Electrochemical Reduction of Tetrachloromethane. Electrolytic Conversion to Chloroform

2002 ◽  
Vol 67 (3) ◽  
pp. 279-292 ◽  
Author(s):  
Victor M. Molina ◽  
Domingo González-Arjona ◽  
Emilio Roldán ◽  
Manuel Dominguez
Keyword(s):  
Supporting Electrolyte ◽  
Industrial Effluents ◽  
Differential Pulse ◽  
Experimental Conditions ◽  
Ph Values ◽  
Peak Deconvolution ◽  
Through Flow ◽  
Voltammetric Peak ◽  
Electrolysis Products ◽  
Made In

The feasibility of electrolytic removal of tetrachloromethane from industrial effluents has been investigated. A new method based on the electrochemical reductive dechlorination of CCl4 yielding chloroform is described. The main goal was not only to remove CCl4 but also to utilize the process for obtaining chloroform, which can be industrially reused. GC-MS analysis of the electrolysed samples showed that chloroform is the only product. Voltammetric experiments were made in order to select experimental conditions of the electrolysis. Using energetic and economic criteria, ethanol-water (1 : 4) and LiCl were found to be the optimum solvent and supporting electrolyte tested. No great differences were found while working at different pH values. Chronoamperometric and voltammetric experiments with convolution analysis showed low kf0 and α values for the reaction. A new differential pulse voltammetric peak deconvolution method was developed for an easier and faster analysis of the electrolysis products. Electrolysis experiments were carried out using both a bulk reactor and a through-flow cell. Thus, three different kinds of galvanostatic electrolyses were carried out. Under all conditions, CCl4 conversions ranging from 60 to 75% and good current efficiencies were obtained.

Rapid Differential Pulse Polarographic Determination of Tiaprofenic Acid

1984 ◽  
Vol 67 (4) ◽  
pp. 684-687
Author(s):  
Mohamed E Mohamed ◽  
Abdel-Aziz M Wahbi ◽  
EL Rasheed A Gad-Kariem ◽  
Mahmoud M A Hassan
Keyword(s):  
Supporting Electrolyte ◽  
Tiaprofenic Acid ◽  
Reference Electrode ◽  
Differential Pulse ◽  
Differential Pulse Polarography ◽  
Experimental Conditions ◽  
Tablet Form ◽  
Peak Current ◽  
Pulse Polarography

Abstract Tiaprofenic acid (Surgam®) has been determined directly by using differential pulse polarography (DPP) and pH 5.5 acetate buffer as a supporting electrolyte. The differential pulse polarogram was obtained under constant amplitude pulses of 50 mV superimposed on a linearly increasing dc ramp. Peak current was measured at the peak potential of — 0.990 V vs Ag/AgCl reference electrode. Under the experimental conditions used, a linear relationship between peak current and concentration was established over the range 0.5-5.0 ng/mL. Mean percentage recoveries for tiaprofenic acid in authentic and tablet forms were 100.27 ± 2.25 and 99.45 ± 1.44, respectively. The results obtained by the DPP method were compared with those of the spectrophotometric method used by the manufacturer for the analysis of tiaprofenic acid and its tablet form.

scholarly journals Differentiation between phenol- and amino-substances in voltammetry determination of synthetic antioxidants in oils

2010 ◽  
Vol 8 (3) ◽  
pp. 607-616 ◽  
Author(s):  
Jaromíra Chýlková ◽  
Renáta Šelešovská ◽  
Jaroslava Machalíková ◽  
Libor Dušek
Keyword(s):  
Differential Pulse Voltammetry ◽  
Aromatic Amines ◽  
Supporting Electrolyte ◽  
Differential Pulse ◽  
Phenolic Antioxidants ◽  
Potential Range ◽  
Experimental Conditions ◽  
Lubricating Oils ◽  
Pulse Voltammetry

