Molar Ratio Research Articles

Probing the relevance of synergistic lipid membrane disruption to the eye irritation of binary mixed nonionic surfactants

Nonionic surfactant aerosols play a crucial role in many industries, but they can cause acute irritation to users’ eyes during spraying. This cytotoxic process is associated with corneal cell necrosis causing cell membrane disruption. Industrial grade surfactants are typically polydisperse mixtures described by their nominal chemical structure but how the polydispersity affects their interactions with cell membrane, remains largely unexplored. A better understanding could benefit product formulations to maximise their efficiency whilst minimising their toxicity to the users. In this study, poly-oxyethylene glycol monododecyl ethers (C12E4, C12E23) were used to form ideal binary surfactant mixtures. The cytotoxicities of mono and polydispersed surfactants towards human corneal epithelial cells were examined, followed by a series of biophysical characterisations of interactions between surfactants and model cell membranes. Notably, to probe the journey of individual C12E4 and C12E23 surfactant molecules across the cell membrane from a binary surfactant mixture, “two-colour” neutron reflection measurements were achieved via Hydrogen/Deuterium substitution. The relative distributions of C12E4 and C12E23 across cell membranes and their nanostructural conformations revealed a synergistic membrane-lytic ability initiated by surfactant mixing, with the more hydrophobic C12E4 exhibiting stronger membrane binding potency than the hydrophilic C12E23. The exact molar ratio of C12E4 against C12E23 in the mixture determined how the mixed surfactant interacted with the cell membrane, and how the process directly impacted cytotoxicity and eye irritation. Thus, the cytotoxicity of polydisperse surfactants is not the same as monodisperse surfactant of the same average structure. This work provides a useful basis for the assessment of surfactant mixing by balancing their efficiency and toxicity.

Synergistic xylan decomposition by a reducing-end xylose-releasing exo-oligoxylanase with other xylanolytic enzymes derived from Paenibacillus xylaniclasticus strain TW1.

Paenibacillus xylaniclasticus strain TW1 is a promising tool for decomposing xylan-containing lignocellulosic biomass, since this strain possesses various genes encoding cellulolytic/hemicellulolytic enzymes. In this study, PxRex8A from the TW1 strain was found to be a reducing-end xylose-releasing exo-oligoxylanase of glycoside hydrolase family 8, which cleaves xylose from xylooligosacchrides of corn core xylan. In synergistic assay, the efficient decomposition of oat spelt xylan (OSX) and beech wood xylan was exemplified in the combination of endo β-1,4-xylanase (PxXyn11A) and PxRex8A from the TW1 strain in a molar ratio of 4:1. Furthermore, it was found that the addition of β-d-xylosidase/α-l-arabinofuranosidase (PxXyl43A) from this strain with PxXyn11A and PxRex8A achieved twice the amount of reducing sugars (1.1 mg/mL) against OSX after 24 hours compared to PxXyn11A alone (0.5 mg/mL). These results present that synergy effect of PxRex8A and PxXyl43A with PxXyn11A promotes xylan degradation into xylose.

The impact of altering the molar ratio on formaldehyde content and the physical and mechanical properties of MDF panels

This study aimed to evaluate the influence of the molar ratio of urea-formaldehyde resin (UF) on formaldehyde content and the physical and mechanical properties of MDF panels. The goal was to determine the optimal composition, i.e. the one that exhibits the lowest formaldehyde content without compromising the properties. To that end, there were five treatments. They were characterized by five F:U molar ratios (0.9:1; 1.0:1; 1.1:1; 1.2:1; and 1.3:1). The panels had a nominal density of 750 kg.m−3, dimensions of 40 × 40 × 1.5 cm, 12% resin, 1% paraffin. They were produced with a pressing cycle with a temperature of 170 °C and pressure of 3.6 MPa per 10 min. The physical-mechanical properties of the panels and the formaldehyde content were determined and evaluated following the NBR 15316-2 (2019) standard. Results showed that the formaldehyde content was lower for panels produced with resin molar ratios of 0.9:1, 1.0:1, and 1.1:1, classified as E1. Panels with a resin molar ratio of 1.2:1 were classified as E2. The molar ratio of 1.3:1 exceeded the limits of the standard. Panels with resin molar ratios of 1.1:1, 1.2:1, and 1.3:1 met the standard requirements for all physical-mechanical properties of non-structural MDF for use in dry conditions. These results indicate that the most suitable UF resin molar ratio for producing MDF panels is 1.1:1. This radio provides low formaldehyde content and technological properties compatible with the reference standard.

