Diffusion Of HCl Research Articles

Gastric Histopathological Image of Winstar Rats Induced by Ethanol After Red Ginger Extract Administration

Background: Alcohol can cause damage to the gastric mucosal barrier and reverse diffusion of HCL which results in damage to gastric tissue. The flavonoids in red ginger act as exogenous antioxidants which can ward off free radicals which reduce damage to the gastric mucosa caused by alcohol.Objective: To determine the differences in the histopathology of the rats gastric induced by 40% ethanol after administration of red ginger (Zingiber officinale var. rubrum) extract at graded doses.Methods: A post-test only group design method. 25 rats samples were divided into 5 groups: K(-) standard feed; K(+) ethanol 40% 1.8ml/200g/day; P1 red ginger extract 250mg/KgBW; P2 red ginger extract 500mg/KgBW; and P3 red ginger extract 750mg/KgBW. After 60 minutes, 40% ethanol was given at a dose of 1.8ml/200g/day. Treatment was carried out for 30 days, then on day 31 termination was carried out and gastric histopathology preparations were made with hematoxylin-eosin staining. Calculation of hull damage scores using the Barthel-Manja criteria. Analysis of differences in gastric mucosal damage between groups using the Kruskal Wallis Test and Mann Withney Test.Results: The difference between groups obtained significant results (p=0.003). There were significant differences between the K- and K+ groups (p=0.016), the K- and P1 groups (p=0.032), between the K- and P2 groups (p=0.032), between the K+ and P3 groups (p =0.032). Conclusion: Administration of red ginger extract at a dose of 750mg/KgBW was proven to be effective in preventing damage to the gastric mucosa induced by 40% ethanol.

Enhanced Hot Salt-Water Corrosion Resistance of NiCoCrAlY-AlSiY Coating by Ion-Beam-Assisted Deposition

A promising ion-beam-assisted deposition (IBAD) method was developed to improve the salt-water corrosion resistance of NiCoCrAlY-AlSiY coating. During hot salt-water exposure, hydrochloric acid (HCl) was produced when chloride salt, water, and metal oxide reacted with each other, while HCl was also produced when chlorine reacted with water. The as-deposited AlSiY layer exhibited a loose texture accompanied by numerous pore defects, which triggered the multi-scale diffusion of HCl, resulting in the large-area corrosion degradation of the coating texture and the rapid diffusion of the NiCoCrAlY bonding layer. By contrast, the ion-beam-assisted AlSiY layer showed a dense texture that effectively inhibited the inner diffusion of HCl and suppressed the corrosion reactions as well as the diffusion of the NiCoCrAlY bonding layer. The current results confirmed the significant potential of IBAD in inhibiting corrosion damage and diffusion of thermal protective coatings.

Durability of an Epoxy Resin and Its Carbon Fiber- Reinforced Polymer Composite upon Immersion in Water, Acidic, and Alkaline Solutions.

The usage of polymer composites in various engineering fields has increased. However, the long-term service performance of such materials under aggressive conditions is still poorly understood, which limits the development of safe and economically effective designs. In this study, the aging of an epoxy resin and its carbon fiber-reinforced polymer (CFRP) composites upon immersion in water, acidic, and alkaline solutions was evaluated at different temperatures. The service life of the CFRP composites under various conditions could be predicted by the Arrhenius theory. The thermal and mechanical analysis results indicated that the CFRP composites were more vulnerable to HCl owing to the higher moisture absorption and diffusion of HCl into their cracks. The scanning electron microscopy results showed that the polymer matrix was damaged and degraded. Therefore, to allow long-term application, CFRP composites must be protected from acidic environments.

Vancomycin HCl-loaded lauric acid in situ-forming gel with phase inversion for periodontitis treatment

An antimicrobial agent-loaded in situ-forming gel (ISG) was recently used for periodontitis treatment. This study aimed to use lauric acid, a biocompatible hydrophobic material, as a matrix former. Non-drug and vancomycin HCl-loaded lauric acid-based ISGs were prepared by using various solvents, including N-methyl pyrrolidone, 2-pyrrolidone and dimethyl sulphoxide (DMSO). Increased concentrations of lauric acid resulted in faster gel self-transformation behaviour. The ISG using DMSO as the solvent showed the fastest transformation with the least water tolerance. Higher concentrations of lauric acid promoted the immediate formation of a dense lauric acid network on the gel surface and obstructed water/solvent diffusion. Through the solvent-exchange mechanism, the hydrophobic property of lauric acid and its rapid surface network formation retarded the diffusion of vancomycin HCl, resulting in prolonged drug release over 6 days. Vancomycin HCl-loaded ISG revealed effective antimicrobial activity against methicillin-resistant Staphylococcus aureus and Porphyromonas gingivalis for periodontitis treatment. All of the preparations exhibited low viscosity and high injectability, thereby indicating their ease of use. The developed system was found to be effective for periodontal pocket drug delivery for periodontitis treatment.

