Synthesis Reaction Time Research Articles

Evaluation of Processing Parameters in the Solvothermal Synthesis of Cu-Rich Tetrahedrites for Potential Application as Thermoelectric Materials

The major issue associated with thermoelectric performance is the low efficiency of power conversion. The main challenge is achieving a combination of high Seebeck coefficient, high electrical conductivity, and low thermal conductivity for a significantly improved figure of merit (ZT). Developing strategies include the production of tetrahedrites with an intrinsically low thermal conductivity through the solvothermal method, using a low reaction time and processing temperature. Here, we report on the preparation of Cu-rich tetrahedrites through the solvothermal technique at low temperature, providing a promising strategy for the preparation of materials with potential applications in thermoelectricity. The influence of synthesis reaction time and temperature on the morphological, structural, and thermoelectrical properties of the samples was investigated through different characterization techniques. Tetrahedrite synthesized at 180 °C for 19 h yielded a favorable ZT value of >0.43 and a thermal conductivity of 0.2 Wm−1 K−1 (423 K), related to the Sb3+/Sb5+ and Cu+/Cu2+ ratio, as was observed by XPS. The cubic tetrahedrite phase attributed to the (222) plane was confirmed by XRD and TEM and the intense Raman mode observed at 351 cm−1. SEM images revealed that nanotetrahedral Cu-rich tetrahedrites efficiently assemble into spherical structures, resulting in an improvement in the Seebeck coefficient (437 µVK−1) and electrical conductivity.

A porous phenolic resin sorbent for enhanced CO2 capture: Synthesis, optimization, and techno-economic analysis

Amidst rising global concerns about climate change, the capture and sequestration of carbon dioxide (CO2) from industrial emissions is becoming increasingly critical. In the present study, a phenolic resin-based porous polymer for CO2 capture is developed, offering a solution to the dual challenges of efficacy and cost in current carbon capture technologies. Optimization of synthesis parameters, including temperature, reaction time, and catalyst amount was performed using response surface methodology (RSM) to maximize surface area and economic benefits. The optimized polymer demonstrated a substantial CO2 adsorption capacity of 3.06 mmol/g at 273 K and 1 bar, with a specific surface area of 860 m2/g. An early-stage techno-economic analysis of sorbent synthesis was conducted, relating cost to sorbent quality and surface area. It was found that producing the polymer at low temperatures is more cost-effective, while synthesis at higher temperatures offers operational advantages. This research addresses a gap in existing literature by focusing on the sorbent material and its economic viability, paving the way toward the commercialization of such adsorption technology.

Facile synthesis of yellow emissive heteroatom doped carbon quantum dots fluorescent probe with superior quantum yield for fast-track ionic detection in aqueous media

In this work, heteroatom (B and N) doped carbon quantum dots (CQDs) materials were synthesized via facile hydrothermal method using o-phenylenediamine (o-PD) as a nitrogen source and 3-aminophenyl boronic acid (3APBA) as a boron source. The synthesis parameters were optimized and optimal synthesis temperature and reaction time were 260 °C and 2 h, respectively. The chemical structures were characterized using various techniques. The experimental results showed that B,N co-doped CQDs had the strongest fluorescence intensity when the weight ratio of 3APBA:o-PD was 3:1 and showed a phenomenal quantum yield of 59% with high selectivity for Fe3+ and Hg2+ ions, with quenching constants 1.25 × 103 M–1 and 8.3 × 103 M–1, respectively. The high fluorescence quenching was attributed to the photoinduced electron transfer phenomenon, making it suitable for fluorescent sensing materials. Cytotoxicity data revealed synthesized materials are safe for biomedical applications within a 1–10 µg/mL concentration.

