Kinetic Studies Research Articles

Co(II)-N4 Catalysts for the Coupling of CO2 with Epoxides into Cyclic Carbonates: Catalytic Activity, Computational and Kinetic Studies.

In this study, we synthesized and characterized a series of cobalt(II) complexes bearing linear tetradentate N4 ligands. These Co(II)-N4 complexes proved to be efficient catalysts for the cycloaddition reaction between carbon dioxide and epoxides even at room temperature and 1 bar pressure of carbon dioxide without the need for solvents or cocatalysts. Furthermore, when combined with (triphenylphosphoranylidene)ammonium chloride (PPNCl) as a cocatalyst, the Co-N4 catalysts exhibited an impressive turnover frequency of up to 41,000 h-1 for coupling of epichlorohydrin/CO2. These Co(II)-N4 catalysts were found to have excellent stability and reusability, retaining their catalytic activity after they were recycled seven times. Density functional theory (DFT) calculations provided a comprehensive mechanism for the cycloaddition reaction, indicating that the rate-determining step is the epoxide ring opening, in both the presence and absence of PPNCl. Further kinetic studies allow us to determine the activation parameters (ΔH‡, ΔS‡, and ΔG‡ at 25 °C) of the coupling reaction using the Eyring equation. The Gibbs free activation energy obtained from the kinetic studies was in close agreement with that of the DFT calculations. The substituent effect on the cycloaddition reaction of CO2 with various substituted styrene oxides was also examined for the first time.

Improvement strategy of citrate and biochar assisted nano-palladium/iron composite for effective dechlorination of 2,4-dichlorophenol.

Rapid passivation and aggregation of nanoscale zero-valent iron (nZVI) seriously limit its performance in the remediation of different contaminants from wastewater. To overcome such issues, in the present study, nano-palladium/iron (nPd/Fe) was simultaneously improved by biochar (BC) prepared from discarded peanut shells and green complexing agent sodium citrate (SC). For this purpose, a composite (SC-nPd/Fe@BC) was successfully synthesized to remove 2,4-dichlorophenol (2,4-DCP) from wastewater. In the SC-nPd/Fe@BC, BC acts as a carrier with dispersed nPd/Fe particles to effectively prevent its agglomeration, and increased the specific surface area of the composite, thereby improving the reactivity and stability of nPd/Fe. Characterization results demonstrated that the SC-nPd/Fe@BC composites were well dispersed, and the agglomeration was weakened. The formation of the passivation layer on the surface of the particles was inhibited, and the mechanism of SC and BC improving the reactivity of nPd/Fe was clarified. Different factors were found to influence the reductive dichlorination of 2,4-DCP, including Pd loading, Fe:C, SC addition, temperature, initial pH, and initial pollutant concentration. The dechlorination results revealed that the synergistic effect of the BC and SC made the removal efficiency and dechlorination rate of 2,4-DCP by SC-nPd/Fe@BC reached to 96.0 and 95.6%, respectively, which was better than that of nPd/Fe (removal: 46.2%, dechlorination: 45.3%). Kinetic studies explained that the dechlorination reaction of 2,4-DCP and the data were better represented by the pseudo-first-order kinetic model. The reaction rate constants followed the order of SC-nPd/Fe@BC (0.0264min-1) > nPd/Fe@BC (0.0089min-1) > SC-nPd/Fe (0.0081min-1) > nPd/Fe (0.0043min-1). Thus, SC-nPd/Fe@BC was capable of efficiently reducing 2,4-DCP and the dechlorination efficiency of BC and SC synergistically assisted composite on 2,4-DCP was much better than that of SC-nPd/Fe, nPd/Fe@BC and nPd/Fe. Findings suggested that SC-nPd/Fe@BC can be promising for efficient treatment of chlorinated pollutants.

Azobenzene-Integrated NHC Ligands: A Versatile Platform for Visible-Light-Switchable Metal Catalysis.

