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The heavy utilization of fossil fuels and efforts to reduce carbon footprint worldwide led to the development of biofuels. Therefore, this paper investigates the kinetic study for the catalytic cracking reaction of refined rubber seed oil (RSO) for bio gasoline production using Cu/ZSM5 catalyst. The reaction was carried out at 440 ᵒC and at atmospheric condition within the WHSV range of 1.5–3.5 h−1 in a fixed bed reactor. The kinetic rate constants were estimated based on 3, 4 and 5 lumped models sequentially. In the 3-lump model, the RSO was converted mostly to organic liquid product (OLP) and only forming some undesired gas and coke. Both refined RSO and OLP contributed to the formation of gas and coke products in the 4-lump model. In the 5-lump model, the RSO and OLP both favoured gasoline production. The absence of gaseous product suggests that no secondary cracking reactions occurred in gasoline fractions, but coke deposition was formed due to condensation. The high R2 squared values suggest that the predicted model data was in good agreement with the experimental data.

Conventional oligopeptide synthesis techniques involve environmentally harmful procedures and materials. In addition, the efficient accumulation of oligopeptides under Hadean Earth environments regarding the origin of life remains still unclear. In these processes, the formation of diketopiperazine is a big issue due to the strong inhibition for further elongation beyond dipeptides. Hydrothermal media enables environmentally friendly oligopeptide synthesis. However, hydrothermal oligopeptide synthesis produces large amounts of diketopiperazine (DKP), due to its thermodynamic stability. DKP inhibits dipeptide elongation and also constitutes an inhibitory pathway in conventional oligopeptide synthesis. Here, we show an efficient pathway for oligopeptide formation using a specially designed experimental setup to run both thermal and non-thermal discharge plasma, generated by nano-pulsed electric discharge with 16-23 kV voltage and 300-430 A current within ca. 500 ns. DKP (14%) was converted to dipeptides and higher oligopeptides in an aqueous solution containing alanine-DKP at pH 4.5, after 20 min of 50 pps thermal plasma irradiation. This is the first study to report efficient oligopeptide synthesis in aqueous medium using nano-pulsed plasma (with thermal plasma being more efficient than non-thermal plasma) via DKP ring-opening. This unexpected finding is implicative to evaluate the pathway how the oligopeptides could have accumulated in the primitive Earth with high-energy plasma sources such as thunder as well as to facilitate the green synthesis of oligopeptides.

Lead halide perovskite quantum dots (QDs) have attracted significant attention because of their excellent optoelectronic properties. In this study, we focused on reversibly modulating the photolumi...

Rutin is a flavonoid glycoside, well-known for its antioxidant, anticarcinogenic, and cardioprotective properties. However, it exhibits lower bio absorptivity and bioactivity than its aglycon form, quercetin. Although liquid acid catalysts are conventionally utilized to obtain quercetin via rutin hydrolysis, the neutralization procedure is a major disadvantage owing to the added cost. In this study, graphene oxide (GO) was used as an alternative catalyst under microwave (MW) irradiation, owing to its easy separation from the reaction solution and high MW absorptivity, resulting in improved thermal efficiency. Two types of GOs were prepared (GO-HU using Hummer's method and GO-TO using Tour's method), and their catalytic performance for rutin hydrolysis was evaluated and compared. The highest rutin conversion (98.8 %) and quercetin yield (81.9 %) were obtained at 180 °C when the reaction was conducted for 15 min using 3 mg of GO-TO and 2400 ppm of initial rutin concentration in 50 mL of water.

Water electrolysis is an environment-friendly process of producing hydrogen with zero-carbon emission. Herein, we studied the water vapor electrolysis using a proton-conducting membrane composed of graphene oxide (GO) nanosheets intercalated with cations (Al3+ and Ce3+). We examined the effect of cation introduction on the physical and chemical structures, morphology, thermal and chemical stabilities, and the proton conductivity of stacked GO nanosheet membranes by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), X-ray photoemission spectroscopy (XPS), Raman spectroscopy, atomic force microscopy (AFM), dynamic light scattering (DLS), thermogravimetric-differential thermal analysis (TG-DTA), and electrochemical impedance spectroscopy (EIS). Concentration cell measurements revealed that the cation-modified membranes are pure proton conductors at room temperature. The proton conductivity of a GO membrane was much improved by cation modification. The cation-modified GO membranes, sandwiched with Pt/C electrodes as the cathode and anode, electrolyzed humidified air to produce hydrogen at room temperature, indicating the feasibility of this carbon-based electrochemical device.

Lead-halide perovskite quantum dots (QDs) have been intensively studied, owing to their excellent optical properties. Herein, the photoluminescence (PL) emission of perovskite QDs was controlled by...

