Presence Of Formic Acid Research Articles

Computational and Experimental IM-MS Determination of the Protonated Structures of Antimalarial Drugs.

A combination of ion mobility-mass spectrometry (IM-MS) measurements and computational methods were used to study structural and physicochemical properties of a range of quinoline-based drugs: amodiaquine (AQ), cinchonine (CIN), chloroquine (CQ), mefloquine (MQ), pamaquine (PQ), primaquine (PR), quinacrine (QR), quinine (QN), and sitamaquine (SQ). In experimental studies, ionization of these compounds using atmospheric pressure chemical ionization (APCI) yields monoprotonated species in the gas phase while electrospray ionization (ESI) also produces diprotonated forms of AQ, CQ, and QR and also for PQ, SQ, and QN in the presence of formic acid as an additive. Comparison of the trajectory-method-calculated and experimental IM-derived collisional cross sections (CCSN2) were used to assign both the protonation sites and conformer geometry of all drugs considered with biases of 0.7-2.8% between calculated and experimental values. It was found that, in solution, AQ and QR are protonated at the ring nitrogen of the quinoline group, whereas the other drugs are protonated at the amine group of the alkyl chain. Finally, the conformers of [M + H]+ and [M + 2H]2+ assigned according to the lowest energies and CCSN2 calculations were used to calculate the pKa values of the antimalarial drugs and the relative abundance of these ions at different pH values that provided validation of the computational and experimental IM-MS results.

The preparation of a bismuth-based complex and the influence of double protonation

Bismuth as a relatively non-toxic and inexpensive metal has a wide range of applications. There are numerous compounds based on bismuth that exhibit excellent semiconductive, photochromic, intensely luminous, and other properties. In this work, we synthesized a new bismuth-based complex (C10H8N2BiCl4, named complex 1) by a hydrothermal method. The crystal structure of complex 1 is resolved using single-crystal X-ray diffraction. When replacing water by methanol as solvent, the color of the obtained crystals (denoted as complex 2) changes from colorless to pink. The analysis of IR and XPS suggests that partial double protonation of the pyridine nitrogen occurs in complex 2. Because of partial double protonation, complex 2 displays visible light absorption and stronger fluorescence intensity. Further investigation found that complex 1 could change its color from colorless to pink in the presence of formic acid and acetic acid, suggesting that complex 1 can be used as formic acid (HCOOH) and acetic acid (CH3COOH) sensors. This work provides new insights into the exploration of bismuth-based complexes and provides a new way to broaden light absorption and enhance luminescence.

Criegee Intermediate-Mediated Oxidation of Dimethyl Disulfide: Effect of Formic Acid and Its Atmospheric Relevance.

The oxidation-reduction reactions of disulfides are important in both chemistry and biology. Dimethyl disulfide (DMDS), the smallest reduced sulfur species with a disulfide bond, is emitted in significant quantities from natural sources and contributes to the formation of aerosols and hazardous haze. Although atmospheric removal of DMDS via the reactions with OH or NO3 radicals and photolysis is known, the reactions of DMDS with other atmospheric oxidants are yet to be explored. Herein, using quantum chemical calculations, we explored the reactions of DMDS with CH2OO (formaldehyde oxide) and other methyl-substituted Criegee intermediates. The various reaction pathways evaluated were found to have positive energy barriers. However, in the presence of formic acid, a direct oxygen-transfer pathway leading to the corresponding sulfoxide (CH3SS(O)CH3) was found to proceed through a submerged transition state below the separated reactants. Calculations for the methyl-substituted Criegee intermediates, particularly for anti-CH3CHOO, show a significant increase in the rate of the direct oxygen-transfer reaction when catalyzed by formic acid. The presence of formic acid also alters the mechanism and reduces the enthalpic barrier of a second pathway, forming thioformaldehyde and hydroperoxide without any rate enhancement. Our data indicated that, although Criegee intermediates are unlikely to be an important atmospheric sink of DMDS under normal conditions, in regions rich in DMDS and formic acid, the formic acid-catalyzed Criegee intermediate-mediated oxidation of DMDS via the direct oxygen-transfer pathway could lead to organic sulfur compounds contributing to atmospheric aerosol.

