A two-parameter model for the determination of the partition coefficient for TRS in a culture medium


  • Javier Silva Pontificia Universidad Catolica de Valparaíso
  • Rodrigo Ortiz
  • Samuel Carrasco
  • German Aroca




activity coefficient; culture medium; partition coefficient; liquid-vapor balance; liquid-vapor equilibria


A two-parameters model was applied for the determination of the activity coefficient for a culture medium, and compared with Henry's law, the extended UNIQUAC, and experimental data obtained from an experimental setup system, consisting of a liquid culture media Thiobacillus (ATCC 290) with hydrogen sulfide (H2S), dimethyl sulfide (DMS), methyl mercaptan (MM), and dimethyl disulfide (DMDS), respectively.

 The ANOVA indicates that the use of Henry's law is not appropriate for MM and H2S with R2adj values of -106.15% and -53.33%, respectively. The extended UNIQUAC model and the two-parameter model were able to describe the system with values of 76.94% and 94.15% for DMS and DMDS in the case of UNIQUAC Extended, respectively, and 88.50% and 98.08% using the two-parameter model.


These results show that the two-parameter model is able to describe the system, using a low number of parameters. However, the extended UNIQUAC shows better results but presenting a high level of over-parameterization. Henry's law showed significant deviations, not being representative of all analyzed cases.

 The two-parameter model is presented as an alternative to describing systems in which vapor-liquid mass transfer is involved in culture media, providing a better approximation than traditional models and lower calculation costs than complex models.