Aqueous Ammonium Chloride Solution Research Articles

Synthesis of iso-amyl ester rosin and its evaluation as an alternative to paraffin in medium density fiberboard production

Iso-amyl ester rosin was synthesized and investigated for its potential utilization in medium density fiberboard (MDF) production. The isoamyl alcohol, the main starting material for the synthesis of isoamyl ester rosin, was obtained through the fractional distillation of fusel oil, a byproduct of bioethanol production. The optimum condition for the iso-amyl ester rosin synthesis was determined as: rosin (165 mmol), isoamyl alcohol (413 mmol), P-TSA/rosin 1.5% (w/w), and commercial additive/rosin 0.15% (w/w). The esterification reaction was followed by FT-IR and mass analysis. For MDF production, a water-repellent material, commercial paraffin (1.5% w/w relative to the dry fiber weight), iso-amyl ester rosin (1.5% and 2.0%; w/w), and unmodified rosin (1.5% and 2.0% w/w) were separately used. In addition, fresh wood fibers, 10% w/w urea formaldehyde (UF) adhesive (relative to the total dry fiber weight), and a 25% aqueous solution of ammonium chloride (as the hardening agent for the UF adhesive, at 0.5% w/w based on the solid adhesive content) were used. MDFs underwent various physical and mechanical tests. Isoamyl ester rosin showed promising results based on the analysis. The results showed that the isoamyl ester rosin can be considered as an alternative to paraffin in sustainable and environmentally friendly MDF production.

Effect of Structural Reorganization of the Surface Layer in AMN-P and OPMN-P Membranes on the Transport Characteristics of the Electronanofiltration Separation of Aqueous Ammonium Chloride Solution

Effect of Structural Reorganization of the Surface Layer in AMN-P and OPMN-P Membranes on the Transport Characteristics of the Electronanofiltration Separation of Aqueous Ammonium Chloride Solution

Effect of Structural Reorganization of the Surface Layer in AMN-P and OPMN-P Membranes on the Transport Characteristics of the Electronanofiltration Separation of Aqueous Ammonium Chloride Solution

Effect of Structural Reorganization of the Surface Layer in AMN-P and OPMN-P Membranes on the Transport Characteristics of the Electronanofiltration Separation of Aqueous Ammonium Chloride Solution

SYNTHESIS AND CHARACTERIZATION OF SOME NEW NITRONES DERIVATIVES AND SCREENING THEIR BIOLOGICAL ACTIVITIES

Synthetic approached towards the synthesis of some novel nitrones derivatives have been started with reduction of nitrobenzene derivatives as starting material bearing electron withdrawing and electron donating groups to corresponding phenylhydroxylamine in presence of zinc dust as reducing agent in aqueous solution of ammonium chloride (NH4Cl). The prepared phenylhydroxylamine derivatives were reacted with different substituted benzaldehydes to give the target derivatives of nitrone. The structures of the synthesized nitrones were characterized by spectroscopic methods FT-IR, 1H-NMR and 13C NMR. Finally, the newly synthesized compounds were screened for their microorganism activities at different concentration, and inhibited growth of Escherichia coli (E. coli) Gram negative, Staphylococcus aureus (S. aureus) Gram positive, and fungi (candida albicans).

Synthesis and Characterization of Some New Nitrones Derivatives and Screening their Biological Activities

Synthetic approached towards the synthesis of some novel nitrones derivatives have been started with reduction of nitrobenzene derivatives as starting material bearing electron withdrawing and electron donating groups to corresponding phenylhydroxylamine in presence of zinc dust as reducing agent in aqueous solution of ammonium chloride (NH4Cl). The prepared phenylhydroxylamine derivatives were reacted with different substituted benzaldehydes to give the target derivatives of nitrone. The structures of the synthesized nitrones were characterized by spectroscopic methods FT-IR, 1H-NMR and 13C NMR. Finally the newly synthesized compounds were screened for their microorganism activities at different concentration, and inhibited growth of Escherichia coli (E. coli) Gram negative, Staphylococcus aureus (S. aureus) Gram positive, and fungi (candida albicans).