Catalytic evaluation of eggshell‐based calcium methoxide over Al2O3 for biodiesel generation from waste cooking oil

AbstractShell‐derived materials are promising heterogeneous catalysts for biodiesel production due to their nontoxic and renewable nature, but they have the disadvantage of being highly leachable. To overcome this issue, Ca(OCH3)2 formed through the reaction of CaO with methanol, and supported in turn on Al2O3 is proposed as a catalytic system for the transesterification of fresh soybean oil and waste cooking oil (WCO). First, catalysts with several Al/Ca molar ratios (0.2, 0.5, and 0.8‐AC), as well as their precursors (CaO and Al2O3) alone, were tested at 60 °C, catalyst loading 6% wt, methanol‐to‐oil molar ratio (MOR) 10, for 1 h for fresh oil, and 3 h for WCO. The 0.2‐AC catalyst generated the highest biodiesel yield for both oils. The optimum operating conditions for WCO transesterification, determined by using a univariable approach, were 60 °C, 9 wt% catalyst loading, MOR of 12.5, and a reaction time of 3 h. These improved conditions led to yields higher than 90% for pure CaO and the 0.2, 0.5, and 0.8‐AC catalysts. The density, kinematic viscosity, and refractive index of the biodiesel obtained were measured.

Functionalization of pyrolyzed hydrochar with nitrogen containing deep eutectic solvent for carbon capture at low and high pressure

The purpose of this research is to evaluate the effectiveness of pyrolyzed hydrochar functionalized with nitrogen containing deep eutectic solvent (DES) in the absorption of CO2 under low- and high-pressure conditions. Pyrolyzed hydrochars were synthesized by hydrothermally carbonizing pine at the temperature of 200°C and 260°C, followed by pyrolysis at 600°C. These pyrolyzed hydrochars were impregnated with 3 different nitrogen containing DES namely choline chloride: urea, choline chloride: glycerol, and tetrabutylammonium bromide: glycerol all in 1:2 molar ratio. It was found that the functionalized pyrolyzed hydrochars were enhanced with nitrogen and oxygen functionalities (N-H, C-N, and CO). The results also show a substantial reduction in surface area for the functionalized pyrolyzed hydrochars, ranging from 10.19 to 227.74 m2g−1, compared to the surface areas of pyrolyzed hydrochars of 306–337 m2g−1. On the other hand, an increase in N content up to 38 % was identified after functionalization of pyrolyzed hydrochars. Upon conducting CO2 uptake at low (0.1–1 bar) and high (2.5–3.5 bar) pressure, the functionalized pyrolyzed hydrochars exhibited an CO2 uptake of up to 9.5 mmol/g at high pressure, which was attributed to the increased total nitrogen content, enhanced surface functionalities, and available micropore volume. The low-pressure isotherm for functionalized pyrolyzed hydrochars showed Langmuir-type isotherm, suggesting a monolayer adsorption. In contrast, the high-pressure isotherms were better fitted to the Freundlich isotherm, suggesting a multilayer adsorption behavior. It was concluded that the enhanced CO2 uptake is the result of the combined impact of increased surface functionalities and porosity, which results in improved physical and chemical adsorption mechanisms at the high pressure.

