A Theoretical and Experimental Approach to E-pH Diagram for the Niobium-Water System

CORROSION ◽  
10.5006/3871 ◽  
2021 ◽  
Author(s):  
Rodney Santandrea ◽  
Simone BRASIL ◽  
Leila Reznik ◽  
Ladimir Carvalho ◽  
Luiz Miranda
Keyword(s):  
Experimental Approach ◽  
Ph Monitoring ◽  
Aqueous Media ◽  
Water System ◽  
Chemical Species ◽  
Polarization Curves ◽  
Buffer Solutions ◽  
Excellent Corrosion Resistance ◽  
Experimental Diagram ◽  
Selection Of

E-pH diagrams are usually built from thermodynamic databases available in the literature or from specific software. However, depending on the conditions and the chemical species defined for elaborating a diagram, it may present completely different immunity, passivation, and corrosion domains. In order to obtain a result closer to a real system, experimental E-pH diagrams can be built from polarization curves obtained in the evaluated conditions. This work discloses the construction of a diagram for the Nb-H<sub>2</sub>O system at 25°C from theoretical study and the specific selection of chemical species in the solutions through computer simulations. The polarization curves for the construction of the experimental diagram were gathered without the use of buffer solutions and under pH monitoring in the solution bulk throughout all assays. The methodology proposed was considered adequate since, from experimental data, a final result compatible with the classic diagram for the Nb-H<sub>2</sub>O system and the excellent corrosion resistance of niobium in aqueous media were achieved.

scholarly journals Formation of flavorant–propylene Glycol Adducts With Novel Toxicological Properties in Chemically Unstable E-Cigarette Liquids

2018 ◽  
Vol 21 (9) ◽  
pp. 1248-1258 ◽  
Author(s):  
Hanno C Erythropel ◽  
Sairam V Jabba ◽  
Tamara M DeWinter ◽  
Melissa Mendizabal ◽  
Paul T Anastas ◽  
...  
Keyword(s):  
Propylene Glycol ◽  
Electronic Cigarettes ◽  
Aqueous Media ◽  
Chemical Species ◽  
Resonance Spectroscopy ◽  
Reaction Products ◽  
Chemical Systems ◽  
Toxicological Effects ◽  
Wide Range ◽  
Irritant Receptors

Abstract Introduction “Vaping” electronic cigarettes (e-cigarettes) is increasingly popular with youth, driven by the wide range of available flavors, often created using flavor aldehydes. The objective of this study was to examine whether flavor aldehydes remain stable in e-cigarette liquids or whether they undergo chemical reactions, forming novel chemical species that may cause harm to the user. Methods Gas chromatography was used to determine concentrations of flavor aldehydes and reaction products in e-liquids and vapor generated from a commercial e-cigarette. Stability of the detected reaction products in aqueous media was monitored by ultraviolet spectroscopy and nuclear magnetic resonance spectroscopy, and their effects on irritant receptors determined by fluorescent calcium imaging in HEK-293T cells. Results Flavor aldehydes including benzaldehyde, cinnamaldehyde, citral, ethylvanillin, and vanillin rapidly reacted with the e-liquid solvent propylene glycol (PG) after mixing, and upward of 40% of flavor aldehyde content was converted to flavor aldehyde PG acetals, which were also detected in commercial e-liquids. Vaping experiments showed carryover rates of 50%–80% of acetals to e-cigarette vapor. Acetals remained stable in physiological aqueous solution, with half-lives above 36 hours, suggesting they persist when inhaled by the user. Acetals activated aldehyde-sensitive TRPA1 irritant receptors and aldehyde-insensitive TRPV1 irritant receptors. Conclusions E-liquids are potentially reactive chemical systems in which new compounds can form after mixing of constituents and during storage, as demonstrated here for flavor aldehyde PG acetals, with unexpected toxicological effects. For regulatory purposes, a rigorous process is advised to monitor the potentially changing composition of e-liquids and e-vapors over time, to identify possible health hazards. Implications This study demonstrates that e-cigarette liquids can be chemically unstable, with reactions occurring between flavorant and solvent components immediately after mixing at room temperature. The resulting compounds have toxicological properties that differ from either the flavorants or solvent components. These findings suggest that the reporting of manufacturing ingredients of e-liquids is insufficient for a safety assessment. The establishment of an analytical workflow to detect newly formed compounds in e-liquids and their potential toxicological effects is imperative for regulatory risk analysis.

scholarly journals Colour properties of cigarette smoke-exposed cotton and silk fabrics and their nicotine release

