Second-order Reaction Research Articles

The correlation among residual nitrites, biogenic amines, N-nitrosamine formation, and degradation occurrence of punicalagin α/β, rosmarinic acid, carnosol, and carnosic acid in extract-treated sausage during storage.

The aim of this study was to investigate the relation between residual α- and β-punicalagin in Punica granatum L.; PPE and rosmarinic acid, carnosol, and carnosic acid in Salvia eremophila (SE) with residual nitrites, biogenic amines (cadaverine, putrescine, and histamine), N-nitrosodimethylamine (NDMA), microbial counts, lipid oxidation indices, and color values in extract-treated sausage over 14 days of storage. Sausage containing SE + nitrite 60 ppm (SSN) showed minimum levels of the residual nitrites (13.14 mg/kg), NDMA (0.74 ± 0.05 μg/kg), and biogenic amine (histamine, 1.8 mg/kg; cadaverine, 3.7 mg/kg; and putrescine, 4.3 mg/kg) due to retarded degradation rate of 285.84-216.44 mg/kg; rosmarinic acid, 41.62-33.16 mg/kg; carnosol, and 88.70-76.73 mg/kg; carnosic acid over storage time. The first-order kinetic model fitted well for the degradation of rosmarinic acid and carnosol acid in SSN sample. TBA value remained below the threshold limit (0.32 mg kg-1) through 14 days for SSN. Second-order and zero-order reaction models had the best agreement with sausages' PV and TBA values, respectively. After 2 weeks of storage, E. coli and Cl. perfringens counts in the SN120 (sausage containing 120 ppm nitrite) and SSN were significantly lower than the other samples (p < .05), with the values 2.1 and 1.5 log cfu/g for SN120 and 2.2 and 1.6 log cfu/g for SSN formulation. Conversely, oxidation indices, residual nitrites, NDMA, and biogenic amine increased in sausage samples containing PPE extracts (SPN) owing to total degradation of α- and β-punicalagin during storage. The results indicated that SE can be used as potential co-preservative by reducing the levels of required nitrite in food industry.

Removal of heavy metals from the aqueous solution by nanomaterials: a review with analysing and categorizing the studies.

With the development of nanotechnology and its application in various sciences, scientists have investigated the use of nanoparticles as adsorbents to remove heavy metals from aqueous solutions all over the world. So far, the results of many of these studies have been published in reputable journals. Obviously, reviewing these articles and summarizing the results of these studies from different aspects will provide new perspectives for the development of this technology for heavy metals removal from water. So the current study was performed to review the results of the published studies between 1/January/1980 to 1/January/2022. The focus of the study is on the analysis of these studies and their classification. In addition, a more detailed investigation was carried out. Among the 5155 articles, 576 articles were included based on Cochrane protocols. Results show that most of the studies (90.8%) were conducted on a laboratory scale and used synthetic solutions. Most studies were performed for Pb, Cd and Cu, removal respectively. Compared to other countries, authors with affiliation from China and Iran have published more articles. The ranking of the use of various nanomaterials were: nanocomposites > metal oxide nanomaterials > metal-based nanomaterials > carbon-based nanomaterials > dendrimers, with the wide range of sizes from less than 10nm to several hundreds of nanometers. The required amount of carbon-based nanoparticles to remove many heavy metals were lower than other nanoparticles. In most studies, pH ≤ 7 has been reported as optimal. Most studies have been followed pseudo second-order and pseudo first-order reactions and have been more agreement with Langmuir and Freundlich adsorption isotherms respectively. The results of studies show that the synthesis and optimization of new nanomaterials can be considered as a new and competitive technology. However, more studies are needed to investigate the removal of heavy metals in real samples and to overcome some challenges in the full-scale application.