Highly efficient direct air capture using solid–liquid phase separation in aqueous diamine solution as sorbent

Abstract To reduce climate change, absorbing CO2 directly from the air (DAC) with high-efficient CO2 absorption, low-cost, and environmentally friendly system has been attracted much attention for several decades. In this work, a series of aqueous diamine solutions was examined for 400ppm CO2 absorption at ambient temperature. The absorbents exhibited CO2 absorption with molar ratio of 1 molCO2/molamine, and aqueous isophorone diamine (IPDA) in particular showed >99% CO2 removal even under a 500 mL min−1 flow of 400ppm CO2-N2 with the contact rate of 13,761.5 h−1 between CO2 and IPDA aqueous solution and the CO2 absorption rate of 4.46 mmol/L·min. A precipitate of carbamic acid of IPDA was formed by reaction with CO2, and the CO2 removal efficiency was enhanced by increasing the solution viscosity by the formation of this precipitate. The CO2 was absorbed in aqueous IPDA solution as carbamic acid of IPDA and bicarbonate/carbonate species, and the absorbed CO2 could desorb by heating under O2-containing gas flow, which indicates our system is applicable to the CO2 condensation for a plant growth. This work provides a fundamental information to establishing a solid–liquid phase change system with a high-efficient and environmentally friendly DAC system using aqueous solvent.

Characterization of salt brine sulfated polysaccharides: immunomodulatory activity based on gut microbiota

A sulfated polysaccharide consisting of two components with molecular weights of 439 kDa and 16 kDa was extracted from the salt brine. The structural properties, immunomodulatory activity, in vitro fermentation behaviors, and effects of SP on regulating the gut microbiota were investigated. The chemical composition and monosaccharide composition analysis showed that the neutral sugar, protein, uronic acid, and sulfated group contents of SP were 60.42 ± 0.04%, 2.90 ± 0.01%, 13.34 ± 0.01% and 10.51 ± 0.01%, respectively, containing arabinose, galactose, glucose, rhamnose, xylose, mannose, and glucuronic acid in a molar ratio of 33.24:19.18:16.64:13.25:8.31:4.11:5.27. Results from the macrophage cell model showed that SP intervention improved the proliferation activity, phagocytosis of neutral red, and production of IL-6 and TNF-α in RAW 264.7. Furthermore, in vitro fermentation of SP by gut microbiota showed that SCFA production in all treatment groups was significantly higher than that of the blank control group after 48 h of fermentation, especially butyric acid which was 1.70 folds that of the control group. Moreover, long-term fermentation (48 h) of SP improved the diversity of microbiota, decreased the F/B ratio (30.75 at 0 h vs. 1.22 at 48 h), and promoted the growth of probiotics (Parabacteroides, Bacteroidetes, Ruminococcaceae, and Phascolarctobacterium). The positive regulatory effect of SP on the gut microbiota and its metabolites is considered a potential target for its immunomodulatory activity.Graphical abstract

Exosomal fragment enclosed polyamine-salt nano-complex for co-delivery of docetaxel and mir-34a exhibits higher cytotoxicity and apoptosis in breast cancer cells