The Effect of Carbon Nanofibers on the Hydrocracking of Vacuum Residue in the Presence of Formic Acid

This study was devoted to the processing of vacuum residue to produce lighter oil fractions, such as gasoline and diesel fuel. The hydrocracking and catalytic hydrocracking of vacuum residue in the presence of formic acid (FA) were performed in the temperature range of 250–550 °C. Carbon nanofibers (CNFs) were used as catalytic additives. In contrast to conventional hydrocracking, an important stage in the catalytic hydrocracking of vacuum residue is the decomposition of formic acid. Experimental studies on the effect of CNFs on the decomposition of FA demonstrated that CNFs pre-treated in a NaOH solution (CNF (NaOH)s) had the highest activity and selectivity for the production of H2 and CO2. The maximum yield of liquid products in the catalytic hydrocracking process, equal to 34 wt.%, was observed at 300 °C in the presence of CNF (NaOH)s. The characterization of the fractional compositions of the liquid products showed that the ratios of the fractions changed with an increase in the reaction temperature. The maximum concentrations of the light fractions (gasoline and diesel) in the liquid products of the catalytic hydrocracking of vacuum residue were observed at 300–350 °C in the presence of CNF (NaOH)s.

Sol-gel synthesis of photoactive PtO/Bi2WO6 nanocomposites for improved photoreduction of Hg (II) ions under visible illumination

Heterostructure semiconductor photocatalysts have attracted much research interest for wastewater remediation under visible irradiation. The current study describes synthesizing and characterizing novel nanocomposites based on a mesoporous Bi2WO6 with variation PtO amount through a sol-gel procedure. The effect of PtO content on structural, optical, and photocatalytic features was thoroughly discussed. The Hg(II) ions photocatalytic reduction was utilized to evaluate the performance of the constructed heterojunctions under visible irradiation, in the presence of formic acid as a hole scavenger. The most efficient 1.5wt% PtO/Bi2WO6 nanocomposite demonstrated 100% reduction within 60 min with the greatest photoreduction rate constant (0.062 min−1), which was approximately 5.16 folds greater than pristine Bi2WO6 (0.012 min−1). The enhanced efficiency of the developed heterojunctions in the photoreduction of Hg(II) ions could be attributed to the incorporating 1.5wt% PtO, which increases the light-harvesting, decrease the bandgap (Eg) to 2.23 eV, boost the isolation and mobility of the photoexcited carriers. Utilizing a 1.6 g/L of 1.5wt% PtO/Bi2WO6 nanocomposite demonstrated complete photoreduction efficiency after 40 min and outstanding stability after five cycles without losing their photocatalytic activity. This study offers a cost-effective method of producing Bi2WO6 -based nanocomposites with remarkable ability in wastewater remediation.

Hierarchical ternary titanium dioxide decorated with graphene quantum dot/ZIF-8 nanocomposite for the photocatalytic degradation of doxycycline and dye using visible light

Herein, the ternary nanostructure of titania (TiO2) decorated with graphene quantum dot (GQD)/zeolitic imidazolate framework-8 (ZIF-8) (T/G/Z: TiO2/GQD/ZIF-8) was synthesized by a hierarchical approach, and its photocatalytic activity was investigated for the degradation of the doxycycline (DOX) as a pharmaceutical and dyes under visible light irradiation. Increasing the doping content of the graphene quantum dot from 0.002 g to 0.02 g was accompanied by an increase in photocatalytic activity. A further increase to 0.2 g, the thickening or aggregation of the GQD layer on the TiO2 surface, or the thorough coverage of the TiO2 surface with the GQD occurred and effective light irradiation to TiO2 nanoparticles has not been done well. Thus the reduction of the catalytic activity happened. The photocatalytic degradation rate has increased outstandingly over this period of time for ternary composite in this concentration at intervals of the sampling period. The increase in pollutant concentration was associated with decreased photocatalytic degradation. Increasing the dose of photocatalysts improved the rate of pollutant degradation. The degradation efficiency of doxycycline in the presence of l-ascorbic acid scavenger had a notable decrease, while the presence of formic acid and isopropyl alcohol was less effective in the DOX degradation. It can be explained that the superoxide anion radical has the greatest effect on the degradation process of doxycycline. The DOX degradation kinetics followed the first-order kinetics with high correlation coefficients. This work has provided profound insight based on heterogeneous structures for efficient photocatalysts in the degradation of wastewater pollutants (pharmaceutical and dyes).

