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•The sulfonated carbon catalyst can be used in biodiesel production from waste cooking oil.•The biodiesel yield of carbon catalyst was reached to 90%.•The sulfonated carbon catalyst ...is interest as an environmentally benign and low-cost catalyst.
The application of an environmentally benign sulfonated carbon microsphere catalyst for biodiesel production from waste cooking oil was investigated. This catalyst was prepared by the sequential hydrothermal carbonization and sulfonation of xylose. The morphology, surface area, and acid properties were analyzed. The surface area and acidity of the catalyst were 86m2/g and 1.38mmol/g, respectively. In addition, the presence of sulfonic acid on the carbon surface was confirmed by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The catalytic activity was tested for biodiesel production from waste cooking oil via a two-step reaction to overcome reaction equilibrium. The highest biodiesel yield (89.6%) was obtained at a reaction temperature of 110°C, duration time of 4h, and catalyst loading of 10wt% under elevated pressure 2.3bar and 1.4bar for first and second step, respectively. The reusability of the catalyst was investigated and showed that the biodiesel yield decreased by 9% with each cycle; however, this catalyst is still of interest because it is an example of green chemistry, is nontoxic, and makes use of xylose waste.
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•The SO3H-KIT-6 catalyst allowed for a high conversion rate in the xylose dehydration reaction.•The 3-D structure of KIT-6 is important for overcoming the pore diffusion limit.•Both ...high xylose conversion and furfural selectivity were obtained in over 94%.
A highly efficient and selective dehydration of xylose to furfural was achieved using a sulfonic acid-functionalized, mesoporous silica KIT-6 type catalyst in a water/toluene biphasic system. The catalyst was prepared by co-condensation between tetraethoxysilane and 3-mercaptopropyl(methyl)dimethoxysilane, in the presence of poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (Pluronic, P123, Mw = 5800). The catalytic performance was then investigated with respect to the molar ratio of tetraethoxysilane and 3-mercaptopropyl(methyl)dimethoxysilane, as well as the reaction temperature and reaction time. The optimal catalyst was prepared using tetraethoxysilane and 3-mercaptopropyl(methyl)dimethoxysilane in a molar ratio of 0.8:0.2, giving both high xylose conversion and furfural selectivity (greater than 94%) at 170 °C for 2 h. In addition, the catalyst had a high turnover frequency and could be reused without treatment for up to three cycles. The high turnover frequency in the xylose dehydration reaction was attributed to the three-dimensional structure of the KIT-6 mesoporous silica that facilitates the diffusion of both the reactant and products in the xylose dehydration reaction.
The present study aimed to evaluate the effectiveness of using platelet-rich fibrin (PRF) as the apical matrix for the placement of MTA in nonsurgical endodontic therapy for teeth with periapical ...lesions and open apices.
Twelve teeth from eleven patients with periapical periodontitis and open apices were enrolled in the study. Nonsurgical endodontic therapy was performed with the PRF used as an apical barrier and the MTA manipulated as an apical plug for further thermoplasticized gutta percha in the remaining part of the root canal. Clinical signs and periapical digital radiographs were recorded and analyzed to evaluate the curing progress after periodical follow-ups of 1, 3, and 6 months. The horizontal dimension of the periapical lesion was determined, and the changes in the dimensions were recorded each time. The Friedman test was used for statistical analysis, with P < .05 serving as the threshold for determining statistical significance.
All patients had no clinical symptoms after the first month of treatment, with a significant reduction in the periapical lesion after periodical appointments.
PRF is an effective barrier when combined with MTA for the treatment of teeth with periapical periodontitis and open apices.
The atmospheric-pressure hydrodeoxygenation (HDO) of waste cooking oil (WCO) was investigated in a continuous fixed-bed reactor over a series of activated carbon (AC)-supported nickel phosphide ...catalysts with different initial Ni/P molar ratios (0.5–2.0) and nickel loading levels (1.16–38.90 mmol/g AC). The formation of the Ni2P phase on the AC, which was produced from commercial charcoal, as well as its structural and acidic properties was characterized by hydrogen-temperature programmed reduction (TPR), X-ray diffraction analysis, N2 adsorption–desorption measurements performed at −196 °C, and ammonia-temperature programmed desorption. The effects of the Ni/P molar ratio, nickel loading level, reaction temperature, and gas hourly space velocity (GHSV) on the catalytic activity were elucidated. The complete formation of the Ni2P phase on the AC was observed at a Ni/P ratio of 1.5, while smaller Ni2P crystallite sizes were observed at lower Ni/P ratios. In addition, it was observed that the acidity increased and the specific surface area decreased with an increase in the nickel loading level, presumably because nickel phosphate is not readily reduced to Ni2P. The 5.37-Ni2P/1.5-TPR catalyst (Ni loading level of 5.37 mmol/g AC and Ni/P molar ratio of 1.5) exhibited good activity and stability during the HDO of WCO. The high-quality deoxygenated product primarily consisted of n-alkanes at the moderately high temperature of 300 °C and GHSV of 2.33 min−1. Based on the results, we propose that the mechanism underlying the hydrotreatment of WCO involves hydrogenolysis, hydrodeoxygenation, dehydration-decarbonylation, and hydrogenation. To conclude, the synthesized Ni2P/AC catalyst could readily deoxygenate WCO at atmospheric pressure, producing n-paraffins as the primary component.