Hydrodechlorination of chlorophenols over Pd catalysts supported on zeolite Y, MCM-41 and graphene

Hydrodechlorination (HDC) reaction of chlorophenols was carried out using Pd catalysts supported over zeolite Y, MCM-41 or graphene. Pd-MCM-41 and Pd-Y zeolite were prepared by impregnation and ion-exchange method, respectively. Pd-graphene (Pd-G) was prepared by hydrazine hydrate reduction of palladium ion dispersed on graphene oxide. The catalysts were characterized by several analytical tools such as X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDS). These catalysts were subjected to HDC reaction of chlorophenols, such as 4-chlorophenol (4-CP), 2,4-dichlorophenol (2,4-DCP), 2,6-dichlorophenol (2,6-DCP) and 3,4-dichlorophenol (3,4-DCP). The reaction rate of HDC of chlorophenols catalyzed by Pd catalysts with various solid bases, such as KF/Al2O3 (alumina), sodium acetate (NaOAc) and K2CO3 was compared. First, Pd-MCM-41 and Pd-Y catalysts were compared. 2,4- and 3,4-DCPs were completely decomposed within 6 h, in the case of Pd-MCM-41 with NaOAc. Using Pd-Y instead of Pd-MCM-41 with NaOAc, much faster decomposition was observed. Faster decomposition of 4-CP and DCPs was observed with NaOAc base than K2CO3 or KF/Al2O3 under the same condition. In the case of Pd-Y with KF/Al2O3, slower decomposition of 4-CP and DCPs was observed. These base effects were interpreted using the solubility of NaCl and KCl in alcohol and the basic sites of KF/Al2O3. Because the solubility of NaCl is known to be larger than KCl solubility in alcohol, byproduct NaCl could be easily dissolved and ionized in solvents. For Pd-Y with KF/Al2O3, the small pore size of Y zeolite can interfere with the diffusion of HCl to KF/Al2O3 basic site. Second, three catalysts, including Pd-graphene, were compared. 2,4-DCP was decomposed within 2 h using Pd-G with either K2CO3, NaOAc or KF/Al2O3. Pd-G catalyst showed the highest catalytic activity among Pd-G, Pd-MCM-41 and Pd-Y catalysts. The high activity and stability of the Pd-G could be attributed to the strong metal–support interaction with an electron-deficient site and a critical Pd particle size (ca. 3.5 nm) of Pd-G nanocatalyst with a stronger resistance to the deactivation and good affinity toward aromatic organic molecules, especially phenols. The progress of HDC reaction was monitored by gas chromatography with flame ionization detection (GC/FID), and a feasible degradation process could be explained by analyzing the degradation products such as phenol, cyclohexanone and cyclohexanol from resulting GC chromatograms. The effect of reaction temperature on HDC in Pd-G catalyst was also discussed. In conclusion, Pd-G is an efficient catalyst for decomposition of chlorophenols and can be applied to remediation of chlorophenol-contaminated water under mild conditions.

Diffusion of levodopa in aqueous solutions of hydrochloric acid at 25 °C

Ternary mutual diffusion coefficients (D11, D22, D12 and D21) measured by the Taylor dispersion method are reported for aqueous solutions of {levodopa (l-dopa)+HCl} solutions at 25°C and HCl concentrations up to 0.100mol·dm−3. The coupled diffusion of l-dopa (1) and HCl (2) is significant, as indicated by large negative cross-diffusion coefficients. D21, for example, reaches values that are larger than D11, the main coefficient of l-dopa. Combined Fick and Nernst–Planck equations are used to analyze the proton coupled diffusion of l-dopa and HCl in terms of the binding of H+ ions to l-dopa and ion migration in the electric field generated by l-dopa and HCl concentration gradients.