A new class of photoswitchable NHC ligands, named azImBA, has been developed by integrating azobenzene into a previously unreported imidazobenzoxazol-1-ylidene framework. These rigid photochromic carbenes enable precise control over confinement around a metal's coordination sphere. As a model system, gold(I) complexes of these NHCs exhibit efficient bidirectional E-Z isomerization under visible light, offering a versatile platform for reversibly photomodulating the reactivity of organogold species. Comprehensive kinetic studies of the protodeauration reaction reveal rate differences of up to 2 orders of magnitude between the E and Z isomers of the NHCs, resulting in a quasi-complete visible-light-gated ON/OFF switchable system. Such a high level of photomodulation efficiency is unprecedented for gold complexes, challenging the current state-of-the-art in photoswitchable organometallics. Thorough investigations into the ligand properties paired with structure-reactivity correlations underscored the unique ligand's steric features as a key factor for reactivity. This effective photocontrol strategy was further validated in gold(I) catalysis, enabling in situ photoswitching of catalytic activity in the intramolecular hydroalkoxylation and -amination of alkynes. Given the significance of these findings and its potential as a widely applicable, easily customizable photoswitchable ancillary ligand platform, azImBA is poised to stimulate the development of adaptive, multifunctional metal complexes.

Basic Red 46 adsorption studies onto pyrolyzed by-product biomass

In this study, the objective was to examine the utilization of the pyrolyzed by-products biomass as an adsorbent for extracting the dye Basic Red 46 (BR 46) from a solution. The pyrolyzed by-product containing Pleurotus mutilus biomass was characterized by thermogravimetric analysis (TGA), FTIR and µXRF. Different parameters effects such as, adsorbent dose, solution pH, contact time, temperature and initial dye concentration on the adsorption capacity of the pyrolyzed by-product biomass were examined. The solution was analyzed before and after the adsorption studies. With adsorbent dose of 1 g/L, contact time of 14 min, and solution pH of 7.5, the optimum yield of 88% was achieved. In order to fit the equilibrium data, the Langmuir, Freundlich, Temkin, and Khan isotherm models were used, and in order to fit the kinetics data, the pseudo-first-order, pseudo-second-order, Elovich, and Ritchie models were employed. Statistical analysis such as R2, RMSE,χ2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\chi }^{2}$$\\end{document} and ARE was used to assess which model has the best fit with the experimental data. The results demonstrated that the experimental equilibrium data are well described by the Langmuir model, and the kinetic studies indicated that the adsorption of BR46 followed the Ritchie model. The greatest BR 46 adsorption capacity determined from experimental equilibrium data was around 135 mg/g at pH = 7.5, adsorbent dosage of 1 g/L. Moreover, thermodynamic analysis has demonstrated that the adsorption process was physical, exothermic, and spontaneous in nature. These results indicated that pyrolyzed by-product biomass might be used as a cheap material to extract textile colors out of aqueous effluents.

Consecutive high-performance removal of Cu2+ metal ions and Deltamethrin using multifunctional pyrolysis cuttlebone/cotton fabric nanocomposite.

A simple technique was developed for the modification of cotton materials that is inexpensive, environmentally friendly, and very effective. Waste Cotton fabrics (WCFs) are loaded with propolis extract (PE) for Cu2+ removal. Then, Cu2+ underwent a pyrolysis process with modified cuttlebone (CB) at 900 °C for 5 h. The surface of the prepared materials was characterized using X-ray diffraction (XRD), scanning electron microscopy with energy-dispersive X-ray (SEM-EDX), Fourier transform infrared (FTIR), BET, particle sizes, thermogravimetric analysis (TGA) and zeta potential analysis. The Cu2+ metal ions from an aqueous solution were removed using WCFs/PE, and DLM was subsequently removed using pyro WCFs/PE/Cu/CB. The as-prepared NPs exhibited the face-centered cubic structure of WCFs/PE/Cu/CB with crystallite sizes ranging from 386.70 to 653.10 nm. FTIR spectra revealed that CB was present on the surface of the resulting WCFs/PE/Cu. SEM revealed the dispersion of a uniformly flower-like morphology over a large area. Sorption studies were performed based on parameters that included pH, dose, contact time, and initial concentration. The adsorption isotherm and the kinetic studies of the DLM adsorption process were applied at a pH of 5.0 and a temperature of 25 °C using several isotherms and kinetic models. The results revealed qmax (20.51 mg/g) with R2 = 0.97, the Langmuir isotherm that best matches the experimental data. Hence, the Langmuir isotherm suggests that it is the model that best describes sorption on homogenous surfaces or surface-supporting sites with various affinities. The correlation coefficient R2, χ2, adjusted correlation coefficient, and error functions like root mean square (RMSE), normalized root mean square error (NRMES), and mean absolute error (MAE) were used to evaluate the best-fit models to the experimental adsorption data. Moreover, cost estimation for the prepared adsorbent WCFs/PE/Cu showed that it costs approximately 3 USD/g, which is a cheap adsorbent compared to other similar adsorbents reported in the literature. The examined WCFs/PE have significant applicability potential for Cu2+-laden wastewater treatment due to their superior Cu2+ metal ions adsorption capability and reusability. The cytotoxicity and safety study showed that at higher concentrations, it resulted in much less cell viability. Additionally, the removal efficiency of Cu2+ metal ions from synthetic, realistic industrial wastewater using WCFs/PE reached up to 96.29 %, demonstrating good adsorption capability. Thus, there is a huge possibility of accomplishing this and performing well. This study paves the way for the reuse and valorization of selected adsorbents following circular economy principles. Two green metrics were applied, the Analytical Eco-scale and the Analytical GREEnness Calculator (AGREE).

