Preparation of High-quality Oil from Vegetable Oil with High-free Fatty Acid (FFA) Content Using an Ammonia/Methanol Solution.

There are significant concerns regarding the quality of vegetable oils in the food and biofuel industries. In this study, we explored the preparation of high- quality oil from high-free fatty acid (FFA) vegetable oil using an ammonia/MeOH solvent as an alkali base. Among the six tested solvents, MeOH was the most suitable for the separation of the oil and FFAs. Among the three alkali bases, ammonia enhanced the miscibility of FFAs in MeOH by forming ammonium salts. The amounts of FFAs in the upper layer and oil in the lower layer were positively correlated (r = 0.9348 and 0.9617, respectively) with MeOH. With increasing MeOH concentration, the amount of oil in the lower layer increased along with the FFAs in the upper layer. Using the molar ratio of ammonia to FFA 1:1 and the ratio (v/w) of MeOH to oil 4:3, 91.6% FFAs and 97.8% oil in the upper and lower layers, respectively, were produced from 50% FFA oil. Using a relational expression of FFAs and oil in the upper layer, 97.1% FFAs and 99.6% oil in each layer was obtained from 10% FFA oil. The oil in the lower layer was further purified by extraction with MeOH. This method is easy and efficient for the separation and purification of oil, accompanied by the reuse of reagents with almost no loss of raw materials.

Bio-diesel Fuel Material Supply in Vietnam and Its Current and Future Potentiality with a Focus on Rubber Seed Oil.

Diesel fuel usage in Vietnam is increasing rapidly, but most of it is imported from overseas. In this study, we investigated the possibility of popularizing bio-diesel fuel (BDF) made from Vietnamese origin resources as a sustainable energy solution. The world's energy cost fluctuates significantly depending on economic or political movements, especially after the Russian invasion of Ukraine began in 2022. This caused energy prices soar, attacking the global economy in a short period and requiring a wide range of energy supply sources. We aim to promote commercial BDF production in Vietnam for future energy security and contribution to the Vietnamese economy. Eight necessary factors were investigated to choose suitable material for BDF production. The factors are as follows: 1) material with Vietnamese origin, 2) sufficient and continuous supply volume, 3) sufficient quality to run diesel engines, including common-rail diesel engines, 4) inedibility, 5) low enough freezing point, 6) ease of collection, 7) affordability, and 8) availability of valuable elements in the material. If a suitable material candidate is not stable, it may be changed over time. In this study, the focus material was rubber seed oil. Because rubber production in Vietnam is quite stable with over 900,000 ha plantation area, and there is a potentiality to collect seeds and produce about 50,000 tons of BDF annually. In addition, the quality of rubber seeds based BDF is very high, such as low enough freezing point, etc. However, most of those rubber seeds are currently not collected and used.

Optimization of Procedure for Determining Dissolved Oxygen in Surface Water and Seawater Exploiting the UV-vis Absorption of Mn(III) Species.

We present an analytical method for dissolved oxygen based on the quantification of Mn(III) absorbance in a water sample. After Mn(II) reacts with the oxygen molecules in water, Mn(III) is formed and stabilized by hexa-metaphosphate under acidic conditions. The UV visible absorbance of Mn(III) is proportional to the oxygen concentration in the water sample. Compared to the Winkler method, the proposed method has the same accuracy (R = 0.9992 at 0 - 52 mg dm-3) but requires fewer reagents; furthermore, it does not involve titration. Interferences from nitrite and iodate were not observed. This procedure can be used to accurately and quickly determine the oxygen concentrations in different natural water sources, including seawater.

Development of a Photometric Method to Measure Molecular Oxygen in Water.