A novel core–shell nanocarrier system has been designed for co-delivery of a small anticancer drug, docetaxel (DTX) and tumor suppressor (TS) miR-34a named as Exo(PAN34a+DTX). The core is formed by pH dependent polyamine salt aggregates (PSA) containing both the payloads and the shell is formed by RAW 264.7 cell derived exosomal fragments. Herein, phosphate driven polyallylamine hydrochloride (PAH, MW:17,500 Da) PSA was formed in presence of miR-34a and DTX to form PAN34a+DTX. The formulation exhibited pH dependent DTX release with only 33.55 ± 2.12% DTX release at pH 7.2 and 75.21 ± 1.8% DTX release till 144 h at pH 5.5. At 1.21 molar ratio of phosphate to the amine (known as R value), efficient complexation of miR-34a (3.6 μM) in the PAN particles was obtained. PAN34a+DTX demonstrated particle size (163.86 ± 12.89 nm) and zeta-potential value of 17.53 ± 5.10 mV which upon exosomal fragment layering changed to − 7.23 ± 2.75 mV which is similar to the zeta-potential of the exosomal fragments, i.e., − 8.40 ± 1.79 mV. The final formulation Exo(PAN34a+DTX), loaded with 40 ng/mL DTX and 50 nM miR-34a exhibited 48.20 ± 4.59% cytotoxicity in triple negative breast cancer (TNBC) cells, 4T1. Co-localization of CM-DiI (red fluorescence) stained exosomal fragments and FAM-siRNA (green fluorescence) in the cytoplasm of 4T1 cells after 6 h of Exo(PANFAM) treatment confirmed the efficiency of the designed system to co-deliver two actives. Exo(PAN34a+DTX) also reduced BCL-2 expression (target gene for miR-34a) by 8.98 folds in comparison to free DTX confirming promising co-delivery and apoptosis inducing effect of Exo(PAN34a+DTX) in 4T1.

Synthesis of near‐spherical BN powders by templated carbothermal reduction and nitridation

AbstractBoron nitride (BN) powders with near‐spherical particles of more than 10 µm were synthesized by templated carbothermal reduction and nitridation. The effects of processing factors, such as raw material mixing methods, C/B2O3 molar ratios, and carbon templates, were systematically studied, and the reaction mechanism was discussed. The experimental results showed that the integrity and morphology of the carbon templates was usually destroyed during ball milling or grinding, but preserved during magnetic stirring. The morphology of synthesized BN particles depended on the C/B2O3 molar ratio in starting reactant mixtures and gradually changed from sheet‐like to near‐spherical shape with decreasing C/B2O3 molar ratio. The morphology and size of synthesized BN particles agreed with that of the carbon templates, which means that the morphology and size of synthesized BN particles can be tailored by controlling that of the carbon template. The BN near‐spherical particles synthesized in this work may be used as thermally conductive fillers for electronic packaging.

Machine learning prediction of dye adsorption by hydrochar: Parameter optimization and experimental validation

In response to escalating global wastewater issues, particularly from dye contaminants, many studies have begun using hydrochar to adsorb dye from wastewater. However, the relationship between the preparation conditions of hydrochar, the properties of hydrochar, experimental conditions, types of dyes, and equilibrium adsorption capacity (Q) has not yet been fully explored. This study conducted a comprehensive assessment using twelve distinct ML models. The Gradient Boosting Regressor (GBR) model exhibited superior performance with R² (0.9629) and RMSE (0.1166) in the test dataset, marking it as the most effective among the evaluated models. Moreover, this study also proved the feasibility of the GBR model through stability testing and residual analysis. A feature importance analysis prioritized the variables as follows: experimental conditions (41.5 %), properties of hydrochar (26.0 %), preparation conditions (18.1 %), and type of dye (14.4 %). Meanwhile, experimental conditions (C0 > 30 mmol/g, pH > 8, and higher solvent temperatures) and hydrochar properties (the BET surface area > 2000 m²/g, an (O+N)/C molar ratio < 0.6, and an H/C molar ratio of approximately 0.06) show higher Q for dyes. Experimental validation of the GBR model confirmed its practical utility with a suitable predictive accuracy (R² = 0.8704). Moreover, the study developed a Python-based GUI that has integrated the best GBR models to facilitate researchers' ongoing application and improvement of this predictive model. This study not only underscores the efficacy of ML in enhancing the understanding of dye adsorption by hydrochar but also sets a precedent for future research on sustainable contaminants removal through bio-based adsorbents.