2018 ◽  
Vol 69 (04) ◽  
pp. 328-333
Author(s):  
NONGNUCH WANTANEEPORN ◽  
SUWANRUJI POTJANART ◽  
SETTHAYANOND JANTIP
Keyword(s):  
Cigarette Smoke ◽  
Cotton Fabric ◽  
Potential Risk ◽  
Aqueous Media ◽  
Colour Change ◽  
Colour Properties ◽  
Buffer Solutions ◽  
Colour Strength ◽  
Dyed Fabrics ◽  
Silk Fabrics

Exposure to cigarette smoke caused colour change to undyed cotton and silk fabrics by a yellowing effect. The degree of yellowing was more dominant on cotton fabric. When the dyed fabrics were subjected to cigarette smoke, a more pronounced effect was observed on the pale shade dyed fabrics. Shade alteration was inversely related to the colour strength of the dyed fabrics. In addition, a longer exposure time also induced colour change in the fabrics while the colour strength of the dyed fabrics was unaffected. Nicotine release from the cigarette smoke-exposed fabrics in the wet state was studied in different aqueous media, viz. water, buffer solutions (pH 5.5 and 8.0) and artificial sweats (acid and alkaline) in order to reflect the potential risk to textile users of the toxicants from textiles contaminated with cigarette smoke.

scholarly journals Host-Guest Interaction between Herbicide Oxadiargyl and Hydroxypropyl-β-Cyclodextrin

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Sofia Benfeito ◽  
Tiago Rodrigues ◽  
Jorge Garrido ◽  
Fernanda Borges ◽  
E. Manuela Garrido
Keyword(s):  
Aqueous Media ◽  
Industrial Effluents ◽  
Ultrapure Water ◽  
Buffer Solutions ◽  
Water Treatment Plants ◽  
Pesticide Formulations ◽  
The Face ◽  
Ph Buffer ◽  
Environmentally Sound ◽  
And Storage

In the face of a growing human population and increased urbanization, the demand for pesticides will simply rise. Farmers must escalate yields on increasingly fewer farm acres. However, the risks of pesticides, whether real or perceived, may force changes in the way these chemicals are used. Scientists are working toward pest control plans that are environmentally sound, effective, and profitable. In this context the development of new pesticide formulations which may improve application effectiveness, safety, handling, and storage can be pointed out as a solution. As a contribution to the area, the microencapsulation of the herbicide oxadiargyl (OXA) in (2-hydroxypropyl)-β-cyclodextrin (HP-β-CD) was performed. The study was conducted in different aqueous media (ultrapure water and in different pH buffer solutions). In all cases an increment of the oxadiargyl solubility as a function of the HP-β-CD concentration that has been related to the formation of an inclusion complex was verified. UV-Vis and NMR experiments allowed concluding that the stoichiometry of the OXA/HP-β-CD complex formed is 1 : 1. The gathered results can be regarded as an important step for its removal from industrial effluents and/or to increase the stabilizing action, encapsulation, and adsorption in water treatment plants.

Evaluation of a system for intragastric pH monitoring of intensive care unit patients: preliminary report

1992 ◽  
Vol 1 (1) ◽  
pp. 81-84 ◽  
Author(s):  
JM Clochesy
Keyword(s):  
Ph Monitoring ◽  
Gastric Ph ◽  
Gastric Aspirate ◽  
Ph Probe ◽  
Buffer Solutions ◽  
Ph Values ◽  
Small Series ◽  
Significant Difference

BACKGROUND: A new pH probe-tipped nasogastric sump tube is available to monitor gastric pH conveniently. This study assesses its ability to measure gastric acidity accurately. METHODS: The accuracy of the combined pH probe nasogastric tube (GrapHprobe ST) was determined by comparing it with standard buffer solutions (pH 1.0, 2.0, 4.0 and 7.0) traceable to the National Institute of Standards and Technology. Gastric pH values obtained were compared with values obtained using indicator paper and a calibrated glass electrode on gastric aspirate. RESULTS: Although statistically significant differences were found in vitro between the pH of three of the buffer solutions and the pH values obtained by the nasogastric sump tube, the results were within 0.5 pH unit. When rounded to the nearest pH unit, all values were the same as the buffer solutions. No significant difference was found in the pH values obtained during in vivo testing. CONCLUSIONS: The GrapHprobe ST measured gastric pH within reasonable accuracy in this small series.