Reduction of the calcium leaching effect on the physical and mechanical properties of concrete by adding chopped basalt fibers

Calcium leaching is one of the essential diseases of cementitious materials and is a time-varying irreversible process that reduces the structural reliability of concrete. Although some research has found methods to inhibit this phenomenon, various limitations have prevented its widespread application. In this paper, high-performance and low-cost basalt fiber (BF) was used for the first time in an attempt to mitigate the deterioration effect of calcium leaching on the physical and mechanical properties of concrete. The properties such as mass loss, porosity, relative dynamic elastic modulus, and compressive and splitting tensile strengths of concrete (with ten types of BF addition combination schemes) exposed to 6 mol/L ammonium chloride aqueous solution were measured. Scanning electron microscope (SEM) and energy dispersive spectrometer (EDS) measurements were conducted to investigate the evolution of the micro-structural morphology and composition of concrete during the leaching process. The results show that the addition of an appropriate length and volume dosage of BF to the concrete can effectively mitigate the effect of calcium leaching on the physical and mechanical properties of concrete. The BF with a longer length and a higher volume dosage not only can not mitigate the deterioration effect of calcium leaching but has the opposite effect. Furthermore, the addition of BF with a length of 6 mm and a volume dosage of 0.4 % in concrete was suggested to mitigate the effect of calcium leaching on the physical and mechanical properties of concrete.

Mechanical shock-induced nucleation in solution: Is cavitation necessary?

Mechanical shock-induced nucleation (MSIN) of crystals from aqueous supersaturated solutions of ammonium chloride is reported. A simple apparatus was constructed to expose solutions in glass vials to a single impact, while images were recorded using a fast camera. A strong correlation between cavitation in the liquid and nucleation of solid ammonium chloride was revealed. The measured fraction of solutions nucleated as a function of impact height was fitted using a Poisson model. The mean number of solution samples nucleated increased quadratically with impact height above a threshold height. Analysis of images showed that the accelerations achieved were sufficient to induce cavitation based on the cavitation number proposed by Pan et al. [Proc. Natl. Acad. Sci. USA 114 (2017) 8470]. The use of a hydrophobic coating on the internal glass surface was shown to significantly increase both the number of cavities observed and the probability of MSIN of solid crystals. The results presented suggest that MSIN of ammonium chloride salt is mediated by cavitation.

Validation of a capillary-driven fragmentation model during mixed columnar-equiaxed solidification with melt convection and grain transport

A mixed columnar-equiaxed solidification model was recently extended to capture the capillary-driven fragmentation phenomenon, which was considered the only mechanism for the formation of equiaxed crystals. The purpose of the present study was to validate the model by replicating a laboratory experiment on the solidification of an aqueous ammonium chloride solution (Gao and Wang, 1999). The experiment was performed by cooling the solution in a vertical test cell from the top surface to allow columnar dendrites to grow. Owing to the fragmentation of the downward-growing columnar dendrites, equiaxed fragments appeared, sedimented, and created a bed of crystals at the bottom of the cell. This pile-up of crystals ultimately met the columnar-tip front coming from the top, thereby leading to a structural transition (columnar-to-equiaxed transition). This experiment was successfully reproduced numerically for the first time, which involved coupling between the following phenomena: fragmentation, melt convection, grain transport, a pile-up of equiaxed crystals, and the potential growth of columnar dendrites from a bed of equiaxed crystals (equiaxed-to-columnar transition). A satisfactory agreement was achieved between the simulation and experimental results. Knowledge about capillary-driven fragmentation was strengthened by analyzing the microstructural evolution. Alloy-dependent parameters Ss0, K0, and a that govern dendrite coarsening and fragmentation were proposed for an aqueous ammonium chloride solution. Finally, the limitations of the current version of the fragmentation model were discussed.