Oxidation of 1,3-diphenylguanidine (DPG) by goethite activated persulfate: Mechanisms, products identification and reaction sites prediction

As emerging pollutants continue to be discovered, studies on the degradation behavior of emerging pollutants have proliferated, but few studies have focused on the reactivity of the new pollutants themselves. The work investigated the oxidation of a representative roadway runoff-derived organic contaminant, 1,3-diphenylguanidine (DPG) by goethite activated persulfate (PS). DPG exhibited the highest degradation rate (kd = 0.42 h−1) with present of PS and goethite at pH 5.0, then started to decrease with increasing pH. Chloride ion inhibited DPG degradation by scavenging HO·. Both HO· and SO4−· were generated in goethite activated PS system. Competitive kinetic experiments and flash photolysis experiments were conducted to investigate free radical reaction rate. The second-order reaction rate constants for DPG reacting with HO· and SO4−· were quantified (kDPG + HO·,kDPG + SO4-·), which both reached above 109 M−1 s−1. Chemical structures of five products were identified, four of them were previously detected in DPG photodegradation, bromination and chlorination processes. By density functional theory (DFT) calculations, ortho- and para- C were more easily attacked by both HO· and SO4−·. Abstraction of H on N by HO· and SO4−· were the favorable pathways, and the product TP-210 might be generated by cyclization of DPG radical from abstraction of H on N (3). The results of this study help us to better understand the reactivity of DPG with SO4−· and HO·.

A linear stability analysis of instabilities with reactive flows in porous medium

Convection, diffusion, and reaction dynamics of radial displacement of reactive fluids undergoing second-order chemical reaction in a porous medium are modeled and understood numerically. In the case of iso-viscous reactants and products, reaction dynamics are examined to understand the effect of reaction rate after solving a system of convection–diffusion–reaction equations using a method of lines. Various temporal scalings for reaction characteristics like the total amount of product and width of reaction front are obtained in terms of the Damköhler number (Da) for the first time in this work. The generation of the product having different viscosity than the reactants results in a hydrodynamic instability called viscous fingering. The numerical technique based on hybrids of compact finite difference and pseudo-spectral methods is utilized, for the first time, for the linear stability analysis (LSA) of miscible viscous fingering induced by chemical reaction. The onset time of instability (ton) is found to depend on the reaction rate, and we obtain a stable zone sandwiched between two unstable zones in the Mc,ton plane for a fixed Péclet number and Damköhler number, where Mc is the log-mobility ratio. The results agree with existing numerical studies validating the novel LSA technique utilized.

Rapid Synthesis of PbO-NPs Photocatalysts, Investigation of Methylene Blue Degradation Kinetics

The study focused on the green synthesis of lead oxide nanoparticles (PbO-NPs) using green tea extract and its use for photocatalytic degradation. The effect of experimental conditions such as green tea extract concentrations and reaction temperatures on the structure and size of PbO-NPs has been investigated. Reaction temperatures of 25, 50 and 85 ℃ and green tea extract concentrations of 5, 10, 20, 40, 80 and 100 mg/mL were used for preparing of PbO-NPs. Amount of the phenolic acid contained in the green tea extracts was determined according to the Folin-Cioceltau method. The synthesized PbO-NPs were further confirmed by UV–visible Spectroscopy, Fourier Infrared Transformation Spectroscopy (FTIR), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Energy Dispersive (EDX) analysis. Tetragonal and orthorhombic morphology of PbO-NPs were observed in SEM images. While the crystallite structure of the PbO-NPs was obtained for the samples prepared using 5 and 10 mg/mL extract concentration for all reaction temperatures, the amorphous structures of PbO-NPs were seen for the samples prepared using extract concentrations of 20, 40, 80 and 100 mg/mL. Finally, PbO-NPs catalyst was tested for the degradation of methylene blue (MB) under UV light. The effect of dye concentration, catalyst amount and pH on degradation were investigated. By determining suitable experimental conditions, MB degradation reached 89% with PbO-NPs in 60 minutes. The reaction kinetics of MB removal from aqueous solution under UV lamp and in the dark media were compared for first-order and second-order reaction kinetics.