Well-Controlled Formation of Polymeric Micelles with a Nanosized Aqueous Core and Their Applications as Nanoreactors

Polymeric micelles with a polystyrene (PS) shell and a protonated poly(4-vinylpyridine) (P4VP)/water core were readily prepared via diffusion of HCl and water from the top aqueous phase containing HCl (pH = 1) into the bottom phase of the PS-b-P4VP solution in chloroform. The resultant protonation of the pyridine units of the P4VP block drove the micellization. Meanwhile, due to the high polarity of the core, water molecules also diffused through the chloroform medium into the core. 1H NMR characterizations demonstrate that at the early stage, the water molecules in the core are the bound and intermediate water; longer diffusion times resulted in the appearance of free water molecules coexisting with the bound and intermediate water in the core. Thus, polymeric micelles with an aqueous core (PMACs) were formed. The process of forming PMACs is well-controllable, and the stability of PMACs in chloroform is high. These characteristics make PMACs promising as nanoreactors to prepare inorganic nanoparticles or...

Distribution of Orally Ingested Hydrochloric Acid in the Thoracoabdominal Cavity After Death

The authors encountered a case of hydrochloric acid (HCl) poisoning, thought to be caused by oral ingestion of concentrated HCl. Coagulation of the surface of the tongue and the mucosa of the pharynx, esophagus, and stomach were observed at forensic autopsy. An overabundance of Cl- was found in the gastric contents, corresponding to 8.19 mL of concentrated HCl. This was suggested to be a lethal oral dose of concentrated HCl, and the cause of death was determined to be HCl poisoning. Measuring the pH and concentrations of various ions in body fluids and contents of the alimentary tract enabled postmortem diffusion of HCl to be determined.

Modeling the reaction of gaseous HCl with CaO in fluidized bed

An integrated mathematical model is developed to evaluate the performance of the reaction of gaseous HCl and CaO in fluidized bed. The model considers initial pore size distribution of solid reactant, pore structure change and attrition caused by particles movement. Bethe network is used to describe the pore space topology, and the percolation theory is used to determine the accessible reaction surface area of the sorbent particles and the effective diffusion coefficient of gaseous HCl. This model prediction accounts for the diffusion of HCl in shrinking pore space as well as in product layer, and clearly demonstrates the increasing diffusion resistance and the isolation of partially reacted pores causing incomplete conversion of solid. The model shows excellent agreement with the experimental data.

Kinetics of MgO chlorination with HCl gas

The kinetics of chlorination of MgO particles with HCl gas in the temperature range from 450 °C to 650 °C were measured and analyzed in terms of the shrinking core model. The MgO particles were produced by the thermal decomposition of MgOHCl manufactured in-house and were found to have a d50 of 510 nanometers. Over 90 pct of the MgO was converted to MgCl2 within 30 minutes at 650 °C. Analysis of the data indicated that the chlorination process was initially controlled by the kinetics of the chemical reaction between MgO and HCl, but as the thickness of the MgCl2 product layer increased as the chlorination progressed, the rate of chlorination became controlled by the diffusion of HCl through the MgCl2 ash layer surrounding a MgO core in the particles. A mathematical model that predicted the shrinkage of the MgO core with time was found to be in good agreement with the measurements over the range of temperatures studied. The ash layer thickness for the onset of the diffusion control regime was found to increase linearly with temperature. The apparent rate constant for chlorination in the initial reaction-controlled regime was well described by the Arrhenius equation: k (m/s)=0.0787 exp (−7596/T).

Reactive Uptake of Nitric Acid into Aqueous Sodium Chloride Droplets Using Real-Time Single-Particle Mass Spectrometry

The kinetics and rate-limiting mechanism of reactive uptake of nitric acid into submicron, deliquescent sodium chloride aerosols are determined. The reaction was performed in a flow tube with a real-time single-particle mass spectrometer connected to the outlet to determine the chloride-to-nitrate ratio of the transformed particles. Pseudo-first-order conditions were maintained by keeping the nitric acid pressure constant, as measured with a chemiluminescence analyzer. Experiments were performed with 100−220 nm diameter droplets at ca. 80% relative humidity and nitric acid concentrations between 60 and 380 ppb. Rate constants and uptake coefficients were determined from time-dependent changes in the chloride concentration of individual particles that traversed the reactor. The initial reactive uptake coefficient for 100 nm droplets was found to be 4.9 ± 2.7 × 10-3 and, to a first approximation, independent of the nitric acid concentration. The uptake coefficient also was found to increase linearly with increasing droplet size over the size range studied. These dependencies suggest that transport phenomena (diffusion of HNO3(g) to the droplet surface, accommodation of HNO3 into the droplet, diffusion of HNO3(aq) and HCl(aq) inside the droplet, and transport of HCl across the droplet surface into the gas phase) do not limit the reaction rate. Instead, reactive uptake of HNO3(g) is limited by formation of molecular HCl in the aqueous phasea thermodynamically controlled process. The results are consistent with related measurements that show uniform chloride/nitrate/sodium mole ratios in submicron-size aerosols, a large uptake coefficient for aerosols in the low micron-size range, and decreasing chloride-to-nitrate ratios (because of transport limitations) in supermicron-size aerosols.