Bulky HybridC‐Scorpionate/Amidinate Complexes of Lithium and Zinc

AbstractLithiation of the bis(pyrazolyl)methanes H2C(PzAd,Me)2(1 a) and H2C(PzPh,Ph)2(1 b) and subsequent addition ofN,N’‐diisopropylcarbodiimide in THF yields [(thf)Li{(PzAd,Me)2HC−C(=NiPr)(NiPr)}] (2 a) and [(thf)Li{(PzPh,Ph)2HC−C(=NiPr)(NiPr)}] (2 b). For comparison reasons, the structure of [(thf)Li{(PztBu,tBu)2HC−C(=NCy)(NCy)}] (I) has been determined as well. Protolysis with aqueous ammonium chloride solution gives (PzAd,Me)2HC−C(=NiPr)(NHiPr) (3 a) and (PzPh,Ph)2HC−C(=NiPr)(NHiPr) (3 b). Zincation with diethylzinc leads to the formation of [EtZn{(PzAd,Me)2HC−C(=NiPr)(NiPr)}] (4 a) and [EtZn{(PzPh,Ph)2HC−C(=NiPr)(NiPr)}] (4 b). The metathetical approach allows preparation and isolation of [ClZn{(PzPh,Ph)2HC−C(=NiPr)(NiPr)}] (5). A comparison of the molecular structures of the lithium and zinc complexes allows to elucidate the influence of electronegativity on structural parameters because tetra‐coordinate Li and Zn ions have very similar radii.

The phase behaviour of cetyltrimethylammonium chloride surfactant aqueous solutions at high concentrations: an all-atom molecular dynamics simulation study.

We explore the phase behaviour of aqueous solutions of the cetyltrimethyl ammonium chloride (CTAC) surfactant and in particular the transition from the micellar phase (L1) to the hexagonal columnar phase (H1) by employing all-atom (AA) molecular dynamics (MD) simulations for six CTAC concentrations in the range of 34.1 wt% to 70.5 wt%, at the temperature of 318 K and pressure of 1 atm. For the concentrations considered, we examine the spontaneous occurrence of the H1 phase by testing a number of plausible values for the linear density (molecules per unit length) along the cylindrical columns. Using large simulation cells and starting from random initial configurations, the MD simulations demonstrate that the micellar phase occurs for concentrations up to 50.0 wt%, with CTAC molecules self-assembling into a mixture of spherical and rod-like micelles. At even higher concentrations, the system self-organizes into the H1 phase in accordance with the available experimental data. For the analysis of the MD trajectories, we devise a clustering algorithm based on Voronoi tesselation which enables (a) the thorough characterization of the shape and structure of both molecules and assemblies, and (b) the investigation of the positional and orientational order in the system that are further scrutinised using radial pair correlation functions and X-ray diffraction patterns. Our work paves the way for the investigation of the phase behaviour at high concentrations of other surfactants.

Features of anodic plasma electrolytic treatment of an ultra-light alloy of the Mg-Li system in an aqueous electrolyte

The possibility of plasma electrolytic treatment of an alloy of the Mg-Li system in an aqueous solution of ammonium chloride, ammonium nitrate and boric acid has been studied. The specific features of the process in the voltage range from 10 to 600 V are determined. The current-voltage and voltage-temperature characteristics during alloy processing are shown, as well as the effect of the processing time on the temperature of the samples. Plasma electrolytic boronitriding of the alloy can be carried out to study the efficiency of the technology at avoltage of 240 V, which corresponds to a sample temperature of 300 ± 10 °C.

Cathodic boriding and anodic polishing of medium-carbon steel by plasma electrolysis

The possibility of cathodic plasma electrolytic boriding of medium-carbon steel in an aqueous solution of ammonium chloride and boric acid followed by anodic plasma electrolytic polishing in an ammonium sulfate solution on the same equipment with a change in the operating voltage is shown. The morphology and roughness of the surface, microhardness of the modified layer have been investigated. Wear resistance was studied under dry friction conditions. It has been established that cathodic boriding at 850 °C for 5–30 min leads to the hardening of the surface layer up to 1050 HV with an increase in roughness by 1.5–2.5 times and wear resistance by 3.5 times. Subsequent anodic plasma electrolytic polishing of the boriding surface leads to a decrease in roughness with an increase in wear resistance by 2.3 times.