Heterogeneous and Photosensitized Oxidative Degradation Kinetics of the Plastic Additive Bisphenol-A in Sea Spray Aerosol Mimics.

Plastics have become ubiquitous in the world's oceans, and recent work indicates that they can transfer from the ocean to the atmosphere in sea spray aerosol (SSA). Hazardous chemical residues in plastics, including bisphenol-A (BPA), represent a sizable fraction of consumer plastics and have been measured consistently in air over both terrestrial and marine environments. However, the chemical lifetimes of BPA and mechanisms by which plastic residues degrade with respect to photochemical and heterogeneous oxidation processes in aerosols are unknown. Here, we present the photosensitized and OH-initiated heterogeneous oxidation kinetics of BPA in the aerosol phase consisting of pure-component BPA and internal mixtures of BPA, NaCl, and dissolved photosensitizing organic matter. We found that photosensitizers enhanced BPA degradation in binary-component BPA + photosensitizer aerosol mixtures when irradiated in the absence of OH. OH-initiated degradation of BPA was enhanced in the presence of NaCl with and without photosensitizing species. We attribute this enhanced degradation to greater mobility and thus reaction probability between BPA, OH, and reactive chlorine species (RCS) formed through reaction between OH and dissolved Cl- in the more liquid-like aerosol matrix in the presence of NaCl. Addition of the photosensitizers in the ternary-component BPA + NaCl + photosensitizer aerosol led to no enhancement in the degradation of BPA following light exposure compared to the binary-component BPA + NaCl aerosol. This was attributed to quenching of triplet state formation by dissolved Cl- in the less viscous aqueous aerosol mixtures containing NaCl. Based upon measured second-order heterogeneous reaction rates, the estimated lifetime of BPA with respect to heterogeneous oxidation by OH is one week in the presence of NaCl compared to 20 days in the absence of NaCl. This work highlights the important heterogeneous and photosensitized reactions and the role of phase state, which affect the lifetimes of hazardous plastic pollutants in SSA with implications for understanding pollutant transport and exposure risks in coastal marine environments.

A pyrolysis model for the thermal decomposition of low-density polyethylene blended with ammonium polyphosphate and pentaerythritol

In this work, a semi-empirical pyrolysis model is developed to predict the thermal decomposition behavior of an intumescent fire retardant (IFR) system consisting of ammonium polyphosphate/pentaerythritol (APP/PER) with the ratio 3:1 (wt/wt) in a low-density polyethylene (LDPE) matrix. This work is based on a previously developed semi-global reaction mechanism for the degradation of LDPE and APP/PER, which consists of two consecutive first-order reactions for the LDPE and five first and second-order reactions for the APP/PER combination. The apparent properties that define heat transport inside the pyrolyzing solid are determined via inverse modeling of cone calorimeter experiments for the pure LDPE and then for the complete IFR system. This is achieved by using the Shuffled Complex Evolution optimization algorithm. The flame heat flux in the cone calorimeter experiments is also evaluated by targeting the heat release rate (HRR) data in the optimization process of one of the cone radiative heat setups. The optimized parameters and flame heat feedback are in line with the literature and the robustness of the model is assessed by a comparison with the experimental data for a wide range of cone heat fluxes. Ignition times and peaks of HRR and total HRs are within the engineering accuracy whatever the flux conditions for both pure LDPE and the IFR system.

Nickel-Carbon Bond Oxygenation with Green Oxidants via High-Valent Nickel Species.

