Solution TOC concentration in-situ initial measurement and pre-judgment method

[0023] Standard solution, electrode system and measurement conditions

[0024] Standard solution: Voltammetry is a measurement method based on the linear relationship between the diffusion current generated by the oxidation reaction of the substance on the electrode surface under a certain applied voltage and the concentration of the substance. Since most of the organic matter in soil solution and natural water body is weakly reducing organic matter, after analysis and comparison, we choose citrate as the standard substance of organic carbon to make the standard working curve for voltammetric determination. And because TOC analyzers generally require measurement under weakly acidic conditions to reduce CO in the air 2 Therefore, diammonium citrate was selected as the standard substance because the pH of diammonium citrate aqueous solution (0.01 mol / L) was around 5.0. The actual measurement results show that when the applied voltage is 0.9V, pH5.1, and the reading is 120 second

[0029] Preliminary measurement and prediction of TOC in soil solution

[0030] Select a soil with high organic matter content, and extract soil TOC at the ratio of 1 g soil to 5 mL water. Soil samples with deCO 2 High-purity water mixing, shaking for 1 hour, high-speed centrifugation to separate solid / liquid phases, soil solution through a 0.45 μm filter membrane, adjust the pH of the soil solution to 5.1, measure the diffusion current of the solution by voltammetry described in Example 1, according to the working curve The initial measured TOC value of the soil solution was calculated to be 148.6 mg / L ( Figure 4 ). The concentration range of the daily optimal standard working curve when using TOC analyzer to measure TOC is 0-100 mg / L. According to the preliminary test results of voltammetry, it is preliminarily judged that it is more appropriate to dilute the solution by 2 times and measure it with TOC analyzer. According to this operation, the measurement result obtai

[0032] Preliminary Measurement and Prediction of TOC in Straw Culture Solution

[0033] Straw culture solution is often used as a simulated soil dissolved organic carbon solution to study its chemical reaction in soil. Use rice straw as a representative of crop straw, grind it through a 2mm sieve, and then mix the rice straw with the CO2-removing 2 Mix high-purity water, anaerobic fermentation at constant temperature at 25°C for 1 week, then centrifuge at high speed to separate the solid / liquid phase, pass the culture solution through a 0.45 μm filter membrane, adjust the pH of the culture solution to 5.1, and measure the solution by voltammetry described in Example 1 The diffusion current of the straw culture solution was calculated according to the working curve, and the preliminary TOC value of the straw culture solution was 3950 mg / L ( Figure 7 ). The concentration range of the daily optimal standard working curve when using TOC analyzer to measure TOC is 0-100 mg / L.