5-Hydroxymethylfurfural (HMF) is a promising building block for the production of biofuels and fine chemicals. While HMF can be derived from biomass, specifically sugars, its synthesis typically re...

Objective and Method: In this present research, a simple hydrothermal implantation technique for synthesizing N,S co-doped reduced graphene oxide (NS-r-GO) has been presented in which thiourea was used as a single-source precursor of N and S atoms. Results: Maximum N and S atoms, with an atomic percentage of 3.50 and 7.50 (at.%), were achieved in the GO matrix at the reaction temperature of 250°C. Introduction of N and S atoms into the GO lattice was confirmed by X-ray photoelectron spectroscopy (XPS). Different chemical bonds such as –C– S–C, C=O, N–O, and C–N–C have been suggested from the corresponding C1s, N1s, O1s, and S2p high-resolution XPS spectral analyses. Conclusion: FT-IR measurement also confirmed the presence of different functional groups as well as the formation of different bonds such as –OH, –N–H, –C=O, –C–OH, and C-S. XRD and Raman spectroscopy analyses confirmed the defects structures that arose from the penetration of N and S atoms into the GO lattice.

In this study, the esterification reaction of oleic acid (OA) with methanol was investigated in the presence of a sulfonated hydrothermal carbon-based catalyst under microwave irradiation. The reaction conditions were optimized using response surface methodology based on a central composite design. Three following variables were studied: methanol to OA molar ratios (2.5:1–7.5:1), reaction time (50–70 min) and catalyst loading (2–5 wt.%) to provide a statistical model with the coefficient of regression (R2) of 0.9407. Based on the model, the optimum OA conversion of 95.6% was predicted at 5.8:1 methanol to OA molar ratio, 60 min and 3.05 wt.% catalyst loading. The experimental validation indicated that the model gave a good prediction of OA conversion (2.8% error). Furthermore, the reaction was found to be reasonably described by the pseudo-first order kinetics. The dependency of the reaction rate constant on temperatures gave a value of the activation energy of 64 kJ/mol. Copyright © 2020 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Perovskite lead halide quantum dots (QDs) have attracted much attention because of their excellent optical properties such as high photoluminescence (PL) quantum yields, narrow Full Width at Half M...

Semiconducting metal oxide-based gas sensors are an attractive option for a wide array of applications. In particular, sensors based on WO3 are promising for applications varying from indoor air qu...

Proton conduction in graphene oxide (GO) allows for a variety of electrochemical applications. This study focuses on the application of a stacked GO nanosheet membrane for water vapor electrolysis....

Carbon quantum dots (CQDs; luminescent carbon nanoparticles, size < 10 nm) have attracted much attention with respect to their eco-friendliness and multi-functionality. The solvent-dependent photoluminescence of CQDs has been well investigated to optimize the synthesis process and homogeneous dispersion. Although some alkan-1-ol solvents, such as ethanol, have been well utilized empirically as good solvents when synthesizing highly photoluminescent CQDs, the role of alkan-1-ol solvents, particularly long-chain alkan-1-ols (e.g., 1-nonanol, 1-decanol), has not yet been clarified. Herein, we demonstrate a method for the synthesis of strongly yellow emitting CQDs using solvothermal treatment and elucidate the role of alkan-1-ol solvents in the photoluminescence of CQDs. These CQDs have been characterized using theoretical calculations, ex situ morphological observations using transmission electron microscopy (TEM) and dynamic light scattering (DLS), and 500 MHz 1H nuclear magnetic resonance (NMR) and 13C NMR spectroscopy. A comparative study of alkan-1-ol solvents suggests a mechanism for the agglomeration and aggregation of carbon precursors, intermediates, and CQDs, which is expected to lead to further synthesis studies on highly luminescent CQDs.

Averrhoa bilimbi fruit has been studied to find out a possible source of bioactive compounds against antimicrobial and cytotoxic activity. To achieve this goal, total phenolic content and total flavonoid content, antioxidant, antimicrobial and cytotoxic activities of five different fractionates such as methanolic crude, petroleum ether, chloroform, ethyl acetate and water fraction of A. bilimbi were investigated by UV-vis spectrophotometry, disc diffusion and brine shrimp lethality test methods simultaneously. Other phytochemicals viz. carbohydrate, tannins, polyphenols, glycosides, etc. were also screened out by conventional test methods concurrently. Total phenolic contents and total flavonoid contents were found to be ranging from 3.807-262.129 mg GAE g–1 and 67.848-1159.061 mg CE g–1, respectively, in all the analyzed fractions. DPPH free radical scavenging activity revealed distinctive IC50 value of 5.63 and 10.26 μg mL–1 in the chloroform and ethyl acetate extractives. Fractionates of petroleum ether and methanolic crude also presented strong cytotoxic potential with the LD50 values of 8.89 and 20.3 μg mL–1 in the brine shrimp lethality bioassay test. Petroleum ether and ethyl acetate fractions exhibited good antimicrobial activity with the zone of inhibition against Bacillus cereus (11 mm and 14 mm) and Escherichia coli (7 mm and 9 mm). Finally, it has been recommended that A. bilmbi fruit might be an effective source of bioactive compounds against antimicrobial and cytotoxic activity as well as antioxidant with potent radical scavenging activity.