Described herein is the synthesis of the NiII complex (tBuMe2tacn)NiII(cycloneophyl) (tBuMe2tacn = 1-tert-butyl-4,7-dimethyl-1,4,7-triazacyclononane, cycloneophyl = -CH2CMe2-o-C6H4-) and its reactivity with dioxygen and peroxides. The new tBuMe2tacn ligand is designed to enhance the oxidatively induced bond-forming reactivity of high-valent Ni intermediates. Tunable chemoselectivity for Csp2-O vs Csp2-Csp3 bond formation was achieved by selecting the appropriate solvent and reaction conditions. Importantly, the use of cumene hydroperoxide and meta-chloroperbenzoic acid suggests a heterolytic O-O bond cleavage upon reaction with (tBuMe2tacn)NiII(cycloneophyl). Mechanistic studies using isotopically labeled H2O2 support the generation of a high-valent Ni-oxygen species via an inner-sphere mechanism and subsequent reductive elimination to form the Csp2-O bond. Kinetic studies of the exceptionally fast Csp2-O bond-forming reaction reveal a first-order dependence on both (tBuMe2tacn)NiII(cycloneophyl) and H2O2, and thus an overall second-order reaction. Eyring analysis further suggests that the oxidation of the NiII complex by H2O2 is the rate-determining step, which can be modulated by the presence of coordinating solvents. Moreover, computational studies fully support the conclusions drawn from experimental results. Overall, this study reveals for the first time the ability to control the oxidatively induced C-C vs C-O bond formation reactions at a Ni center. Importantly, the described system merges the known organometallic reactivity of Ni with the biomimetic oxidative transformations resembling oxygenases and peroxidases, and involving high-valent metal-oxygen intermediates, which is a novel approach that should lead to unprecedented oxidative catalytic transformations.

Studying the mechanism and kinetics of fuel desulfurization using CexOy/NiOx piezo-catalysts as a new low-temperature method

In order to advance desulfurization technology, a new method for excellent oxidative desulfurization of fuel at room temperature will be of paramount importance. As a novel desulfurization method, we developed piezo-catalysts that do not require adding any oxidants and can be performed at room temperature. A microwave method was used to prepare CeO2/Ce2O3/NiOx nanocomposites. Model and real fuel desulfurization rates were examined as a function of synthesis parameters, such as microwave power and time, and operation conditions, such as pH and ultrasonic power. The results showed that CeO2/Ce2O3/NiOx nanocomposites demonstrated outstanding piezo-desulfurization at room temperature for both model and real fuels. Furthermore, CeO2/Ce2O3/NiOx nanocomposites exhibited remarkable reusability, maintaining 79% of their piezo-catalytic activity even after 17 repetitions for desulfurization of real fuel. An investigation of the mechanism of sulfur oxidation revealed that superoxide radicals and holes played a major role. Additionally, the kinetic study revealed that sulfur removal by piezo-catalyst follows a second-order reaction kinetic model.

Tandem Heck/Tsuji-Trost Reaction for Uncaging of Alloc-Protected Amines with Palladium Complexes in Living Cells

The palladium-catalyzed uncaging of alloc-protected amines in living cells has been extensively studied mostly in the form of nanostructures or mesostructures. However, the scarcity of kinetic and mechanistic studies of discrete palladium complexes for deallylation reactions has hindered progress. Herein, we report the development of a series of discrete palladium complexes bearing acetanilide ligands, which exhibit a good balance between reactivity and stability in living cells. We investigated the catalytic activity and cytotoxicity of these complexes in SiHa cells and found that acetanilide[tri(2-furyl)phosphine]palladium(II) triflate showed promising results. Under physiological conditions, this palladium complex exhibited a second-order reaction rate of 30 M−1s−1, and liquid chromatography-mass spectrometry (LC-MS) studies suggested the possibility of a tandem Heck/Tsuji-Trost mechanism. Our results demonstrate the potential of using these discrete palladium complexes for bioorthogonal chemistry studies in living cells.

