Removal of Naphthenic Acids from OSPW Using Pore-Widened Activated Carbons: An FT-ICR-MS Study

This study focuses on the remediation of oil sands process-affected water (OSPW) using activated carbons (AC), specifically examining how thermal cycling affects AC’s ability to remove naphthenic acids (NA). The research aims to determine the effectiveness of single- and triple-cycled ACs in reducing contaminants from the OSPW using two analytical methods: total organic carbon (TOC) analysis and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). TOC analysis shows that triple-cycled ACs remove 71% of naphthenic acids from the OSPW, compared to 33% for single-cycled ACs, highlighting the enhanced performance of thermally cycled ACs. FT-ICR-MS is used to identify and classify the complex NA species present in the OSPW, revealing that Ox and OxSy classes dominate the NA composition. This method underscores the importance of controlling the porosity and surface functionality of ACs for effective remediation. Further analysis of double-bond equivalent (DBE) versus carbon number plots for the O2, O3, and O4 classes shows that species with higher DBE values are more effectively removed by single-cycled ACs. However, triple-cycled ACs demonstrate a broader range of DBE removal (DBE of 2–9), indicating their superior ability to eliminate highly conjugated naphthenic acids. These findings emphasize the critical role of optimizing AC pore size to enhance mesoporosity and improve the uptake of complex organic contaminants from the OSPW. The study highlights the potential of thermally tailored ACs as a viable strategy for the effective remediation of the OSPW.