Characterizing equilibrium dissolution of trichloroethene and toluene from binary NAPL mixtures as a function of molecular structure

Abbott J. B., Tick G. R., Akyol N. H., Carroll K. C.

Journal of Hazardous Materials, cilt.498, 2025 (SCI-Expanded, Scopus) identifier identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 498
  • Basım Tarihi: 2025
  • Doi Numarası: 10.1016/j.jhazmat.2025.139889
  • Dergi Adı: Journal of Hazardous Materials
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, PASCAL, Aerospace Database, Applied Science & Technology Source, Aquatic Science & Fisheries Abstracts (ASFA), BIOSIS, Biotechnology Research Abstracts, CAB Abstracts, Chemical Abstracts Core, Chimica, Communication Abstracts, Compendex, Computer & Applied Sciences, Environment Index, Food Science & Technology Abstracts, Geobase, INSPEC, Metadex, Pollution Abstracts, Public Affairs Index, Veterinary Science Database, Civil Engineering Abstracts
  • Anahtar Kelimeler: Dissolution, Multicomponent NAPL, Raoult's Law, Toluene, Trichloroethene
  • Kocaeli Üniversitesi Adresli: Evet

Özet

Significant uncertainties exist, due to dissolution behavior variability, for the remediation of multicomponent nonaqueous-phase liquid (NAPL) contaminants impacting groundwater. Equilibrium batch experiments were conducted to quantify the systematic influence of bulk NAPL carbon-chain length on the dissolution behavior of trichloroethene and toluene within binary NAPL-sources of n-hexane, n-decane, and n-hexadecane. Different mole-fractions of the targeted contaminants within the bulk-NAPL sources were tested. Raoult's Law was used to assess the relative ideality of the mass-transfer processes for each dissolution experiment. Results show as the mole-fraction ratio of trichloroethene and toluene decrease, dissolution nonideality generally increases for the multicomponent-NAPL mixtures. The differences between the observed and Raoult's-Law-predicted concentrations are likely due to specific intra-NAPL component interactions that affect mass-transfer from the multicomponent-NAPL mixture. A semi-empirical thermodynamic model, xlUNIFAC, was used to estimate activity-coefficients for trichloroethene and toluene within various carbon-length aliphatic bulk NAPL mixtures. This group contribution model was used to simulate phase equilibrium for the mixtures compared to the batch systems. Toluene (aromatic-structure) showed greater nonideal dissolution behavior than trichloroethene (aliphatic-structure) in the presence of the different bulk-NAPL components. Results suggest that aqueous-phase concentration in groundwater, released from complex multicomponent-NAPL, is highly dependent upon both NAPL-mixture composition and molecular structure variability.