AbstractThe paper describes a method of voltammetric determination of antioxidants in lubricating oils developed with the use of Linear Sweep Voltammetry (LSV) and Fast Scan Differential Pulse Voltammetry (FSDPV). Experimental conditions have been found for simultaneous determination of phenol-based antioxidants and amino-antioxidants: the phenols can be electrochemically oxidized using the polarisation of gold disc electrode (AuDE) in the potential range of 0–1400 mV in 0.2 M H2SO4 in the presence of ethanol and acetonitrile at the ratio of 3:1. Secondary aromatic amines can be determined directly in this supporting electrolyte; the presence of phenolic antioxidants does not interfere with this analysis. On the other hand, secondary aromatic amines interfere with the determination of phenolic substances; therefore, the amines present have to be eliminated in a suitable way. A procedure for masking the aromatic amines using their reaction with nitrous acid has been suggested and optimised. The nitrosamines thus formed can be used for sensitive and selective determination of amino-antioxidants by means of cathodic reduction on the hanging mercury drop electrode (HMDE) using Fast Scan Differential Pulse Voltammetry. The method was applied in analysis of real samples of lubricating oils.

scholarly journals Measurement of Voltammetric Peak Area and Resolution of Overlapping Peaks in the Simultaneous Determination of Copper, Lead, Cadmium, and Nickel in Environmental Matrix

2000 ◽  
Vol 83 (6) ◽  
pp. 1321-1326 ◽  
Author(s):  
Clinio Locatelli
Keyword(s):  
Simultaneous Determination ◽  
Analytical Procedure ◽  
Supporting Electrolyte ◽  
Differential Pulse ◽  
Standard Reference Materials ◽  
Experimental Conditions ◽  
Relative Standard ◽  
Resolution Of Overlapping Peaks ◽  
Determination Of Copper

Abstract Peak area was used for the simultaneous determination of copper(II), lead(II), cadmium(II), and nickel(II) in environmental matrixes by differential pulse voltammetry. The voltammetric measurements were performed with a conventional 3-electrode cell and an ammonia–ammonium chloride buffer, pH 9.1, as the supporting electrolyte. The analytical procedure was verified first in aqueous reference solutions and later by analysis of the standard reference materials Estuarine Sediment BCR-CRM 277 and River Sediment BCR-CRM 320. The precision and accuracy of the method, expressed as the relative standard deviation and the relative error, respectively, were <5% in all cases; the detection limit for each element under the experimental conditions used was in the range 1–5 μg/L. In the case of mutual interference between neighboring elements, an analytical procedure is proposed that is based on the standard additions technique, which allows the resolution of the overlapping voltammetric peaks.

Natural clay from Cuba for environmental remediation

Clay Minerals ◽  
2018 ◽  
Vol 53 (2) ◽  
pp. 193-201 ◽  
Author(s):  
S. A. Martín ◽  
L. Valdés ◽  
F. Mérida ◽  
L. C. de Ménorval ◽  
M. Velázquez ◽  
...  
Keyword(s):  
Environmental Remediation ◽  
Low Cost ◽  
Industrial Effluents ◽  
Xrd Analysis ◽  
Natural Clay ◽  
X Ray Diffraction ◽  
Experimental Conditions ◽  
Ph Values ◽  
Natural Clays ◽  
Adsorptive Properties

ABSTRACTThe use of natural clays for the removal of dyes from wastewater, an important part of environmental remediation, is desirable due, not least, to their low cost. Palygorskite (PAL), a rigid-structure clay, is a good candidate for use in the elimination of industrial effluents, based on its exceptional adsorptive properties. Recently, a new palygorskite deposit has been discovered in Cuba and its use in the adsorption of dyes has not yet been explored in detail. In the present study, the use of unmodified natural Cuban palygorskite as a host for dyes was evaluated. Congo red (CR) and methylene blue (MB) were the anionic and cationic dyes tested, respectively, because of their wide use and toxicity to the environment. Several physical-chemical parameters were studied in order to establish the best experimental conditions under which to achieve the greatest dye load per gram of clay. Natural mixtures with different percentages of montmorillonite were also tested to evaluate their effect on the adsorption of the dyes. The results indicated that at pH values of ~7–9 and an initial dye concentration of 0.1 mg mL–1, the process was efficient. X-ray diffraction (XRD) analysis proved the surface adsorption of both dyes on the clays. The main interactions involved in the clay-dye system were electrostatic forces and H-bonds. Adsorption of CR seemed to be controlled fundamentally by the palygorskite phase. Such results support the use of this natural clay as an efficient host for the removal of MB and CR from wastewater.