Potential of the Biomass Waste Originating from Saccharum officinarum as a Fenton Precursor for the Efficient Oxidation of Azo Dye from an Aqueous Stream

In the current investigation, elements extracted from Saccharum officinarum were identified as exporters of Fenton catalysts. Saccharum officinarum was soaked in an alkali prior to acidic treatment and then subjected to pyrolysis for elemental recovery. X-ray diffraction (XRD) and scanning electron microscopy (SEM) augmented with energy-dispersive X-ray spectroscopy (EDX) were used to identify the prepared catalyst. The material was combined with hydrogen peroxide, which led to Fenton’s reaction. Then, the modified Fenton system was applied to eliminate the textile dye, named Bismarck Brown Azo dye, contaminating the aqueous effluent. Response surface methodological model (RSM) analysis was used to identify the most effective operational parameters, and the model set the optimized values as 39 and 401 mg/L for Saccharum officinarum and H2O2 doses, respectively, at pH 2.9. The maximum Bismarck Brown Azo dye removal achieved was 85%. Increasing the temperature to 60 °C improved the dye oxidation efficiency. However, the dye treatment efficacy was reduced when the dye loading increased. Additionally, the kinetic rate order was investigated and the system was fitted to second-order rate reaction kinetics. The thermodynamic variables show that the reaction is endothermic and non-spontaneous.

Insight into the adsorption thermodynamics, kinetics, and photocatalytic studies of polyaniline/SnS2 nanocomposite for dye removal

The study aims to address the synthesis, the kinetics of adsorption, and photocatalytic application of Polyaniline/tin sulfide (PANI/SnS2) nanocomposite against brilliant blue (BB) dye. PANI/SnS2 was prepared by in-situ polymerization of the aniline to which hydrothermally synthesized SnS2 was added. Adsorption thermodynamics and kinetics of PANI/SnS2 were discussed against the BB dye using Langmuir and Freundlich adsorption isotherm. Maximum adsorption capacity (qm) and adsorption equilibrium constant (K) were found to be 165.2 mg g−1, and 0.027 min−1. Moreover, Adsorption kinetics were studied by the pseudo-first and second-order reactions. The adsorption rate constant k1 and diffusion rate constant k2 were found to be 0.1274 and 0.0233 min−1. PANI and SnS2 with tunable band gap energy, adsorption, and redox property exhibited excellent activity towards the photodegradation of BB dye. The effect of heterojunction between PANI/SnS2 was observed by an increased rate of transfer of electrons. The rate constant was highest in the case of PANI/SnS2 (20%), which is 0.0172 min−1 and a maximum of 96.2% of BB dye was degraded in 45 min. The hydroxyl (•OH) and superoxide (•O2−) radicals were generated during photocatalysis that degrades the BB dye into nontoxic products, which were confirmed by the trapping experiment. The obtained results indicate the excellent adsorption and photocatalytic activity of PANI/SnS2 nanocomposite.

Oxidation characteristics and thermal stability of Butylated hydroxytoluene

Butylated hydroxytoluene (BHT) is an excellent antioxidant widely used in food, polymer materials, and other fields. In order to understand the hazards of BHT, it is necessary to study its thermal stability, oxidation properties, and reaction products. This paper investigated BHT's oxidation characteristics and products using a mini-closed pressure vessel test (MCPVT), UV radiation reaction method, iodometric method, and gas chromatography-mass spectrometry (GC–MS). The MCPVT results showed that no chemical reaction of BHT was observed under a nitrogen atmosphere even when the temperature was increased to 450 K, which indicated that it was stable. However, BHT was readily oxidized under an oxygen atmosphere with an initial oxidation temperature of 332 K. Notably, oxidation reactions can occur as low as 293 K under 365 nm UV radiations in the atmosphere. The kinetics of the initial oxidation of BHT was investigated. The kinetics of the reaction of BHT in MCPVT was a second-order reaction with the kinetic equation lnk = -1.2194 × 104(1/T) + 21.4. And Ea = 101.4 kJ mol−1. The difference is that a pseudo-first-order reaction was shown under UV radiation, with a linear relationship between the apparent activation energy and the logarithm of the light intensity (I): Ea = -1.878 lnI + 74.56, the apparent activation energy was significantly reduced compared to the former, indicating that UV light has a great effect on the oxidation of BHT. The peroxide value of the BHT oxidation product in MCPVT was determined with the iodometric method. When the reaction was carried out at 358 K for 8 h, the peroxide value of BHT was 3.2 mmol kg−1. The main oxidation products of BHT were identified with GC–MS, such as 2, 6-di-tert-butyl-p-benzoquinone, 1-(2, 4, 6-trihydroxyphenyl) butanone, 3, 5-di-tert-butyl- 4-hydroxybenzaldehyde, 3, 5-di-tert-butyl-4-hydroxyacetophenone. Based on these oxidation products, the oxidation pathway of BHT was described. In conclusion, the oxidation characteristics of BHT were studied in detail with MCPVT, and a method for evaluating thermal stability was developed. UV radiation made BHT more susceptible to oxidation reactions. These data provided a reference for BHT's storage, transportation, and safety evaluation.