A photometric method to determine molecular oxygen in water was developed. When manganese(II) is oxidized by oxygen under alkaline conditions, the presence of polyphosphate can prevent precipitation due to a coacervate reaction. The oxidized manganese later dissolves in acid to form a pink Mn(III) species, which has a stable UV/vis spectrum. Monitoring of the oxygen concentration based on the absorbance of the pink Mn(III) species at 517 nm showed a strong correlation with both the Winkler method and an optical sensor. As a result, the present method can measure not only dissolved oxygen, but also fine bubbles oxygen in in the water sample with high reliability (0 - 26 mg dm-3, r2 = 0.9995). During this process, no significant interference from nitrite or metal ions was observed. The accuracy of the measurement was steady at high temperatures of the water samples (≤ 363 K).

Ultrasound Assisted Cascade Extraction of Oil, Vitamin E, and Saccharides from Roselle (Hibiscus Sabdariffa L.) Seeds.

Roselle seeds, a waste biomass of the roselle calyx processing industry, were utilized to recover valuable compounds of oil, vitamin E, and water-soluble saccharides. Firstly, ultrasound-assisted extraction (UAE) and conventional stirring extraction were conducted for saccharide extraction, and the advantage of UAE was confirmed. Secondly, oil, vitamin E, and saccharides extracted from Vietnamese roselle seeds by UAE were analyzed for the first time. Oil of tri-, di-, and mono-glycerides, fatty acids of linoleic-, oleic-, palmitic-, and stearic-acids, vitamin E of γ- and α-tocopherol, and saccharides of sucrose, raffinose, stachyose, etc. were identified, and the amounts of these components were compared with those in other country's roselle seeds. Thirdly, cascade extraction of oil, vitamin E, and saccharides by UAE was investigated with solvents of hexane, hexane:ethyl acetate binary solvent, and water. The results indicated that the order of using solvents was very important for high and selective extraction: the best order to recover oil (almost 100%), vitamin E (95.7%), and saccharides (86.2%) was hexane, and then water.

Screening of fatty acids, saccharides, and phytochemicals in Jatropha curcas seed kernel as their trimethylsilyl derivatives using gas chromatography/mass spectrometry.

Jatropha curcas is a multipurpose plant, of which the seed kernel oil (up to 60% content) has been exploited for BDF production. In this report, we explored the various kinds of minor compounds of saccharides, phytochemicals, fatty acids (FAs), and amino acids in the seed kernel using gas chromatography/mass spectrometry (GC/MS) as their trimethylsilyl (TMS) derivatives. The homogenized seed kernels were extracted with methanol, and the extract was distributed into ethyl acetate/water phase. The components of each layer were derivatized with N, O-bis (trimethylsilyl) trifluoroacetamide (BSTFA) and their TMS derivatives were screened by GC/MS analysis. In ethyl acetate layer, the four FAs of palmitic acid, oleic acid, linoleic acid, and stearic acid were identified with total content of 12 wt% in kernel. In addition, the two tocochromanols of γ-tocopherol and γ-tocotrienol, and three phytosterols of campesterol, stigmasterol, and ß-sitosterol were also identified. Meanwhile, as the main saccharide components, di-saccharide of sucrose with content of 3 wt% in kernel, tri-saccharide of raffinose, and sugar alcohol of sorbitol and myo-inositol, were identified in aqueous layer. Furthermore, metabolites of amino acid, and a series of metabolite were also identified. These results suggested that the Jatropha curcas seed kernel can be applied to cascade use for metallic soap, liquid fuel, food and medical supplement, and cosmetics in addition to biodiesel production.

Production of Biodiesel from Candlenut Oil Using a Two-step Co-solvent Method and Evaluation of Its Gaseous Emissions.

Candlenut oil (CNO) is a potentially new feedstock for biodiesel (BDF) production. In this paper, a two-step co-solvent method for BDF production from CNO was examined. Firstly, esterification of free fatty acids (FFAs) (7 wt%) present in CNO was carried out using a co-solvent of acetonitrile (30 wt%) and H2SO4 as a catalyst. The content of FFAs was reduced to 0.8 wt% in 1 h at 65°C. Subsequent transesterification of the crude oil produced was carried out using a co-solvent of acetone (20 wt%) and 1 wt% potassium hydroxide (KOH). Ester content of 99.3% was obtained at 40°C in 45 min. The water content in BDF was 0.023% upon purification using vacuum distillation at 5 kPa. The components of CNO BDF were characterized using a Fourier-transform infrared spectrometry and gas chromatography-flame ionization detector. The physicochemical properties of BDF satisfied the ASTM D6751-02 standard. The gaseous exhaust emissions from the diesel engine upon combustion of the BDF blends (B0-B100) with petrodiesel were examined. The emissions of carbon monoxide and hydrocarbons were clearly lower, but that of nitrogen oxides was higher in comparison to those from petro-diesel.