Application of composite persulfate oxidation to remediate weathered lubricating oil-contaminated soils: Batch and pilot-scale studies

In this study, two novel composite persulfate (PS) oxidants [base pulverized NaOH composite persulfate (BPS) and metal (iron and manganese) composite persulfate (MPS)] were developed. The feasibility, mechanisms, and optimal conditions for remediating weathered lubricating oil (WLO)-contaminated soils using composite PS oxidants were evaluated. BPS was prepared by blending PS and NaOH powders (molar ratio = 1:0.3), while MPS was prepared by mixing PS, FeCl2, and KMnO4 at a molar ratio of 1:0.3:0.05 for PS:Fe:Mn. The oxidation of rhodamine B (RhB) dye using BPS and MPS followed second-order kinetics. MPS process was more effective in organic oxidation, likely due to its electron transfer mechanism. The generation of •SO4- in the BPS process required activation by •OH, potentially leading to more efficient and stable •SO4- generation and subsequent organic chemical oxidation. Radical analyses revealed that •SO4- was present in the pH range of 3–12, with the strongest •OH signal at pH 7–9. Employing hybrid BPS and MPS for WLO-contaminated soil remediation could achieve optimal TPH removal efficiency due to the combined generation of •OH (high reactivity) and •SO4- (stable characteristics). The addition of BPS helped neutralize acidified soils and maintained a higher soil pH (around 6.1). The multi-stage oxidation using the hybrid composite PS oxidants (MPS + BPS) at a 1:1 ratio (w/w) achieved 84 % TPH removal (initial TPH = 7721 mg/kg) after three oxidation stages (5 % w/w oxidant dosage). The composite oxidation process offers a more reactive oxidation potential with an extended oxidant life without causing a substantial pH drop.

Novel Cu(II) and Zn(II) Nanocomplexes Based on 5,6‐Diphenyl‐1,2,4‐Triazine: Preparation, Spectroscopic, TD‐DFT Calculations, Molecular Docking and Solvatochromic Studies

ABSTRACTThe reaction between 2‐hydroxy‐1‐naphthaldehyde and 3‐hydrazino‐5,6‐diphenyl‐1,2,4‐triazine produced a novel hydrazone ligand (DTHMN), which reacted with Cu(II) and Zn(II) metal ion in molar ratio 1:1, giving octahedral Cu(II)‐DTHMN and tetrahedral Zn(II)‐DTHMN nanosized complexes. The structural geometries have been elucidated on the basis of elemental analysis, nuclear magnetic resonance, infrared, electronic, and electron spin resonance spectra, and magnetic and molar conductance measurements as well as x‐ray diffraction and thermal analysis. TEM analysis showed that Zn(II)‐DTHMN complex has nano‐rode morphology shape. On the other hand, Cu(II)‐DTHMN has sphere shape within nanodomain. The DTHMN ligand exhibits ONN chelating sites through N‐triazine ring, azomethine nitrogen, and deprotonated OH group, forming the mononuclear metal complexes. The synthesized compounds showed a distinct solvatochromic behavior in different polar solvents. A bathochromic alteration is observed when moving from less to high polar solvents, indicating strong solute–solvent interactions accompanied by intramolecular charge transfer (ICT). The ground and excited state dipole moments of these compounds were determined experimentally by solvatochromic shift method using Bilot–Kawski, Lippert–Mataga, Bakhshiev, and Kawski–Chamma–Viallet functions and a microscopic Reichardt's solvent polarity parameter (ETN). The dipole moment is increased significantly upon excitation referring to stabilizing the excited species includes n–π* transition by polarity of solvent. The experimental results are generally consistent with those values obtained by B3LYP/GENECP method at 6‐311G(d,p) basis set for C, H, N, and O atoms and SDD (Stuttgart/Dresden) basis set for the metal atoms. The compounds were tested for antimicrobial efficiency against Gram‐positive bacteria, Gram‐negative bacteria, and fungus strain. Finally, molecular docking was used to study the interactions between donors (the current compounds) and receptors FabH–CoA complex (PDB code: 1HNJ).