Controllable preparation of polymetallic selenides and their application in high-performance supercapacitors

Transition metal selenides (TMSes) have garnered considerable interest as potential electrode materials for supercapacitors owing to their promising electrochemical properties, but the fabrication of intricate nanostructured electrodes utilizing these compounds still poses a formidable challenge. In this study, a ternary transition metal selenide nanomaterial Cu2MnSnSe4, which has rarely been reported, was successfully synthesized on nickel foam (NF) by a simple solvothermal method, and its electrochemical properties have not been concern by researchers. We systematically studied the electrochemical properties of the materials synthesized under different solvothermal reaction times, and discussed the relationship between reaction time and electrochemical properties. The unique porous surface architecture of the sea urchin-like nanosphere configuration in Cu2MnSnSe4 material grants it a significantly enhanced specific surface area and a proliferation of electrochemically active sites, surpassing those of other comparable materials. According to the synthesis reaction time from short to long, the materials were named Cu2MnSnSe4-1 (20h), Cu2MnSnSe4-2 (25h) and Cu2MnSnSe4-3 (30h), among which Cu2MnSnSe4-2 showed better electrochemical performance than the other two. Electrochemical results show that the prepared Cu2MnSnSe4-2 electrode possesses an outstanding specific capacitance of 930.6 mF cm−2 at 2 mA cm−2, good rate performance (92 %), and a capacitance retention rate is 67.57 % after 3000 cycles of charging and discharging. The asymmetric supercapacitor (ASC) exhibits a voltage window spanning 0–1.6 V, reaching an outstanding energy density of 0.076 mWh cm−2 at 1.47 mW cm−2. Remarkably, it maintains 129.63 % cycling stability even after enduring 5000 charge-discharge cycles. From the above results, it can be seen that Cu2MnSnSe4 material may be a promising electrode material with broad application prospects in the practical application of supercapacitors.

Green Synthesis of Silver Nanoparticles from Anthocyanin Extracts of Peruvian Purple Potato INIA 328-Kulli papa.

In this work, AgNPs were synthesized using an anthocyanin extract from Peruvian purple potato INIA 328-Kulli papa. The anthocyanin extract was obtained through a conventional extraction with acidified ethanolic aqueous solvent. This extract acted as both a reducing and stabilizing agent for the reduction of silver ions. Optimization of synthesis parameters, including pH, reaction time, and silver nitrate (AgNO3) concentration, led to the optimal formation of AgNPs at pH 10, with a reaction time of 30 min and an AgNO3 concentration of 5 mM. Characterization techniques such as X-ray diffraction (XRD) and dynamic light scattering (DLS) revealed that the AgNPs had a crystallite size of 9.42 nm and a hydrodynamic diameter of 21.6 nm, with a zeta potential of -42.03 mV, indicating favorable colloidal stability. Fourier Transform Infrared (FTIR) analysis confirmed the presence of anthocyanin functional groups on the surface of the AgNPs, contributing to their stability. Furthermore, the bacterial activity of the AgNPs was evaluated by determining the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). For E. coli, the MIC was 0.5 mM (0.05 mg/mL) and the MBC was 4.5 mM (0.49 mg/mL). Similarly, for S. aureus, the MIC was 0.5 mM (0.05 mg/mL) and the MBC was 4.0 mM (0.43 mg/mL). These results highlight the potential benefits of AgNPs synthesized from Peruvian purple potato anthocyanin extract, both in biomedical and environmental contexts.

Study on the tribological properties and corrosion resistance of the modified NiZnAl-LDH coating on anodic aluminum surface

