Liquefied Dimethyl Ether Research Articles

Removal of acetyl-rich impurities from chitosan using liquefied dimethyl ether

Chitosan, recognized for its excellent biodegradability, biocompatibility, and antibacterial properties, has several potential applications, particularly in the biomedical field. However, its widespread use is hindered by inherent limitations such as low mechanical strength and safety concerns arising from a low degree of deacetylation and the presence of impurities. This study aimed to introduce an innovative purification method for chitosan via liquefied dimethyl ether (DME) extraction. The proposed technique effectively addresses the challenges associated with chitosan by facilitating deacetylation and impurity removal. Liquefied DME is emerging as the extraction solvent of choice owing to its advantages, such as low boiling point, safety, and environmental sustainability. The degree of deacetylation of chitosan was extensively evaluated using thermogravimetric–differential thermal analysis, Fourier transform infrared spectroscopy, X-ray diffraction, intrinsic viscosity measurements, solid-state nuclear magnetic resonance spectroscopy and X-ray photoelectron spectroscopy, and elemental analysis. The solubility of chitosan in liquefied DME was investigated using Hansen solubility parameters. This study contributes to the improvement of the safety profile of chitosan, thereby expanding its potential applications in various fields. The use of liquefied DME as an extraction solvent proved to be efficient in addressing the existing challenges and is consistent with the principles of safety and environmental sustainability.

Direct Extraction of Lipids, β-Carotene, and Polyphenolic Compounds from Wet Microalga Dunaliella salina by Liquefied Dimethyl Ether.

Extraction of lipids and high-value products from highly wet microalgae requires significant energy for the drying pretreatment. In this study, we examined the direct extraction of lipids, β-carotene, and polyphenolic compounds from wet Dunaliella salina using liquefied dimethyl ether (DME), which is effective in lipid extraction for biofuel production. The amount of DME-extracted β-carotene was 7.0 mg/g, which was higher than that obtained from the chloroform-methanol extraction. Moreover, the total phenolic content extracted with DME and its antioxidant capacity were slightly higher than those extracted with chloroform-methanol. DME removed almost all the water and extracted 29.2 wt% of total lipids and 9.7 wt% of fatty acids. More lipids were extracted from wet samples by liquefied DME than by chloroform-methanol extraction. The C/N ratio of lipids extracted with DME was 112.0, higher than that of chloroform-methanol. The high C/N ratio suggests that nitrogen-containing phosphatidylcholines may be less easily extracted by liquefied DME and may be highly selective. However, the ratio of saturated fatty acids was 34.8%, lower than that of chloroform-methanol. Na+ and Mg2+ in the culture medium were not extracted using DME. Thus, using the extract with DME has both advantages and disadvantages compared to using the extract with chloroform-methanol; however, it has satisfactory extraction properties. DME is expected to be an environment-friendly alternative solvent because it does not require drying, which is necessary for conventional extraction solvents.

Effective Lipid Extraction from Fat Balls Using Liquefied Dimethyl Ether: Process Optimization with a Box-Behnken Design.

In recent years, lipids reused from urban wastewater materials have come to prominence as possible raw materials for biodiesel production. The present work investigated liquefied dimethyl ether (DME) for the lipid extraction of fat balls from sewage pumping stations. A response surface methodology (RSM) based on a Box-Behnken design (BBD) was utilized to optimize DME extraction parameters (sample size, velocity of liquefied DME, and DME/sample ratio). The maximum lipid yield was 65.2% under optimal DME extraction conditions (sample size 1 mm, velocity of liquefied DME 3.3 m/h, and DME/sample ratio 80 mL/g). Under the optimum conditions, the DME technique exhibited higher lipid recovery than that of mechanical shaking extraction (49.0%) or Soxhlet extraction (62.0%). The extracted lipids were converted into biodiesel, resulting in an approximately 35.2-46.2% biodiesel yield. Furthermore, the fatty acid methyl ester composition of the extracted lipids was characterized. These significant findings highlight the promising potential of fat balls as sustainable biodiesel feedstocks and provide valuable insight that will aid the development of better technology for lipid extraction.