Spectral studies of a selenium(IV) vitamin B3 compounds prepared in the form of nanometer using simple chemical reactions to further use as antioxidant in the preparation of drugs

The current study dealt with selenium metal ion complexes with mixed ligands, consisting of nicotinamide (vitamin B3) as the first ligand, and amino acids such as (histidine, tryptophan, and tyrosine) as the second ligand. It was synthesized in (1:1:1) (selenium: vitamin: amino acid) in molar ratio. By using different characterization techniques such as elemental analysis, the conductance, FTIR, XRD, UV-Vis, TG/DTG, 1H-NMR, XRD, SEM, TEM analyses, the chemical structures and the morphological properties of the synthesized complexes were checked and discussed. The nicotinamide was coordinated as monodentate ligand via the nitrogen of pyridine ring but all amino acids as a secondary ligand coordinated as bidentate through oxygen of carboxylic group and nitrogen of amino group. The complexes demonstrate antioxidant activity with potent scavenging property, the synthesized in the form of nanometer give great importance in increasing efficiency of absorption of human cells to selenium giving the highest efficiency of medical product. All complexes in this study were evaluated for their anticancer effect towards HepG2 and A2780 cell lines. From these data the complex (Se/Nia/ Tyr) can be used as antitumor agents. KEY WORDS: Selenium, Amino acids, Vitamin B3, Mixed ligand, Complexes, Antioxidant Bull. Chem. Soc. Ethiop. 2024, 38(6), 1759-1774. DOI: https://dx.doi.org/10.4314/bcse.v38i6.20

Investigation into the Fuel Characteristics of Biodiesel Synthesized through the Transesterification of Palm Oil Using a TiO2/CH3ONa Nanocatalyst

Biodiesel is a renewable and sustainable alternative fuel to petrol-derived diesel. Decreasing the operating costs by improving the catalyst’s characteristics is an effective way to increase the competitiveness of biodiesel in the fuel market. An aqueous solution of sodium methoxide (CH3ONa), which is a traditional alkaline catalyst, was immersed in nanometer-sized particles of titanium dioxide (TiO2) powder to prepare the strong alkaline catalyst TiO2/CH3ONa. The immersion method was used to enhance the transesterification reaction. The mixture of TiO2 and CH3ONa was calcined in a high-temperature furnace in a range between 150 and 450 °C continuously for 4 h. The heterogeneous alkaline catalyst TiO2/CH3ONa was then used to catalyze the strong alkaline transesterification reaction of palm oil with methanol. The highest content of fatty acid methyl esters (FAMEs), which amounted to 95.9%, was produced when the molar ratio of methanol to palm oil was equal to 6, and 3 wt.% TiO2/CH3ONa was used, based on the weight of the palm oil. The FAMEs produced from the above conditions were also found to have the lowest kinematic viscosity of 4.17 mm2/s, an acid value of 0.32 mg KOH/g oil, and a water content of 0.031 wt.%, as well as the highest heating value of 40.02 MJ/kg and cetane index of 50.05. The lower catalyst amount of 1 wt.%, in contrast, resulted in the lowest cetane index of 49.31. The highest distillation temperature of 355 °C was found when 3 wt.% of the catalyst was added to the reactant mixture with a methanol/palm oil molar ratio of 6. The prepared catalyst is considered effective for improving the fuel characteristics of biodiesel.

Optimization of potassium (K) recovery via electrochemical precipitation of K-struvite upon magnesium addition in urine