Triplet Photochemistry of Effluent Organic Matter in Degradation of Extracellular Antibiotic Resistance Genes.

Wastewater effluent is a major source of extracellular antibiotic resistance genes (eArGs) in the aquatic environment, a threat to human health and biosecurity. However, little is known about the extent to which organic matter in the wastewater effluent (EfOM) might contribute to photosensitized oxidation of eArGs. Triplet states of EfOM were found to dominate the degradation of eArGs (accounting for up to 85%). Photo-oxidation proceeded mainly via proton-coupled electron transfer reactions. They broke plasmid strands and damaged bases. O2•- was also involved, and it coupled with the reactions' intermediate radicals of eArGs. The second-order reaction rates of blaTEM-1 and tet-A segments (209-216 bps) with the triplet state of 4-carboxybenzophenone were calculated to be (2.61-2.75) × 108 M-1 s-1. Besides as photosensitizers, the antioxidant moieties in EfOM also acted as quenchers to revert intermediate radicals back to their original forms, reducing the rate of photodegradation. However, the terrestrial origin natural organic matter was unable to photosensitize because it formed less triplets, especially high-energy triplets, so its inhibitory effects predominated. This study advances our understanding of the role of EfOM in the photo-oxidation of eArGs and the difference between EfOM and terrestrial-origin natural organic matter.

Parametric simulation of hybrid nanofluid flow consisting of cobalt ferrite nanoparticles with second-order slip and variable viscosity over an extending surface

Abstract This study explores the unsteady hybrid nanofluid (NF) flow consisting of cobalt ferrite (CoFe2O4) and copper (Cu) nano particulates with natural convection flow due to an expanding surface implanted in a porous medium. The Cu and CoFe2O4 nanoparticles (NPs) are added to the base fluid water to synthesize the hybrid NF. The effects of second-order velocity slip condition, chemical reaction, heat absorption/generation, temperature-dependent viscosity, and Darcy Forchheimer are also assessed in the present analysis. An ordinary differential equation system is substituted for the modeled equations of the problem. Further computational processing of the differential equations is performed using the parametric continuation method. A validation and accuracy comparison are performed with the Matlab package BVP4C. Physical constraints are used for presenting and reviewing the outcomes. With the increase in second-order velocity slip condition and unsteady viscosity, the rates of heat and mass transition increase significantly with the variation in Cu and Fe2O4 NPs. The findings suggest that the uses of Cu and Fe2O4 in ordinary fluids might be useful in the aerodynamic extrusion of plastic sheets and extrusion of a polymer sheet from a dye.