The porous structure of anodized aluminum creates an opportunity for corrosive media to contact the aluminum substrate, resulting in diminished corrosion resistance and wear performance under adverse conditions. In this study, ternary hydrotalcite containing Ni, Zn, and Al elements, named NiZnAl-LDH, was synthesized on anodized aluminum surfaces using an in-situ growth method. The corrosion and wear resistance of the aluminum substrate were further enhanced by intercalation modification with sodium molybdate. The impact of synthesis parameters, including pH, reaction temperature, and reaction time, on the corrosion and wear resistance of the coating was investigated. Morphology, structure, and properties of the coating were analyzed. The results confirm the synthesis of NiZnAl-LDH modified with sodium molybdate intercalation. Electrochemical tests revealed that immersing NiZnAl-LDH in a sodium molybdate solution with a pH of 9.5 for 2.5 h at 35 °C resulted in a minimum self-corrosion current density of 4.131 × 10−8 A cm−2, significantly enhancing the corrosion resistance of the coating. Friction tests demonstrated a coating friction coefficient of 0.28, indicating excellent tribological performance. The discussed process parameters in this study provide valuable insights for the synthesis and application of LDH, expanding the application of aluminum alloys in the field of corrosion resistance and wear resistance.

Fluorescent nanocomposites of Ag nanoclusters grown in anionic polymer layers grafted to plastic substrate: Preparation, characterization and evaluation in Hg2+ sensing and white light generation

AbstractFluorescent noble metal nanoclusters (NCs) are emerging optical nanomaterials with properties similar to those of quantum dots. Their applications can be expanded by combining them with polymer matrices to obtain flexible and transparent light‐emitting nanocomposites. However, achieving highly fluorescent nanocomposites of this type remains challenging due to phase separation and aggregation of NCs in polymer hosts leading to a strong reduction in fluorescence efficiency. We address this key issue by covalently grafting a layer of a specifically selected matrix polymer onto a transparent plastic film and photochemically synthesizing the fluorescent metal NCs directly in the grafted layer. The surface‐grafted matrix polymer effectively captures the noble metal (Ag) ions, photo‐reduces them to atoms, acts as a capping ligand for the growing Ag NCs, and immobilizes them on the substrate surface. The Ag NCs were produced by both wet and dry synthesis, and effects of synthesis method, reaction time, and matrix polymer layer thickness on the fluorescence properties of the resulting nanocomposites were investigated and discussed. Importantly, the fluorescence intensity of these nanocomposite films is sensitive to submicromolar concentrations of aqueous Hg2+ that makes them useful as fluorescent sensing materials for selective and ultrasensitive detection of Hg2+ ions in water. Besides, the nanocomposite films obtained by the dry synthesis of NCs exhibit an intensive emission covering the whole green to red range of the visible spectrum and, hence, produce bright white light under illumination with a blue LED that makes them attractive as down‐conversion materials in one‐phosphor‐converted white LEDs.

Synthesis and characterization of novel fluorene–based green copolymers and their potential application in organic light-emitting diodes

Fluorene-benzothiadiazole (PFBT), commercially known as F8BT, and fluorene-thiophene (PFT) copolymers were synthesized by the Suzuki-Miyaura coupling polycondensation technique in the presence of a phase transfer catalyst (Aliquat 336). These novel copolymers showed higher molar masses, lower dispersivity, and thermal stability above 400 °C when synthesized under the modified (M) action of Aliquat 336 (F8BT-M). Polymer Light-emitting diodes (PLEDs) were assembled with the novel synthesized copolymers as the emitter layer. For F8BT-M, a maximum luminance of 327 cd/m2 was achieved, while a diode containing just the commercial F8BT resulted in only 210 cd/m2. As for the PFT copolymers, it was observed that for the Aliquat 336 sample synthesized in a 60h extended (E) (PFT-ME), the luminance of the PLED was much higher than that where the reaction time was 48 h (PFT-M), with a luminance of 168 cd/m2 and 54 cd/m2, respectively. Without Aliquat 336, the PFT copolymer did not show an electroluminescent signal. The improved electroluminescence in the copolymers with Aliquat 336 was attributed to the improved synthesis conditions, i.e., reaction time and catalytic system employed. The results suggest that copolymers with luminescent and morphological properties, more suitable for light-emitting devices, might be obtained with simple modifications during synthetic polycondensation reactions.