Kinetics study and bio-phase characteristics of drainage in paddy fields purified by a compound ecological ditch

Kinetics study and bio-phase characteristics of drainage in paddy fields purified by a compound ecological ditch

Cobalt(II)-Catalyzed Synthesis of γ-Diketones from Aryl Alkenes and Its Utilization in the Synthesis of Various Heterocyclic Compounds.

An earth-abundant Co(II) salt-catalyzed mild and affordable synthetic route has been developed for the synthesis of industrially relevant 1,4-dicarbonyl compounds (or γ-diketones) via oxidative coupling between aryl alkenes and ketones (both cyclic and acyclic) using TBHP and DBU as the oxidant and base, respectively. 1,4-Dicarbonyl compounds are known to be synthesized using expensive metal catalysts, dual catalysts, or low-cost metal complexes combined with an additive or ligand template, which further needs to be synthesized. Herein, we report the synthesis of 1,4-dicarbonyl compounds using cobalt(II) acetate as a catalyst without any expensive co-catalyst or ligand templates. This methodology has a broad substrate scope with significant yields and good functional group tolerance. Generation of unsymmetrical 1,4-dicarbonyls at room temperature and its versatile synthetic expansion to produce synthetically and biologically valuable heterocyclic compounds are salient features of this novel methodology. In addition, various controlled experiments such as primary kinetic isotope effect study, Hammett analysis with variation of the nature of the substituents on the styrene ring, and theoretical calculations (density functional theory) unravel the mechanistic intricacies involved in this new, simple, and atom-economic methodology.

Photocatalytic Degradation of Tartrazine and Naphthol Blue Black Binary Mixture with the TiO2 Nanosphere under Visible Light: Box-Behnken Experimental Design Optimization and Salt Effect

In this study, TiO2 nanospheres (TiO2-NS) were synthesized by the solvothermal method. Firstly, the synthesized nanomaterial was characterized by X-ray diffraction (XRD), Fourier Transformed Infrared (FTIR), scanning electron microscopy (SEM) and UV-Vis Diffuse Reflectance Spectroscopy (DRS). To study the photocatalytic degradation of Tartrazine (TTZ) and Naphthol Blue Black (NBB) in a binary mixture, the influence of some key parameters such as pH, pollutant concentration and catalyst dose was taken into account under visible and UV light. The results show a 100% degradation efficiency for TTZ after 150 min of UV irradiation and 57% under visible irradiation at 180 min. The kinetic study showed a good pseudo-first-order fit to the Langmuir–Hinshelwood model. Furthermore, in order to get closer to the real conditions of textile wastewater, the influence of the presence of salt on TiO2-NS’s photocatalytic performance was explored by employing NaCl as an inorganic ion. The optimum conditions provided by the Response Surface Methodology (RSM) were low concentrations of TTZ (2 ppm) and NBB (2.33 ppm) and negligible salt (NaCl) interference. The percentage of photodegradation was high at low pollutant and NaCl concentrations. However, this yield became very low as NaCl concentrations increased. The photocatalytic treatment leads to 31% and 53% of mineralization yield after 1 and 3 h of visible light irradiation. The synthesis of TiO2-NS provides new insights that will help to develop an efficient photocatalysts for the remediation of contaminated water.

