Journal of Solid State Electrochemistry ( IF 2.5 ) Pub Date : 2020-06-05 , DOI: 10.1007/s10008-020-04685-0 Patrícia Schmidt , Rayane Bueno Goularte , Rejane Secretti Cargnin , Paulo C. Do Nascimento , Leandro Machado de Carvalho
This work describes the voltammetric and amperometric behavior of a high number of PASHs (sulfides, thiophenes, benzothiophenes, dibenzothiophenes, indenothiophenes, naphtothiophenes, thienothiophenes, phenanthrothiophenes, and acenaphtothiophenes) at gold disc electrodes aiming at their identification and determination in petroleum asphalts. The adsorption/redox processes expected for sulfur compounds at gold electrodes could be observed in all the studied PASHs in DMSO and hydromethanolic medium. Differential pulse (DP) voltammetry in non-aqueous solutions (0.1 mol L−1 NaClO4 in DMSO) was approached for determining non-volatile PASHs in asphalts submitted to different aging processes. It was found herein that the DP voltammetric monitoring of PASH oxidation at + 0.7 V (vs. Ag/AgCl/LiCl 3 mol L−1) for virgin/aged asphalts can be used for the comparative study of asphalts based on the consumption of PASHs. Additionally, pulsed amperometric detection (PAD) in hydroalcoholic solution (10 mmol L−1 acetate buffer in 65% methanol) coupled with a chromatographic separation was approached for determining volatile PASHs in asphalts submitted to thermal decomposition processes. A detection cycle of 2 s involving oxidative (0.4 s at + 0.4 V) and reductive (1.2 s at − 1.0 V) cleaning pulses after a detection pulse of − 0.8 V (0.4 s) applied successively to the gold electrode (vs. Pd/PdO) was found to be optimal for regenerating the gold surface during successive chromatographic runs of PASHs. Thus, reversed-phase liquid chromatography (LC)–coupled PAD was found useful to separate a complex mixture of PASHs. The optimized PAD and LC separation was further applied to investigate the presence of electroactive PASHs as volatile compounds in asphalt fumes generated at 260 °C.
中文翻译:
金圆盘电极上的多环芳族硫杂环(PASH)脉冲伏安/安培检测,用于石油沥青研究
这项工作描述了许多PASH(硫化物,噻吩,苯并噻吩,二苯并噻吩,茚并噻吩,萘噻吩,噻吩并噻吩,苯并噻吩和对苯并噻吩)的伏安和安培行为,旨在于石油沥青中对其进行鉴定和测定。在所有研究的DMSO和氢甲醇介质中的PASH中都可以观察到金电极上含硫化合物的吸附/氧化还原过程。非水溶液(0.1 mol L -1 NaClO 4的差分脉冲(DP)伏安法在DMSO中使用)来确定经受不同老化过程的沥青中的非挥发性PASH。在此发现,对于原始/老化的沥青,在+ 0.7 V(vs. Ag / AgCl / LiCl 3 mol L -1)下对PASH氧化的DP伏安监测可用于基于PASH的消耗量进行沥青比较研究。 。此外,在乙醇水溶液(10 mmol L -1中进行脉冲安培检测(PAD)采用色谱分离法(65%甲醇中的乙酸缓冲液)和色谱分离法来确定沥青中的挥发性PASH进行热分解过程。在依次向金电极上施加-0.8 V(0.4 s)的检测脉冲后,检测到2 s的检测周期,包括氧化(0.4 s在+ 0.4 V时)和还原(1.2 s在-1.0 V时)清洁脉冲。 / PdO)被认为是连续进行PASH色谱分析时再生金表面的最佳方法。因此,发现反相液相色谱(LC)偶联的PAD可用于分离复杂的PASH混合物。优化的PAD和LC分离度进一步应用于研究在260°C产生的沥青烟雾中作为挥发性化合物的电活性PASH的存在。