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The study aimed to analyze how variations in TiO2/NaOH mole ratio, stirring time, and washing pH affect the formation process of TiO2 nanotubes (TNT) through one-stage hydrothermal. TiO2 micro powder was mixed with 10M NaOH with the variation of TiO2/NaOH mole ratio (0.005:1, 0.015:1, and 0.025:1). The hydrothermal process was then conducted at 130 ℃ in an autoclave for 24 h with stirring time intervals of 10, 15, and 20 minutes/h. The samples underwent 1 M HCl washing to produce diverse pH variations (pH = 2, pH = 3, and pH = 4). Characterization of the synthesized TNT was conducted using SEM, TEM, XRD, SAA, and UV-Vis DRS. After analysis of the micrographs revealed the fiber shape of the particles, it was noted that TNT particle size increased due to smaller mole ratio variation, longer stirring, and lower pH. The synthesized TNT featured a tubular morphology with an inner diameter of 3.30 nm, an outer diameter of 6.15 nm, and a wall thickness of 1.64 nm. The increase in sodium titanate content of the sample results in an increase in surface area. Additionally, small pore size contributes towards an increase in both surface area and total pore size. The best result of the TNT photocatalytic test against diazinon can be observed in the fifth sample with a mole ratio of 0.025:1, stirring time of 20 minutes/h, and washing pH of 3. With an irradiation time of 210 min, diazinon degradation reached 90%. Copyright © 2023 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).

Esterification of acetic acid with methanol to produce methyl acetate and water has been studied in a continuous packed bed catalytic reactive distillation. The key challenge is the startup method of the experiments fora continuous reactive distillation as well as reactive zone height selection. In the present study, the effect of various operating conditions on the methyl acetate composition (mole fraction) is studied. Indion 180 ion-exchange resin solid catalyst is used in the reactive zone. The catalyst is immobilized by using a novel equivalent Katapak-S in the reactive section. Experiments were performed under different operating conditions to find the high purity methyl acetate product in the distillation. The experiments were performed for various conditions like total feed flow rate, reboiler temperature, reflux ratio, methanol to acetic acid mole ratio and catalyst loading with the time. The experiments were carried out till the system reaches to the steady state under different conditions. The maximum methyl acetate concentration is obtained at 80 °C reboiler temperature, 2.01 reflux ratio, 16.3 g/min flow rate, 60 g catalyst loading and 1 mol ratio of methanol to acetic acid. The highest purity of methyl acetate obtained under optimal condition is 95 % by mole. [ABSTRACT FROM AUTHOR]

As the world grapples with the urgent need for sustainable energy sources, biodiesel production from waste cooking oil (WCO) has emerged as a promising solution. This paper delves into the comprehensive journey of biodiesel synthesis, from feedstock selection and pretreatment to catalysis, post-treatment, and its effects on diesel engines. The role of catalysts, including the exploration of nanoscale catalysts and enzymatic approaches, is scrutinized for efficiency and cost-effectiveness. Biodiesel’s character is revealed through rigorous characterization techniques, shedding light on properties crucial for engine performance. Additionally, the paper investigates the production of oxygenated fuel additives from by-products like glycerol and their impact on combustion and emissions. In conclusion, biodiesel, particularly when derived from WCO, emerges as a compelling alternative to conventional diesel, with the potential to reshape the future of sustainable transportation fuels and mitigate environmental challenges. [ABSTRACT FROM AUTHOR]

The study aimed to analyze how variations in TiO2/NaOH mole ratio, stirring time, and washing pH affect the formation process of TiO2 nanotubes (TNT) through one-stage hydrothermal. TiO2 micro powder was mixed with 10M NaOH with the variation of TiO2/NaOH mole ratio (0.005:1, 0.015:1, and 0.025:1). The hydrothermal process was then conducted at 130 °C in an autoclave for 24 h with stirring time intervals of 10, 15, and 20 minutes/h. The samples underwent 1 M HCl washing to produce diverse pH variations (pH = 2, pH = 3, and pH = 4). Characterization of the synthesized TNT was conducted using Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM), X-ray Diffraction (XRD), Surface Area Analyzer (SAA), and Ultra Violet Visible Diffuse Reflectance Spectroscopy (UV-Vis DRS). After analysis of the micrographs revealed the fiber shape of the particles, it was noted that TNT particle size increased due to smaller mole ratio variation, longer stirring, and lower pH. The synthesized TNT featured a tubular morphology with an inner diameter of 3.30 nm, an outer diameter of 6.15 nm, and a wall thickness of 1.64 nm. The increase in sodium titanate content of the sample results in an increase in surface area. Additionally, small pore size contributes towards an increase in both surface area and total pore size. The best result of the TNT photocatalytic test against diazinon can be observed in the fifth sample with a mole ratio of 0.025:1, stirring time of 20 minutes/h, and washing pH of 3. With an irradiation time of 210 min, diazinon degradation reached 90%. [ABSTRACT FROM AUTHOR]