Novel Electrospun Composite Membranes Based on Polyhydroxybutyrate and Poly(vinyl formate) Loaded with Protonated Montmorillonite for Organic Dye Removal: Kinetic and Isotherm Studies.

The use of biodegradable polyesters derived from green sources and their combination with natural abundantly layered aluminosilicate clay, e.g., natural montmorillonite, meets the requirements for the development of new sustainable, disposable, and biodegradable organic dye sorbent materials. In this regard, novel electrospun composite fibers, based on poly β-hydroxybutyrate (PHB) and in situ synthesized poly(vinyl formate) (PVF), loaded with protonated montmorillonite (MMT-H) were prepared via electrospinning in the presence of formic acid, a volatile solvent for polymers and a protonating agent for the pristine MMT-Na. The morphology and structure of electrospun composite fibers were investigated through SEM, TEM, AFM, FT-IR, and XRD analyses. The contact angle (CA) measurements showed increased hydrophilicity of the composite fibers incorporated with MMT-H. The electrospun fibrous mats were evaluated as membranes for removing cationic (methylene blue) and anionic (Congo red) dyes. PHB/MMT 20% and PVF/MMT 30% showed significant performance in dye removal compared with the other matrices. PHB/MMT 20% was the best electrospun mat for adsorbing Congo red. The PVF/MMT 30% fibrous membrane exhibited the optimum activity for the adsorption of methylene blue and Congo red dyes.

Исследование влияния примесей различного характера на пенообразование аминовых абсорбентов установок очистки высокосернистых газов

The article focuses on studying the foaming process in the amine solutions (diethanolamine (DEA) and methyldiethanolamine (MDEA)) on an example of the model mixtures containing different organic and inorganic impurities and their combinations: oxalic acid, formic acid, corrosion inhibitor, hydrocarbons, amine decomposition products, mechanical impurities. It has been found that the greatest influence on foaming in the DEA solution is exerted by its decomposition products containing the formic acid, and at a concentration of 3% by weight the foam height increased by more than 3 times, and the foam stability - by 20 times. Oxalic acid also has a significant effect on foaming: at a concentration of 1 g/l the foam height increased by 3 times, and the foam stability - by more than 5 times. The decomposition products of DEA containing oxalic acid have a rather noticeable effect - the height and stability of the foam increased by 2.8 and 6.8 times, respectively. The foam grew least in the presence of formic acid - by 2 times, at the same time the stability was enhanced by more than 4 times. It has been stated that hydrocarbons have the greatest influence on foaming of the MDEA solution - at a concentration of 0.5% vol. the foam height increased by more than 1.7 times, and the stability of the foam - by 5 times. Similarly, the decomposition products of MDEA made a significant impact – the foam height increased by more than 1.7 times, and the foam stability - by 11 times. Mechanical impurities caused an increase in the foam height by more than 1.6 times and in stability by 1.4 times. Introducing a corrosion inhibitor foaming gave the least result - the foam height decreased by 2.8 times, and the stability increased by 2 times. There has been found the mutual influence of impurities in the MDEA solution, which could be seen in the mutual suppression of foaming in the double and triple mixtures compared with the single-component solutions.

MIL-101-NH2-TFR and MIL-101-NH2-TFR/Cu2+ as novel hybrid materials for efficient adsorption of iodine and reduction of Cr(VI)

Today, due to the earnest jeopardies of environmental contaminants from various sources and their deteriorating effects on the ecosystem, the adsorption and reduction of these highly toxic pollutants with an efficient and cost-effective protocol can be considered a desirable phenomenon. Herein, a chromium-based metal-organic framework (MIL-101-NH2) was modified with thiourea and formaldehyde to form a polymeric layer on the surface (MIL-101-NH2-TFR). The resulting nanohybrid, as an adsorbent, was applied for efficient capture of iodine (I2) molecules from cyclohexane solution. MIL-101-NH2-TFR nanohybrid signified a superior adsorption performance for the capture of I2, compared to the pristine MIL-101-NH2, with a theoretical maximum uptake value of 625 mg/g and adsorption efficiency of 96.9 % through thionyl (CS), amino, and phenyl groups. The pseudo-second-order rate equation and the Langmuir model were best fitted for the I2 adsorption over MIL-101-NH2-TFR adsorbent. Quantum chemical calculations were conducted to reveal the mechanism of I2 adsorption onto the surface of MIL-101-NH2-TFR. Moreover, MIL-101-NH2-TFR was used to anchor Cu2+ to generate a catalytic system (MIL-101-NH2-TFR/Cu2+) for detoxification of Cr(VI) in the presence of formic acid as an eco-friendly reducing reagent in an aqueous medium. MIL-101-NH2-TFR and MIL-101-NH2-TFR/Cu2+ were reused several times for the adsorption/desorption process and the catalytic reduction, respectively.

