Hexane Extraction with Improved Efficiency by Ultrasonication
Probe-type ultrasonication can improve conventional hexane extraction by intensifying the process and making it significantly more efficient. Ultrasonic extraction improves mass transfer and disrupts cells to release targeted bioactive substances into the solvent, resulting in higher extraction yields compared to conventional methods alone. Ultrasound-assisted extraction is highly effective in increasing the yield of oil extraction, including rapeseed oil and flax seed oil, resulting in a high-quality fatty acid composition and higher content of bioactive components.
Hexane Extraction Improved by Power Ultrasound
Ultrasonic extraction is a process intensifying method that can improve solid-liquid and solvent extraction processes significantly.
- More complete extraction
- Higher yield
- Faster extraction
- Reduced hexane consumption
- Overall improved efficiency
Limitations of Conventional Hexane Extraction
Hexane extraction is a common technique used to extract organic compounds, particularly non-polar substances, from various sources such as plants, seeds, or soil. Hexane is a hydrocarbon solvent that is highly efficient at dissolving and extracting lipids, oils, and other non-polar compounds. Hexane is widely used for oil extraction because of its solubilizing ability for non-polar compounds (e.g., oils), easy subsequent oil separation, and a narrow boiling point (63–69°C).
However, the efficiency of hexane extraction processes can vary heavily in depending on raw material and extraction : Extraction yield and extraction time are largely correlated. This means for a high extract yield a longer retention time of the biomass in the hexane solvent is required. Another limiting factor is often the insufficient penetration of hexane into the matrix of the biomass. Rigid cellular structures are mostly wetted with hexane on the surface, whilst the cell interior get only partially in contact with hexane. Such insufficient penetration results in an incomplete extraction process as the targeted substances such as lipids (i.e., fatty acids, fats, oils) remain in the interior of the cell matrix.
The Solution: Ultrasonically Intensified Hexane Extraction
Probe-type sonication, also known as ultrasonic probe sonication, is a method that utilizes high-intensity ultrasound waves to create acoustic cavitation bubbles in a liquid medium. These bubbles collapse rapidly, generating intense localized energy fields and creating microturbulences and high-shear forces within the solvent.
Due these ultrasonically generated energy-dense conditions, probe-type sonication can intensify and improve the hexane extraction process in several ways:
- Enhanced mass transfer: Sonication enhances mass transfer between the solid sample and the solvent. The microturbulence and the rapid collapse of cavitation bubbles create strong shear forces and localized pressure changes. This disrupts the boundary layer around the solid sample, promoting the release of the target compounds into the solvent, thus improving extraction efficiency.
- Accelerated extraction: Sonication accelerates the extraction kinetics by increasing the contact area between the solvent and the solid sample. The cavitation bubbles provide agitation and create a homogenized mixture, ensuring that the solvent comes into close contact with the entire surface of the solid material, leading to faster extraction rates.
- Disruption of cell structures: In plant-based extractions, sonication can disrupt the cellular structures, such as cell walls and membranes, facilitating the release of intracellular components. This allows for more efficient extraction of lipids and other target compounds that may be enclosed within the cells.
- Decreased extraction time: By combining the increased mass transfer and accelerated extraction kinetics, probe-type sonication can significantly reduce the extraction time required to obtain the desired yield. This can be particularly beneficial when processing large volumes of samples or working with time-sensitive applications.
Due to these improved process factors, probe-type ultrasonication can enhance hexane extraction significantly. The ultrasonic hexane extraction can be optimized based on the specific compounds and volumes being extracted. Ultrasound intensity (amplitude), duration, temperature, pressure and the extraction setup can be adjusted to optimum extract yields within a shortened extraction period.
Examples for Ultrasonically-Assisted Hexane Extraction
- Algae oil
- Vegetable oils (soy, flax, rapeseed, sunflower, rice bran etc.)
- Essential oils
- Vanilla oleoresin from Vanilla pods
- Lutein from egg yolk
- Astaxanthin from algae
- Defatting of insects
Ultrasonically-Intensified Soxhlet Extraction using Hexane as Solvent
Ultrasonically-intensified Soxhlet extraction is a process that combines traditional Soxhlet extraction with ultrasonic waves to improve the efficiency of the extraction process. Soxhlet extractio is a procedure commonly used in laboratories and for the production of smaller extract volumes, such as essential oils or certain bioactive compounds.
