Fractionation of oil sands-process affected water using pH-dependent extractions: a study of dissociation constants for naphthenic acids species.

• 影响指数: 8.943
• 发表时间: May 2015
• 来源期刊: Chemosphere
• DOI: 10.1016/j.chemosphere.2014.11.041
• PMID: 25782756
• 文章类型: Journal Article
• 中科院分区: Q1
• 方向: 生物
• 作者列表: Huang R,Sun N,Chelme-Ayala P,McPhedran KN,Changalov M,Gamal El-Din M

关键词: Dissociation constant; Naphthenic acids; Oil sands process-affected water; Ultra-performance liquid chromatography time-of-flight mass spectrometry; pH fractionation

Mesh: Canada; Carboxylic Acids / analysis; Chemical Fractionation; Chromatography, Liquid; Hydrogen-Ion Concentration; Liquid-Liquid Extraction; Mass Spectrometry; Oil and Gas Fields; Waste Water / analysis chemistry; Water Pollutants, Chemical / analysis; Water Purification / methods

Abstract

The fractionation of oil sands process-affected water (OSPW) via pH-dependent extractions was performed to quantitatively investigate naphthenic acids (NAs, CnH2n+ZO2) and oxidized NAs (Ox-NAs) species (CnH2n+ZO3 and CnH2n+ZO4) using ultra-performance liquid chromatography time-of-flight mass spectrometry (UPLC-TOFMS). A mathematical model was also developed to estimate the dissociation constant pKa for NAs species, considering the liquid-liquid extraction process and the aqueous layer acid-base equilibrium. This model provides estimated dissociation constants for compounds in water samples based on fractionation extraction and relative quantification. Overall, the sum of O2-, O3-, and O4-NAs species accounted for 33.6% of total extracted organic matter. Accumulative extracted masses at different pHs revealed that every oxygen atom added to NAs increases the pKa (i.e., O2-NAs