Metal-free synthesis of quinazolinone from 2-amino benzonitrile in the presence of formic acid as a C1 source

Quinazolinones are primarily found in natural products and serve as the basic building blocks in a plethora of commercially available drugs. Quinazolinones are nitrogen-containing heterocyclic compounds having a range of biological activities. The traditional synthesis of quinazolinone often employs toxic and environmentally harmful chemicals, making it imperative to find alternative green chemistry routes. In this study, we report the synthesis of quinazolinones from 2-aminobenzonitrile employing formic acid as a C1 source in the presence of triethylamine as a base. This study’s main objective is to develop a catalyst-free synthesis method, utilizing the green chemistry principles of atom economy and reducing toxicity. The reaction was conducted under mild conditions and provided high yields of the target compounds. The findings demonstrate that this simple and efficient synthetic approach is a promising alternative to conventional routes and provides a sustainable solution for synthesising quinazolinone derivatives. The current strategy enabled broad substrate scope for synthesizing quinazolinones with good to excellent yields.

Nitrogen-doped biochar-supported metal catalysts: High efficiency in both catalytic transfer hydrogenation of furfural and electrocatalytic oxygen reactions

The versatility of several N-doped biochar-supported metal catalysts (M/N-BioC) derived from vineyard pruning waste, to promote circular bioeconomy, was evaluated in catalytic transfer hydrogenation (CTH) of furfural (FF), electrocatalytic oxygen reduction and evolution reactions (ORR and OER). The CTH of FF to prepare high valuable chemicals was performed in the presence of formic acid as hydrogen donor at 160 °C, reaching high conversion (up to 80 %) and selectivities towards furfuryl alcohol (ca. 88 %), establishing a promising catalytic route to valorise a biomass platform molecule using 3d-transition metal-based catalysts in absence of molecular hydrogen. The prepared materials also demonstrated moderate ORR electrocatalytic performance in alkaline medium with diffusion-limiting current densities between − 3.48 (Co/N-BioC) and − 1.27 mA cm−2 (Cu/N-BioC) and potential onset values of 0.88 ≥ Eonset ≥ 0.66 V vs. RHE. Additionally, the materials tested showed selectivity towards indirect pathway in which O2 is reduced to H2O2 and then further reduced to water with the number of electrons transferred per O2 molecule ranging from 2.1 to 3.6 electrons. The materials also presented moderate OER electrocatalytic performances in alkaline medium, with overpotential values between 0.48 (Co/N-BioC) and 0.63 V vs. RHE (Fe/N-BioC) and maximum current densities between 0.28 (BioC) and 42.60 mA cm−2 (Co/N-BioC). This research contributes to the development of a new type of promising (electro)catalyst based on biomass residue for biomass valorisation and energy conversion as a promising contribute to the future of biorefineries implementation.

Study on Degradation of Natural Rubber Latex Using Hydrogen Peroxide and Sodium Nitrite in the Presence of Formic Acid.

Liquid natural rubber (LNR), a depolymerized natural rubber (NR) consisting of shorter chains, was prepared via oxidative degradation using NaNO2 and H2O2 degrading agents in the presence of HCOOH. The influence of reagent concentrations, temperature, and reaction time on the number-average molecular weight (Mn) was studied. Results showed the higher concentration of H2O2 and HCOOH employed faster degradative rates. However, a higher concentration of NaNO2 decreased the Mn reduction. Prolonged reaction time and high temperature resulted in a product with low Mn. FTIR spectra indicated the synthesized LNR contained hydroxyl end groups resulting from the breaking of the NR chains at an acidic pH, whereas a carboxyl terminated LNR was formed at an alkaline pH. SEM micrographs showed the latex particles of LNR were spherical and smaller compared to NR. The experimental results showed the reaction orders of [H2O2], [HCOOH], and [NaNO2] were 1.58, 0.79, and -0.65, respectively. In addition, the pre-exponential factor and activation energy were 1.04 × 109 M-1.72 t-1 and 78.66 kJ/mol, respectively. Based on TGA analysis, the thermal stability of the rubber depended on its Mn. The LNR containing functional end groups exhibited thermal instability and could be a starting material for many applications.

