Jatropha curcas L. oil extracted by switchable solvent N, N-dimethylcyclohexylamine for biodiesel production

Biodiesel, which is a renewable and environmentally friendly fuel, has been studied widely to help remedy increasing environmental problems. One of the key processes of biodiesel production is oil extraction from oilseed materials. Switchable solvents can reversibly change from molecular to ionic solvents under atmospheric CO_2,and can be used for oil extraction. N, N-dimethylcyclohexylamine(DMCHA), a switchable solvent, was used to extract oil from Jatropha curcas L. oil seeds to produce biodiesel. The appropriate extraction conditions were:1:2 ratio of seed mass to DMCHA volume, 0.3–1 mm particle size, 200 r·min-1agitation speed, 60 min extraction time, and 30 °C extraction temperature. The extraction ratio was about 83%. This solvent extracted the oil more efficiently than hexane, and is much less volatile. By bubbling CO_2 under 1 atm and 25 °C for 5 h, the oil was separated, and DMCHA was recovered after releasing CO_2 by bubbling N_2 under 1 atm and 60 °C for 2 h. The residual solvent content in oil was about 1.7%. Selectivity of DMCHA was evaluated by detecting the protein and sugar content in oil. Using the oil with residual solvent to conduct transesterification process, the oil conversion ratio was approximately 99.5%.

Responsive switchable deep eutectic solvents:A review

Deep eutectic solvents(DESs)have drawn considerable attention as a new type of green solvent since they were reported.Subsequent studies have shown that DESs have the potential to be used as“designable”solvents,which means that the precursors of DESs with different structures and properties can be screened to customize DESs for specific functions.Researchers have found that during the sample preparation process involving DESs,the specific properties of some“smart”DESs can be switched by directing external driving forces,leading to a reversible phase transition of the target solution.These"smart"DESs are called switchable deep eutectic solvents(SDESs).The advent of SDES simplifies the sample pretreatment steps,reduces the use of organic solvents,and makes solvents easy to recycle,which matches the concept of green and sustainable chemistry.Compared with the number of previous experimental studies,the reviews and summaries on SDESs are rare.Therefore,this review made a summary of the concept and research progress of SDESs based on some related works in the past decade,including composition and type,characterization,switching mechanism,etc.It is expected to provide a certain reference and guidance for the subsequent in-depth research of SDESs in the analytical sample pretreatment.

Effective Antarctic krill oil extraction using switchable hydrophilicity solvents

Antarctic krill has been widely studied because of its abundant biomass,rich nutritional value,and great production potential.Notably,krill oil(KO)is rich in phospholipids(PLs),polyunsaturated fatty acids(PUFAs),and astaxanthin.A method based on a green switchable hydrophilicity solvent N,7V-dimethyIcyclohexylamine(DMCHA),which can reversibly change from oil soluble to water soluble in the presence of CO2 was used to extract KO from frozen Antarctic krill as it consumes less energy than traditional methods.We showed that DMCHA destroyed the surface structure of Antarctic krill and accelerated the dissolution of KO.In addition,this method enabled the PL extraction to reach up to 80.2%of total PLs,among which PC accounted for the highest proportion,up to 90.91%in PL.In fact,the astaxanthin extraction reached up to 81.44%of total astaxanthin while the fatty acid(FA)extraction up to 84.35%.The KO extracted through DMCHA was rich in PUFA,up to 47.74%,and the content of EPA+DHA reached 42.16%of total FA content.Furthermore,the amount of residual solvent in the lipid phase was just 0.23%of the DMCHA used for the extraction and the recovery rate of solvent was up to 93.2%.Our results demonstrated the high efficiency of oil extraction and the environmental friendliness of this method.

Microalgae wet extraction using N-ethyl butylamine for fatty acid production

Microalgae are considered a promising feedstock for the production of food ingredients, cosmetics, pharmaceutical products and biofuels.The energy intensity of drying and cell breaking of algae and solvent recovery afterwards hindered the route of algae biorefinery. In this work the influences of freeze drying and cell breaking to the extraction efficiency of crude lipid yield and fatty acid yield were investigated. Results showed that drying and cell breaking are not necessary for N-ethyl butylamine extraction, because good yields were obtained without. Crude lipid yield and fatty acid yield using N-ethyl butylamine were comparable with Bligh & Dyer extraction, making N-ethyl butylamine a candidate for further development of an energy efficient lipid extraction technology for non-broken microalgae.

A New Approach for the Determination of Metronidazole Using Switchable Solvent Coupled with Au-MWCNTs-Modified Electrochemical Sensor

In this work,a new liquid-phase microextraction method coupled with an electrochemical technique using a switchable solvent was proposed for the determination of metronidazole.The extraction solvent used was dipropylamine(DPA),which exhibited switchable hydrophilicity.This means that it can become miscible or immiscible when in contact with carboxylic acids in the aqueous sample.The metronidazole was then measured using a glassy carbon electrode that was modified with Au-multiwalled carbon nanotubes(MWCNTs).The eff ect of diff erent parameters such as the type and amount of trigger,the addition of salt,and the volume of extraction solvent on the e fficiency of switchable hydrophilic solvent-based liquid-phase microextraction(SHS-LPME)was investigated using the one-factor-at-a-time method.After optimizing the conditions,the linear calibration curve was obtained in the concentration range of 0.005–250μmol/L.Accordingly,the limit of quantification(LOQ)of 0.005μmol/L and the limit of detection(LOD)of 0.0015μmol/L were obtained,respectively.

Lipid extraction and CO_(2)capture with switchable polarity solvent

In this study,lipid extraction and CO_(2)capture are combined using N,N-dimethylcyclohexylamine(DMCHA)as switchable polarity solvent.The effects of operation parameters are discussed according to the CO_(2)absorption/desorption and lipid/DMCHA recovery results.A triphasic models considering lipid,water,and gas phases are established to analyze the kinetic behaviors.The results show that DMCHA is reversible through CO_(2)absorption/desorption,and the enhanced dispersion of droplets and bubbles in water phase improves the lipid/DMCHA recovery and CO_(2)absorption/desorption.The triphasic kinetic models fit well with experimental data,and gas-liquid mass transfer is regarded as the rate-determining step.The lower interfacial areas result in the poorer gas-liquid mass transfer for the DMCHA recovery than lipid recovery process.