Abstract:The content of sulfuric acid and zinc ion in zinc electrolyte directly affects the purity and product quality of zinc. At present, the detection of sulfuric acid and zinc ion content in electrolyte depends on offline detection, the degree of automation is low, and the research and application of combined determination device is less. In this paper, the photometric titration on-line analysis system is introduced, and the content of sulfuric acid and zinc ion is determined by optimizing the detection parameters and the absorbance mutation.Under the conditions of sampling speed of 30mL/min and waiting time of 2s after liquid extraction, the sampling accuracy of the sample can be guaranteed. Zinc ion was determined by EDTA complexometric titration, with xylenol orange as the indicator, the amount of 0.2mL, the amount of hexamethylenetetramine buffer solution was 50mL, and the zinc ion was determined at the wavelength of 525nm. Sulfuric acid was determined by acid-base titration with methyl red-methylene blue indicator at a dosage of 0.2mL, and the wavelength was controlled at 420nm. The titration end point was determined by the color change of the indicator. The results showed that it was feasible to determine the titration end point according to the absorbance mutation by using the photometric sensor to collect the signal under the optimized experimental conditions. The stability test of the standard sample was carried out in the experiment, and the actual value was basically consistent with the identified value, indicating that the device and method were accurate and reliable. According to the method, the precision of the actual sample (n=7) and the recovery rate of the standard addition were tested and compared with the manual off-line detection. The overall RSD of the precision was less than 1.2%, and the recovery rate of the standard addition was 98.4%~101% and 99.1%~99.8%, respectively. The t test proves that there is no difference between the instrument test results and the manual test. The device can realize automatic analysis, simple operation, and the analysis items are carried out at the same time, which can meet the needs of online continuous production detection.