Liquefied dimethyl ether as alternative extraction solvent for high γ-oryzanol rice bran oil: Systematic HSP theory and experimental evaluation

This study aimed to systematically find an alternative solvent to replace hexane for the extraction of bio-oil with high γ-oryzanol content from rice bran (RB). The selection involved predicting solubility through Hansen solubility theory, experimental validation, determination of suitable extraction conditions, and comparison of oil quality with that of conventional hexane. A wide variety of solvents: subcritical water (SCW), supercritical carbon dioxide (SCCO2), bio-based solvents (alcohols and terpenes), and liquefied dimethyl ether (LDME), were initially assessed for rice bran oil (RBO) and γ-oryzanol solubility using Hansen solubility spheres. Solvents demonstrating high solubility for both RBO and γ-oryzanol, including LDME, ethyl acetate, acetone, and others (alcohols and SCCO2) known for effective vegetable oil extraction, were selected/identified for experimental extraction comparison. Among these, LDME performed better overall, affording greater solubility and requiring less solvent, shorter duration, lower pressure, and no additional co-solvents for equivalent extractions. Optimal conditions for LDME extraction were identified as 30 °C with a solvent-to-sample ratio of 10 mL/g and an extraction time of 10 min. Oils extracted with LDME and hexane displayed similar fatty acid compositions and no adverse effects on RB protein and carbohydrate structures after LDME extraction were observed. This study demonstrates LDME as a promising alternative to replace hexane for RBO extraction to further valorize this abundant low-cost RB residue into bio-oil and its γ-oryzanol and de-oil RB co-products.

Sludge deep dewatering by liquefied dimethyl ether: selection of operating conditions based on response surface methodology

ABSTRACT Sludge is an inevitable by-product of the sewage treatment process and its high moisture content poses significant challenges for its treatment and disposal. This study focuses on the technology of sludge deep dewatering using liquefied dimethyl ether (DME) and explores the relationship between operating parameters (DME/sludge ratio, extraction time and stirring speed) and the water content of the sludge after deep dewatering. After deep dewatering, the sludge's lower heating value (LHV) was significantly increased. The dehydrated filtrate is highly biodegradable and could be treated together with sewage. Based on the response surface method of central composite design, a second-order regression model of the above three variables and sludge water content as the response was established. Finally, the operating conditions diagram was drawn by target water content (36.96 wt.%) which meets the requirement of self-sustained incineration and model equation. This study provides a valuable perspective on sludge drying and fuelisation.

Environmental-friendly extraction of di(2-ethylhexyl) phthalate from poly(vinyl chloride) using liquefied dimethyl ether

Poly(vinyl chloride) (PVC) is one of the most widely used plastics. However, a major challenge in recycling PVC is that there is no economical method to separate and remove its toxic phthalate plasticizers. This research made a breakthrough by extracting PVC with liquefied dimethyl ether (DME) and successfully separating the plasticizer components. Nearly all (97.1 %) of the di(2-ethylhexyl) phthalate plasticizer was extracted within 30 min by passing liquefied DME (285 g) through PVC at 25 °C. The compatibility of PVC with organic solvents, including liquefied DME, was derived theoretically from their Hansen solubility parameters (HSP), and actual dissolution experiments were conducted to determine the optimal PVC solvents. A liquefied DME mixture was used to dissolve PVC, and the extract was diluted with ethanol to precipitate the dissolved PVC. We demonstrated that liquefied DME is a promising method for producing high quality recycled products and that the process retains the fundamental properties of plasticizers and PVC without inducing degradation or depolymerization. Because of its low boiling point, DME can be easily separated from the solute after extraction, allowing for efficient reuse of the solvent, extracted plasticizer, and PVC. DME does not require heat and produces little harmful wastewater, which significantly reduces the energy consumption of the plasticizer additive separation process.

Extraction and Separation of Natural Products from Microalgae and Other Natural Sources Using Liquefied Dimethyl Ether, a Green Solvent: A Review.

Microalgae are a sustainable source for the production of biofuels and bioactive compounds. This review discusses significant research on innovative extraction techniques using dimethyl ether (DME) as a green subcritical fluid. DME, which is characterized by its low boiling point and safety as an organic solvent, exhibits remarkable properties that enable high extraction rates of various active compounds, including lipids and bioactive compounds, from high-water-content microalgae without the need for drying. In this review, the superiority of liquefied DME extraction technology for microalgae over conventional methods is discussed in detail. In addition, we elucidate the extraction mechanism of this technology and address its safety for human health and the environment. This review also covers aspects related to extraction equipment, various applications of different extraction processes, and the estimation and trend analysis of the Hansen solubility parameters. In addition, we anticipate a promising trajectory for the expansion of this technology for the extraction of various resources.