Mordanting of mercury on styrene-divinylbenzene copolymer beads from aqueous solutions

2007 ◽  
Vol 95 (5) ◽  
Author(s):  
Nasir Khalid ◽  
Saqib Ali ◽  
Arif Iqbal ◽  
Shujaat Ahmad
Keyword(s):  
Aqueous Solutions ◽  
Contact Time ◽  
Aqueous Media ◽  
Mercury Ions ◽  
Chemical Parameters ◽  
Radiotracer Technique ◽  
Physico Chemical ◽  
Styrene Divinylbenzene ◽  
Selection Of

The sorption of mercury ions from aqueous solutions on styrene-divinylbenzene copolymer beads (St-DVB) has been investigated for the decontamination of mercury from aqueous media. Various physico-chemical parameters, such as selection of appropriate electrolyte, contact time, amount of adsorbent, concentration of adsorbate, effect of diverse ions and temperature were optimized to simulate the best conditions which can be used to decontaminate mercury from aqueous media using St-DVB beads as an adsorbent. The radiotracer technique was used to determine the distribution of mercury. The highest adsorption was observed at 0.001 mol L

Monitoring of Chemical Speciation of DEA – CO2 – Water System by Raman Spectroscopy

2015 ◽  
Vol 1113 ◽  
pp. 358-363 ◽  
Author(s):  
Muhammad Zubair Shahid ◽  
Humbul Suleman ◽  
Adulhalim Shah Maulud ◽  
Mohammad Azmi Bustam Khalil ◽  
Zakaria Man
Keyword(s):  
Raman Spectroscopy ◽  
Water System ◽  
Chemical Species ◽  
Principal Component Regression ◽  
Principal Component ◽  
Carbon Dioxide Separation ◽  
Key Factor ◽  
Kinetics Of ◽  
Respective Characteristic ◽  
Good Agreement

Carbon dioxide separation has gained immense importance since its detrimental effects towards our environment has been realized. Commercially, CO2has been captured by absorption in alkanolamines such as diethanolamine (DEA), since many years. The thermodynamics and kinetics of the process is a key factor towards its efficiency and significantly depends on its qualitative and quantitative speciation. In this work, the analysis of speciation for CO2loaded aqueous DEA has been performed by Raman spectroscopy. Experimentally determined CO2loading data and modified Kent Eisenberg equation was used to quantify the chemical species present. The speciation results were fitted with the respective characteristic Raman peaks of (CO3-, HCO3-, DEACOO-, DEA, DEA+, CO2) by Principal Component Regression (PCR). The fitted results showed good agreement with thermodynamically predicted chemical species.

scholarly journals Selection of rational electrochemical methods for controlling the efficiency of machining of corrosion-resistant steel

2021 ◽  
Vol 2131 (4) ◽  
pp. 042016
Author(s):  
Yu Astsaturov ◽  
S Solovyov ◽  
V Zhigulsky
Keyword(s):  
Anodic Polarization ◽  
Metal Cutting ◽  
Electrolyte Solutions ◽  
Rotating Disk Electrode ◽  
Polarization Curves ◽  
Work Piece ◽  
Mechanical Processing ◽  
Electrode Potentials ◽  
Cutting Zone ◽  
Selection Of

Abstract The article discusses methods of controlling the processes of mechanical processing based on electrochemical effects. The corresponding anodic polarization curves of 1X18H9T steel obtained in electrolyte solutions without and with stirring are presented. The article discusses methods of machining processes control based on electrochemical effects. Lubricating and cooling technological media (LCTM) used in machining are in most cases electrolytes, therefore, electrochemical processes and phenomena actively occur during contact dynamic machining. It is possible to control the processes of machining by acting on the system elements of the tool - LCTM- part, in particular by activating the LCTM and reducing the strength characteristics of the processed steel in the cutting zone. A reserve for increasing the efficiency of mechanical processing can be the composition selection of the applied LCTM, combined with the simultaneous electrochemical polarization of the treated surface of friction pair parts. It was found that when cutting, the efficiency of machining and the chip shapes are changed, which is explained by the influence of the current density on the strength of the processed steel. In the conditions of machining, complex dynamic processes occur due to the rotation of the work piece and/or tool, so it is necessary to take into account the hydrodynamic phenomena and processes that arise in this case. Electrode potentials are considered to be the most important characteristic of the metal cutting process. The potential of the system can regulate such processes and indicators as wear and surface micro hardness. Anodic polarization curves of the steel 1X18H9T obtained in various electrolyte solutions without stirring and with stirring on a rotating disk electrode are given. The study allowed determining the factors affecting the processes occurring in the cutting zone and to identify rational current densities due to simulating the conditions of real technological processes of the combined steel processing. The increase in the processing intensity of the steel 1X18H9T with the cutting zone polarization is associated with the action of factors activating the selective anodic dissolution of the processed alloy.

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