Electroanalysis of Crude Oil and Petroleum-Based Fuel for Trace Metals: Evaluation of Different Microwave-Assisted Sample Decompositions and Stripping Techniques

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• 作者：Rodrigo A. A. Munoz ; Paulo R. M. Correia ; Angerson N. Nascimento ; C&iacute ; ntia S. Silva ; Pedro V. Oliveira ; Lucio Angnes
• 刊名：Energy & Fuels
• 出版年：2007
• 出版时间：January 2007
• 年：2007
• 卷：21
• 期：1
• 页码：295 - 302
• 全文大小：80K
• 年卷期：v.21,no.1(January 2007)
• ISSN：1520-5029

文摘

Electroanalytical stripping techniques have been well-used for trace-metal determinations, because of theirremarkable sensitivity and selectivity. However, when these techniques are applied for organic materials, suchas crude oil and petroleum-based fuels, the samples must be decomposed. This paper evaluates the use ofdifferent microwave ovens for the decomposition of crude oil and diesel fuel to determine the content ofcopper, lead, mercury, and zinc in the digestates. A focused-microwave (FM) oven using H₂SO₄/HNO₃/H₂O₂,operated at atmospheric pressure, and a closed-vessel microwave (CVM) oven using HNO₃/H₂O₂, operatedunder pressure in a vessel, were evaluated. Square-wave stripping voltammetry (SWSV) and strippingchronopotentiometry (SCP) at gold film electrodes were applied for copper, lead, and mercury. Potentiometricstripping analysis (PSA) at mercury film electrodes was applied for copper, lead, and zinc. SWSV was moreaffected by residual organic matter, especially for lead determination. SCP presented higher sensitivity forcopper and mercury at gold electrodes. PSA at mercury electrodes was preferred for lead and zinc determination.Better detection limits were attained for FM-digested solutions, after 0.8-1.0 g of sample can be digested, incontrast to the low quantities (0.10-0.25 g) used when pressurized vessels were explored. Nevertheless, theloss of mercury was verified when samples were decomposed in the FM oven.