Remarkable surface area engineering of nanosheet-assembled hierarchical p-n Ag-loaded NiO-CeO2 heterostructure for superior ethanol sensing performance

The creation of ultra-high surface areas of heterostructures based on p-n NiO-CeO2 hierarchical nanospheres and nanosheet-assembled Ag-loaded p-n NiO-CeO2 is reported, employing a straightforward hydrolysis method. A porous NiO-CeO2 heterostructure was produced by an improved 24 h urea synthesis reaction time, while the addition of Ag nanoparticles reduced the grain size and produced a remarkable surface area of 472 m2 g−1 with a significant number of adsorption sites. For the 1.0 wt% Ag-loaded p-n NiO-CeO2 heterostructure, the optical band decreased from 3.01 to 2.37 eV. Photoluminescence experiments revealed larger surface defects for the 1.0 wt% Ag-loaded NiO-CeO2 heterostructure provided additional evidence for the reduced band. Therefore, compared to its counterparts, the 1.0 wt% Ag-loaded NiO-CeO2 demonstrated superior ethanol sensing, an excellent sensitivity of 0.81 ppm−1, and an ultra-low limit of detection of 1.23 ppb, towards ethanol vapor at 100 °C. The sensing mechanism illustrated that the greater gas-sensing characteristics were associated with the catalytic effect and electronic sensitization of AgO and the engineering of nanosheet-assembled hierarchical heterostructures with an extraordinary specific surface area providing sufficient active sites for the adsorption of ethanol gas, highly porous structures, and an interlayer gap, which accelerated the ethanol diffusion, leading to enhanced sensitivity and response speed of the sensor. Therefore, this study provided a simplistic approach to engineering the nanosheet-assembled hierarchical 1.0 wt% Ag/NiO-CeO2 microspheres with enhanced ethanol sensing performance.

Study on some factors affecting the process of synthetic MIL-100(Fe) by sonochemical synthesis method

The Metal-Organic Framework material MIL-100(Fe) has been synthesized into iron (III) based on a 1,3,5 benzentricacboxylic organic ligand (H3BTC) by sonochemical synthesis method using a solvent that is water. Factors that affect the synthesis of materials have been investigated including sonochemical synthesis power, reaction time, reaction rate and reactant concentration. Research results show that the suitable condition for the synthesis of MIL-100 (Fe) materials by the sonochemical method is the Fe3+:H3BTC=3:2 reaction ratio with sonochemical synthesis power of 1080W at a concentration of 0.1M for a period of 10 minutes for a reaction yield of more than 72%. The resulting material was subjected to X-ray diffraction analysis, and surface area BET. The synthesized material has a high surface area of up to 1033.8 m2/g and a pore volume of 0,79 cm3/g.

Continuous flow catalysis with CuBTC improves reaction time for synthesis of xanthene derivatives.

The copper-based metal-organic framework (MOF) CuBTC (where H3BTC = benzene-1,3,5-tricarboxylate) has been shown to be an efficient heterogeneous catalyst for the generation of 1,8-dioxo-octa-hydro xanthene derivatives, which are valuable synthetic targets for the pharmaceutical industry. We have applied this catalytic capability of CuBTC to a continuous flow system to produce the open chain form of 3,3,6,6-tetramethyl-9-phenyl-3,4,5,6,7,9-hexahydro-1H-xanthene-1,8(2H)-dione, a xanthene derivative from benzaldehyde and dimedone. An acid work-up after producing the open chain form of the xanthene derivative was used to achieve ring closure and form the final xanthene product. The CuBTC used to catalyze the reaction under continuous flow was confirmed to be stable throughout this process via analysis by SEM, pXRD, and FT-IR spectroscopy, elemental analysis, and XPS. The reaction to produce the open-chain form of the xanthene derivative produced an average yield of 33% ± 14% under the continuous flow (compared to 33% ± 0.12% of performing it under batch conditions). Based on the data obtained from this work, the continuous flow system required 22.5x less time to produce the desired xanthene derivative at comparable yields to batch reaction conditions. These results would allow for the xanthene derivative to be produced much faster, at a lower cost, and require less personal time while also removing the need to perform catalyst remove post reaction.