Fractional Step Scheme to Approximate a Non-Linear Second-Order Reaction–Diffusion Problem with Inhomogeneous Dynamic Boundary Conditions

Two main topics are addressed in the present paper, first, a rigorous qualitative study of a second-order reaction–diffusion problem with non-linear diffusion and cubic-type reactions, as well as inhomogeneous dynamic boundary conditions. Under certain assumptions about the input data: gd(t,x), gfr(t,x), U0(x) and ζ0(x), we prove the well-posedness (the existence, a priori estimates, regularity and uniqueness) of a solution in the space Wp1,2(Q)×Wp1,2(Σ). Here, we extend previous results, enabling new mathematical models to be more suitable to describe the complexity of a wide class of different physical phenomena of life sciences, including moving interface problems, material sciences, digital image processing, automatic vehicle detection and tracking, the spread of an epidemic infection, semantic image segmentation including U-Net neural networks, etc. The second goal is to develop an iterative splitting scheme, corresponding to the non-linear second-order reaction–diffusion problem. Results relating to the convergence of the approximation scheme and error estimation are also established. On the basis of the proposed numerical scheme, we formulate the algorithm alg-frac_sec-ord_dbc, which represents a delicate challenge for our future works. The benefit of such a method could simplify the process of numerical computation.

Adsorption capacity of biocarbons from residue of supercritical extraction of raw plants

Abstract Bioadsorbents prepared by chemical activation (H3PO4) of the residue of supercritical extraction of green tea leaves and marigold flowers were characterized by elemental analysis, Boehm titration, adsorption/desorption isotherm and scanning electron microscopy (SEM). The adsorption performance aimed at the removal of malachite green, nitrogen oxide and hydrogen sulfide was investigated. The impacts of various influential parameters of malachite green adsorption such as: contact time (8 h), initial dye concentration (20–140 mg/L), temperature (25–65 °C) and adsorbent mass (0.015–0.025 g) were investigated. The adsorption kinetic follows pseudo second-order reaction kinetics (R 2 &gt; 0.99). The adsorption process was best described by the Langmuir isotherm and the maximum capacity of the monolayer was from 126.58 mg/g to 333.33 mg/g for the biocarbons obtained. The negative values of Gibbs free energy indicate the spontaneous character of the process. The presence of steam in the stream of the mixture of gases had a positive effect on adsorption of nitrogen oxide and hydrogen sulfide by the bioadsorbents obtained. The most effective adsorbent of malachite green and toxic gas pollutants proved to be the biocarbon obtained from the residues of supercritical extraction of green tea leaves.

Snapshots of Early-Stage Quantitative N2 Electrophilic Functionalization.

Electrophilic functionalization of N2 moieties in metal dinitrogen complexes typically initiates the catalytic synthesis of N-containing molecules directly from N2. Despite intensive research in the last six decades, how to efficiently and even quantitatively convert N2 into diazenido and hydrazido species still poses a great challenge. In this regard, systematic and comprehensive investigations to elucidate the reaction intricacies are of profound significance. Herein, we report a kinetic dissection on the first and second electrophilic functionalization steps of a new Cr0-N2 system with HOTf, MeOTf, and Me3SiOTf. All reactions pass through fleeting diazenido intermediates and furnish long-lived final hydrazido products, and both steps are quantitative conversions at low temperatures. All of the second-order reaction rates of the first and second transformations were determined as well as the lifetimes of the intervening diazenido species. Based on these findings, we succeeded in large-scale and near-quantitative preparation of all hydrazido species.

Modeling of adsorptive removal of azithromycin from aquatic media by CoFe2O4/NiO anchored microalgae-derived nitrogen-doped porous activated carbon adsorbent and colorimetric quantifying of azithromycin in pharmaceutical products

