E-mail: michael@shboqu.com   |   Expert in Water Quality Measurement and Water Treatment Project

Talk about the steps of electrode method to measure total chlorine and free chlorine in water quality

by:BOQU     2023-03-22
There are many detection methods for total chlorine and free chlorine in water, commonly used are spectrophotometry, titration and electrode method. Among them, the operation steps of spectrometry and titration have been introduced to you. Today we will talk about the steps of electrode method to determine total chlorine and free chlorine in water quality. Detection principle The working electrode set contains two working electrodes, which are used to detect free chlorine and total chlorine respectively. The free chlorine electrode is coated with tetramethylbenzidine. After a fixed voltage is applied, the free chlorine undergoes a reduction reaction on the surface of the working electrode to obtain electrons and generate current; the total chlorine working electrode is coated with potassium iodide to promote the reduction reaction of combined chlorine. Gain electrons and generate an electric current. When measuring, insert the working electrode group into the water sample to be tested, apply a fixed working voltage to the working electrode through the voltage stabilizer, and record the resulting current-power-on time relationship in real time. The intensity of the generated current is proportional to the concentration of free chlorine and total chlorine in the water sample. Chlorine dioxide, a common interference in the detection process, will undergo a reduction reaction similar to chlorine on the surface of the working electrode, which will interfere with the detection of chlorine. However, chlorine dioxide itself is volatile and can be removed by blowing air into the water for 5 minutes. The acceptable pH range for water sample detection is 4-9, and the detection will be affected if the pH value is too high or too low. Reagents and equipment used in the test 1. Sodium hydroxide solution: 2.0mol/L Weigh 80g of sodium hydroxide, dissolve in 500ml of laboratory grade 1 pure water, transfer the solution to a 1000ml volumetric flask after cooling, add pure water to the mark, mix uniform. 2. Laboratory primary pure water 3. Portable electrochemical residual chlorine analyzer includes free chlorine working electrode, total chlorine working electrode, reference electrode and counter electrode, etc. The water quality testing instrument should meet the following working conditions: ambient temperature, 0°C-50°C; ambient humidity, ≤90%. The instrument should have temperature compensation function. Accuracy performance: free chlorine: ≤±0.05mg/L, 10±0.05mg/L (20°C); ≤±2mg/L, 20±2mg/L (10°C). Total chlorine: ≤±0.5mg/L, 10±0.5mg/L L (20°C); ≤±10mg/L, 200±10mg/L (10°C). Precautions for water sample collection Free chlorine and total chlorine are unstable, and water samples should be measured on site as much as possible. If the water sample cannot be measured on site, add the 1% NaOH solution of the sampling volume into the brown glass bottle in advance, collect the water sample to fill the sampling bottle, and seal it immediately to prevent the water sample from being lost and exposed to the air. If the water sample is acidic, the amount of NaOH solution should be increased to ensure the pH of the water sample>12. In addition, the turbidity and color of the water sample have no effect on the measurement and can be directly measured. The temperature of the water sample should be between 2°C and 35°C. Water samples were stored at 4°C protected from light and measured within 5 days. Test steps Before the test, connect the working electrode group and the measuring instrument correctly, and check the performance of the instrument. Determination of the blank water sample, the measured value should be less than the detection limit of the method. Adjust the pH value of the water sample to 4-9, rinse the measuring cup with the water sample, and then measure the water sample to the mark. Select free chlorine and total chlorine measurement items on the instrument, insert the working electrode group of the water quality detector into the water sample, and read after it is stable. After the measurement is completed, discard the water sample and clean the measuring cup, turn off the power, and end the measurement. The concentration of free chlorine and total chlorine can be read directly from the display of the instrument (calculated as Cl2). If the water sample is diluted before determination, the concentration of free chlorine and total chlorine should be directly read out and multiplied by the dilution factor. The concentration of combined chlorine in the water sample can be calculated according to the formula C3=C2 (total chlorine concentration)-C1 (free chlorine).
Everyone who has a water quality monitoring device wants it to look water quality monitoring device. However, in order to achieve that, it normally involves investing in a water quality monitoring device water analyzer. Shanghai Boqu Instrument Co., Ltd. can offer you the best solution.
If you are interested in , click BOQU Water Quality Analyzer to see some items with features that you will be amazed at.
Many business owners and professionals use services like Shanghai Boqu Instrument Co., Ltd. to stay on top of manufacturing industry, monitor products’ quality and keep an eye on competitors.
Shanghai Boqu Instrument Co., Ltd. has been making a name for itself as a producer of some of the finest in the China, and it has been singing its praises for some time.
Shanghai Boqu Instrument Co., Ltd. are trained to think about problems and coming up with solutions, as well as presenting the whole idea in a logical and coherent manner.
Custom message
Chat Online 编辑模式下无法使用
Leave Your Message inputting...