Ethanol monitoring gas sensor based on Co2P nanomaterials by a facile hydrothermal approach

Co2P nanocomposites were successfully synthesized via a facile hydrothermal method. The microstructure, morphology and elemental composition were examined by XRD, SEM, TEM and XPS. The effects of synthesis temperature and reaction time on the sensing properties of Co2P nanocomposites were analyzed. The Co2P sensor at 200[Formula: see text]C and 3 h reaction condition exhibited optimum sensitivity toward 100 ppm ethanol. In comparison with other gases, ethanol possesses good selective characteristics at optimal operating temperature of 160[Formula: see text]C, which greatly reduce energy consumption. The above results showed that Co2P nanocomposites have the potential application as an effective sensor for ethanol detection.

Eco-friendly synthesis of various tri-substituted imidazole derivatives by using a novel functionalized NCP@SiO3PrNHPrSiO3TiO2 under solvent-free conditions

In this research, a novel NCP@SiO3PrNHPrSiO3TiO2 nano catalyst has been designed, synthesized and fully characterized using various analytical techniques such as; XRD, FT-IR, SEM, EDS, BET and TG analyses. The catalytic activity of NCP@SiO3PrNHPrSiO3TiO2 was also employed for the synthesis of tri-substituted imidazoles via three-component condensation reactions of aldehydes, benzyl and NH4OAc under solvent-free conditions. This synthesis features environmentally benign, short reaction time, efficiency, and feasibility of large-scale synthesis compared to classical reactions.

Optimizing scalable synthesis of high-quality FeSe quantum dot in organic and aqueous states

A typical layered transition metal chalcogenide nanostructure, FeSe quantum dots (QDs) have recently begun to attract for their unique optical properties, i.e., multicolored excitation dependent emission (MEDE) property that breaks conventional Kasha - Vavilov rule as well as their potential applications in biological, and optical/electronic sensing and imaging. In this article, we present robust and optimized protocols for the scalable synthesis of FeSe QDs either in aqueous or organic syntheses. The synthesis conditions were carefully compared to obtain insistent synthesis parameters, e.g., solvents, precursors, stabilizers, pH, temperature, concentration, and reaction time after reproduction experiments. Furthermore, post-treatment procedures, i.e., phase transition and PEGylation are also optimized for further potential environmental and biological applications. In the scale-up experiments, a 5-liter reactor was utilized to produce approximately 55 g of QDs per batch, showing a robust optical MEDE property. The most optimized experimental condition reached quantum yield (QY) up to 60 % at the typical synthesis conditions of pH 9.0, 95 °C for 4 h of reflux, and the production yield of ca. 20%. These high fluorescent QDs can be potentially applied for biological fluorophores as well as next-generation QD displays.

Molten salt synthesis and antioxidation property of SiC‐coated mesocarbon microbeads

AbstractMesocarbon microbead (MCMB) is a prospective candidate as the raw material for nuclear graphite. However, the poor resistance to high‐temperature oxidation limits its application. Herein, a dense SiC coating was prepared by molten salt synthesis on the surface of MCMB to improve its antioxidation performance. The effect of molten salt synthesis reaction time on the phase composition, microstructure, and antioxidation performance of the SiC‐coated MCMB particles was investigated. A theoretical model was established to explain the SiC coating growth rule well, in conformity with the carbon vacancy diffusion mechanism in SiC coating. The SiC coating synthesized for 7 h with the thickness of .385 µm remarkably promoted the high‐temperature antioxidation property of MCMB. The kinetics analysis indicated that the SiC coating obstructed the oxygen diffusion effectively during the oxidation process. The as‐fabricated SiC‐coated MCMBs with good oxidation resistance show great promise for application in nuclear industry and other antioxidative fields.