Impact of calcium leaching on mechanical and physical behaviors of high belite cement pastes

Water conservancy engineering such as dams and canals built with high belite cement (HBC) concrete for reducing temperature cracks have been running for many years and are still constantly under construction. However, little research has been conducted on the calcium leaching behaviors of HBC. In this paper, mechanical and physical properties such as mass loss, porosity, leaching depth, compressive strength and hardness of HBC-based pastes (with three w/b ratios and contents of fly ash) exposed to ammonium chloride aqueous solution were measured. In addition, slice specimens of HBC and ordinary Portland cement (OPC) were designed to study their Ca/Si ratio changes in leaching process, XRD, SEM and EDS mapping scanning were also carried out to investigate the variations of composition and microstructures between degraded and intact cement hydrates. Results show that the macro-properties of leached HBC pastes are similar to but slightly worse than those of OPC, while there is a lower calcium leaching rate of HBC in both stages of CH dissolution and C-S-H decomposition. Furthermore, the w/b ratio has an appreciable effect on the physical and mechanical performance of HBC pastes subjected to leaching, and the corrosion damage could be alleviated by adding fly ash. Eventually, a distribution model of Vickers hardness based on Logistic function is proposed to evaluate the degradation of leached pastes with high accuracy, and the axial compressive strength could be quantified by equivalent Vickers hardness with a well linear relationship.

Distinctive features of electric current passing through vapour gaseous envelope in anodic plasma electrolytic processes

This article focuses on the study of the effect of anodic composition of electrolyte on electric conductivity of a vapour gaseous envelope, formed in the mode of anode stationary heating. The investigation methods were based on measuring current-voltage characteristics in aqueous solutions of ammonium chloride, chlorohydric acid and hydrobromic acid at equal anion concentrations. It has been established that conductivity in vapour gas medium is primarily determined by electric field intensity which varies depending on its composition and thickness, ion mobility considered as factor of secondary importance. It has been assumed that emissive capacity of aqueous solutions can be limited by a critical concentration of their components.

The effect of plasma electrolytic polishing on the surface properties of nitrocarburised steel

The effect of anodic plasma electrolytic polishing on the characteristics of low carbon steel (0.2 % C) after nitrocarburising was investigated. The formation of the modified layer including a hardened diffusion layer and a surface oxide layer occurs as a result of anodic plasma electrolytic nitrocarburising in an aqueous solution of glycerol (8 %), ammonium nitrate (5 %) and ammonium chloride (15 %) at 850 °C. Conducting a plasma electrolytic polishing of the surface leads to the removal of a loose part of the oxide layer (predominantly FeO), which affects the reduction the surface roughness of 2 times. The rate of the weight loss of steel in this process is 0.5 mg/s. The corrosion current density in a 3.5 % sodium chloride solution decreases from 41.0 μA/cm2 in an untreated sample to 32.6 μA/cm2 in the steel after nitrocarburising and polishing during 30 s and to 22–24 μA/cm2 when the second operation lasted 60-300 s due to the protective action of the nitride zone and the dense part of the oxide layer. Wear test shows that plasma electrolytic polishing enhances the wear resistance of a nitrocarburised sample by 1.8 times.

Simultaneous optical measurement of temperature and velocity fields in solidifying liquids

We introduce a complex image processing scheme for the simultaneous application of liquid crystal thermometry (LCT), in addition to the previously established method in Anders et al. (Exp Fluids 60(4):68, 2019. https://doi.org/10.1007/s00348-019-2703-8) for particle tracking velocimetry and particle image velocimetry. This scheme was developed for an experimental study on the double-diffusive convection in an aqueous ammonium chloride solution NH4Cl(aq) during crystallization. The use of thermochromic liquid crystals (TLC) enables to visualize the flow and temperature field simultaneously. We present a color interpolation method that enhances the accuracy of the LCT by yielding RGB images only representative of the TLC’s coloration. An artificial neural network (ANN) which processes RGB triplets and spatial color dependencies transforms these images into temperature fields. The combination of the ANN system and a corresponding calibration procedure enhances the accuracy and measurable temperature range of the LCT compared to state-of-the-art procedures. By using the here established measurement scheme, quantitative global studies of the mutual influence between solidification and convection are enabled and exemplary results are presented.Graphic abstract

An efficient procedure for preparing high-purity pingyangmycin and boanmycin from Streptomyces verticillus var. pingyangensis fermentation broth via macroporous cation-exchange resin and subsequent reversed-phase preparative chromatography