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•We studied deoxygenation of waste cooking oil (WCO) using Ni2P/AC catalysts.•Deoxygenation was performed at atmospheric pressure.•Ni2P/AC resulted in oxygen removal rate of 85% during WCO deoxygenation.•Ni2P phase has determining effect on oxygen removal efficiency.•Deoxygenation proceeds through hydrogenolysis and dehydration of triglycerides.
The disposal of cigarette filters (CF) consisted of non-biodegradable cellulose acetate gives rise to severe environmental contamination. In an endeavor to transfer destructive refuse to wealth, ...hence, we prepare the silver nanowires (AgNWs) decorated on the cellulose microfibres derived from the CF skeleton by the dip-coating method to ameliorate the through-plane thermal conductivity and electromagnetic interference shielding effectiveness (EMI SE) of epoxy composites. The resultant composites reach the through-plane thermal conductivity of 1.71 W·m−1·K−1 at the AgNWs loading of 2.8 vol%. The AgNWs@CF10/epoxy composite reveals the EMI SE value of 40 dB. The heat-dissipating evaluation indicates the outstanding rate of heating or cooling of the composite owning to the excellent heat transferability. This facile approach paves the way for the fabrication of a highly thermoconductive material with excellent EMI shielding for thermal-management applications.
STEM education, which stands for science, technology, engineering, and mathematics, is an important educational model in primary and secondary schools, including elementary schools. STEM education is ...being emphasized in many countries around the world. In Southeast Asia, the current state of STEM education is quite diverse and there is a discrepancy between countries. This study focuses on analyzing quantitative scientific indicators based on 490 publications on STEM education in elementary schools from 2000 to December 2022 in the Scopus database. The data is analyzed by bibliometrics software Biblioshiny and VOSviewer on the collaboration network between scientists in the field of STEM education in elementary schools, countries with the most publications, emerging keywords and related keywords, as well as research trends on STEM education in elementary schools for Southeast Asian countries. The results of the study show that publications on STEM education in elementary schools in Southeast Asian countries started to be studied from 2008 and have been increasing rapidly; scientific papers published in some high-impact factor journals; the countries with the most publications are not necessarily Southeast Asian countries, mainly in the Americas, Europe, Asia, with Indonesia being the only Southeast Asian country in the top-5 countries with the most publications on this research trend. Based on the analysis, the article proposes some directions for STEM education research in elementary schools in Southeast Asian countries to achieve high effectiveness in training at elementary schools.
Compounds containing benzimidazole moiety occupy privileged chemical space for discovering new bioactive substances. In continuation of our recent work, 69 benzimidazole derivatives were designed and ...synthesized with good to excellent yields of 46–99% using efficient synthesis protocol i.e. sodium metabisulfite catalyzed condensation of aromatic aldehydes with o-phenylenediamines to form 2-arylbenzimidazole derivatives followed by N-alkylation by conventional heating or microwave irradiation for diversification. Potent antibacterial compounds against MSSA and MRSA were discovered such as benzimidazole compounds 3k (2-(4-nitrophenyl), N-benzyl), 3l (2-(4-chlorophenyl), N-(4-chlorobenzyl)), 4c (2-(4-chlorophenyl), 6-methyl, N-benzyl), 4g (2-(4-nitrophenyl), 6-methyl, N-benzyl), and 4j (2-(4-nitrophenyl), 6-methyl, N-(4-chlorobenzyl)) with MIC of 4–16 μg mL−1. In addition, compound 4c showed good antimicrobial activities (MIC = 16 μg mL−1) against the bacteria strains Escherichia coli and Streptococcus faecalis. Moreover, compounds 3k, 3l, 4c, 4g, and 4j have been found to kill HepG2, MDA-MB-231, MCF7, RMS, and C26 cancer cells with low μM IC50 (2.39–10.95). These compounds showed comparable drug-like properties as ciprofloxacin, fluconazole, and paclitaxel in computational ADMET profiling. Finally, docking studies were used to assess potential protein targets responsible for their biological activities. Especially, we found that DHFR is a promising target both in silico and in vitro with compound 4c having IC50 of 2.35 μM.
