scholarly journals Effective lipid extraction from undewatered microalgae liquid using subcritical dimethyl ether

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Quan Wang ◽  
Kazuyuki Oshita ◽  
Masaki Takaoka
Keyword(s):  
Fatty Acid ◽  
Trace Metals ◽  
Dimethyl Ether ◽  
Inductively Coupled Plasma ◽  
Lipid Extraction ◽  
Cell Disruption ◽  
Energy Output ◽  
High Water Content ◽  
Inductively Coupled ◽  
Acid Methyl

Abstract Background Recent studies of lipid extraction from microalgae have focused primarily on dewatered or dried samples, and the processes are simple with high lipid yield. Yet, the dewatering with drying step is energy intensive, which makes the energy input during the lipid production more than energy output from obtained lipid. Thus, exploring an extraction technique for just a thickened sample without the dewatering, drying and auxiliary operation (such as cell disruption) is very significant. Whereas lipid extraction from the thickened microalgae is complicated by the high water content involved, and traditional solvent, hence, cannot work well. Dimethyl ether (DME), a green solvent, featuring a high affinity for both water and organic compounds with an ability to penetrate the cell walls has the potential to achieve this goal. Results This study investigated an energy-saving method for lipid extraction using DME as the solvent with an entrainer solution (ethanol and acetone) for flocculation-thickened microalgae. Extraction efficiency was evaluated in terms of extraction time, DME dosage, entrainer dosage, and ethanol:acetone ratio. Optimal extraction occurred after 30 min using 4.2 mL DME per 1 mL microalgae, with an entrainer dosage of 8% at 1:2 ethanol:acetone. Raw lipid yields and its lipid component (represented by fatty acid methyl ester) contents were compared against those of common extraction methods (Bligh and Dryer, and Soxhlet). Thermal gravimetry/differential thermal analysis, Fourier-transform infrared spectroscopy, and C/H/N elemental analyses were used to examine differences in lipids extracted using each of the evaluated methods. Considering influence of trace metals on biodiesel utilization, inductively coupled plasma mass spectrometry and inductively coupled plasma atomic emission spectroscopy analyses were used to quantify trace metals in the extracted raw lipids, which revealed relatively high concentrations of Mg, Na, K, and Fe. Conclusions Our DME-based method recovered 26.4% of total raw lipids and 54.4% of total fatty acid methyl esters at first extraction with remnants being recovered by a 2nd extraction. In additional, the DME-based approach was more economical than other methods, because it enabled simultaneous dewatering with lipid extraction and no cell disruption was required. The trace metals of raw lipids indicated a purification demand in subsequent refining process.

scholarly journals A Novel Method for Extraction of Lipids From Liquid Microalgae Without Dewatering

2020 ◽  
Author(s):  
Quan Wang ◽  
Kazuyuki Oshita ◽  
Masaki Takaoka
Keyword(s):  
Fatty Acid ◽  
Trace Metals ◽  
Inductively Coupled Plasma ◽  
Lipid Extraction ◽  
Acid Methyl Ester ◽  
Cell Disruption ◽  
Energy Output ◽  
High Water Content ◽  
Inductively Coupled ◽  
Acid Methyl

Abstract Background: Recent studies of lipid extraction from microalgae have focused primarily on dewatered or dried samples, and the processes are simple with high lipid yield. Yet, the dewatering with drying step is energy-intensive, which makes the energy output from the extracted lipid is less than the energy needed to produce it. Thus, exploring an extraction technique for just a thickened sample without the dewatering, drying and auxiliary operation (such as cell disruption) is very significant. Whereas lipid extraction from the thickened microalgae is complicated by the high-water content involved, and traditional solvent hence cannot work well. Dimethyl ether (DME), a green solvent, featuring a high affinity for both water and organic compounds with an ability to penetrate the cell walls, has the potential to achieve this goal. Results: This study investigated an energy-saving method for lipid extraction using DME as the solvent with an entrainer solution (ethanol and acetone) for flocculation thickened microalgae. Extraction efficiency was evaluated in terms of extraction time, DME dosage, entrainer dosage, and ethanol:acetone ratio. Optimal extraction occurred after 30 minutes using 4.2 mL DME per 1 mL microalgae, with an entrainer dosage of 8% at 1:2 ethanol:acetone. Raw lipid yields and fatty acid methyl ester contents were compared against those of common extraction methods (Bligh & Dryer and Soxhlet). Thermal gravimetry/differential thermal analysis, Fourier-transform infrared spectroscopy, and C/H/N elemental analyses were used to examine differences in lipids extracted using each of the evaluated methods. Considering influence of trace metals on biodiesel utilization, inductively coupled plasma mass spectrometry and inductively coupled plasma atomic emission spectroscopy analyses were used to quantify trace metals in the extracted raw lipids, which revealed relatively high concentrations of Mg, Na, K, and Fe.Conclusions: Our DME-based method recovered 26.4% of total raw lipids and 54.4% of total fatty acid methyl esters at first extraction with remnants being recovered by a 2nd extraction. In additional, the DME-based approach was more economical than other methods, because it enabled simultaneous dewatering with lipid extraction and no cell disruption was required. The trace metals of raw lipids indicated a purification demand in subsequent refining process.