As the world grapples with the urgent need for sustainable energy sources, biodiesel production from waste cooking oil (WCO) has emerged as a promising solution. This paper delves into the comprehensive journey of biodiesel synthesis, from feedstock selection and pretreatment to catalysis, post-treatment, and its effects on diesel engines. The role of catalysts, including the exploration of nanoscale catalysts and enzymatic approaches, is scrutinized for efficiency and cost-effectiveness. Biodiesel’s character is revealed through rigorous characterization techniques, shedding light on properties crucial for engine performance. Additionally, the paper investigates the production of oxygenated fuel additives from by-products like glycerol and their impact on combustion and emissions. In conclusion, biodiesel, particularly when derived from WCO, emerges as a compelling alternative to conventional diesel, with the potential to reshape the future of sustainable transportation fuels and mitigate environmental challenges.

The construction of novel efficient catalysts for the treatment of organic pollutants in the aqueous environment is essential. The lamellar-like Cu-Al layered double hydroxides (CuAl-LDHs) with various mole ratios were synthesized by a simple route of co-precipitation, and the corresponding degradation characteristic was tested for the removal of tetracycline (TC) using PMS activation. The degradation efficiency of TC over CuAl-LDHs increased up to 93% within 10 min for the Cu/Al mole ratio of 3:1 and almost not changed at a higher mole ratio. For further calcining the optimal catalyst at 300 ℃, the degradation efficiency of TC was found to be increased to 96%. Sulfuric radicals and singlet oxygen were analyzed to be the main reason for the change in degradation characteristics, which was proved by radical quenching experiments and electron paramagnetic resonance technique. The parameters including PMS concentration, catalyst dosage, and reaction temperature on the TC degradation as well as the degradation mechanism for PMS activation were elaborated. The best proportion of CuAl-LDHs owned splendid stability and catalytic activity after reusing, which showed enormous potential in practical application. [ABSTRACT FROM AUTHOR]

Vehicular SOx emissions have a huge detrimental impact on public health, catalytic converters, and the environment. Developing strategies to remove sulfur from diesel and thus safeguard the above is imperative. A series of SnO2–MoO3 mixed oxides and mono oxides MoO3 and SnO2 were prepared by soft template method, calcined at 450 °C and successfully tested in model diesel oxidative desulfurisation (ODS). The impact of the SnO2/MoO3 mole ratio (hereinafter denoted as Sn/Mo) on catalytic efficiency was investigated, among other catalytic parameters. The obtained samples were analyzed using X-ray diffraction (XRD), Raman spectrocscopy, scanning electron microscopy (SEM), N2-physisorption and titration method for acidic properties. The study demonstrates that mixing SnO2 and MoO3 improves acidic sites, crystallinity, and morphological properties of pure SnO2. The addition of MoO3 increased oxygen vacancies and the surface area of SnO2. High acidic site densities of 49.3, 47.4, and 46.7 mEqg−1 were observed for the catalysts with 2:1, 1:1, and 1:2 Sn/Mo mole ratio, respectively. The catalytic efficiency increased with an increase in Sn content with the highest catalytic efficiency of 99.8% for the dibenzothiophene (DBT) oxidation achieved in 30 min for Sn/Mo (2:1) catalyst compared to 92 and 70% for Sn/Mo 1:1 and 1:2 catalysts, respectively. The rate constant for the reaction was 0.057 min−1, which is eight times that of MoO3; 0.007 min−1 and three times that of SnO2; 0.017 min−1. The ODS mechanism utilizing the SnO2–MoO3 catalyst was proposed. The prepared SnO2–MoO3 catalyst demonstrated a high potential for industrial desulfurisation applications.

