اندازه‌گيري اسيد‌هاي كلرو‌استيك در واكنشگاه و پساب كارخانه‌ي نيرو كلر يزد با استفاده از تحليل چند‌متغيره داده‌هاي الكتروشيميايي

Determination of Chloroacetic Acids in Reactor an‎d Wastewater of the Yazd Nirouchlor Plant Using Multivariate Analysis of Electrochemical Data

شيمي تجزيه

In this study, the efficiency of electrochemical methods for measuring the concentration of chloroacetic acids in the wastewater of Niroo Chlor Yazd Company has been investigated. According to the experimental results, using electrochemical methods, the amounts of monochloroacetic acid an‎d dichloroacetic acid present in the wastewater can be measured simultaneously. This study required the preparation of an electrochemical cell consisting of a silver working electrode with a circular cross-sectional area of 3.1 mm², an Ag/AgCl (3M KCl) reference electrode, a platinum auxiliary electrode, an‎d sodium perchlorate electrolyte. The electrolyte, concentration range, an‎d suitable method for measuring monochloroacetic acid an‎d dichloroacetic acid were selec‎ted as sodium perchlorate electrolyte, a concentration range of 5 to 80 mM, an‎d square wave voltammetry, respectively. Subsequently, the effect of monochloroacetic acid an‎d dichloroacetic acid on each otherʹs measurement was investigated. In the next step, the electrochemical reduction process of the wastewater under the determined conditions for conducting the experiment was examined. For quantitative measurement, using Minitab software, solutions containing different concentrations of monochloroacetic acid an‎d dichloroacetic acid were designed, covering the concentration space maximally. The concentration of each component in the presence of a wide range of concentrations of other components was investigated, an‎d the voltammograms of these solutions were recorded. Finally, the measured current intensities for the stan‎dard solutions at 241 potentials, along with the concentrations of the species in the stan‎dard solutions, were input into a multivariate calibration method (PLS) to develop a model for the relationship between currents an‎d concentrations in unknown samples. It is noteworthy that, according to the chosen multivariate analysis method (PLS), the presence of unmodeled species in the stan‎dard solutions should not cause serious problems in the measurement of real samples. Finally, by applying this trained model to the voltammogram of the diluted wastewater solution, simultaneous measurement of monochloroacetic acid an‎d dichloroacetic acid concentrations in the wastewater became possible. The concentration measurement results using the electrochemical method were 6.82 M an‎d 2.59 M for monochloroacetic acid an‎d dichloroacetic acid, respectively. To validate the proposed method, proton nuclear magnetic resonance (¹H NMR) spectroscopy, in which the spectral responses of monochloroacetic acid an‎d dichloroacetic acid are distinct, was used. In the first step, the relative concentrations of monochloroacetic acid an‎d dichloroacetic acid in the wastewater were found to be 67% an‎d 27% using NMR spectroscopy, which showed good agreement with the electrochemical method results (72% an‎d 28%, respectively). In the next step, to quantitatively determine the absolute concentrations of the components (not just relative concentrations), the internal stan‎dard addition method was used, where methanol served as the internal stan‎dard. The concentration measurement results using this method were 5.94 M an‎d 2.73 M for monochloroacetic acid an‎d dichloroacetic acid, respectively, which were in good agreement with the results obtained by the electrochemical method. This comparison demonstrated that the multivariate analysis of electrochemical data is highly reliable

3

35607