Thermal treatment impact on the evolution of active phases in layered double hydroxide-based ZnCr photocatalysts: Photodegradation and antibacterial performance

Abstract This study investigated the influence of thermal treatment on the photocatalytic performance of ZnCr layered double hydroxide-based mixed metal oxides in the degradation of methylene blue and brilliant cresyl blue organic dyes under simulated solar light irradiation. The photocatalysts were synthesized using a simple coprecipitation method and subjected to thermal treatment at temperatures ranging from 100°C to 900°C. Additionally, the study explored the antibacterial activity against Escherichia coli and Staphylococcus aureus using a novel antibacterial experimental setup. It not only involved the introduction of ZnCr samples into BioPeptone/prepared cell suspension to enhance photocatalyst–bacteria cell contact but also included research on antibacterial activity induced by solar irradiation and also in the absence of light, providing crucial insights into photocatalytic antibacterial activity of ZnCr photocatalysts. Despite satisfactory efficiencies observed for all thermally treated ZnCr samples (removal efficiency ranging from 40% to 90%), ZnCr 900 (thermally treated at 900°C) exhibited exceptional performance, achieving nearly 100% removal efficiency and complete growth inhibition for both bacteria. Integrating these findings with structural and textural characterization data, as well as kinetic studies, our comprehensive analysis enhances the understanding of structure-dependent photocatalytic activities. These insights open possibilities for the application of ZnCr photocatalysts in water purification and environmental remediation.

New Instrument for Time-Resolved OH and HO2 Quantification in High-Pressure Laboratory Kinetics Studies.

We have constructed a new time-resolved high-pressure fluorescence assay by gas expansion (HP-FAGE) apparatus, optimized for the detection of OH and HO2 radicals in complex gas-phase reactions. The new instrument fills a gap in the existing experimental toolkit for chemical kinetics by enabling the quantification of two key reactive species with microsecond time resolution from high-pressure sources, which was previously not attainable. The HP-FAGE is interfaced with a flow reactor, designed for pressures up to 100 bar and temperatures up to 1000 K, in which reactions are initiated by laser photolysis of radical precursors at repetition rates of 1-10 Hz. The HP-FAGE samples gas out of the reactor into a miniature FAGE chamber, where OH is detected by resonant laser-induced fluorescence using a time-delayed probe laser pulse. HO2 is converted to OH via reaction with NO and then detected by OH fluorescence. The novel FAGE design places the probe region very close to the gas expansion, minimizing the transport time of sampled molecules and resulting in time resolution better than 20 μs for both OH and HO2. We calibrate the sensitivity of HP-FAGE, validate its performance with measurements of well-known reaction kinetics (OH + CH4, OH + OH, OH + HO2, and HO2 + HO2), and discuss prospects for its future use.

High-temperature oxidation behaviours of rare earth-based pyrochlore structured A2B2O7/yttria-stabilized zirconia thermal barrier coatings

Addressing the challenge of cost-effectively synthesizing stable thermal barrier coating materials has been a significant hurdle. This study describes the bulk synthesis of stannate-based pyrochlore compounds, specifically erbium tin oxide (Er2Sn2O7) and yttrium tin oxide (Y2Sn2O7). These synthesized pyrochlore oxides and commercially available yttria-stabilized zirconia (YSZ) were coated onto nickel super alloy. The coated specimens were subjected to thermal oxidation kinetics studies at 900 ± 5°C for 200 h, and alterations in physico-chemical characteristics, modifications in surface morphology, and variations in the composition of thermal barrier coating (TBCs) before and after exposure to oxidation conditions were evaluated. Oxidation kinetics results demonstrate that Er2Sn2O7 pyrochlore oxide has better performance than other Y2Sn2O7 and commercial YSZ TBC materials in high-temperature thermal barrier systems.

Tunable optoelectronic performances of fluorinated benzene-EDOT based hybrid electrochromic polymers