β-Sitosterol (βs) is one of important phytosterols, which is well known for its ability to lower the cholesterol level and is also useful in the treatment of various diseases. Keeping in mind its biological activities, complexation of βs with Cu(II) was performed and it was found that βs-Cu complex enhances the biological activities of βs. The pH-metric titration technique was used to control the formation of metal (M)—ligand (L) complexes βs-Cu in solutions with variable mole ratio of metal ion to ligand, 1:1, 1:2 and 1:3 (denoted as ML, ML2 and ML3 respectively). The complex formation was indicated by change in the solution color due to change in pH. Results obtained by the mole ratio variation and isomolar series method revealed the formation of ML2 complex. The synthesized βs-Cu complex was characterized by elemental analysis and various spectroscopic techniques including IR, UV/Vis, and 1H NMR. The results of analysis indicated that complexes contained Cu(II) ions coordinated via OH and C=C groups of the steroid. The data of antimicrobial activity assay showed higher activity of βs-Cu in 1:2 (ML2) form as compared to other mole ratios. [ABSTRACT FROM AUTHOR]

• Synthesis of high-purity ZnO/Fe 3 O 4 nanocomposites by a facile hydrothermal method. • Enhancement in their photocatalytic activity under UV–Vis light. • A proposed mechanism to explain increasing degradation efficiency for MB. • Excellent stability of ZnO/Fe 3 O 4 nanocomposites under both UV and visible irradiation. ZnO/Fe 3 O 4 heteronanostructures (HNSs) have attracted great attention due to their possibility of removing organic pollutants in aqueous solutions, then detaching from aqueous solutions by magnetic fields. However, there is a lack of research on their photocatalytic performance under visible light irradiation and the mechanism for the degradation process is still arguable. We present here the enhancement in the photocatalytic activity of ZnO/Fe 3 O 4 HNSs, synthesized by a facile hydrothermal technique, under both Ultraviolet (UV) and visible light irradiation. Particularly, the methylene blue (MB) degradation efficiency exhibited a great enhancement of up to 99.7% and 79.7% for HNSs with different ZnO:Fe 3 O 4 mole ratios of 16:1 and 8:1 under UV and visible light, respectively. It could be explained by the transfer of electrons (i) from the conduction band (CB) of ZnO to that of Fe 3 O 4 or/and (ii) from the CB of Fe 3 O 4 to new defect states (e.g., Fe2+/Fe3+ levels) below the CB of ZnO. Additionally, ZnO/Fe 3 O 4 HNSs show great stability in their photocatalytic activities when remained 95.1% and 92.1% after 5-reused cycles under UV and visible light irradiation, respectively. Therefore, the fabricated ZnO/Fe 3 O 4 HNSs show great potential for enhancing the MB degradation efficiency under both UV and visible light. [ABSTRACT FROM AUTHOR]

Tung oil with an iodine value (IV) of 99.63 g I2/100 g was epoxidized in-situ with glacial acetic acid and hydrogen peroxide (H2O2), in the presence sulfuric acid as catalyst. The objective of this research was to evaluate the effect of mole ratio of H2O2 to unsaturated fatty acids (UFA), reaction time and catalyst concentration in Tung oil epoxidation. The reaction kinetics were also studied. Epoxidation was carried out for 4 h. The reaction rates and side reactions were evaluated based on the IV and the conversion of the epoxidized Tung oil to oxirane. Catalytic reactions resulted in higher reaction rate than did non-catalytic reactions. Increasing the catalyst concentration resulted in a large decrease in the IV and an increase in the conversion to oxirane at the initial reaction stage. However, higher catalyst concentration in the epoxidation reaction caused to a decrease in reaction selectivity. The mole ratio of H2O2 to UFA had an influence identical to the catalyst concentration. The recommended optimum mole ratio and catalyst concentration in this study were 1.6 and 1.5%, respectively. The highest conversion was 48.94% for a mole ratio of 1.6. The proposed kinetic model provided good results and was suitable for all variations in reaction temperature. The activation energy (Ea) values were around 5.7663 to 76.2442 kcal/mol. Copyright © 2021 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).