Operando Laboratory X-ray Absorption Spectroscopy and UV–Vis Study of Pt/TiO2 Photocatalysts during Photodeposition and Hydrogen Evolution Reactions

Photocatalytic hydrogen (H2) production is a promising route for alternative energetics. Understanding structure–activity relationships is a crucial step towards the rational design of photocatalysts, which requires the application of operando spectroscopy under relevant working conditions. We performed an operando investigation on a catalytic system during the photodeposition of Pt on TiO2 and photostimulated H2 production, using simultaneous laboratory X-ray absorption spectroscopy (XAS), UV–Vis spectroscopy, and mass spectrometry. XAS showed a progressive increase in Pt fluorescence for Pt deposited on TiO2 for over an hour, which is correlated with the signal of the produced H2. The final Pt/TiO2 catalyst contained Pt(0) particles. The electronic features corresponding to the Pt4+ species in the UV–Vis spectrum of the solution disappear as soon as UV radiation is applied in the presence of formic acid, which acts as a hole scavenger, resulting in the presence of Pt(0) particles in solution.

Atomistic Details of Peptide Reversed-Phase Liquid Chromatography from Molecular Dynamics Simulations

Peptide separations by reversed-phase liquid chromatography (RPLC) are an integral part of bottom-up proteomics. These separations typically employ C18 columns with water/acetonitrile gradient elution in the presence of formic acid. Despite the widespread use of such workflows, the exact nature of peptide interactions with the stationary and mobile phases is poorly understood. Here, we employ microsecond molecular dynamics (MD) simulations to uncover details of peptide RPLC. We examined two tryptic peptides, a hydrophobic and a hydrophilic species, in a slit pore lined with C18 chains that were grafted onto SiO2 support. Our simulations explored peptide trapping, followed by desorption and elution. Trapping in an aqueous mobile phase was initiated by C18 contacts with Lys butyl moieties. This was followed by extensive anchoring of nonpolar side chains (Leu/Ile/Val) in the C18 layer. Exposure to water/acetonitrile triggered peptide desorption in a stepwise fashion; charged sites close to the termini were the first to lift off, followed by the other residues. During water/acetonitrile elution, both peptides preferentially resided close to the pore center. The hydrophilic peptide exhibited no contacts with the stationary phase under these conditions. In contrast, the hydrophobic species underwent multiple transient Leu/Ile/Val binding interactions with C18 chains. These nonpolar interactions represent the foundation of differential peptide retention, in agreement with the experimental elution behavior of the two peptides. Extensive peptide/formate ion pairing was observed in water/acetonitrile, particularly at N-terminal sites. Overall, this work uncovers an unprecedented level of RPLC molecular details, paving the way for MD simulations as a future tool for improving retention prediction algorithms and for the design of novel column materials.

CRISPRi screen highlights chromatin regulation to be involved in formic acid tolerance in Saccharomyces cerevisiae

Formic acid is one of the main weak acids in lignocellulosic hydrolysates that is known to be inhibitory to yeast growth even at low concentrations. In this study, we employed a CRISPR interference (CRISPRi) strain library comprising >9000 strains encompassing >98% of all essential and respiratory growth-essential genes, to study formic acid tolerance in Saccharomyces cerevisiae. To provide quantitative growth estimates on formic acid tolerance, the strains were screened individually on solid medium supplemented with 140 mM formic acid using the Scan-o-Matic platform. Selected resistant and sensitive strains were characterized in liquid medium supplemented with formic acid and in synthetic hydrolysate medium containing a combination of inhibitors. Strains with gRNAs targeting genes associated with chromatin remodeling were significantly enriched for strains showing formic acid tolerance. In line with earlier findings on acetic acid tolerance, we found genes encoding proteins involved in intracellular vesicle transport enriched among formic acid sensitive strains. The growth of the strains in synthetic hydrolysate medium followed the same trend as when screened in medium supplemented with formic acid. Strains sensitive to formic acid had decreased growth in the synthetic hydrolysate and all strains that had improved growth in the presence of formic acid also grew better in the hydrolysate medium. Systematic analysis of CRISPRi strains allowed identification of genes involved in tolerance mechanisms and provided novel engineering targets for bioengineering strains with increased resistance to inhibitors in lignocellulosic hydrolysates.