A 3-Step Chemiluminescence Method for Chemical Oxygen Demand Measurement.

Direct chemiluminescence emission from the reaction of acidic permanganate and organic compounds was employed for determining the chemical oxygen demand (COD) in water (1-step CL COD). Due to the diversity of organic pollutants in water, there are no standards for COD measurements, and many compounds do not show any chemiluminescence signal in the 1-step CL COD method. As a result, this method shows a low correlation with the conventional CODMn method. In this study, a new 3-step CL COD method was developed to overcome these drawbacks. The basic principle of the 3-step CL COD method is based on the principle of "back titration" in the CODMn method: (i) the sample is treated with permanganate under heating, (ii) the excess permanganate is treated with pyrogallol, and (iii) the excess pyrogallol is measured by the chemiluminescence reaction with permanganate. The reagent concentration, sample volume, and heating temperature were optimized, and the 3-step CL COD method successfully obtained the signal from some samples that cannot be detected by 1-step CL COD method. The calibration graph is linear in the range of 0 - 12.86 mg/L with a detection limit of 0.082 mg/L. This method is continuous, sensitive and low cost compared with the conventional method, and is applicable for on-site monitoring. The effect of the chloride ion was investigated, and showed an insignificant effect after two-times dilution of high-salinity samples. The correlation with the CODMn method for various organic compounds showed a good coefficient of determination, R2 = 0.9773 (n = 16).

Binary Solvent Extraction of Tocols, γ-Oryzanol, and Ferulic Acid from Rice Bran Using Alkaline Treatment Combined with Ultrasonication.

Alkaline treatment (Alk) combined with ultrasound-assisted extraction (UAE) (Alk+UAE) was examined as a means of extracting tocols and γ-oryzanol from rice bran into an organic phase while simultaneously recovering ferulic acid into an aqueous phase. The tocols and γ-oryzanol/ferulic acid yields were determined using high-performance liquid chromatography with fluorescence and UV detection. The effects of extraction conditions were evaluated by varying the Alk treatment temperature and extraction duration. The maximum yields of tocols and γ-oryzanol were obtained at 25 °C over a time span of 30 min. When the temperature was increased to 80 °C, the yield of ferulic acid increased dramatically, whereas the recovery of γ-oryzanol slightly decreased. Employing the Alk+UAE procedure, the recovered concentrations of tocols, γ-oryzanol, and ferulic acid were in the ranges of 146-518, 1591-3629, and 352-970 µg/g, respectively. These results are in good agreement with those reported for rice bran samples from Thailand.

Semi-preparative HPLC separation followed by HPLC/UV and tandem mass spectrometric analysis of phorbol esters in Jatropha seed.

Phorbol esters (PEs) are well known as the main toxic compounds in Jatropha curcas Linnaeus (JCL), the seed oil of which has been considered as a major feedstock for the production of biodiesel. In the present study, we investigated a series of PEs extracted from JCL seed kernels with methanol (MeOH), and identified more than seven components contained in the PEs. The isolation of main five components of a series of PEs was revised using a semi-preparative reversed phase HPLC analysis of ODS-3 column. The five peaks of components were successfully isolated, and peaks of J2, J3, J5, and J7 were assigned to be Jatropha factors C1, C2, C3, and C4/5, but J6 was a mixture of Jatropha factor C6 and its isomer based on the data of UV and LC-MS/MS, and J2 was identified using 1H NMR analysis. By characterization using LC-MS/MS analysis, all components of a series of PEs were elucidated to be the 12-deoxy-16-hydroxyphorbol esters composed of isomeric form of dicarboxylic groups with same m/z value of 380.