Kinetics of Ice Particle Conversion to the Hydrates of HCl

Reaction rates for the conversion of ice nanocrystals within 3-D arrays to mono-, tetra- and hexahydrates of HCl have been determined for different HCl(g) exposure levels and reaction temperatures. The extent of reaction was monitored and the hydrate product identified, using transmission FT-IR spectroscopy. The direct method of observation provides evidence that HCl diffusion through the hydrate encrusting the ice particles is often the rate-limiting factor in the conversion of ice to a hydrate phase. Values for the HCl diffusion coefficient for the mono- and tetrahydrate are reported. By comparison, diffusion of HCl in ice is considered to be a nonfactor in most ice−HCl interactions.

Evaluation of depth profiling using laser resonant desorption as a method to measure diffusion coefficients in ice.

Diffusion of gases in ice is involved in cloud, snow, and ice core chemistry, but few data exist on the relevant diffusion coefficients. A novel method to measure diffusion coefficients in ice has recently been proposed by Livingston et al. (Anal. Chem., 2000, 72, 5590-5599). It is based on depth profiling of doped ice crystals epitaxially grown on Ru(001) by laser resonant desorption (LRD). Using this method, Livingston et al. obtained a value of the diffusion coefficient of the HCl hydrate in ice at 190 K of about 5 x 10(-11) cm2/s. We argue here that this value is many orders of magnitude higher than what could be expected from literature values, which are not reported in sufficient detail by Livingston et al. We investigate the possibilities that their high value could be due to (1) diffusion in defects in the ice, which would be present in very high concentrations because of the ice growth method; and (2) the fact that diffusion of high concentrations of HCl in ice at 190 K forms an amorphous HCl:H2O solid mixture, where HCl diffusion is fast. We present new infrared spectroscopic data on solid HCl:H2O mixtures that confirm that such mixtures can indeed be formed in an amorphous state at 190 K. Our proposed interpretation is that by depositing large amounts of HCl on epitaxially grown ice, Livingston et al. created a superficial amorphous binary mixture and that fast diffusion of HCl in the ice, possibly accelerated by a high defect density, produced an amorphous HCl:H2O mixture. We conclude that the processes studied by Livingston et al. are different from those involved in the atmospheric and cryospheric sciences, and that their data, obtained by depth profiling using LRD, probably cannot be applied to those fields.

ChemInform Abstract: Uptake Dynamics and Diffusion of HCl in Sulfuric Acid Solution Measured in Single Levitated Microdroplets.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

An Empirical Model for the De Novo Formation of PCDD/F in Medical Waste Incinerators

Tests in a 10 kg h-1 pilot scale incinerator burning medical waste showed that the amounts of PCCD/F formed when cooling from 900 °C to ambient were almost proportional to the residence time in the 400−200 °C range. This suggests that gas-phase adsorption control rather than kinetic control was operating. A generalized model of PCCD/F formation was developed for a chlorine-rich gas phase, based on diffusion of HCl to the fly ash surface. It was necessary to incorporate a “sticking factor” α, which specifies the fraction of molecules that are retained on the ash surface and subsequently enter into reaction. The calculation combines rates for the formation and destruction mechanisms that are effective in the range of 400−225 °C. Application of the model requires knowledge of the cooling regime, the specific surface area of fly ash, its concentration at the sampling point, and the initial surface concentration of PCCD/F. It assumes that all the PCCD/F emitted from waste incinerators is associated with the fl...

Uptake Dynamics and Diffusion of HCl in Sulfuric Acid Solution Measured in Single Levitated Microdroplets

The uptake dynamics of HCl by single sulfuric acid microdroplets under stratospheric conditions is investigated. The droplets are typically 30−70 μm in diameter and weakly charged so that they can be stored in an electrodynamic trap. The gas uptake of the droplets is monitored either by measuring their size by angle resolved Mie- scattering patterns or by electrostatic balancing of the droplets in the trap. At low temperatures and high sulfuric acid concentration (T < 190 K for 48 wt % H2SO4 and T < 195 K for 56 wt % H2SO4, respectively), liquid-phase diffusion inside the droplet is the rate-limiting step in the overall uptake process. In this regime, the diffusion coefficients Dliq of HCl in supercooled sulfuric acid solutions are found to increase strongly with temperature and H2O concentration. The results are discussed with respect to diffusion models that have been proposed recently. In contrast, at higher temperatures and lower sulfuric acid concentrations (30−40 wt % H2SO4, 185−207 K) gas-phase diffusion with subsequent accommodation/dissolution at the liquid surface determines the observed uptake velocity. A new method to deduce accommodation coefficients α is proposed.