Extraction of fucoxanthin, antioxidants and lipid from wet diatom Chaetoceros simplex var. calcitrans by liquefied dimethyl ether

The co-production of lipids and high value-added products from microalgae is a key milestone for practical, microalgae-derived food and biofuel production. However, the use of ethanol as a solvent for lipid extraction requires a drying pretreatment to avoid wastewater contamination and large energy consumption during solvent recovery. Previous studies on lipid production have reported liquefied dimethyl ether (DME) as an alternative solvent that can extract lipids from high water content microalgae with low energy consumption by eliminating the traditional drying step. In this study, liquefied DME is used as a solvent to extract fucoxanthin, antioxidants, and lipids from wet diatom Chaetoceros simplex var. calcitrans. DME extracted 9.2 mg/g-dry microalgae of fucoxanthin from wet sample; this is slightly less than the 11.9 mg/g-dry microalgae extracted from dry sample by ethanol. The total phenolic content and antioxidant capacity of the liquefied DME extracts were only slightly lower than those of the ethanol extract. Using DME, all water and 22.7 wt% of lipid, and 5.6 wt% of atty acid were extracted. Lipids extracted with liquefied DME have a higher C/N, an indicator of suitability for conversion to biofuel, than lipids obtained by ethanol extraction. The microalga contains high levels of unsaturated fatty acids. Liquefied DME extraction is sustainable method because liquefied DME can extract most of the lipids and functional components without drying the diatom. DME avoids risks associated with ethanol.

Surfactant-Free Decellularization of Porcine Auricular Cartilage Using Liquefied Dimethyl Ether and DNase.

The most common decellularization method involves lipid removal using surfactant sodium dodecyl sulfate (SDS) and DNA fragmentation using DNase, and is associated with residual SDS. We previously proposed a decellularization method for the porcine aorta and ostrich carotid artery using liquefied dimethyl ether (DME), which is free from the concerns associated with SDS residues, instead of SDS. In this study, the DME + DNase method was tested on crushed porcine auricular cartilage tissues. Unlike with the porcine aorta and the ostrich carotid artery, it is important to degas the porcine auricular cartilage using an aspirator before DNA fragmentation. Although approximately 90% of the lipids were removed using this method, approximately 2/3 of the water was removed, resulting in a temporary Schiff base reaction. The amount of residual DNA in the tissue was approximately 27 ng/mg dry weight, which is lower than the regulatory value of 50 ng/mg dry weight. Hematoxylin and eosin staining confirmed that cell nuclei were removed from the tissue. Residual DNA fragment length assessment by electrophoresis confirmed that the residual DNA was fragmented to less than 100 bp, which was lower than the regulatory limit of 200 bp. By contrast, in the uncrushed sample, only the surface was decellularized. Thus, although limited to a sample size of approximately 1 mm, liquefied DME can be used to decellularize porcine auricular cartilage. Thus, liquefied DME, with its low persistence and high lipid removal capacity, is an effective alternative to SDS.

Bioactives from Crude Rice Bran Oils Extracted Using Green Technology.

Crude rice bran oils from different rice cultivars and extraction methods bear different contents of nutraceuticals. The health benefits of lowering cholesterol activity of rice bran oil being confirmed by many reports are partly attributed to non-nutrient nutraceuticals, especially γ-oryzanol, phytosterols, and policosanols. As the world has been facing the global warming crisis, green extraction technology is gaining attention from many sectors. The current study aims to compare the nutraceutical composition with respect to γ-oryzanol, phytosterol, and policosanol content as well as the antioxidant properties of crude rice bran oils extracted from white and red rice bran using three green technologies, comparing with conventional hexane extraction. The data show that the traditional solvent extraction gave the highest oil yield percentage (26%), but it was not significantly different from subcritical liquefied dimethyl ether extraction (24.6%). Subcritical liquefied dimethyl ether extraction gave higher oil yield than supercritical CO2 extraction (15.5-16.2%). The crude rice bran oil extracted using subcritical liquefied dimethyl ether extraction produced the highest total phenolic contents and antioxidant activities. The highest γ-oryzanol content of the crude rice bran oil was found in oil extracted by conventional cold press (1370.43 mg/100 g). The γ-oryzanol content of the oil obtained via subcritical liquefied dimethyl ether extraction was high (1213.64 mg/100 g) compared with supercritical CO2 extraction. The red rice bran yielded the crude rice bran oil with the highest total phytosterol content compared with the white bran, and the oil from red rice bran extracted with subcritical liquefied dimethyl ether generated the highest total phytosterol content (1784.17 mg/100 g). The highest policosanol content (274.40 mg/100 g) was also found in oil obtained via subcritical liquefied dimethyl ether extraction.