scholarly journals Using FlFFF and aTEM to determine trace metal–nanoparticle associations in riverbed sediment

2010 ◽  
Vol 7 (1) ◽  
pp. 82 ◽  
Author(s):  
K. L. Plathe ◽  
F. von der Kammer ◽  
M. Hassellöv ◽  
J. Moore ◽  
M. Murayama ◽  
...  
Keyword(s):  
Trace Metals ◽  
Toxic Metals ◽  
Inductively Coupled Plasma ◽  
Large Scale ◽  
Size Fraction ◽  
Metal Nanoparticle ◽  
Contaminated Sediment ◽  
Inductively Coupled ◽  
Clark Fork River ◽  
Nano Size

Environmental context. Determining associations between trace metals and nanoparticles in contaminated systems is important in order to make decisions regarding remediation. This study analysed contaminated sediment from the Clark Fork River Superfund Site and discovered that in the <1-μm fraction the trace metals were almost exclusively associated with nanoparticulate Fe and Ti oxides. This information is relevant because nanoparticles are often more reactive and show altered properties compared with their bulk equivalents, therefore affecting metal toxicity and bioavailability. Abstract. Analytical transmission electron microscopy (aTEM) and flow field flow fractionation (FlFFF) coupled to multi-angle laser light scattering (MALLS) and high-resolution inductively coupled plasma mass spectroscopy (HR-ICPMS) were utilised to elucidate relationships between trace metals and nanoparticles in contaminated sediment. Samples were obtained from the Clark Fork River (Montana, USA), where a large-scale dam removal project has released reservoir sediment contaminated with toxic trace metals (namely Pb, Zn, Cu and As) which had accumulated from a century of mining activities upstream. An aqueous extraction method was used to recover nanoparticles from the sediment for examination; FlFFF results indicate that the toxic metals are held in the nano-size fraction of the sediment and their peak shapes and size distributions correlate best with those for Fe and Ti. TEM data confirms this on a single nanoparticle scale; the toxic metals were found almost exclusively associated with nano-size oxide minerals, most commonly brookite, goethite and lepidocrocite.

scholarly journals Yttrium Residues in MWCNT Enable Assessment of MWCNT Removal during Wastewater Treatment

Nanomaterials ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 670 ◽  
Author(s):  
Justin Kidd ◽  
Yuqiang Bi ◽  
David Hanigan ◽  
Pierre Herckes ◽  
Paul Westerhoff
Keyword(s):  
Wastewater Treatment ◽  
Trace Metals ◽  
Inductively Coupled Plasma ◽  
Wastewater Treatment Plants ◽  
Analytical Techniques ◽  
High Volume ◽  
Inductively Coupled ◽  
Multi Walled Carbon Nanotubes ◽  
Plasma Mass Spectrometry ◽  
Walled Carbon Nanotubes

Many analytical techniques have limited sensitivity to quantify multi-walled carbon nanotubes (MWCNTs) at environmentally relevant exposure concentrations in wastewaters. We found that trace metals (e.g., Y, Co, Fe) used in MWCNT synthesis correlated with MWCNT concentrations. Because of low background yttrium (Y) concentrations in wastewater, Y was used to track MWCNT removal by wastewater biomass. Transmission electron microscopy (TEM) imaging and dissolution studies indicated that the residual trace metals were strongly embedded within the MWCNTs. For our specific MWCNT, Y concentration in MWCNTs was 76 µg g−1, and single particle mode inductively coupled plasma mass spectrometry (spICP-MS) was shown viable to detect Y-associated MWCNTs. The detection limit of the specific MWCNTs was 0.82 µg L−1 using Y as a surrogate, compared with >100 µg L−1 for other techniques applied for MWCNT quantification in wastewater biomass. MWCNT removal at wastewater treatment plants (WWTPs) was assessed by dosing MWCNTs (100 µg L−1) in water containing a range of biomass concentrations obtained from wastewater return activated sludge (RAS) collected from a local WWTP. Using high volume to surface area reactors (to limit artifacts of MWCNT loss due to adsorption to vessel walls) and adding 5 g L−1 of total suspended solids (TSS) of RAS (3-h mixing) reduced the MWCNT concentrations from 100 µg L−1 to 2 µg L−1. The results provide an environmentally relevant insight into the fate of MWCNTs across their end of life cycle and aid in regulatory permits that require estimates of engineered nanomaterial removal at WWTPs upon accidental release into sewers from manufacturing facilities.

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