Hydrothermal Reactions of Biomass-Derived Platform Molecules: Mechanistic Insights into 5-Hydroxymethylfurfural (5-HMF) Formation during Glucose and Fructose Decomposition

The study investigates the primary reaction mechanisms of hydrothermal decomposition of glucose and fructose at 150–225 °C under various initial pH conditions (i.e., with an initial pH of 3–7) to reveal the formation mechanism of 5-hydroxymethylfurfural (5-HMF) from glucose and fructose. The results clearly show that dehydration to produce 5-HMF is not a primary reaction during hydrothermal decomposition of both glucose and fructose under noncatalytic conditions, indicating that 5-HMF cannot be directly produced from either glucose or fructose in water (with an initial pH of ∼7). In the presence of formic acid, dehydration to produce 5-HMF becomes a primary reaction during the hydrothermal decomposition of both glucose and fructose. The selectivity of dehydration reaction to produce 5-HMF increases with reducing the initial pH, i.e., up to ∼40% for glucose decomposition at 175 °C and ∼49% for fructose decomposition at 150 °C when the initial pH reduces to 3. Further kinetic analyses show that the rate constants of isomerization and retro-aldol condensation reactions almost remain unchanged under all initial pH conditions, while the rate constants of dehydration reactions to produce 5-HMF and levoglucosan increase almost linearly with the hydrogen ion concentration at the reaction temperature. This leads to increases in the selectivities of dehydration reactions, at the expense of other primary reactions. Our data also clearly indicate that dehydration reactions are acid-catalyzed reactions, while organic acid has almost no effect on isomerization and retro-aldol condensation reactions. Since organic acids can be formed at the early stage of sugar decomposition, this study provides the first experimental evidence in the field to clarify the formation mechanism of 5-HMF during sugar hydrothermal decomposition.

Highly exfoliated graphitic carbon nitride for efficient removal of wastewater pollutants: Insights from DFT and statistical modelling

The present work entails the synthesis of thermally modified graphitic carbon nitride (GCN) using a two-step thermal treatment procedure and its subsequent use in the photocatalytic reduction of toxic pollutants such as rhodamine B dye (RhB) and chromium (VI) (Cr(VI)) from aquatic environments. The as-synthesised exfoliated GCN (GCNX) is characterised by X-ray diffraction (XRD) analysis, Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDS), Brunauer–Emmett–Teller analysis (BET), diffuse reflectance spectroscopy (DRS), photoluminescence spectroscopy (PL), field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). These characterisations helped to elucidate the phase formation, chemical structure, composition, surface area, optical properties, and morphology of the sample. With assistance from a visible light source, GCNX can degrade RhB dye within 30 min in the presence of hydrogen peroxide (H2O2) and reduce Cr(VI) to Cr(III) in under 2 h in the presence of formic acid (FA/HCOOH). Variations in different catalytic parameters, including catalyst amount, pH of the solution, initial RhB or Cr(VI) concentration, and variation in H2O2 or FA concentration, are performed to inspect their effects on the photodegradation activity of GCNX. Moreover, the GCNX catalyst exhibits impressive stability and reusability. A thorough statistical evaluation follows the response surface methodology to understand the complex interaction between the factors contributing to the catalytic activity. The band alignment of differently functionalised GCN blocks in their pristine form and their H2O2/FA-adsorbed states is investigated using first-principles calculations to provide a further understanding of the RhB and Cr(VI) reduction mechanisms. The modified GCN can thus be effectively employed as a low-cost material for removing contamination from aquatic environments.

Masterbatch of Chitosan Nanowhiskers for Preparation of Nylon 6,10 Nanocomposite by Melt Blending.