Ethanol-free extraction of curcumin and antioxidant activity of components from wet Curcuma longa L. by liquefied dimethyl ether

As a solvent, ethanol can extract a wide range of polar substances, but its consumption is sometimes avoided for religious and cultural reasons. In this study, liquefied dimethyl ether (DME) was used to extract curcumin and antioxidants from highly moist, untreated turmeric. Higher amounts of curcumin (7.94 mg/g dry weight (DW)) were extracted using liquified DME compared with ethanol (6.77 mg/g DW). Almost all the water and 5.10 mg/g DW of lipids were extracted from raw turmeric using liquefied DME, corresponding to 56 % the amount extracted using ethanol. In addition, microscopic and spectroscopic analyses revealed that liquefied DME neither destroyed cell walls nor extracted cellulose. However, liquefied DME had a slightly lower extraction capacity for total phenolic compounds than ethanol and slightly lower antioxidant effect. DME extracts an equivalent amount of curcumin as ethanol and only slightly fewer antioxidants while simultaneously avoiding sun-drying degradation and prolonged freeze-drying.

Tensile strength of ostrich carotid artery decellularized with liquefied dimethyl ether and DNase: An effort in addressing religious and cultural concerns

In a previous report, we proposed a method for decellularizing ostrich carotid arteries by removing lipids from the arteries using liquefied dimethyl ether (DME) instead of the conventional sodium dodecyl sulfate (SDS). This is followed by DNA fragmentation with DNase. In the present study, the physical properties of ostrich carotid arteries decellularized using the DME method were evaluated via tensile tests. Results showed that the tissue with SDS broke under less than half the stress of the original ostrich carotid artery. In contrast, the tissue treated with liquefied DME withstood the same level of the original tissue. Both decellularized tissues by liquefied DME showed flexibility comparable to that of the original tissue. We attributed this to the no CN bonds temporarily generated by dehydration through the Schiff-base reaction when lipids were removed by liquefied DME.

High Levels of Policosanols and Phytosterols from Sugar Mill Waste by Subcritical Liquefied Dimethyl Ether.

Extracting nutraceuticals with high value from bagasse, filter mud, and sugarcane leaves discarded as sugar mill by-products, is crucial for the development of a sustainable bio-economy. These by-products are important sources of policosanols and phytosterols, which have a cholesterol-lowering effect. This research focused on using a promising green technology, subcritical liquefied dimethyl ether extraction, with a low pressure of 0.8 MPa, to extract policosanols and phytosterols and on application of pretreatments to increase their contents. For direct extraction by subcritical liquefied dimethyl ether without sample pretreatment, the highest extraction yield (7.4%) and policosanol content were found in sugarcane leaves at 2888 mg/100 g, while the highest and lowest phytosterol contents were found in filter mud at 20,878.75 mg/100 g and sugarcane leaves at 10,147.75 mg/100 g, respectively. Pretreatment of filter mud by ultrasonication in hexane solution together with transesterification before the second subcritical liquefied dimethyl ether extraction successfully increased the policosanol content, with an extract purity of 60%, but failed to increase the phytosterol content.

Tensile Strength of Porcine Aorta Decellularized with Liquefied Dimethyl Ether and DNase.

In a previous report, we proposed a method for decellularizing porcine aortas by removing lipids from the aortas using liquefied dimethyl ether (DME) instead of the conventional sodium dodecyl sulfate (SDS). This is followed by DNA fragmentation with DNase. In the current work, the physical properties of porcine aortas decellularized using the DME method are evaluated by tensile strength tests. Conventional SDS decellularized aortas are typically swollen, rupture very easily, and have poor elasticity. By contrast, DME-treated samples are found to be less elastic. However, the maximum stress required for rupture is greater than that for the original aorta. These results indicate that decellularization with DME and DNase increases the maximum stress that can be withstood. Reduction of elasticity may derive from the appearance of temporary C=N bonds due to Schiff-base reactions that occur during the lipid removal process by liquefied DME, and methods to avoid this are desirable.

Efficient extraction of biodiesel feedstock and dehydration of kitchen waste: A method based on co-dissolution of liquefied dimethyl ether and water

In the context of low-carbon development, as a waste rich in lipids, kitchen waste (KW) has received increasing attention for resource utilization and low-carbon utilization. In this study, we explored a method for efficient extraction of lipids and dehydration using liquefied dimethyl ether (L-DME) to address the problem of high lipids and the difficulty of dewatering of KW. A closed DME reaction vessel was used to conduct experiments on the effects of lipids extraction and dehydration of KW under different reaction times, mass ratios, temperatures and moisture contents. It was found that DME could extract more than 90% of the lipids and the dehydration rate could reach approximately 80%. The main components of the lipids in the liquid phase extract were fatty acids (C18:2, C18:1, C16:0, and C18:0) whose good thermal properties made them suitable for use as a feedstock for biodiesel production. Moreover, the greatly increased heating value of the solid residue facilitated low-carbon utilization. This study also demonstrated a promotion effect of the co-dissolution system of L-DME and water on the extraction of lipids and explored the related mechanism.

