Ionic liquids (ILs) are used in separation of organic substances in industry. In order to screen suitable ILs for industrial separation, the interaction between molecules is studied based on the extraction mechanism. The result is verified by experiments. The binary interaction parameters obtained from experiments are applied to process simulation. In this work, the liquid−liquid extraction of cyclohexane and tert-butanol azeotropic mixture with different ILs {1-butyl-3methylimidazolium bis(trifluoromethylsulfonyl), 1-butyl-3methylimidazolium trifluoromethanesulfonate, and 1-butyl-3methylimidazolium hydrogen sulfate} is studied. The extraction mechanism is discussed based on the molecular scale. The relationship of the hydrogen bond donor and acceptor between ILs and TBA is analyzed by COSMO-SAC. Then the hydrogen-bonding interaction between ILs and TBA is determined by using quantum chemical calculation, including bond length, total charge density, deformation charge density, and interaction energy. The experimental results are verified. The liquid−liquid equilibrium experiment is carried out at 298.15 K. The NRTL and UNIQUAC models are adopted to correlate the liquid−liquid equilibrium data, and results could well correlate the experiments. Then NRTL binary interaction parameters obtained from the experiment are used to simulate the extraction process. Minimum total annual cost is calculated.
n-Propanol, as an important chemical
raw material, is used
as a solvent and intermediate in chemical industrial production and
drug synthesis. In chemical production, alcohol and water easily form
an azeotrope which is difficult to separate. In this work, a method
of dehydration of n-propanol by pervaporation-assisted
extractive distillation is proposed. Glycerol is selected as entrainer
by quantum chemical calculation. A combined pervaporation unit with
cellophane as a membrane is designed to separate the entrainer and
water. The pervaporation unit is developed by using the Aspen Custom
Modeler. Based on the minimum total annual cost, the extractive distillation
process, feed-preheating extractive distillation process, and pervaporation-assisted
extractive distillation process are optimized. The results show that
the total annual cost of pervaporation-assisted extractive distillation
is minimum and can reduce the total annual cost by 21.25%, compared
with extractive distillation. Life cycle analysis is used to evaluate
the environmental impact of processes. The results of environmental
performance evaluation show that the pervaporation-assisted extractive
distillation has the least environmental impact. Thus, the integration
technology of membrane and distillation is of great significance in
the sustainable process of chemical design and development.
Diisopropyl ether and isopropyl alcohol have attracted interest as promising raw materials. Finding an environmentally
friendly and sustainable production is a goal that people are constantly
pursuing. Extractive distillation is a traditional technique for separation
of the mixture diisopropyl ether/isopropyl alcohol/water. The traditional
technique should be improved due to its high energy consumption. In
this work, feed preheating and hybrid membrane distillation are explored
as two alternatives for separation and evaluated from the economic,
environment, and human health points of view. Two different solvents
(ethylene glycol and dimethyl sulfoxide) are considered and compared.
To analyzethe thermodynamic efficiency, condenser exergy analysis,
stage enthalpy, and exergy loss are studied. Life cycle assessment
is used to assess the effects of extractive distillation, feed preheating,
and mixed membrane distillation on human health and the environment.
In terms of energy consumption and the total annual cost, hybrid membrane
distillation is superior to extractive distillation and feed preheating.
At the same time, hybrid membrane distillation produces the lowest
human toxicity and environmental impact. Thus, in the process of separation,
the combination of distillation and pervaporation membrane should
be considered because it is an environmentally friendly process.
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