Details

Autor(en) / Beteiligte

• Stoffers, Martin
• Górak, Andrzej

Titel

Continuous multi-stage extraction of n-butanol from aqueous solutions with 1-hexyl-3-methylimidazolium tetracyanoborate

Ist Teil von

• Separation and purification technology, 2013, Vol.120, p.415-422

Ort / Verlag

Elsevier B.V

Erscheinungsjahr

2013

Link zum Volltext

Quelle

Access via ScienceDirect (Elsevier)

Beschreibungen/Notizen

• •Technical feasibility for continuous extraction of n-butanol with an ionic liquid in a mixer–settler unit is shown.•NRTL correlation of liquid–liquid equilibrium enables modelling of multi-stage extraction in an equilibrium model.•Laboratory scale and pilot-scale experiments confirm the use of an equilibrium approach.•Extraction model is validated with pilot-scale experiments. The separation of n-butanol from fermentation broth is very challenging. Due to low n-butanol mass fractions in the broth, purification by distillation is energy- and thus cost-intensive. Therefore, alternative processes are required. One potential alternative process is liquid–liquid extraction, which is promising due to mild operating conditions. In this paper, a continuous multi-stage extraction of n-butanol with the ionic liquid 1-hexyl-3-methylimidazolium tetracyanoborate is investigated experimentally and theoretically. Liquid–liquid equilibrium compositions of the system ionic liquid/synthetic medium are analysed in laboratory scale and compared to pilot scale experiments in a mixer–settler unit at 35°C. The results confirm that a continuous separation of n-butanol is feasible. The solvent-to-feed ratio and n-butanol mass fraction in the aqueous feed influence the n-butanol recovery which lies between 85% and 99% in the mixer–settler unit depending on the process parameters. In the theoretical part of our study, the NRTL model is applied successfully to correlate experimental liquid–liquid equilibrium compositions of the ternary system ionic liquid/n-butanol/water. Using this correlation, the multi-stage extraction is modelled and validated with pilot scale experiments. The results confirm the use of an equilibrium approach for the multi-stage extraction model without the need of stage efficiency. Furthermore, they allow for a detailed process analysis, which reduces the experimental and financial effort.