suspension, oscillating by a shaking table, centrifuging and passing through a membrane, and extracting the soluble organic matter in the soil suspension to obtain the organic matter solution; (3) Taking an Ag/AgCl electrode, a platinum wire and a glassy carbon electrode as reference electrodes, a counter electrode and a working electrode as a three-electrode system respectively, connecting an electrochemical workstation, setting a scanning voltage window, a scanning speed, a scanning number of turns, a scanning time interval and a rest time by using the organic matter solution in the step (2) as electrolyte, obtaining a cyclic voltammetry curve, and calculating a soluble organic matter electron transfer rate constant k 0 in a soil sample according to a peak current, a peak potential, a working electrode surface area, an electron transfer number, a Faraday constant and the concentration of soluble organic matters in the organic matter solution by using a formula according to a Butler-Volmer equation: Wherein intersept is the Intercept of linear fitting of natural logarithm of absolute value of peak current and overpotential under different scanning speeds, the overpotential is the difference value of peak potential and form potential, and the form potential is the average value of oxidation peak potential and reduction peak potential; n is the electron transfer number, and n is 2; f is Faraday constant; A is the surface area of a working electrode, and the unit is m 2; c is the concentration of the soluble organic matter solution, and the unit is mol/L; e is a natural constant, and the whole text is the same; Calculating the arithmetic average value of the samples k 0 above 3 layers to characterize and quantify the electron transfer speed of the soluble organic matters in the shallow soil of the wetland. And (2) extracting the soluble organic matters in the soil, wherein the ratio of the soil to the water is 1:3-1:10 g/mL. And (2) the temperature of the shaking table is 25-30 ℃, the shaking speed is 100-200 rpm, the time is 12-48 h, and the centrifuge tube in the shaking table is horizontally placed. The centrifugal rotating speed of the step (2) is 2000-4000 r/min, the centrifugation time is 15-30 min. The pore diameter of the filter membrane is 0.45 μm when the step (2) is performed. The voltage window of the step (3) is-2V, the scanning speed is 10-160 mV/s, the scanning circle number is 2-6, the time interval is 0.001-0.1 s, and the resting time is 1-30 s. The invention has the advantages that: 1. the soil sample is flexible and simple in material taking, and the experimental process is environment-friendly. 2. The method has simple process