Potassium (K)-struvite precipitation is a promising approach to K recovery but faces the critical challenge of co-precipitation of sodium (Na)-struvite mainly due to the addition of sodium hydroxide (NaOH) for pH adjustment. To avoid using NaOH, this study investigated the electrochemical addition of magnesium (Mg) and hydroxide ions for K-struvite recovery. Results showed that a high release rate of Mg and hydroxide ions in the electrolysis led to a Mg:Phosphorus (P) ratio higher than 1:1 and pH higher than 11.3, which however resulted in a decrease in the K recovery efficiency. Subsequent optimization experiments conducted in synthetic urine, diluted fivefold, maintained a process pH of 10.811.0, with a current density of 5 mA/cm2 and an electrode spacing of 20 mm. Under these conditions, K recovery efficiency reached 38 %, while P recovery efficiency reached 93 % after 30 minutes of electrolysis. Compared to chemical precipitation methods, electrochemical recovery exhibited a 41 % increase in K recovery efficiency and a 153 % increase in K-struvite:Na-struvite molar ratio in the precipitates. Furthermore, a predictive model was developed to estimate optimal K recovery time and energy consumption, showcasing the effectiveness of electrochemical Mg addition in urine for high-efficiency K recovery.

RP-CAD for Lipid Quantification: Systematic Method Development and Intensified LNP Process Characterization.

Lipid nanoparticles (LNPs) and their versatile nucleic acid payloads bear great potential as delivery systems. Despite their complex lipid composition, their quality is primarily judged by particle characteristics and nucleic acid encapsulation. In this study, we present a holistic reversed-phase (RP)-charged aerosol detection (CAD)-based method developed for commonly used LNP formulations, allowing for intensified LNP and process characterization. We used an experimental approach for power function value (PFV) optimization termed exploratory calibration, providing a single PFV (1.3) in an appropriate linearity range for all six lipids. Followed by the procedure of method calibration and validation, linearity (10-400 ng, R2 > 0.996), precision, accuracy, and robustness were effectively proven. To complement the commonly determined LNP attributes and to evaluate the process performance across LNP processing, the developed RP-CAD method was applied in a process parameter study varying the total flow rate (TFR) during microfluidic mixing. The RP-CAD method revealed a constant lipid molar ratio across processing but identified deviations in the theoretical lipid content and general lipid loss, which were both, however, entirely TFR-independent. The deviations in lipid content could be successfully traced back to the lipid stock solution preparation. In contrast, the observed lipid loss was attributable to the small-scale dialysis following microfluidic mixing. Overall, this study establishes a foundation for employing RP-CAD for lipid quantification throughout LNP processing, and it highlights the potential to extend its applicability to other LNPs, process parameter studies, or processes such as cross-flow filtration.

Efficient hydrogen production from formic acid dehydrogenation over ultrasmall PdIr nanoparticles on amine-functionalized yolk-shell mesoporous silica

Developing heterogeneous catalysts with exceptional catalytic activity over formic acid (HCOOH, FA) dehydrogenation is imperative to employ FA as an effective hydrogen (H2) carrier. In this work, ultrasmall (1.4 nm) and well-dispersed PdIr nanoparticles (NPs) immobilized on amine-functionalized yolk-shell mesoporous silica nanospheres (YSMSNs) with radially oriented mesoporous channels have been synthesized by a co-reduction strategy. The optimized catalyst Pd4Ir1/YSMSNs-NH2 (Pd/Ir molar ratio = 4:1) exhibited a remarkable turnover frequency (TOF) of 5818 h−1 and remarkable stability at 50 °C with the addition of sodium formate (SF), resulting in complete FA conversion and H2 selectivity, exceeding most of the solid heterogeneous catalysts in previous reports under similar circumstances. Kinetic isotope effect (KIE) exploration indicates the cleavage of the CH bond is regarded as the rate-determining step (RDS) during the FA dehydrogenation process. Such excellent catalytic properties arise from the ultrafine and well-dispersed PdIr NPs supported on the nanosphere support YSMSNs-NH2, the electronic synergistic effect of PdIr alloy NPs, and the strong metal-support interaction (MSI) effect between the introduced PdIr NPs and YSMSNs-NH2 support. This work offers a new paradigm for exploiting the highly effective silica-supported Pd-based heterogeneous catalysts over the dehydrogenation of FA.