Experimental and computational insights into the direct cyclopalladation of different unsymmetrical, yet closely related pincer ligands with thione sulfur donors

A series of three closely related unsymmetrical pincer ligands featuring thione sulfur donors have been derived from m-thiophosphorylated phenyl isothiocyanate to probe the effect of a spectator heteroatom in the flanking ring on their direct cyclopalladation. The reaction efficiency is shown to drastically increase on passing from a thionated thiazolidinone derivative to its oxazolidinone analog, and further to an imidazolidinone ligand. The investigations by IR and NMR spectroscopy as well as X-ray diffraction confirmed the realization of S,C,S'-type pincer coordination but did not reveal considerable differences in the molecular structures of the Pd(II) complexes obtained; however, the results of DFT calculations provided some valuable insights into the peculiarities of their formation. In addition, the possibility of solid-phase synthesis of the target pincer complexes upon thermally induced CH activation has been demonstrated. This methodology does not afford a significant yield enhancement over the conventional solution-based technique but appears to be highly advantageous in terms of the absence of a solvent at the synthesis step and reaction time.

Synthesis and Characterisation of Monolacunary Keggin Monovanado-deca-tungstophosphate and Its Complexes with Transition Metal Cations.

Five new complexes with metal cations (Mn2+, Fe3+, Co2+, Ni2+, and Cu2+) of monolacunary Keggin monovanado-deca-tungstophosphate, K8[PVW10O39]·15H2O, have been synthesised. The molar ratio of the combination between metal cations and K8[PVW10O39]·15H2O has been established to be 1:1, and its general molecular formulas were found to be: Kn[MPVW10O39(H2O)]·xH2O (n = 5 for M = Fe3+ and n = 6 for M = Mn2+, Co2+, Ni2+, and Cu2+). Optimal conditions for complexes' synthesis (pH, temperature, and reaction time) have been determined. The characterisation of K8[PVW10O39]·15H2O and of its compounds Kn[MPVW10O39(H2O)]·xH2O have been performed using AAS, TG-DTA-DTG, UV-VIS, IR, Raman, and powder XRD methods. In UV spectra, two maximums of absorption were obtained, at 200 and 250 nm, characteristic of Keggin polycondensate compounds. The coordination of cations Ni2+, Co2+, and Cu2+ through oxygen atoms from K8[PVW10O39]·15H2O in an octahedron system has been reflected with VIS spectroscopy. All these methods have proved the compositions and structures of K8[PVW10O39]·15H2O and Kn[MPVW10O39(H2O)]·xH2O, their similarity with other vanadotungstophosphates, and their achievements in the Keggin class. Additionally, all analysis methods have shown an increase in the degree of structural symmetry and the thermal stability of a polyoxoanion complex after attaching metal cations compared to the monolacunary, K8[PVW10O39]·15H2O.

Deep insights to explain the mechanism of carbon dot formation at various reaction times using the hydrothermal technique: FT-IR, 13C-NMR, 1H-NMR, and UV-visible spectroscopic approaches.

A well-explained mechanism for synthesizing carbon dots (CDs) is not yet explored and is still a subject of great debate and challenge. This study used a one-step hydrothermal method to prepare highly efficient, gram-scale, excellent water solubility, and blue fluorescent nitrogen-doped carbon dots (NCDs) with the particle size average distribution of around 5 nm from 4-aminoantipyrine. The effects of varying synthesis reaction times on the structure and mechanism formation of NCDs were investigated using spectroscopic methods, namely FT-IR, 13C-NMR, 1H-NMR, and UV-visible spectroscopies. The spectroscopic results indicated that increasing the reaction time affects the structure of the NCDs. As the hydrothermal synthesis reaction time is extended, the intensity of the peaks in the aromatic region decreases, and new peaks in the aliphatic and carbonyl group regions are generated, which display enhanced intensity. In addition, the photoluminescent quantum yield increases as the reaction time increases. The presence of a benzene ring in 4-aminoantipyrine is thought to contribute to the observed structural changes in NCDs. This is due to the increased noncovalent π-π stacking interactions of the aromatic ring during the carbon dot core formation. Moreover, the hydrolysis of the pyrazole ring in 4-aminoantipyrine results in polar functional groups attached to aliphatic carbons. As the reaction time prolongs, these functional groups progressively cover a larger portion of the surface of the NCDs. After 21 h of the synthesis process, the XRD spectrum of the produced NCDs illustrates a broad peak at 21.1°, indicating an amorphous turbostratic carbon phase. The d-spacing measured from the HR-TEM image is about 0.26 nm, which agrees with the (100) plane lattice of graphite carbon and confirms the purity of the NCD product with a surface covered by polar functional groups. This investigation will lead to a greater understanding of the effect of hydrothermal reaction time on the mechanism and structure of carbon dot synthesis. Moreover, it offers a simple, low-cost, and gram-scale method for creating high-quality NCDs crucial for various applications.