Adsorption and Desorption of HCl on Ice

Pulsed molecular beam and mass spectrometric techniques are used to study the adsorption of hydrogen chloride on thin ice films at temperatures from 100 to 170 K. The adsorption and desorption of HCl from an ice surface is relevant to the polar stratosphere where it is thought that chlorine atoms are liberated from reservoir species such as HCl by heterogeneous reactions occurring on the surface of polar stratospheric clouds. We have measured the sticking coefficient for HCl at an incident translational energy of 0.09 eV on thin film ice surfaces using a modified version of the reflectivity technique of King and Wells. By modeling the HCl partial pressure versus time waveforms for surface temperatures of 100−125 K, we obtain a sticking coefficient of 0.91 ± 0.06. The model incorporates first-order HCl desorption and a loss term also first order in HCl. Fitted kinetic parameters are Edes = 28 kJ/mol, νdes = 2 × 1014 s-1 for desorption and Eloss = 21 kJ/mol, νloss = 4 × 1011 s-1 for the loss. The loss may be associated with the onset of water diffusion on the ice surface and subsequent ionization or hydration of the HCl. The measured waveforms are inconsistent with diffusion of HCl into the bulk. The apparent reflectivity decreases substantially in the temperature range of 126 to 140 K. This decrease cannot be attributed to an increase in sticking coefficient, a phase change in the ice, or the formation of the hexahydrate state of HCl.

Liesegang pattern formation by gas diffusion in silica aerogels

Molecular gas diffusion of HCl and NH 3 has been studied both in air and in aerogel. The two gases react to form NH 4Cl which precipitates when a threshold concentration is reached. When the gases diffuse from opposite ends of a tube, the precipitate appears as a white ring whose position is determined by the ratio of the gas diffusion constants and follows Graham's law. When the diffusion process takes place in an aerogel, NH 4Cl precipitates in sheets that span a cross-section of the gel. As the diffusion process continues, more bands are formed. The assembly of bands is called a Liesegang pattern. This phenomenon is known to occur in diffusion reaction systems. Numerical simulations based on the Ostwald nucleation theory qualitatively agree with experiments.

Kinetics of chloridization of nickel-bearing lateritic iron ore by hydrogen chloride gas

The selective chloridization of nickel in a lateritic iron ore by gaseous HCl is based on the principle of relative thermal stability of iron and nickel chlorides. This aspect has been discussed with differential thermal analysis (DTA) and thermogravimetric (TG) data of the hydrated chlorides of iron and nickel. The kinetics of chloridization of nickel in a lateritic nickel ore from Orissa, India, have been studied by using both pure HCl (g) and the HCl (g) + N2 mixture. The sharp decrease in the rate of chloridization of nickel at temperatures above 250 °C is attributed to the rapid decomposition of molten ferric chloride hydrate (FeCl3 · 3H2O), which blocks the pores of the reactant solid. Therefore, kinetics of chloridization follow both the pore-blocking model (logarithmic rate law) and diffusion-controlled mechanisms. Very low values of apparent activation energy and effective diffusivity derived from the rate constants of the diffusion-controlled process suggest that diffusion of HCl (g) takes place either in a dissolved state in the molten ferric chloride (at 100 °C to 150 °C) or through cracks and fissures formed on the surface due to rapid decomposition of ferric chloride at 200 °C to 250 °C. Because of the complexity of the reaction system, the rate of chloridization of nickel is almost independent of grain size.

Determining past atmospheric HCl mixing ratios from ice core analyses

Laboratory and field measurements have been performed in order to improve our understanding of the HCl air-snow transfer function. The solubility and diffusion of HCl in laboratory grown single crystals of ice have been measured as a function of HCl partial pressure,P HCl, between −8 and −25 °C. Measurements ofP HCl and of the mole fraction of HCl in snow,X'HCl, have been measured at Summit, Greenland. Comparison of the field and laboratory measurements show that theX'HCl values are well below equilibrium values. The major processes involved in the formation of snow crystals and in their evolution after deposition are discussed in order to attempt to understand theX'HCl values and their variations. The discussion is focussed on a few well identified snow layers. It is concluded that sublimation and recrystallization of snow probably play a major role in the evolution ofX'HCl, but that our understanding of the HCl transfer function is very incomplete. Laboratory and field measurements are suggested to improve this situation.