Increase in ozone due to the use of biodiesel fuel rather than diesel fuel.

The consumption of fuel by vehicles emits nitrogen oxides (NOx) and non-methane hydrocarbons (NMHCs) into the atmosphere, which are important ozone precursors. Ozone is formed as a secondary pollutant via photochemical processes and is not emitted directly into the atmosphere. In this paper, the ozone increase resulting from the use of biodiesel and diesel fuels was investigated, and the different ozone formation trends were experimentally evaluated. Known amounts of exhaust gas from a power generator operated using biodiesel and diesel fuels were added to ambient air. The quality of the ambient air, such as the initial NMHC and NOx concentrations, and the irradiation intensity have an effect on the ozone levels. When 30 cm(3) of biodiesel fuel exhaust gas (BFEG) or diesel fuel exhausted gas (DFEG) was added to 18 dm(3) of ambient air, the highest ratios of ozone increase from BFEG compared with DFEG in Japan and Vietnam were 31.2 and 42.8%, respectively, and the maximum ozone increases resulting from DFEG and BFEG compared with the ambient air in Japan were 17.4 and 26.4 ppb, respectively. The ozone increase resulting from the use of BFEG was large and significant compared to that from DFEG under all experimental conditions. The ozone concentration increased as the amount of added exhaust gas increased. The ozone increase from the Jatropha-BFEG was slightly higher than that from waste cooking oil-BFEG.

Distribution and depth profiles of polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, and polychlorinated biphenyls in sediment collected from offshore waters of Central Vietnam.

Concentrations of PCBs and OCPs were measured in 35 surface sediment samples collected from offshore waters of Central Vietnam. The mean concentrations of PCBs, HCHs, and DDTs in surface sediments were 86.5, 37.0, and 44.5pgg(-1), respectively. Additionally, nine PCDDs, eleven PCDFs, and twelve dl-PCBs were also examined in 19 sediment core samples collected from five locations. Concentration of PCDDs, PCDFs, and dl-PCBs ranged from 200 to 460, 0.39 to 2.9, and 1.6 to 22pgg(-1), respectively. OCDD was detected at the highest concentration, ranged from 100 to 300pgg(-1). Generally, the concentrations of PCDD/Fs at shallower depths were higher, meanwhile the depth profiles of dl-PCBs in sediment cores were different than the depth profiles of PCDD/Fs. The results suggest that the pollution of PCBs might be from many different sources leading to the variation between depths.

Production of biodiesel from Vietnamese Jatropha curcas oil by a co-solvent method.

Biodiesel fuels (BDFs) was successfully produced from Vietnamese Jatropha curcas oil with high content of free fatty acids (FFAs) in two stages. In the first stage, the esterification process was carried out with the optimal conditions as follows; a methanol-to-FFAs molar ratio of 6:1, 1 wt% H2SO4, at a temperature of 65 °C, and using 30% (wt/wt) acetonitrile as co-solvent. This step reduced the concentration of FFAs in the reaction mixture from 15.93 to 2 wt% in 60 min. In the second stage, the transesterification process generated fatty acid methyl esters (FAMEs) with 99% efficiency was performed in 30 min with the optimal conditions as follows; a methanol-to-oil molar ratio of 6:1, 1 wt% KOH, at a temperature of 40 °C, and 20% (wt/wt) acetone as co-solvent. The produced biodiesel quality meets the standards JIS K2390 and EN 14214 regarding FAME yield, FFAs and water contents.

Ultrasound assisted production of fatty acid methyl esters from transesterification of triglycerides with methanol in the presence of KOH catalyst: optimization, mechanism and kinetics.