Hexane is a commonly used solvent for this process, as it is effective at extracting lipids from various sources, including seed oils, algae oil as well as lipid-based bioactive compounds. Ultrasonication disrupts cell structures and promotes the solid-liquid extraction by increased mass transfer and release of compounds into the solvent. Since the solvent such as hexane can penetrate the solid material better and dissolve the oils (lipids, fatty acids) efficiently. Consequently, the extraction process is accelerated, reducing the time required to extract the desired compounds. Additionally, the use of ultrasound can reduce the amount of solvent required, making it a more environmentally friendly option.
Ultrasonic Extraction allows for the Use of Milder, Non-Toxic Solvents
Ultrasonication not only improves hexane extraction, it also allows to use milder, non-toxic solvents such as ethanol, aqueous ethanol, water or natural deep eutectic solvents (DES, NADES). The highly efficacious cell disruption and mass transfer provided by ultrasonic probe-type extractors gives the excellent results using milder solvents. Thereby, ultrasonic extraction in combination with milder, non-toxic, environmentally-friendlier solvents enables for high-quality food-grade extracts, cost-savings and a green extraction process.
High-Performance Ultrasonicators for Improved Hexane Extraction
Hielscher Ultrasonics designs, manufactures, and supplies high-performance ultrasonic extractors, which can be easily integrated into existing hexane extraction facilities or Soxhlet extractors. Besides supply, installation, maintenance service, Hielscher consults and guides its customers during feasibility tests, process optimization and plant design to the final installation and commissioning of the extraction process.
Major advantages of Hielscher ultrasonicators are the full process control, linear scalability, and the capability of all industrial ultrasonic processors to deliver very high amplitudes. Amplitudes of up to 200µm can be easily continuously run in 24/7 operation. High amplitudes are especially important, when it comes to the extraction of harder cell structures such as seeds and kernels.
Our technical staff and our fully-equipped process laboratory will assist you with knowledge and guidance!
Design, Manufacturing and Consulting – Quality Made in Germany
Hielscher ultrasonicators are well-known for their highest quality and design standards. Robustness and easy operation allow the smooth integration of our ultrasonicators into industrial facilities. Rough conditions and demanding environments are easily handled by Hielscher ultrasonicators.
Hielscher Ultrasonics is an ISO certified company and put special emphasis on high-performance ultrasonicators featuring state-of-the-art technology and user-friendliness. Of course, Hielscher ultrasonicators are CE compliant and meet the requirements of UL, CSA and RoHs.
The table below gives you an indication of the approximate processing capacity of our ultrasonicators:
|Batch Volume||Flow Rate||Recommended Devices|
|0.5 to 1.5mL||n.a.||VialTweeter||1 to 500mL||10 to 200mL/min||UP100H|
|10 to 2000mL||20 to 400mL/min||UP200Ht, UP400St|
|0.1 to 20L||0.2 to 4L/min||UIP2000hdT|
|10 to 100L||2 to 10L/min||UIP4000hdT|
|15 to 150L||3 to 15L/min||UIP6000hdT|
|n.a.||10 to 100L/min||UIP16000|
|n.a.||larger||cluster of UIP16000|
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Literature / References
- A. Meullemiestre, C. Breil, M. Abert-Vian, F. Chemat (2017): Manothermosonication as a useful tool for lipid extraction from oleaginous microorganisms. Ultrasonics Sonochemistry, Volume 37, July 2017. 216-221.
- A. Perrier, C. Delsart, N. Boussetta, N. Grimi, M. Citeau, E. Vorobiev (2017): Effect of ultrasound and green solvents addition on the oil extraction efficiency from rapeseed flakes. Ultrasonics Sonochemistry, Volume 39, 2017. 58-65.
- Reyman, D. & Almudena, Quiñones (2020): Simultaneous Oil Sono-Extraction And Sono-Transesterification (In Situ) Of Soybean And Sunflower Seeds For The Production Of Biodiesel. Research Square Preprint 2020.
- Djenni, Zoubida; Pingret, Daniella; Mason, Timothy J.; Chemat, Farid (2012): Sono–Soxhlet: In Situ Ultrasound-Assisted Extraction of Food Products. Food Analytical Methods, 2012.