This chapter focuses on the hydrothermal liquefaction of algal biomass to bio-oil. This includes discussion of the physical properties of water under subcritical conditions that are relevant to the liquefaction of biomass components—lignocellulose, proteins, and lipids. This also covers process intensification approaches such as the use of microwave irradiation and addition of supercritical carbon dioxide for liquefaction rate enhancement, improvement of yield, and product quality. The application of carbon-based and metal oxide-based catalysts is discussed together with the parameters such as temperature, salinity, and nutrient concentration that affect the reaction. Lastly, some reaction mechanisms involved in the process are also covered.

Perovskite lead halide quantum dots (pQDs) are a class of interesting nano-emitters that have gathered great attention because of their superior optoelectronic properties. Here we report on the pre...

Palm kernel shell was liquefied using sub- and supercritical water at 330–390 °C and 25 MPa for different reaction times. The overall kinetics of the liquefaction based on the conversion of biomass was analyzed using kinetic equation adopted from the literature, and the kinetic parameters were estimated from the evaluation of the kinetic equation. In this study, the rate constant (k) increased from 0.43 to 0.49 s−1 with reaction temperature from 330 to 390 °C. The relationship of rate constant (k) and temperature agreed reasonably well with the Arrhenius equation. The activation energy (E) and pre-exponential factor (A) values for the liquefaction process were estimated to be 6.70 kJ/mol and 1.65 s−1, respectively. In addition, the experimental bio-oil yields with respect to reaction time were well-fitted using the modified Reverchon-Sesti Osseo equation.

Recently, extraction of impurities such as oligomers, solvent residues, and side products that are present during the production of polyethylene (PE) have attracted attention. These impurities increase the toxicity of PE and may even contaminate the packed products. Therefore, polymer industries put an increasing effort to remove them. In recent times, supercritical carbon dioxide (SCCO2) extraction has gained much attention because CO2 is considered to be cleaner, less expensive, and more environment-friendly than other materials used in the conventional methods. In the present study, aliphatic hydrocarbons such as eicosane, tetracosane, nonadecane, that are present on the surface of low-density polyethylene (LDPE) were extracted using SCCO2. Extraction condition of 22 MPa at 60 °C for 4 h was demonstrated to have better extracting capabilities than Soxhlet extraction. Thermogravimetric-differential thermal analysis (TG-DTA), X-ray diffraction (XRD), and field emission scanning electron microscopy (FE-SEM) demonstrated that LDPE properties were not altered.

This study presents a synergistic catalytic system using the combination of Bronsted hydrothermal carbon-based acid (HTCG-SO3H) and Lewis acid catalysts for one-pot conversion of cellulose to levulinic acid (LA). Chromium chloride (CrCl3), among a number of other Lewis acidic metal chlorides, was found to give the highest LA yields, and was therefore used in combination with the HTCG-SO3H, for cellulose conversion to LA. With the appropriate amount of HTCG-SO3H, the formation of side products could be reduced, resulting in improved selectivity of LA. Compared with that obtained by CrCl3 alone, at 5 wt % HTCG-SO3H, 0.015 M CrCl3, 200 °C and 5 min reaction time, the LA yield was considerably enhanced from 30 wt % to 40 wt %. Since HTCG-SO3H is a heterogeneous catalyst that can be easily prepared from biomass at moderate temperature, its use in such combined catalyst system offers economic and environmental benefits, thus making large-scale implementation of such process potentially feasible.

Highly luminescent silica-coated CsPbX3 quantum dots (QDs) with good photostability were synthesized and coupled with photochromic diarylethene to modulate the QDs’ photoluminescence (PL). Upon successive UV and visible light irradiation, the PL emission from the silica-coated CsPbX3 QDs was repeatedly quenched and restored, demonstrating the promising feasibility of the QD/diarylethene-based photoswitches.

