河北冶金

为准确测量镀锡板71钝化工艺铬酸溶液中的SO₄^2-的浓度，研究了可见光分光光度仪及其检测方法的适用性，并对检测效果进行了产线验证。通过向铬酸溶液中滴加BaCl₂，使SO₄^2-与Ba²⁺生成BaSO₄沉淀，再对比加药前后的铬酸溶液吸光度和透光率的变化，实现SO₄^2-浓度的检测。为提高测试数据的准确性，使用铁氟龙亲水滤膜对铬酸溶液进行过滤，排除了铬酸溶液中杂质颗粒的干扰;通过向铬酸溶液中滴加盐酸，将Cr O₄^2-转变为Cr_2O₇^2-，排除了BaCrO₄沉淀的干扰;对加药后的铬酸溶液进行超声波振荡，排除了BaSO₄沉淀团聚对测试结果的干扰。实验发现:在分光光度计的测试波长> 570 nm时，光源可透过橙黄色的铬酸检测不透光的BaSO₄沉淀颗粒，SO₄^2-的浓度与样品的吸光度呈线性关系，与透光率呈负对数关系，据此建立硫酸根标准曲线。吸光度和透光率均可用于检测铬酸溶液中的硫酸根浓度，经与离子色谱法测试数据对比，测试准确度和精度均可满足产线的使用需求，大幅降低了检测成本。

To accurately measure the concentration of SO₄^2- in the chromic acid solution for the 71 passivation process of tinplate,the applicability of a visible spectrophotometer and its detection method was investigated,and the detection effect was verified in the production line.SO₄^2- reacted with Ba²⁺to form BaSO₄ precipitate by adding BaCl2 dropwise to the chromic acid solution,and then the concentration of SO₄^2- was detected by comparing the changes in absorbance and light transmittance of the chromic acid solution before and after reagent addition.To improve the accuracy of test data,a Teflon hydrophilic filter membrane was used to filter the chromic acid solution to eliminate the interference of impurity particles in the solution.The hydrochloric acid was added dropwise to convert CrO₄^2- into Cr_2O₇^2-,thus avoiding the interference of BaCrO₄ precipitate.Ultrasonic oscillation was applied to the chromic acid solution after reagent addition to eliminate the interference of BaSO₄ precipitate agglomeration on the test results.The experimental results showed that when the test wavelength of the spectrophotometer was greater than 570 nm,the light source could penetrate the orange-yellow chromic acid and detect the opaque BaSO₄ precipitate particles.The concentration of SO₄^2- had a linear relationship with the absorbance of the sample and a negative logarithmic relationship with the light transmittance,based on which a sulfate radical standard curve was established.Both absorbance and light transmittance can be used to detect the sulfate radical concentration in chromic acid solution.Compared with the test data of ion chromatography,the test accuracy and precision can meet the application requirements of the production line,and the detection cost is greatly reduced.