Pingyangmycin (PYM) and boanmycin (BAM), two individual components of bleomycin (bleomycin A5 and bleomycin A6), are glycopeptide antitumor antibiotics. An efficient procedure for the preparation of PYM and BAM from Streptomyces verticillus var. pingyangensis fermentation broth using macroporous cation-exchange (MCE) resin followed by medium-pressure preparative liquid chromatography (MPLC) based on monodisperse poly(styrene-co-divinylbenzene) (p(st-dvb)) microspheres was investigated in this paper. Nine frequently used MCE resins were screened by static adsorption and desorption to enrich PYM and BAM fromthe fermentation broth, and D157 resin was found to be the most effective. After one run of column-based dynamic adsorption and desorption, the contents of PYM and BAM were increased by factors of 13.8 and 12.1 with recovery yields of 84.21% and 81.47%, respectively. The enriched samples were subjected to MPLC with columns prepacked with the PolyRP 10-300 microspheres. The operational parameters of the MPLC, including the stationary phase and mobile phase compositions, sample/stationary phase ratio, sample loading scale and flow rate, were screened and optimized. The results showed that the separation and purification for PYM and BAM by MPLC were dramatically improved with a mobile phase modifier of 0.15 mol/L ammonium chloride aqueoussolution, a flow rate of 10 mL/min and a sample/stationary phase ratio of 1.0:100 (m/v, g/mL), and PYM and BAM with purities of more than 98.65% and 99.12% were obtained, respectively. The total recoveries of PYM and BAM reached 75.38% and 70.31%. The separation and purification method is simple, efficient, energy-saving, environmentally friendly and suitable for the large-scale preparation of high-purity PYM and BAM from Streptomyces verticillus var. pingyangensis fermentation broth.

Leaching calcium from phosphogypsum desulfurization slag by using ammonium chloride solution: Thermodynamics and kinetics study

Abstract Phosphogypsum (PG) desulfurization slag is a calcium-rich residue from reductive decomposition of PG using sulfur as the reductant. We proposed a technology of preparation light calcium carbonate with PG desulfurization slag, which mainly contains two steps: leaching and carbonizing. In this work, we concentrated on the former, in which ammonium chloride aqueous solution was utilized as leaching agent to extract calcium from the slag, and conducted thermodynamics and kinetics study on it. FactSage software was employed to do thermodynamic and phase equilibrium diagram calculations. The influence of leaching conditions including agitation speed, initial concentration of leaching solution, reaction temperature, and liquid/solid ratio on the calcium leaching rate were discussed in detail by means of experiment optimal design. A kinetic model developed from the shrinking core model was given to describe the leaching process. The apparent kinetic activation energy (Ea) of the leaching reaction was calculated to be 10.58 kJ·mol−1.

Does gas supersaturation by a chemical reaction produce bulk nanobubbles?

HypothesisSupersaturation of dissolved gas is the most commonly reported method for generating long-lived bulk nanobubbles. However, these reports are treated with skepticism because of the lack of techniques that directly show that these particles are gas filled bubbles. Therefore, this work has tested the hypothesis that supersaturation obtained by a chemical reaction produces long-lived nanosized bubbles in bulk using an established protocol that relies on evaluating the density of nanoparticles and measuring their response to external pressure. ExperimentsNanoparticles were generated using a chemical reaction between aqueous solutions of ammonium chloride and sodium nitrite. Standard nanoparticle sizing techniques, such as nanoparticle tracking analysis and dynamic light scattering, were utilized to determine the size and stability of the nanoparticles. Resonant mass measurement was used to measure the buoyant mass of the nanoparticles, and their compressibility was investigated by measuring their size under the application of external pressure. FindingsThe formation of nanoparticles was consistent with the kinetics of nitrogen gas evolution produced in the reaction, where the nanoparticle size was shown to be dependent on the pH and concentration of the reactants. However, the chemical reaction was found to generate incompressible nanoparticles with a density larger than that of the solvent, confirming that these particles were not gas-filled bubbles.