This study reports the fabrication of micro-sized spherical Mn 3 O 4 particles using a precipitation conversion-roasting method. Morphological evolution of the product and mechanism of formation have been investigated. The results showed that the amount of alkali used in the precipitation conversion step had a significant effect on the morphology and particle size of the product. When mole ratio of the alkali to manganese increased from 1.6 to 4.0, morphology of the Mn 3 O 4 precursor gradually evolved from an irregular cubic shape to a regular spherical shape, and finally, a regular cubic shape with uniform particle size. According to transmission electron microscopy (TEM) and selected area electron diffraction (SAED), morphological evolution of the Mn 3 O 4 precursor was caused by the preferred orientation of crystal planes and supersaturation of the reaction system. Scanning electron microscopy (SEM) images of samples before and after calcination showed that morphology of precursor was inherited by the product obtained after calcination. Thus, spherical Mn 3 O 4 particles, with uniform size and no agglomeration, could be prepared by precipitation conversion-roasting method. [ABSTRACT FROM AUTHOR]

The mole ratio of an acid base reaction is one of the important values to state the stoichiometric relationship between acids and bases. However, solving acid-base problems based on stoichiometry is still challenging for new chemists.This issue renders the use of a model for predicting the volume of the acid used an exciting endeavour in academia. This work was to study the individual and interactive effects of the titration parameters such as acid concentration, base concentration and the number of the indicator drops on the volume of acid used in the titration process, using methyl orange as an indicator.We also aimed to study the central composite design (CCD) model of response surface methodology (RSM) for experimental design and modelling of the process. The experimental data were analysed using analysis of variance (ANOVA) and fitted to a second-order polynomial equation using multiple regression analysis. The regression analysis showed a good fit of the experimental data to the second-order polynomial model with a coefficient of determination (R2) value of 0.9751 and model F-value of 43.37. The response surface and contour plots were generated from RSM tool for the interactive effects of the studied parameters on the volume of acid used. The developed model was further validated using existing acid-base titration problems from the Senior Secondary Certificate Examination (SSCE) past questions over 30 years. All observations indicated that the developed model was only valid for a monobasic acid.

Poly (m-diethynylbenzene-methylsilane-phenylsilane)(PDMP), the heat-resistant silicon-alkyne resin, was synthesized from m-diethynylbenzene, methylsilane and phenylsilane by the method of Grignard reagent. FT-IR, NMR and GPC were selected to characterize the structure of PDMP resin. The curing behavior was analyzed by DSC and rheometer, and heat performance was measured by TGA. The study shows that heat-resistant of resins first increases and then decrease with the increase of mole ratio of phenylsilane and methylsilane. When the mole ratio comes to 7:4, PDMP's heat-resistant is the best. And the Td5 (5% mass loss temperature) and residual are respectively 654℃ and 90.3% in N2, 574℃ and 34.0% in air after 1000℃.

The present paper describes the synthesis of four azo-Schiff base named (1a-4a) by diazotization reaction of the synthesized Schiff bases with sulfonamide compound. All new synthesized derivatives were identified by melting points, CHNS, FT-IR and 1H-NMR spectra. All compounds were tested for their antibacterial activity that showed good activity. The synthesized compounds were used as sensitive and selective analytical reagent for the spectrophotometric determination of cadmium (II). The calibration curve is linear between 0.05 and 30 μ g.ml-1 and limit of quantification, LOQ of (1.203, 1.078, 1.443 and 0.875) μ g.ml-1 with molar absorptivity and Sandal's sensitivity values of ligands 2.4778x104, 1.6740x104, 1.70019x104, 1.9002 x104 L mol-1 cm-1 (0.049x10-4, 0.169x10-4, 0.132x10-4, 0.110 x10-4 μ g.cm-2, for 1a, 2a, 3a and 4a, respectively. The composition of the Cd (II) - (1a, 2a, 3a and 4a) complex is established as 1:2 by molar ratio and job methods. An excellent linearity with a correlation coefficient value of (0.9997, 0.9996, 0.9974 and 0.9985) is obtained for the complexes. [ABSTRACT FROM AUTHOR]

The mole ratio of an acid base reaction is one of the important values to state the stoichiometric relationship between acids and bases. However, solving acid-base problems based on stoichiometry is still challenging for new chemists.This issue renders the use of a model for predicting the volume of the acid used an exciting endeavour in academia. This work was to study the individual and interactive effects of the titration parameters such as acid concentration, base concentration and the number of the indicator drops on the volume of acid used in the titration process, using methyl orange as an indicator.We also aimed to study the central composite design (CCD) model of response surface methodology (RSM) for experimental design and modelling of the process. The experimental data were analysed using analysis of variance (ANOVA) and fitted to a second-order polynomial equation using multiple regression analysis. The regression analysis showed a good fit of the experimental data to the second-order polynomial model with a coefficient of determination (R2) value of 0.9751 and model F-value of 43.37. The response surface and contour plots were generated from RSM tool for the interactive effects of the studied parameters on the volume of acid used. The developed model was further validated using existing acid-base titration problems from the Senior Secondary Certificate Examination (SSCE) past questions over 30 years. All observations indicated that the developed model was only valid for a monobasic acid.