Due to its high electronegativity and small atomic radius without undesirable steric hindrance, the incorporation of fluorine atoms into the benzene unit which started from the commercially available compounds is a feasible way to tune the energy levels of polymers, and its electrochromic application is expected to achieve a new breakthrough. Herein, in this paper, benzene units with different fluorine atom numbers were selected as the core and 3,4-ethylenedioxythiophene (EDOT) as the terminal unit, three fluorinated electrochromic precursors (FPh-EDOT, 2FPh-EDOT, and 4FPh-EDOT) were designed and synthesized by Stille coupling reaction, and the corresponding fluorinated π-conjugated electrochromic polymers (P(FPh-EDOT), P(2Ph-EDOT), and P(4FPh-EDOT)) were prepared by electrochemical polymerization method. The effects of different fluorinated benzene units on the photophysics, electrochemistry and electrochromic properties of precursors and polymers were systematically investigated, and the structure-property relationship was further revealed. All of them have low initial oxidation potentials {FPh-EDOT (0.65 V), 2FPh-EDOT (0.72 V), and 4FPh-EDOT (0.70)}, which makes it easy to obtain high-quality new fluorinated polymers at low polymerization potential. With the increase of the number of F atoms, the UV-vis absorption spectra and emission spectra of fluorinated monomer firstly red-shifted and then blue-shifted. The corresponding fluorinated polymers have good electrochemical activity and stability (the P(2Ph-EDOT) activity remained 56.3% after 500 cycles), making it possible to realize their electrochromic devices. All these three fluorinated polymers show obvious color change from the neutral state to the fully oxidized state (P(FPh-EDOT) changes from brown to grayish blue, P(2FPh-EDOT) changes from brown to gray, and P(4FPh-EDOT) changes from dark blue to light blue). The kinetic study further shows that all of them have distinguish electrochromic properties with good optical stability, very short response time (0.9 s for P(2FPh-EDOT) at 700 nm), and favorable coloration efficiency (130.7 cm2 C-1 for P(FPh-EDOT) at 503 nm). Overall, all these three fluorinated polymers have low optical band gap, good redox stability and electrochromic properties, are very promising electrochromic materials, which is worthy for the further research and development.

Effect of cobalt on CeO2 nanorod supported Pt catalyst: Structure, performance, kinetics and reaction mechanism in CO oxidation

Catalytic oxidation represents a highly efficient and extensively employed approach for the elimination of CO in exhaust gas. Rationally designing and preparing catalysts with exceptional activity and stability in the presence of H2O and SO2 at low temperatures represent crucial avenues for future advancements. In this work, a series of Pt catalysts supported on CeO2 nanorods incorporated with varying amounts of Cobalt (Co/CeO2 ratio ranging from 0 to10) were prepared and evaluated for their catalytic activity in CO oxidation under both dry and wet conditions. The ultrahigh dispersion of Pt, outstanding redox properties, and abundant oxygen vacancies on the surface of Co-doped CeO2 nanorod supported Pt catalysts were revealed by XRD, HAADF-STEM, Raman spectroscopy and H2-TPR techniques. The catalytic activity for CO oxidation strongly depends on the Co content and reaction conditions. Among them, Pt/Co-CeO2-5 % exhibits the highest CO oxidation performance with a T90 (the temperature to achieve 90 % conversion of CO) of 170 °C under dry conditions, which is significantly lower by 140 °C compared to T90 of Pt/CeO2. Pt/Co-CeO2-1 % demonstrates superior CO oxidation performance with a T90 of 195 °C under wet conditions, exhibiting a reduction in temperature by 65 °C compared to the T90 of Pt/CeO2. Moreover, Pt/Co-CeO2 exhibits excellent resistance to SO2 compared to Pt/CeO2. Kinetic studies, in situ DRIFT analysis and isotopic experiments demonstrated direct participation of H2O in the reaction. On the catalysts with a low Co/Ce ratio (Co/Ce < 0.03), CO readily reacts with hydroxyl groups dissociated from H2O to form carboxyl intermediates, which subsequently undergo rapid decomposition into CO2, resulting in an enhanced reaction rate of CO oxidation at low temperature.

A new circulation in glycolysis of polyethylene terephthalate using MOF-based catalysts for environmental sustainability of plastic

The relentless growth of plastic has emerged as a significant environmental and human health concern. Catalytic glycolysis of polyethylene terephthalate (PET) has proven to be an effective solution. This study investigated a series of M−BDC (M = Ni, Co, Cu, and Zn) metal–organic frameworks as catalysts for PET glycolysis. Zn-BDC exhibited the best experimental performance. Subsequently, the effects of operating conditions were optimized for the first time through a comprehensive investigation using a model based on deep neural networks (DNNs). The guidance of the DNN model resulted in a BHET selectivity as high as 0.95, outperforming most current heterogeneous catalysts for PET depolymerization. Furthermore, the apparent activation energy was also estimated by kinetic study. In addition, our designed system exhibits high durability after five consecutive runs, reflecting its promising escalation at the industrial level. Notably, the fabrication of the M−BDC framework can utilize the organic linker terephthalic acid (TPA) derived from the BHET monomer. By applying this strategy, we have achieved a significant advancement towards closed-loop PET recycling, contributing to a more comprehensive definition of sustainable development.