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•Activated porous carbon microsphere was synthesized from biomass derived xylose.•A controllable porous structure was fabricated by sequential base-acid activation.•The large surface ...area and acid site on surface enhanced the specific capacitance.
Sequential potassium hydroxide (KOH)-phosphoric acid (H3PO4) activation was applied to biomass waste to fabricate activated carbon microspheres (mCMs) with a controllable porous structure. Carbon microspheres (CMs) were first synthesized from xylose using a bottom-up approach of hydrothermal carbonization. Sequential KOH and H3PO4 activation was applied to the CMs in a KOH-carbon solid reaction. This created pores, which were further enlarged by adsorption of H3PO4. The KOH:carbon (C) and H3PO4:C molar ratios, and the H3PO4 heating rate and activation time, were varied to investigate the effect on average pore size and pore distribution. A uniform porous structure was formed without destruction of the spherical shape, and an almost 700-fold increase in surface area was obtained over the non-activated CMs. Following activation with H3PO4, phosphorous groups were found to be present at the surface of the carbon microspheres. The mCM was tested as a supercapacitor electrode and was shown to have a maximum specific capacitance of up to 277F g−1. A Ragone plot showed the maximum power density to be 173.88 W Kg−1. This increased specific capacitance was attributed to the increase in surface area and the presence of phosphorous-containing acid sites on the material surface.
This study investigated the production of natural nitrogen-doped carbon from expired fresh milk for use in a supercapacitor electrode. The material was prepared by hydrothermal carbonization followed ...by sequential KOH–H3PO4 activation. Carbon modified with KOH at a ratio of 1:1 had the largest Brunauer-Emmett-Teller surface area of 465 m2/g. Furthermore, the presence of surface functional groups played an important role in determining the specific capacitance. The highest specific capacitance of 186.3 F/g was obtained from carbon modified with C:KOH at 1:1 and 50 wt% H3PO4. An electrochemical impedance study suggested that charge storage resembled a modified Randles circuit. Carbon derived from expired milk and exposed to sequential KOH and H3PO4 modification was shown to be a promising candidate material for use as electrodes in electric double-layer supercapacitors, while simultaneously reducing food waste.
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•Carbon from expired fresh milk can be used in a supercapacitor electrode.•The specific capacitance was higher than carbon derived from other forms of waste.•Specific capacitance was affected by surface area and surface functional groups.•Natural doped heteroatoms played a key role in improving capacitance.•Specific capacitance (186.3 F/g) was higher than that of carbon from other waste.
In this work, a gelatin/carboxymethyl cellulose (CMC) base formulation was first modified by using different hydrocolloids like oxidized starch (1404), hydroxypropyl starch (1440), locust bean gum, ...xanthan gum, and guar gum. The properties of modified films were characterized using SEM, FT-IR, XRD and TGA-DSC before selecting of best-modified film for further development with shallot waste powder. SEM images showed that the rough or heterogeneous surface of the base was changed to more even and smooth depending on the hydrocolloids used while FTIR results demonstrated that a new NCO functional group non-existent in the base formulation was found for most of the modified films, implying that the modification led to the formation of this functional group. Compared to other hydrocolloids, the addition of guar gum into the gelatin/CMC base has improved its properties such as better color appearance, higher stability, and less weight loss during thermal degradation, and had minimal effect on the structure of resulting films. Subsequently, the incorporation of spray-dried shallot peel powder into gelatin/CMC/guar gum was conducted to investigate the applicability of edible films in the preservation of raw beef. Antibacterial activity assays revealed that the films can inhibit and kill both Gram-positive and Gram-negative bacteria as well as fungi. It is noteworthy that the addition of 0.5% shallot powder not only effectively decelerated the microbial growth but also destroyed
E. coli
during 11 days of storage (2.8 log CFU g
−1
) and the bacterial count was even lower than that of uncoated raw beef on day 0 (3.3 log CFU g
−1
).
In this work, a gelatin/carboxymethyl cellulose (CMC) base formulation was first modified by using different hydrocolloids like oxidized starch (1404), hydroxypropyl starch (1440), locust bean gum, xanthan gum, and guar gum.
