Selection of mixed solvent for crude caprolactam extraction
The result's identifiers
Result code in IS VaVaI
<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F61989100%3A27710%2F25%3A10259238" target="_blank" >RIV/61989100:27710/25:10259238 - isvavai.cz</a>
Result on the web
<a href="https://www.sciencedirect.com/science/article/pii/S1383586625003600?via%3Dihub" target="_blank" >https://www.sciencedirect.com/science/article/pii/S1383586625003600?via%3Dihub</a>
DOI - Digital Object Identifier
<a href="http://dx.doi.org/10.1016/j.seppur.2025.131763" target="_blank" >10.1016/j.seppur.2025.131763</a>
Alternative languages
Result language
angličtina
Original language name
Selection of mixed solvent for crude caprolactam extraction
Original language description
Most of the world's caprolactam production involves synthesizing caprolactam from cyclohexanone via the Beckmann rearrangement. Due to the presence of both polar and nonpolar impurities in crude caprolactam, purification traditionally includes forward extraction with a nonpolar solvent, such as trichloroethylene, followed by back-extraction with water and then multistage distillation. This study investigates mixed solvents containing 1-octanol or 1-heptanol combined with cyclohexane or n-heptane as safer, non-carcinogenic alternatives to trichloroethylene in caprolactam extraction. Cyclohexane and n-heptane were selected to adjust the solubility of the alcohols in the aqueous phase. Optimal alcohol concentrations in these mixed solvents were estimated through modeling based on Hansen solubility parameters and experimentally validated using a real crude caprolactam sample (70 wt% caprolactam in water). A 40 wt% 1-octanol in heptane mixture demonstrated a caprolactam distribution coefficient closely matching that of trichloroethylene. Liquid-liquid equilibrium data and key physical properties influencing mass transport (density, viscosity, and interfacial tension) for the chosen mixed solvents were experimentally determined and used to design Karr extraction columns for both forward and back-extraction processes. Literature correlations were applied to predict hydraulic characteristics, including Sauter drop diameter and dispersed phase hold-up. The model was further validated through performance trials with an actual extraction unit using trichloroethylene in caprolactam refining. A mixture of 60 wt% 1-octanol in cyclohexane was identified as optimal, offering a balance between column height, maximum caprolactam content in extract and mixed solvent consumption.
Czech name
—
Czech description
—
Classification
Type
J<sub>imp</sub> - Article in a specialist periodical, which is included in the Web of Science database
CEP classification
—
OECD FORD branch
20400 - Chemical engineering
Result continuities
Project
<a href="/en/project/FV40040" target="_blank" >FV40040: Continual purification of Caprolactam.</a><br>
Continuities
P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)
Others
Publication year
2025
Confidentiality
S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů
Data specific for result type
Name of the periodical
Separation and Purification Technology
ISSN
1383-5866
e-ISSN
1873-3794
Volume of the periodical
362
Issue of the periodical within the volume
2
Country of publishing house
NL - THE KINGDOM OF THE NETHERLANDS
Number of pages
10
Pages from-to
131763
UT code for WoS article
001420792200001
EID of the result in the Scopus database
—