Abstract Iron and manganese have been studied as a proposal for new materials that could be used for the adsorption of arsenic (V) (As (V)), in order to remove this contaminant. The objective of this work was to study the effect of the molar ratio of three Mn/Fe + Mn composites (X = 0.17, 0.32, 0.47) on the properties of adsorbent media, and to determine their influence on arsenic removal by comparing them with two metallic oxyhydroxides, that are commonly used as adsorbents of As(V) in aqueous solution (goethite and birnessite). These media were synthesized by chemical precipitation while controlling particle size. They were characterized using X-ray diffraction (XDR), scanning electron microscopy with X-ray dispersive energy spectrometry (SEM-EDS), surface area analysis by the BET method, Fourier transform infrared spectroscopy (FTIR), and isoelectric point analysis (IEP). The surface area (286 m2/g) of the composite with a molar ratio of X = 0.17 was larger than that of the other media. The adsorption kinetics and isotherms were fitted to the mathematical models, specifically, the pseudo-second order and Langmuir, respectively. The X = 017 composite had an adsorption capacity of 3.28 mg/g and removed 99% of As(V) with an initial concentration of 0.5 and 97% with an initial concentration of 10 mg/L, at 180 min, 25 °C, and pH 7. The five adsorbent media were tested with well water with an initial As(V) concentration of 0.075 mg/L, and the best behavior was exhibited with a molar ratio of X = 0.17 at 90 min, resulting in 100% removal of As(V). The results suggest that this material is an effective and viable alternative to remove this contaminant from water. Graphical abstract Unlabelled Image Highlights • Synthesis of new adsorbent media for the removal of arsenic (V) in water • Study of changes in the properties of synthesized materials by adding Mn to the goethite structure • Evaluate changes in adsorbent media and their influence on the removal of arsenic (V) in water • Evaluate removal arsenic (V) rates and adsorption capacities of adsorbent media in model water and real well water • Removal of high (10 mg/L) and low (5 mg/L) arsenic (V) concentrations [ABSTRACT FROM AUTHOR]

The mole ratio of an acid base reaction is one of the important values to state the stoichiometric relationship between acids and bases. However, solving acid-base problems based on stoichiometry is still challenging for new chemists.This issue renders the use of a model for predicting the volume of the acid used an exciting endeavour in academia. This work was to study the individual and interactive effects of the titration parameters such as acid concentration, base concentration and the number of the indicator drops on the volume of acid used in the titration process, using methyl orange as an indicator.We also aimed to study the central composite design (CCD) model of response surface methodology (RSM) for experimental design and modelling of the process. The experimental data were analysed using analysis of variance (ANOVA) and fitted to a second-order polynomial equation using multiple regression analysis. The regression analysis showed a good fit of the experimental data to the second-order polynomial model with a coefficient of determination (R2) value of 0.9751 and model F-value of 43.37. The response surface and contour plots were generated from RSM tool for the interactive effects of the studied parameters on the volume of acid used. The developed model was further validated using existing acid-base titration problems from the Senior Secondary Certificate Examination (SSCE) past questions over 30 years. All observations indicated that the developed model was only valid for a monobasic acid. [ABSTRACT FROM AUTHOR]

In industry, formalin and urea formaldehyde condensates (UFC) are used for the preparation of urea-formaldehyde adhesives. The aim of this study was to evaluate the characteristics of a UF resin prepared with formalin (42% concentration) and two kinds of UFC with various urea content (F/U ∼ 5 and 4.3 malar ratio). The resins were prepared with final molar ratio F/U = 1.1. The UF resin with formalin showed better mechanical properties than those with UFC. The 13C NMR and FT-IR results indicated that methylene, methylene ether and urons groups in a UF resin prepared with formalin were present in higher proportion than observed in industrial UF resins. The DSC (differential scanning calorimetry) results showed that the curing temperature of a UF resin prepared with formalin is lower than that of a UF resin prepared with UFC. The mechanical properties of MDFs prepared with the three types of adhesives showed that MDFs bonded with a UF prepared with formalin yields a better mechanical properties than MDFs prepared with a UF resin based on UFC. Moreover, resin synthesized with UFC (F/U = 5) result in higher IBS (internal bond strength) MOR (modulus of rupture), MOE (modulus of elasticity), TS (thickness swelling) and formaldehyde emission (FE) than resin synthesized with UFC (F/U = 4.3). The MDF bonded with the UF2 resin presented poor results, with the highest TS and the lowest IBS, MOE, MOR and FE. [ABSTRACT FROM AUTHOR]