Molecular dynamics simulation and experimental verification of a biphasic solvent for CO2 capture

In the context of solvent-based carbon capture, researchers and industries are often interested in improvements in the efficiency of CO2 capture along with the reduction in the required energy. This study employs molecular dynamics (MD) simulation based on a reax force field and experimental investigation to study the effects and main mechanisms of a mutual amine absorbent including diethylenetriamine (DETA) and diethylethanolamine (DEEA), accompanied by NMP and water co-solvents, on the performance of CO2 capture in a phase change system. The implementation of time-dependent partial radial distribution functions (TD-PRDF, gαβrtm) and coordination number (CN) analyses revealed the significant formation of C-N bonds between carbon (C) derived from CO2 and nitrogen (N) within the solution. The direct relationship between changes in DETA molar ratios and CO2 loading, coupled with examining the catalytic role of DEEA in facilitating CO2 removal through protonation, has been thoroughly studied with MD. The experimental methodology was followed to validate the MD results. The optimum composition, DETA: DEEA: NMP with a molar ratio of 3:2.5:1, as determined through MD simulations exhibitsgαβr|tm = 9.848, CN=0.403 at tm= 1 ns. The stable C-N absorption bond length is calculated to be between 1.7 and 1.77 Å. Experimental results confirm a CO2 loading capacity of 0.93 mol/mol for this composition.

Sustainable Biocatalytic System for the Enzymatic Epoxidation of Waste Cooking Oil.

The present study is integrated in a global effort to capitalize waste cooking oil (WCO) into versatile compounds by introducing an oxirane ring into the unsaturated carbon chain of fatty acid residues (the epoxidation of double bound). Therefore, an enzymatic method was set up for the epoxidation of artificially adulterated WCO (SFw) and WCO under real conditions (SFr) derived from sunflower biomass. Commercial lipase (Novozyme, NZ) was used as a biocatalyst for generating the peracid requested by the epoxidation pathway. Optimum experimental conditions (e.g., 1.5 wt% NZ, 1:1:0.5 = H2O2/double bonds/peracid precursor (molar ratio) and 12 h reaction time) allowed for the conversion of 90% of the SFw substrate into products with an oxirane ring. Octanoic acid was selected as the best peracid precursor. The versatility of the developed system was tested for olive, milk thistle, hemp and linseed oils as both fresh and WCO samples. The characterization of the oil samples before and after the enzymatic epoxidation allowed for the evaluation of the system performance. SFw/SFr exhibited a better susceptibility to enzymatic epoxidation. In addition, the reusability of the biocatalytic system was investigated. Furthermore, different strategies, such as biocatalyst coating and the addition of organic solvents/buffers were applied, limiting enzyme leaching, for the better recovery of the biocatalyst activity.

Facile boosting catalytic thermal decomposition of ammonium perchlorate from 3D porous nano Co3O4@ZnO composites

The design of efficient catalysts for the pyrolysis of ammonium perchlorate (AP) is important for the performance of composite solid propellants. Co3O4@ZnO heterojunction composites were fabricated by hydrothermal and calcination treatments and used to promote the thermal decomposition of AP. The influences of the Co/Zn molar ratio on the catalytic performance and the content of decomposition products of AP were investigated by various techniques such as TEM, XPS, BET, EIS, and TG-IR. The results revealed that the Co/Zn = 3 sample exhibited excellent performance with the high-temperature decomposition (HTD) temperature of AP reduced from 410°C to 295 °C and the apparent activation energy decreased to 98.7 kJ/mol in the case of 2 wt% addition, attributed to the construction of a heterojunction with abundant active sites enhancing the charge transfer capability between the Co3O4 and ZnO. The decomposition pathway of AP is influenced by the catalyst components, and the Co/Zn = 3 nanostructures demonstrated outstanding catalytic performance by accelerating the decomposition of HClO4 and the conversion of NH3, and promoting the production of N2O, NO, and NO2. This work provides a feasible strategy for the development of Co3O4@ZnO catalysts with excellent catalytic activity towards AP.