Morphology-Controlled Pt Alloy Nanoparticles for Oxygen Reduction Reaction

Proton-exchange membrane (PEM) fuel cell, which can provide clean electricity with high efficiency, is essential for improving the sustainability of our society. Since oxygen reduction reaction (ORR) limits the performance of PEM fuel cells, precious platinum catalyst is crucial in the cathode electrode. Recently, Pt and its alloy nanoparticles (NPs) with controlled morphology have been attracted to reduce the amount of Pt loading. For example, nano-frames, nao-rods, nano-plates, etc. have been reported. As reduction rate and/or stability of a chemical reaction from ionic to metallic state play a key role to synthesize morphology-controlled NPs, in 233rd ECS meeting, we have shown a control technique of oxidation-reduction potential (ORP). However, the controllable range of ORP was revealed to be narrow, which suggests that controllability of the reduction rate needs to be extended. In order to delay the reduction rate for morphology control of Pt alloy NPs, solid precursor instead of ionic counterpart is hopeful. Herein, ammonium hexachloroplatinate which is generated in recycling process is chosen as Pt precursor. The ammonium hexachloroplatinate hardly dissolves in aqueous ammonium chloride solution, whereas it is known to dissolve well in water. In the present work, we demonstrate a facile synthesis method of morphology-controlled Pt alloy NPs by using solid Pt precursor. The ammonium hexachloroplatinate was chemically reduced with Cu ions on carbon support. Synthetic solution was adjusted to be water or ammonium chloride solution, and the samples were labelled as without-NH4Cl and with-NH4Cl, respectively. Transmission electron microscope (TEM) observation revealed that, in the without-NH4Cl, highly dispersed small NPs were deposited on carbon support. On the other hand, in the with-NH4Cl, catalytic NPs were obviously larger than those in the without-NH4Cl, and the morphology was not spherical but plate-like. X-ray diffraction (XRD) profiles indicated that crystal phases of both samples were mainly composed of Pt-Cu alloy crystal. ORR catalytic activities were measured for the small Pt alloy NPs (without-NH4Cl), the plate-like Pt alloy NPs (with-NH4Cl) and commercial Pt. Compared to the commercial Pt, electrochemical active surface area (ECSA) of the without-NH4Cl was almost the same and that of the with-NH4Cl was relatively smaller. This hierarchy is corresponding to particle diameters obtained by the TEM observation. Mass activities of our samples were higher than the commercial Pt, especially, the without-NH4Cl showed a 2-fold increase. The with-NH4Cl exhibited 4 times higher specific activity. Therefore, plate-like Pt alloy NPs will achieve drastically higher mass activity if ECSA is improved. In order to explain the ORR catalytic activities of the synthetic samples, a model of structure of the catalytic NPs was constructed (see Figure). The with-NH4Cl has larger diameter of the catalytic NPs, which indicates more atoms are located at the core of the particles. Since Pt atoms at the core are catalytically inactive, with-NH4Cl showed smaller ECSA than the without-NH4Cl. However, at the same time, the without-NH4Cl has more Cu atoms at the surface, and exposed Cu atoms are easy to leach out during potential scans in acidic solution. In Pt alloy catalysts, transition metals including Cu exhibit an important synergistic effect. When Cu atoms combine with Pt atoms, electronic state of surface Pt changes and surface adsorption energy is tuned, which contributes to an enhancement of ORR catalytic activity. As a result, with-NH4Cl which has larger diameter inhibited leaching of Cu atoms at the core, and sustained the synergistic effect to enhance specific activity. Moreover, plate-like morphology of the with-NH4Cl can be another factor of the high specific activity by selective exposure of active facet. It is reported that Pt nano-plates selectively expose active facet and exhibit high specific activity. In conclusion, we adjusted concentration of ammonium chloride in aqueous synthetic solution to control reduction rate of Pt and morphology of Pt alloy NPs supported on carbon. Highly dispersed small Pt alloy NPs were synthesized in water, whereas plate-like Pt alloy NPs which showed high specific activity were synthesized in aqueous ammonium chloride solution. However, when the concentration of ammonium chloride is excess, the chemical reduction of Pt is inhibited and synthetic yield decreases. Thus, the addition amount of ammonium chloride requires careful consideration. Figure 1