In this study, the influence of the oxygen partial pressures (PO2) on the sensor response to H2 of SnO2 resistive-type gas sensors was evaluated under various humid atmospheres. SnO2 nanoparticles of 8–15 nm in diameter were synthesized using a hydrothermal technique followed by calcination at 600°C. Additionally, a large amount of pores with diameters greater than 10 nm was confirmed in the nanoparticles. The electrical resistance at 350°C was decreased with decreasing the PO2, and the electrical resistance in the presence of 10 ppm H2 was much smaller than that in the absence of H2 in both dry and humid atmospheres regardless of the PO2. Furthermore, the sensor response to 10 ppm H2 at 350°C increased with decreasing PO2 in both dry and humid atmospheres. Thus, decreasing the amount of oxygen adsorption enhanced the effect of rooted hydroxyl formation on the SnO2 surface through a combustion reaction between H2 and adsorbed oxygen and improved the sensor response to H2. These results are important for understanding the fundamental mechanisms of gas detection and for the material surface design of highly sensitive resistive-type semiconductor gas sensors.

In recent years, environmental problems such as production of industrial waste are getting worse in Japan. In particular, food processing residues are typically disposed of by spending a large amount of money. This paper studied the treatment of two by-products from vinegar production (rice bran and sake lees) using subcritical water and analyzing the extracted solution for functional ingredients. The results from sake lees showed that an operating temperature of 180 °C and a reaction time of 30 min solubilized 85% of the nitrogen-containing component (mainly protein) from the raw material into water-soluble peptides. When rice bran was used as the raw material the solubilization rate of the nitrogen-containing components was greatly decreased at a reaction temperature of 190 °C or higher. It was shown that calcium in the raw material caused the formation of water-insoluble complexes with amino acids and ammonia such as CaCN2. Subcritical water treatment was shown to be a useful technique to recover useful water-soluble components from residual solid biomass.

The synergy of sulfonated hydrothermal carbon and microwave (MW) irradiation was applied for the esterification of oleic acid with methanol (MeOH) to produce biodiesel. The effects of temperature, reaction time, ratio of oleic acid to methanol, and catalyst loading were investigated at a fixed MW power of 400 W. The addition of hexane, serving as a co-solvent and separator, was also investigated. The optimum conditions for the proposed process were oleic acid-to-methanol molar ratio of 1:5 and hexane-to-methanol ratio of 0.5 (v/v) in the presence of a 5 wt % catalyst, at 100 °C for 60 min, obtaining a 97% yield of oleic acid methyl ester. The addition of slight amounts of hexane resulted into an eightfold reduction in the amount of MeOH needed to obtain a yield above 90%, which normally required a MeOH-to-oil ratio of 40:1. This proposed novel approach could provide a more cost-effective method for the esterification of oil to produce biodiesel, that is, reactive separation utilizing carbon-based catalysts under MW irradiation.

Catalytic cracking of vegetable oil mainly processed over zeolites, and among all the zeolites particularly HZMS-5 has been investigated on wide range for renewable and clean gasoline production from various plant oils. Despite the fact that HZSM-5 offers a higher conversion degree and boost aromatics yield, the isomerate yield reduces due to high cracking activity and shape selectivity of HZSM-5. Hence, to overcome these problems, in this study the transition metals, such as nickel and copper doped over HZSM-5 were tested for its efficiencies to improve the isoparaffin compounds. The catalysts were screened with linoleic acid in a catalytic cracking reaction conducted at 450 ᵒC for 90 min in an atmospheric condition in batch reactor. Then, the gasoline composition of the organic liquid product (OLP) was analysed in terms of paraffin, isoparaffin, olefin, naphthenes and aromatics (PIONA). The results showed that Cu/ZSM-5 produced the highest liquid yield of 79.1%, at the same time reduced the production of gas and coke to 18.8% and 0.7%. Furthermore, the desired isoparaffin composition in biogasoline increased from 1.6% to 6.8% and at the same time reduced the oxygenated and aromatic compounds to 15.4% and 59.7%, respectively. The linoleic acid as model compound of rubber seed oil, in the catalytic cracking reaction provides a clearer understanding of the process. Besides, the water gas shift (WGS) reaction in catalytic cracking reaction provides insitu hydrogen production to saturate the branched olefin into the desired isoparaffin and the aromatics into naphthenes.

Doping ${\mathrm{V}}_{2}{\mathrm{O}}_{3}$ with Ti stabilizes the corundum paramagnetic metallic phase and restricts the transition to the monoclinic antiferromagnetic insulating phase at lower temperatures. In this study, we investigated the dependence of phase stability on Ti concentration for ${\mathrm{V}}_{2}{\mathrm{O}}_{3}$ nanocrystals as small as 20 nm. Ti doping of several percent induces a high-temperature insulating phase preserving the magnetic transition without the crystal symmetry change. The emergence of the insulating phases, which are peculiar to this crystal size, can be attributed to the enhancement of the on-site Coulomb interaction $U$ and increased mixing between ${a}_{1g}$ and ${e}_{g}^{\ensuremath{\pi}}$ states accompanied by characteristic lattice parameter changes in the high Ti doping region.