Synthesis optimization of ZrO2 nanostructures for photocatalytic applications.

This study aims to optimize the synthesis of semiconductor zirconia (ZrO2) nanoparticles for future photocatalytic applications in degradation of pollutants in wastewater under ultraviolet (UV) light. The synthesis procedure of ZrO2 nanoparticles was optimized by examining the effects of synthesis methods (ultrasound-assisted, hydrothermal method in an autoclave and conventional precipitation), reaction time (2, 6, 10, and 18 h), ambient pH (3, 7, 10, 13), and surfactant type (anionic, cationic, and non-ionic), on the particle size and crystal phase of the nanomaterial. The characterization of the synthesized samples was performed by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), energy-dispersive X-ray spectroscopy (EDS), high-contrast transmission electron microscopy (HR-TEM), and transmission electron microscope (TEM) analysis. Consequently, to synthesize ZrO2 nanoparticles with the smallest particle size and monoclinic/tetragonal phase, the experimental conditions were optimized as ultrasound-assisted synthesis method, pH 10, and 6 h reaction time without surfactant. Moreover, percentage yield, particle size, crystallinity, monoclinic and tetragonal volumes of ZrO2 nanostructures synthesized under optimized conditions were determined as 39.40%, approximately 9 nm, 46.77, 79%, and 21%, respectively. It has been determined that the particle sizes can be kept under control by controlling the phase composition of ZrO2 nanostructures by optimizing the synthesis parameters. Structural and morphological characterization results can be correlated to the photocatalytic application, showing the potential of this material for the photodegradation of organic dye pollutants.

Enhanced Biodiesel Synthesis via a Homogenizer-Assisted Two-Stage Conversion Process Using Waste Edible Oil as Feedstock

In this study, a homogenizer in conjunction with a two-stage process was utilized to facilitate biodiesel production from waste edible oil (WEO). This paper contributes to the improvement of the yield and the shortening of the reaction time for biodiesel synthesis. Sulfuric acid was used in the first stage which was the esterification of the free fatty acids (FFA) of the WEO; then the transesterification reaction of triglycerides took place in the second stage with an alkaline catalysis. The present investigation aimed to explore the parameters affecting the reactions, including homogenizer speed, alcohol/oil molar ratio, catalyst dosage, reaction temperature, and reaction time. Under the operating conditions of the first stage (the reaction temperature was 65 °C, the homogenizer speed was 8000 rpm, the methanol/oil molar ratio was 15:1, and the amount of sulfuric acid was 4 wt%), the acid value fell to below 2 mg KOH/g after 10 min. The best base-catalyzed conditions in the second stage were: homogenizer speed of 8000 rpm, NaOH catalyst concentration of 1 wt%, methanol/oil molar ratio of 9:1 (mol/mol), reaction temperature of 65 °C, and reaction time 10 min. Consequently, the conversion rate from WEO to biodiesel achieved 97% after only 20 min, in line with the EU EN14214 standard, which requires a biodiesel production rate of at least 96.5%.