微電漿光譜法於重金屬檢測之酸化環境調控與基質干擾效應之研究

Abstract

水溶液電漿(Solution Plasma)由電漿與水溶液交互作用產生，伴隨多種化學反應，近年來因其在各領域中的廣泛應用而備受關注。本研究利用水中放電方式產生水溶液電漿，並搭配微型電腦同步控制高壓脈衝模組與光譜擷取系統，成功建立一套可穩定獲取電漿放光之重金屬檢測平台。研究內容涵蓋四個主軸，分別為電漿操作參數之優化、酸化條件對訊號影響之探討、基質干擾效應分析，以及重金屬濃度之定量分析與預測。 第一部分為電漿操作參數之優化，針對操作電壓、脈衝時間與脈衝間隔時間進行分析，並探討調控上述參數對四種重金屬放光訊號之影響。進一步針對各金屬之最佳操作條件，解析其影響機制，增進對金屬激發行為之理解。 第二部分為探討酸化條件對檢測訊號之影響，選用硝酸、鹽酸與硫酸作為酸化劑，並搭配三種酸化程度：0.01 M、0.16 M、0.48 M，比較不同酸化濃度與陰離子特性對光譜與電訊號之影響。綜合金屬放光強度、訊號穩定性與偵測極限等指標，最終選定0.16 M硝酸作為最佳酸化條件。 第三部分為基質干擾效應之分析，選用放流水中常見之鈉與鈣進行系統性探討。於相同導電度條件下，比較硝酸與硝酸鈉溶液之電漿與光譜與電訊號行為，並建立基質校正因子回歸模型，以量化基質干擾對各重金屬訊號之影響，進一步分析不同陰離子：硝酸根、硫酸根、氯離子對干擾程度之差異。 第四部分進行重金屬濃度之定量分析與預測，基於優化後之操作參數與酸化條件，建立重金屬線性回歸模型，並應用於實際工廠廢水樣品。由於水樣中基質干擾嚴重，經基質校正流程後，各金屬回收率均符合法規要求，驗證本系統於複雜水樣中具備良好之準確性與穩定性。

Solution plasma is generated through the interaction between plasma and aqueous solutions, accompanied by a variety of chemical reactions. In recent years, it has attracted considerable attention due to its broad applications across multiple fields. In this study, solution plasma was generated via underwater discharge, and a heavy metal detection platform capable of stably acquiring plasma emission and spectral information was successfully established by integrating a microcontroller-synchronized high-voltage pulse module with a spectral acquisition system. The scope of this study covers four main aspects: optimization of plasma operating parameters, investigation of acidification environment effects on signal behavior, analysis of matrix interference effects, and quantitative analysis and prediction of heavy metal concentrations. The first part focuses on the optimization of plasma operating parameters, analyzing the effects of operating voltage, pulse duration, and pulse interval. The influence of these parameters on the emission signals of four heavy metals was systematically investigated. Furthermore, the optimal operating conditions for each metal were identified, and the underlying mechanisms were analyzed to enhance the understanding of metal excitation behavior. The second part investigates the effects of the acidification environment on detection signals, using nitric acid, hydrochloric acid, and sulfuric acid as acidifying agents, combined with three acidification levels: 0.01 M, 0.16 M, and 0.48 M. The influence of different acid concentrations and anion characteristics on spectral and electrical signals was compared, and the relationship between the platinum electrode–optical fiber distance and signal performance was further explored. Based on emission intensity, signal stability, and detection limit indicators, 0.16 M nitric acid was ultimately selected as the optimal acidification condition. The third part focuses on the analysis of matrix interference effects, using sodium and calcium that common constituents in wastewater as target analytes. Under identical conductivity conditions, the plasma and spectral behaviors of nitric acid and sodium nitrate solutions were compared. A matrix correction factor regression model was established to quantify the impact of matrix interference on the emission signals of each heavy metal. Furthermore, the differences in interference effects among different anions (nitrate, sulfate, and chloride) were systematically analyzed. The fourth part focuses on the quantitative analysis and prediction of heavy metal concentrations. Based on the optimized operating parameters and acidification conditions, linear regression models for heavy metals were established and applied to actual industrial wastewater samples. After applying the matrix correction process, the recovery rates of all metals met regulatory requirements, verifying that the developed system exhibits excellent accuracy and stability in complex aqueous samples.