Composite materials have been extensively studied to optimize properties such as lightness and strength, which are the advantages of plastics. We prepared a highly concentrated (30 wt %) nylon/chitosan nanowhisker (CSW) masterbatch by blending nylon 6,10 and CSW by solvent casting to achieve high dispersion efficiency while considering an industrial setting. Subsequently, 0.3 wt % nylon/CSW nanocomposites were prepared with a large quantity of nylon 6,10 via melt blending. During preparation, the materials were stirred in the presence of formic acid at different times to investigate the effect of stirring time on the structure of the CSW and the physical properties of the composite. The formation of nanocomposites by the interactions between nylon and CSW was confirmed by observing the change in hydrogen bonding using FT-IR spectroscopy and the rise in melting temperature and melting enthalpy through differential scanning calorimetry. The results demonstrated increases in complex viscosity and shear thinning. The rheological properties of the composites changed due to interactions between CSW and nylon, as indicated by the loss factor. The mechanical properties produced by the nanocomposite stirred for 1.5 h were superior, suggesting that formic acid caused minimal structural damage, thus verifying the suitability of the stirring condition.

Tröger's Base Chemistry in Solution and in Zr(IV)-Based Metal-Organic Frameworks.

Tröger's base (TB) and its derivatives have been studied extensively due to their unique concave shape stemming from the endomethylene strap. However, the strap-clipped TB chemistry has been largely overlooked in metal-organic framework (MOF) solids, leading to a gap in our knowledge within this field. In this work, we report the in situ strap elimination of a carboxylate-carrying TB in the presence of formic acid, both in solution and in Zr(IV)-based MOFs. In the solution system, the methanodiazocine nucleus can be exclusively transformed into an N,N'-diformyl-decorated phenhomazine derivative, regardless of the solvent used (DMF, DMA, or DEF), as unambiguously uncovered by single crystal X-ray crystallography. In contrast, while in the MOF synthetic system, the degree of derivatization reaction can be effectively controlled to give either the secondary diamine or formyl-decorated diamine, depending on the solvent used (DMF or DEF), resulting in the formation of two Zr-MOFs with 8-connected bcu (NU-1900) and 12-connected fcu (NU-407) topologies, respectively. The derivatization mechanism is proposed to be topology-guided and dependent on the local acid concentration during the MOF formation processes. Moreover, we discovered a novel post-synthetically water-induced in situ linker formylation process in NU-1900 through sequential formic acid elimination, migration, and condensation processes, affording an isostructural framework with the same linker as in NU-407, which further corroborates our proposed mechanism. Additionally, the highly defective NU-1900 with abundant accessible Zr sites was demonstrated to be an outstanding catalyst for the detoxification of a nerve agent simulant with a half-life of less than 1 min.

Comparative analysis of the effects of hydrogen and formic acid on the vacuum residue hydrocracking

The improvement of the existing technologies aimed at deeper processing of heavy oils and oil residues and development of new ones is an urgent task of modern oil refining. Experiments in a flow installation using a quartz reactor were performed to determine the formic acid decomposition pathway. The experiments showed that the formic acid decomposition over the Ni-Mo/Al2O3 catalyst predominantly yielded hydrogen and CO2. Therefore, in this study comparative experiments on the effects of hydrogen and formic acid on the vacuum residue hydrocracking in the presence of the Ni-Mo/Y-Al2O3 and Ni-Mo/Al2O3 catalysts were performed at 375–400 °C and 0.45 MPa pressure. The concentration of hydrogen or formic acid in argon was 10 vol%. The catalysts were prepared by impregnation of the corresponding supports with the aqueous solution obtained using nickel hydroxide, ammonium heptamolybdate and citric acid. Electron microscopy and XRD studies of the Ni-Mo/Y-Al2O3 and Ni-Mo/Al2O3 catalysts demonstrated that the active component in the studied catalysts was in a finely dispersed state. The size of Ni-Mo particles was 0.4–0.6 nm in the Ni-Mo/Y-Al2O3 catalyst and 0.3–0.6 nm in Ni-Mo/Al2O3. For both catalysts Ni-Mo/Y-Al2O3 and Ni-Mo/Al2O3 higher vacuum residue conversion to liquid products was observed in the presence of formic acid than in the presence of hydrogen. Hydrogen substitution for formic acid vapor during the vacuum residue hydrocracking also results in the lower sulfur content in the liquid reaction products. The use of formic acid as a hydrogen donor significantly simplifies the process hydrocracking.