In this study, microwave-assisted green synthesis of a complex of Ni (II)-2′,4′-dihydroxy 4-fluoro chalcone oxime has been carried out. The structure of the complex was characterized by elemental analysis, molar conductance, magnetic moment, IR, 1H-NMR, 13CNMR spectroscopic data and thermal studies. IR data showed that Ni(II) is coordinated to the ligand through the phenolic-O and azomethine-N of the latter. TGA studies confirmed the presence of coordinated water molecules. The 1 : 2 metal to ligands stoichiometry was indicated by mole ratio method, which was further confirmed by Job’s method of continuous variation modified by Turner and Anderson. Stability constant (Ks) of the complex determined by mole ratio method was 8.5245. Standard free energy change (ΔG0) for metal–ligand complex formation was found to be –11.7026 K cal/mol at 27 ± 2°C. On the basis of analytical data, octahedral structure has been proposed for the complex. All compounds were tested for antibacterial activity and showed moderate to good activity against Escherichia coli and Staphylococcus aureus at different concentrations. In this study, we report synthesis of oxime derivative of chalcone and its Ni(II) complex in the hope of developing new compounds which might be used as analytical reagents or intermediates in the synthesis of various classes of bioactive compounds. [ABSTRACT FROM AUTHOR]

Vehicular SO x emissions have a huge detrimental impact on public health, catalytic converters, and the environment. Developing strategies to remove sulfur from diesel and thus safeguard the above is imperative. A series of SnO 2 -MoO 3 mixed oxides and mono oxides MoO 3 and SnO 2 were prepared by soft template method, calcined at 450 °C and successfully tested in model diesel oxidative desulfurisation (ODS). The impact of the SnO 2 /MoO 3 mole ratio (hereinafter denoted as Sn/Mo) on catalytic efficiency was investigated, among other catalytic parameters. The obtained samples were analyzed using X-ray diffraction (XRD), Raman spectrocscopy, scanning electron microscopy (SEM), N 2 -physisorption and titration method for acidic properties. The study demonstrates that mixing SnO 2 and MoO 3 improves acidic sites, crystallinity, and morphological properties of pure SnO 2 . The addition of MoO 3 increased oxygen vacancies and the surface area of SnO 2 . High acidic site densities of 49.3, 47.4, and 46.7 mEqg -1 were observed for the catalysts with 2:1, 1:1, and 1:2 Sn/Mo mole ratio, respectively. The catalytic efficiency increased with an increase in Sn content with the highest catalytic efficiency of 99.8% for the dibenzothiophene (DBT) oxidation achieved in 30 min for Sn/Mo (2:1) catalyst compared to 92 and 70% for Sn/Mo 1:1 and 1:2 catalysts, respectively. The rate constant for the reaction was 0.057 min -1 , which is eight times that of MoO 3 ; 0.007 min -1 and three times that of SnO 2 ; 0.017 min -1 . The ODS mechanism utilizing the SnO 2 -MoO 3 catalyst was proposed. The prepared SnO 2 -MoO 3 catalyst demonstrated a high potential for industrial desulfurisation applications., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2023 Published by Elsevier Ltd.)

This work examined micro-morphological features responsible for the crystallinity of cured urea-formaldehyde (UF) adhesives, using transmission electron microscopy (TEM) to identify and characterize distinctive crystalline structures in resins obtained with different formaldehyde to urea (F/U) mole ratios and hardener levels. The TEM examination of cured UF resin adhesives impregnated into wood cell lumen revealed the presence of spherical particles with variable diameter and number per unit area. The diameter and number/area of the spherical particles increase for decreasing F/U mole ratio and decrease with an increase in the hardener levels, an effect which is closely related to their crystallinity. Therefore, the present findings suggest that the spherical particles are responsible for the crystallinity of cured UF resin adhesives. The results also indicate that crystalline structures represent an inherent feature of cured UF resin adhesives, particularly for low F/U mole ratios, even though these resins are usually classified as amorphous and cross-linked thermosetting polymers. [ABSTRACT FROM AUTHOR]