Adsorption Isotherms and Kinetic Studies for the defluoridation from Aqueous Solution Using Eco-friendly Natural Adsorbent like Terminalia Chebula

A practical technique for removing fluoride from aqueous solutions by adsorption was created using the natural adsorbent known as Terminalia Chebula with a primary emphasis on adsorption isotherms and kinetic studies. The experimental results showed the best conditions for removing fluorine ions as follows: the dosage of the natural adsorbent: 50 mg / L, contact reaction time: 40 mins, shaking speed = 120 rpm, temperature = 32 o C. The amount of removal of fluorine ions was found to be > 98% fluoride within a shorter time and reached adsorption equilibrium within 40 minutes with a maximum defluoridation capacity of 20.92 mg / g. At lower solution pH (3 to 5), there is higher fluoride adsorption on the adsorbent surface and as the pH becomes alkaline (pH > 7) the adsorption capacity decreased. The two co-ions namely NO3− and Cl− removed the fluoride 79% whereas, the phosphate ions did not have any marked effect on the defluoridation. The pseudo-second-order kinetic order such Langmuir, Empirical Freundlich, Temkin and Dubinin-Radushkevich isotherms can well predict the adsorption equilibrium rate to be at 0.044 mg / L with contact time (t) of 30 mins. In addition to that the adsorption is characterized by SEM, X-ray diffraction and FTIR techniques. This study has ultimately found that the Terminalia Chebula is a workable, natural material for fluoride elimination.

Adsorption, kinetic, and thermodynamic studies of natural curcumin dye on cotton and polyamide fabric and the liberation of its active principle

AbstractThe increasing emphasis on environmental sustainability and the demand for eco‐friendly practices have led to a surge in interest in natural products, particularly natural dyes, across industries, including textiles. Curcumin, extracted from the turmeric plant, has gained widespread application not only for its vibrant colour characteristics but also for numerous therapeutic properties, serving as an antioxidant, anti‐inflammatory agent, and promoting wound‐healing effects. This study aims to understand the physical and chemical phenomena associated with the adsorption and desorption of turmeric extract and its active principles on cotton and polyamide fibres through mathematical models, with the goal of expanding textile applications. Dyeing experiments revealed adsorption equilibrium times of less than 25 min for both fibres, with the pseudo‐second‐order model providing the best fit for dyeing kinetics, suggesting control through the chemisorption process. The Freundlich model better suited cotton adsorption isotherms (R2 = 0.778), while the Langmuir model fit well for polyamide (R2 = 0.981). Thermodynamic parameters indicated non‐spontaneous interactions between curcumin and cotton, with an endothermic process, and an exothermic and spontaneous process for polyamide. Friction and water tests indicated greater colour resistance for polyamide, with grades exceeding 4. Desorption tests in 100% ethanol solution showed a total release of only 0.88% and 0.97% for polyamide and cotton, respectively, sustained for 12 h, fitting the Higuchi mathematical model, indicating a purely diffusive release process. These results demonstrate the potential of curcumin dye for achieving high dye exhaustion percentages in natural and synthetic fabrics and sustained release properties.

Electric-field enhanced three-dimensional flexible carbon felt as a host for Pt4+ ions extraction

The extraction of the precious metal Pt4+ ions from aqueous solution are of great importance for both economic development and environmental protection. In this study, an electric field assisted adsorption process with high efficiency and recyclability was explored in a self-made device using three-dimensional (3D) flexible carbon felt (FCF) as the adsorbent without using conductive adhesive. Under the aid of an electric field (0.4 V), 3D pristine FCF (p-FCF) showed a considerable adsorption capacity for Pt4+ (82 mg/g). As high as 203 mg/g was obtained when o-NFCF adsorbents modified with N doping and surface oxygen-containing groups was used. Kinetic and thermodynamic studies show that the electric field would enhance the interactions between the adsorbent and Pt4+ ions, and improve the intraparticle diffusions. Mechanism study showed that the synergistic effect between N doping and oxygen-containing groups might efficiently tune the electrochemical properties of 3D FCF materials, which significantly contributed to the enhanced adsorption of Pt4+. The electroadsorption technology developed in this study provides a simple and efficient method for industrial recovery of precious metal ions.