Ultrasound assisted transesterification of triglycerides (TG) with methanol in the presence of KOH catalyst was investigated, where the changes in the reactants and products (diglycerides (DG), monoglycerides (MG), fatty acid methyl esters (FAME) and glycerin (GL)) concentrations were discussed to understand the reaction mechanism and kinetics under ultrasound irradiation. The optimum reaction condition for the FAME production was the concentration of KOH 1.0 wt.%, molar ratio of TG to methanol of 1:6, and irradiation time of 25 min. The rate constants during the TG transesterification with methanol into GL and FAME were estimated by a curve fitting method with simulated curves to the obtained experimental results. The rate constants of [Formula: see text] were estimated to be 0.21, 0.008, 0.23, 0.005, 0.14 and 0.001 L mol(-1)min(-1), respectively. The rate determining step for the TG transesterification with methanol into GL and FAME was the reaction of MG with methanol into GL and FAME.

Cellular uptake of octaarginine-conjugated tetraarylporphyrin included by per-O-methylated ß-cyclodextrin.

This paper describes the synthesis, structural characterization and cellular uptake of a supramolecular 1 : 2 inclusion complex of meso-tetraphenylporphyrin having an octaarginine peptide chain (R8-TPP) and heptakis(2,3,6-tri-O-methyl)-ß-cyclodextrin (TMe-ß-CD). R8-TPP was synthesized by 2 approaches: (1) on-resin conjugation of the N-terminal of octaarginine with 5-(4-carboxyphenyl)-10,15,20-triphenylporphyrin, followed by cleavage from the resin, and (2) Michael addition reaction between 5-[4-(3-maleimidopropylamido)phenyl]-10,15,20-triphenylporphyrin and cysteine-octaarginine peptide (Cys-Arg8). The R8-TPP obtained from both the approaches formed stable inclusion complexes with TMe-ß-CD by which non-substituted phenyl groups at the 10- and 20-positions were included to form trans-type 1 : 2 inclusion complexes. The complexation prevented the self-aggregation of R8-TPP, which resulted in the solubilisation of R8-TPP in aqueous media. A cellular uptake study using HeLa cells showed that R8-TPP complexed with TMe-ß-CD in a serum-free medium was efficiently taken up by the cells and uniformly dispersed in the cytosol. In the serum-containing medium, the R8-TPP-TMe-ß-CD complex dissociated, and the serum protein bound R8-TPP. The R8-TPP-protein complex was localized in the endosomes of the cells. The cytosol-dispersed R8-TPP showed a higher photo-induced cytotoxicity than its endosome-trapped counterpart.

A two-step continuous ultrasound assisted production of biodiesel fuel from waste cooking oils: a practical and economical approach to produce high quality biodiesel fuel.

A transesterification reaction of waste cooking oils (WCO) with methanol in the presence of a potassium hydroxide catalyst was performed in a continuous ultrasonic reactor of low-frequency 20 kHz with input capacity of 1 kW, in a two-step process. For the first step, the transesterification was carried out with the molar ratio of methanol to WCO of 2.5:1, and the amount of catalyst 0.7 wt.%. The yield of fatty acid methyl esters (FAME) was about 81%. A yield of FAME of around 99% was attained in the second step with the molar ratio of methanol to initial WCO of 1.5:1, and the amount of catalyst 0.3 wt.%. The FAME yield was extremely high even at the short residence time of the reactants in the ultrasonic reactor (less than 1 min for the two steps) at ambient temperature, and the total amount of time required to produce biodiesel was 15h. The quality of the final biodiesel product meets the standards JIS K2390 and EN 14214 for biodiesel fuel.

Ultrasound-assisted production of biodiesel fuel from vegetable oils in a small scale circulation process.

Biodiesel production from canola oil with methanol was performed in the presence of a base-catalyst by a circulation process at room temperature. In this process, the transesterification was accelerated by ultrasonic irradiation of low frequency (20 kHz) with an input capacity of 1 kW. The influences of various parameters on the transesterification reaction, including the amount of catalyst, the molar ratio of methanol to oil and the reaction time, were investigated. The objective of this work was to produce biodiesel satisfying the biodiesel-fuel standards of low energy consumption and material savings. The optimal conditions were: methanol/oil molar ratio of 5:1 and 0.7 wt.% catalyst in oil. Under these conditions, the conversion of triglycerides to fatty acid methyl esters was greater than 99% within the reaction time of 50 min. Crude biodiesel was purified by washing with tap water and drying at 70 degrees C under reduced pressure.

