Department of Civil and Environmental Engineering, University of Alberta, Edmonton, AB T6G 1H9, Canada.
Shell Health - Americas, Shell Oil Company, 150 North Dairy Ashford Road, Houston, TX 77079, USA.
Sci Total Environ. 2020 Sep 10;734:139191. doi: 10.1016/j.scitotenv.2020.139191. Epub 2020 May 7.
Naphthenic acid fraction compounds (NAFCs), defined herein as the polar organic compounds extracted from the acidified oil sands process water (OSPW) samples using dichloromethane, are becoming the research hotspot due to their presence in large amount in OSPW and along with other potentially NA-contaminated water streams from the mining site. Fourier transform infrared spectroscopy (FTIR) method is commonly used to quantify NAFCs and assumes that the total NA concentration is measured as the sum of the responses for all carboxylic acid functional groups. In this study, the NAFCs in various OSPW and groundwater (GW) samples from an active oil sands mining site were analyzed using FTIR. All water samples were pretreated using either solid-phase extraction (SPE) or liquid-liquid extraction (LLE) methods before analysis. The results showed that SPE produced higher recoveries of NAFCs than LLE for most water samples under current experimental conditions. For the quantification of NAFCs, commercial Fluka NA mixture and a pre-calibrated OSPW extract were employed as the calibration standards. The NAFCs calibrated with Fluka NA mixture and OSPW extract had clear linear relationships. The concentrations of NAFCs obtained using OSPW extract standard curve were 2.5 times the NAFC concentrations obtained using the Fluka NA mixture standard curve. Additionally, good linear correlations were observed between the total NAs and O-O NA species determined by ultra-performance liquid chromatography coupled with time-of-flight mass spectrometry (UPLC-TOFMS) and the NAFCs measured by FTIR. According to these correlations, the NA compositions in NAFCs were developed, and the relative abundances of O-O NA species in NAFCs were similar for SPE and LLE pretreated samples. The findings of this study demonstrated that FTIR could be used as a promising tool to monitor total NA species and to estimate the NA profile in different environmental water samples.
环烷酸馏分化合物（NAFCs），在此定义为使用二氯甲烷从酸化油砂工艺水中（OSPW）样品中提取的极性有机化合物，由于其在 OSPW 中大量存在，以及与来自矿区的其他潜在含 NA 污水流，因此成为研究热点。傅里叶变换红外光谱（FTIR）法通常用于定量 NAFCs，并假设总 NA 浓度是通过测量所有羧酸官能团的响应总和来测量的。在这项研究中，使用 FTIR 分析了来自一个活跃的油砂矿区的各种 OSPW 和地下水（GW）样品中的 NAFCs。在分析之前，所有水样均使用固相萃取（SPE）或液液萃取（LLE）方法进行预处理。结果表明，在当前实验条件下，对于大多数水样，SPE 比 LLE 产生更高的 NAFCs 回收率。对于 NAFCs 的定量，使用商业 Fluka NA 混合物和预校准的 OSPW 提取物作为校准标准。用 Fluka NA 混合物和 OSPW 提取物校准的 NAFCs 具有明显的线性关系。使用 OSPW 提取物标准曲线获得的 NAFCs 浓度是使用 Fluka NA 混合物标准曲线获得的 NAFCs 浓度的 2.5 倍。此外，通过超高效液相色谱与飞行时间质谱（UPLC-TOFMS）测定的总 NAs 和 O-O NA 物种与通过 FTIR 测定的 NAFCs 之间观察到良好的线性相关性。根据这些相关性，开发了 NAFCs 中的 NA 组成，并确定了 SPE 和 LLE 预处理样品中 O-O NA 物种在 NAFCs 中的相对丰度相似。本研究的结果表明，FTIR 可作为一种有前途的工具，用于监测总 NA 物种，并估计不同环境水样中的 NA 分布。
