Abstract
High-porosity mudstone with nm-sized pores is a potentially low-cost and widely available mineral sorbent for crude-oil spill remediation, but its practical reuse depends on whether oil-induced pore blockage and wettability alteration can be effectively reversed after cleaning. Here, three mudstones were investigated in raw, crude-oil-immersed, and solvent-extracted states using X-ray microscopy, N2 physisorption, dynamic vapor sorption, contact-angle measurements, FTIR (Fourier transform infrared spectroscopy) and XPS (X-ray photoelectron spectroscopy), and contrast-variation small-angle neutron scattering. Crude-oil immersion markedly reduced accessible pore volume and surface area, suppressed the low-pressure adsorption responses of water, octane, and toluene, and shifted all three mudstones from strongly water-wet to hydrophobic behavior. Water contact angles increased from 8.5 to 26.4° in the raw state to 94.0–121.1° after oil immersion, and remained at 72.9–78.8° after solvent extraction. Across the three samples, BET (Brunauer, Emmett, and Teller) surface area decreased from 12.6–88.8 to 1.30–29.3 m2/g after oil immersion and recovered to 12.0–86.0 m2/g after extraction, indicating substantial reopening of the pore network but incomplete restoration of interfacial properties. FTIR and XPS analyses further indicate that persistent organic residues, especially resin/asphaltene-rich fractions, remained on mineral surfaces after extraction. Accordingly, solvent-cleaned mudstone should be regarded as a partially regenerated sorbent rather than a fully restored pristine material, with important implications for sorbent reuse and post-remediation management.
Paper Information：
Wang, Q., Hu, Q., Zhao, C., Luo, Z., Liu, Y., Liao, K., He, C., 2026. Nanoconfinement and wettability alteration govern crude-oil persistence in high-porosity mudstone with nm-sized pores. Chemical Engineering Science, 338, 124665. https://doi.org/10.1016/j.ces.2026.124665.