Investigating Autoignition Characteristics of Ammonia/Heptamethylnonane Mixtures Over Wide Pressure Ranges: Rapid Compression Machine Measurements and Kinetic Modeling Study

Investigating Autoignition Characteristics of Ammonia/Heptamethylnonane Mixtures Over Wide Pressure Ranges: Rapid Compression Machine Measurements and Kinetic Modeling Study

Disentangling the formation, mechanism, and evolvement of the covalent methanesulfonyl fluoride acetylcholinesterase adduct: Insights into an aged-like inactive complex susceptible to reactivation by a combination of nucleophiles.

Chemical warfare nerve agents and pesticides, known as organophosphorus compounds inactivate cholinesterases (ChEs) by phosphorylating the serine hydroxyl group located at the active site of ChEs. Over the course of time, phosphorylation is followed by loss of an organophosphate-leaving group and the bond with ChEs becomes irreversible, a process known as aging. Differently, structurally related irreversible catalytic poisons bearing sulfur instead of phosphorus convert ChEs in its aged form only by covalently binding to the key catalytic serine. Kinetic and crystallographic studies of the interaction between Torpedo californica acetylcholinesterase (TcAChE) and a small organosulfonate, methanesulfonyl fluoride (MSF), indeed revealed irreversibly methylsulfonylated serine 200, to be isosteric with the bound aged sarin/soman analogues. The potent bulky reversible inhibitor 7-bis-tacrine (BTA) adopts, in the active site of the crystal structure of the MSF-enzyme adduct, a location and an orientation that closely resemble the one being found in the crystal structure of the BTA-enzyme complex. Remarkably, the presence of BTA accelerates the rate of methanesulfonylation by a factor of two. This unexpected result can be explained on the basis of two facts: i) the steric hindrance exerted by BTA to MSF in accessing the active site and ii) the acceleration of the MSF-enzyme adduct formation as a consequence of the lowering of the rotational and translational degrees of freedom in the proximity of the catalytic serine. It is well known that pralidoxime (2-Pyridine Aldoxime Methyl chloride, 2-PAM) alone or in the presence of the substrate acetylcholine cannot reactivate the active site serine of the TcAChE-MSF adduct. We show that the simultaneous presence of 2-PAM and the additional neutral oxime, 2-[(hydroxyimino)methyl]-l-methylimidazol (2-HAM), triggers the reactivation process of TcAChE within the hour timescale. Overall, our results pave the way toward the likely use of a cocktail of distinctive oximes as a promising recipe for an effective and fast reactivation of aged cholinesterases.

Enhanced white light emission and quantum efficacy of borate-zinc–lithium-aluminium glasses doped with Dy2O3 for potential white light emission applications

The pursuit of efficient and enhanced white light emission in glasses doped with rare earth ions is a noble endeavour, one that has the potential to revolutionise many industries and benefit countless individuals. In view of this, we have prepared the Dy3+ ions doped Borate-Zinc–Lithium-Aluminium glasses via melt-quenching methods and their properties were meticulously studied using XRD, Raman, FTIR, DSC, Luminescence and time decay kinetic studies. To evaluate the influence of Dy2O3 doping, various physical parameters were analysed. The integration of Dy2O3 into the host glass matrix causes significant changes in the numerous physical parameters due to the geometrical structural change, resulting in the formation of non-bridging oxygens (NBOs), resulting in the increased compactness, thus the density and refractive index of the glasses. The DSC profile analysis reveals the thermal stability of the glasses. The UV–visible–NIR absorption spectra reveal the presence of a pronounced peak, owing to a hyperfine transition and other transitions dependent on the host. Furthermore, the Judd-Ofelt theory was applied to support the experimental results and evaluate the radiative parameters and efficiency. It was discovered that the JO parameters are in the following order: Ω2> Ω6> Ω4. The luminescence emission enhancement was observed with Dy2O3, up to 0.75 mol%; beyond that, the concentration quenching effect was observed. The glasses were proficiently fitted to the Inokuti-Hirayama model. Colorimetric parameters such as CIE coordinates, correlated colour temperature, and yellow-to-blue intensity ratios were estimated. It was discovered that, the sample containing 0.75 mol% of Dy2O3 doped glass is capable of white light emission with 72 % efficiency under excitation of 349 nm. Overall, present studies demonstrate that the thermal stability of glasses with phonon energy of 1330 cm−1, when stimulated at 349 nm and capable of producing white light, offers considerable benefits in relevant applications in the field of wLEDs.