Herein, it was aimed to optimize the removal process of Azithromycin (Azi) from the aquatic environment via CoFe2O4/NiO nanoparticles anchored onto the microalgae-derived nitrogen-doped porous activated carbon (N-PAC), besides developing a colorimetric method for the swift monitoring of Azi in pharmaceutical products. In this study, the Spirulina platensis (Sp) was used as a biomass resource for fabricating CoFe2O4/NiO@N-PAC adsorbent. The pores of N-PAC mainly entail mesoporous structures with a mean pore diameter of 21.546 nm and total cavity volume (Vtotal) of 0.033578 cm3. g−1. The adsorption studies offered that 98.5% of Azi in aqueous media could remove by CoFe2O4/NiO@N-PAC. For the cyclic stability analysis, the adsorbent was separated magnetically and assessed at the end of five adsorption-desorption cycles with a negligible decrease in adsorption. The kinetic modeling revealed that the adsorption of Azi onto the CoFe2O4/NiO@N-PAC was well-fitted to the second-order reaction kinetics, and the highest adsorption capacity was found as 2000 mg. g−1 at 25 °C based on the Langmuir adsorption isotherm model at 0.8 g. L−1 adsorbent concentration. The Freundlich isotherm model had the best agreement with the experimental data. Thermodynamic modeling indicated the spontaneous and exothermic nature of the adsorption process. Moreover, the effects of pH, temperature, and operating time were also optimized in the colorimetric Azi detection. The blue ion-pair complexes between Azi and Coomassie Brilliant Blue G-250 (CBBG-250) reagent followed Beer's law at wavelengths of 640 nm in the concentration range of 1.0 μM to 1.0 mM with a 0.94 μM limit of detection (LOD). In addition, the selectivity of Azi determination was verified in presence of various species. Furthermore, the applicability of CBBG-250 dye for quantifying Azi was evaluated in Azi capsules as real samples, which revealed the acceptable recovery percentage (98.72–101.27%). This work paves the way for engineering advanced nanomaterials for the removal and monitoring of Azi and assures the sustainability of environmental protection and public health.

Preparation of building ceramic bricks using waste residue obtained by mutual treatment of electrolytic manganese residue and red mud

The waste residue (ER) obtained by the mutual treatment of electrolytic manganese residue and red mud. ER is a kind of silicon and aluminum waste residue with low pollution. In order to alleviate the shortage of silicon-aluminum raw materials in ceramic bricks industry. In this paper, ER is used as a part of silicon-aluminum raw material to prepare building ceramic bricks. The results show that the impurity ions (Fe3+, Na+, K+, etc.) in ER can promote the formation of liquid phase during the calcination process. This makes the ceramic bricks can be successfully fired at 1150 °C. The mineral composition of ceramic bricks prepared by ER is anorthite, quartz, corundum, mullite and glass phase, and the corresponding contents are 40.31 wt%, 2.48 wt%, 6.81 wt%, 2.58 wt% and 35.07 wt%, respectively. The layer stacking of plate anorthite is closely combined with the corundum to form a microscopic block. The rod-like mullite is interspersed in the microscopic block to form a skeleton structure. This microstructure makes the mechanical properties of the ceramic bricks superior, and the compressive strength is 138.2 MPa. The sintering process of ceramic bricks prepared by ER can be divided into four stages. Stage 1 (25 °C–200 °C) mainly involved the removal of free water and crystal water and the decomposition of part of AlO(OH) into γ-Al2O3, the corresponding kinetic mechanism is phase boundary chemical second-order reaction mechanism. Stage 2 (200 °C–400 °C) mainly involved the residual AlO(OH) decomposed into γ-Al2O3, the corresponding kinetic mechanism is phase boundary–controlled reaction and one-dimensional movement mechanism. Stage 3 (400 °C–900 °C) mainly involved the γ-Al2O3 transformed into α-Al2O3, CaCO3 and CaSO4 decompose into CaO, and CaO reacts with SiO2 and α-Al2O3 to form (Ca,Na)(Al,Si)4O8 and CaAl2Si2O8, the corresponding kinetic mechanism is random nucleation and growth mechanism. Stage 4 (900 °C–1200 °C) mainly involved the melting of (Ca,Na)(Al,Si)4O8, and the continuous formation of CaAl2Si2O8, Ca(Al, Fe)12O19 and mullite, the corresponding kinetic mechanism is Mampel power law exponential form nucleation reaction mechanism.