Characteristics of the abundance of polychlorinated dibenzo-p-dioxin and dibenzofurans, and dioxin-like polychlorinated biphenyls in sediment samples from selected Asian regions in Can Gio, Southern Vietnam and Osaka, Japan.

The levels of polychlorinated dibenzo-p-dioxin and dibenzofuran (PCDD/PCDFs), and dioxin-like polychlorinated biphenyls (DL-PCBs) were determined in sediment samples from Can Gio, South Vietnam, and Osaka, Japan. Can Gio is known for the defoliation of its mangrove forests by aerial spraying with Agent Orange during the Vietnam War, whereas Osaka is renowned for a PCDD/PCDF pollution accident at a municipal solid-waste incinerator. For comparison, we also analyzed PCDD/PCDFs and DL-PCBs in sediment samples from Hue and Hanoi, Vietnam. The toxic equivalent quantity (TEQ) values in Can Gio were as high as those in Hue, Hanoi, and suburban areas of Osaka, but much lower than those in urban areas of Osaka. The proportion of the World Health Organization (WHO)-TEQ value contributed by 2,3,7,8-tetrachlorinated dibenzo-p-dioxin (TCDD) in Can Gio was approximately 30%, higher than the values in the other sample areas. These data suggest that residual sedimentary TCDD that originated from aerial spraying of Agent Orange occur in only low concentrations in Can Gio. The main contributors to WHO-TEQ values in Can Gio are natural sources, as in Hue. In contrast, commercial PCBs are the dominant contributors to WHO-TEQ values in Hanoi. In Osaka, agrochemicals used in rice cultivation, the incineration of solid waste, and commercial PCBs equally contributed to WHO-TEQ values at suburban locations. The dumping of incinerator-related materials and/or the inadequate management of commercial PCBs have resulted in significantly elevated WHO-TEQ values of 240-370 ng kg(-1)dw at urban locations in Osaka.

The chemistry of drying an aqueous solution of salts.

The fate of salts in drying aqueous solution was investigated. In the drying of acidic solutions, weak acid ions and chloride ions combine with protons and evaporate, depending on the proton concentration. In the drying of alkaline solutions, weak acid ions evaporate or remain as salts depending on the ratio of the concentrations of excess nonvolatile cations (the difference between concentrations of nonvolatile cation and nonvolatile anion) to volatile anions defined as DeltaCA. Under neutral and alkaline conditions, the fate of nitrite depends not only on DeltaCA but also on the drying speed. Nitrite is converted to N2, which is formed by reacting nitrite with ammonium (denitrification), NO and NO2, HONO and salts. In urban areas, nitrite and ammonium can appear in high concentrations in dew. HONO in the atmosphere affects the ozone concentration, but dew formation decreases the concentration of HONO. If chemical denitrification occurs, nitrogen species will decrease in the environment, and as a result, the ozone concentration could decrease. Ozone levels show an ozone depression when dew formed, and a Box model simulation showed an ozone depression by decreasing HONO levels.

Seasonal change in the atmospheric concentration of particulate polycyclic aromatic hydrocarbons in Ho Chi Minh City, Vietnam.

We analyzed atmospheric particulate polycyclic aromatic hydrocarbons (PAHs) in Ho Chi Minh City, Vietnam, for 19 months. The average concentrations of total PAHs at dry and rainy seasons were 4.28 +/- 2.83 and 15.71 +/- 8.21 ng m(-3), respectively. The use of motorcycles without catalytic converters, estimated to be main emission sources of PAHs, would be higher during the dry season. PAH concentrations show a negative correlation with sunshine duration (r = -0.51). Furthermore, the ratio of average PAH concentration in the dry season to that in the rainy season shows a positive correlation with photolytic half-life (r = 0.94). Thus, seasonal changes in PAH concentrations are attributable to their photolytic degradation.