A Study of Salvaged Cyanobacteria Slurry Treatment Using Liquefied Dimethyl Ether: Dehydration and Organic Matter Extraction

Liquefied dimethyl ether (L-DME) was used to dehydrate salvaged cyanobacteria slurry (SCS) and extract its organic matter. The dehydration rate and organic matter extraction efficiency were determined by mixing L-DME with SCS in a sealed reactor for 0–25 min, and the amount of solvent was 6–39 times that of SCS at a stirring rate of 0–800 rpm. Free water in SCS was removed entirely at an L-DME amount of 9 times, and then bound water was gradually removed with an increase in L-DME dosage, with a final SCS lowest moisture content of 16.64% at an L-DME amount of 39 times. Moreover, L-DME extracted 8.72%–21.15% of the organic matter from SCS, with almost complete lipid extraction. The phosphorus and nitrogen were also extracted because they mainly exist in phospholipids and proteins. Subsequently, the solid residue and liquid product were characterized, with fatty acids and plasticizers found in the liquid product. The dehydration rate and organic matter extraction efficiency were also investigated using ethanol as adjuvant of L-DME, with ethanol serving as an adjuvant. The performance of dehydration and organic matter extraction from SCS using L-DME was evaluated to explore the feasibility of applying this process to SCS treatment.

Crude Oil Recovery from Oily Sludge Using Liquefied Dimethyl Ether Extraction: A Comparison with Conventional Extraction Methods

Crude Oil Recovery from Oily Sludge Using Liquefied Dimethyl Ether Extraction: A Comparison with Conventional Extraction Methods

Surfactant-free preparation of an ostrich carotid artery scaffold using liquefied dimethyl ether and DNase

Instead of combining the surfactant sodium dodecyl sulphate and DNase, a combination of liquefied dimethyl ether (DME) and DNase was used to decellularise the scaffold of ostrich carotid artery tissue. Firstly, lipids were extracted from ostrich carotid artery tissue using liquefied DME at 25 °C and a pressure of 0.59 MPa. After DME extraction, the ostrich carotid artery tissue was collected from the extraction column, and the DME remaining in the tissue was evaporated at atmospheric pressure and temperature. DNA fragmentation by DNase was then carried out using a method almost identical to the conventional method. Finally, the tissue was washed to remove fragmented DNA. The DNA was completely fragmented to a size of less than 100 bp after 1 day of DNase treatment. The residual DNA had a concentration of 28 ng/mg dry weight after 7 days of treatment with DNase. Haematoxylin and eosin staining showed that most of the cell nuclei were removed from the aortic tissue. These results indicate that the combination of liquefied DME extraction and DNase treatment eliminates the need for surfactant treatment in ostrich carotid artery tissue decellularisation. Although previous decellularisation studies have focused on porcine tissue, we herein show the potential of ostrich tissue as an alternative to alleviate religious concerns.

Enhancement of Lipid Extraction from Soya Bean by Addition of Dimethyl Ether as Entrainer into Supercritical Carbon Dioxide.

Soya beans contain a variety of lipids, and it is important to selectively separate neutral lipids from other lipids. Supercritical carbon dioxide extraction has been used as an alternative to the selective separation of neutral lipids from soya beans, usually using non-polar hexane. However, supercritical carbon dioxide extraction has a high operating pressure of over 40 MPa. On the other hand, liquefied dimethyl ether extraction, which has attracted attention in recent years, requires an operating pressure of only 0.5 MPa, but there is concern about the possibility of an explosion during operation because it is a flammable liquefied gas. Therefore, this study aims to reduce the operating pressure by using a non-flammable solvent, supercritical carbon dioxide extraction mixed with liquefied dimethyl ether as an entrainer. The extraction rate and the amount of neutral lipids extracted increased with increasing amounts of added liquefied dimethyl ether. In the mixed solvent, the amount of neutral lipids extracted was higher at an operating pressure of 20 MPa than in pure supercritical carbon dioxide extraction at 40 MPa. The mixing of liquefied dimethyl ether with supercritical carbon dioxide allowed an improvement in the extraction of neutral lipids while remaining non-flammable.

Combustion Characteristics of High Viscosity and Flame Retardant Material by Blending Liquefied Dimethyl Ether

Combustion Characteristics of High Viscosity and Flame Retardant Material by Blending Liquefied Dimethyl Ether