VOLTAMMETRIC DETERMINATION OF ACETOPHOS IN WATER SAMPLES AT CNTPE

2013 ◽  
Vol 12 (03) ◽  
pp. 1350018
Author(s):  
SARVAREDDY RAJASEKHAR REDDY ◽  
T. RAVEENDRANATH BABU
Keyword(s):  
Water Samples ◽  
Supporting Electrolyte ◽  
Reduction Process ◽  
Standard Addition ◽  
Differential Pulse ◽  
Experimental Conditions ◽  
Controlled Potential Electrolysis ◽  
Universal Buffer ◽  
Controlled Potential ◽  
Ph Range

In this paper, a sensitive differential pulse voltammetric method to determine the residues of acetophos in water samples at CNTPE were reported. The significance of CNTPE is to result in low detection limits, high sensitivities, reduction of over-potentials, high mechanical strength and high conductivity and resistance to surface fouling. The universal buffer with pH range 2.0–6.0 is used as supporting electrolyte. Cyclic voltammetry employed to evaluate electrode mechanism and number of electrons involved in reduction process were found out by using Millicoulometry and the product collected by applying Controlled potential electrolysis. Experimental conditions such as accumulation potential, accumulation time and scan rate were optimized. Calculations were made by standard addition method.

scholarly journals Photocatalytic Treatment of Wastewater Containing Simultaneous Organic and Inorganic Pollution: Competition and Operating Parameters Effects

Catalysts ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 855
Author(s):  
Ahmed Amine Azzaz ◽  
Salah Jellali ◽  
Nasser Ben Harharah Hamed ◽  
Atef El Jery ◽  
Lotfi Khezami ◽  
...  
Keyword(s):  
Ultra Violet ◽  
Degradation Process ◽  
Molar Ratio ◽  
Experimental Conditions ◽  
Retention Capacity ◽  
Isotherm Study ◽  
Related Data ◽  
Ph Values ◽  
Pseudo Second Order ◽  
Maximum Retention

In the present study, methylene blue (MB) removal from aqueous solutions via the photocatalytic process using TiO2 as a catalyst in the presence of external ultra-violet light (UV) was investigated. The results of adsorption in the absence of UV radiation showed that adsorption reached an equilibrium state at 60 min. The experimental kinetic data were found to be well fitted by the pseudo-second-order model. Furthermore, the isotherm study suggested that dye uptake by TiO2 is a chemisorption process with a maximum retention capacity of 34.0 mg/g. The photodegradation of MB was then assessed under various experimental conditions. The related data showed that dye mineralization decreased when dye concentrations were increased and was favored at high pH values and low salt concentrations. The simultaneous presence of organic and inorganic pollution (Zinc) was also evaluated. The effect of the molar ratio Zn2+/MB+ in the solution at different pH values and NaCl concentrations was also monitored. The corresponding experimental results showed that at low values of Zn2+ in the solution (30 mg/L), the kinetic of the MB removal became faster until reaching an optimum at Zn2+/MB+ concentrations of 60/60 mg/L; it then slowed down for higher concentrations. The solutions’ carbon contents were measured during the degradation process and showed total mineralization after about 5 h for the optimal Zn2+/MB+ condition.

The Effect of a Single Oral Morning Dose of Nizatidine and Ranitidine on Intragastric pH under Basal Conditions and after Pentagastrin Stimulation

1992 ◽  
Vol 20 (6) ◽  
pp. 454-460 ◽  
Author(s):  
M Lazzaroni ◽  
O Sangaletti ◽  
G Bianchi Porro
Keyword(s):  
Drug Administration ◽  
Inhibitory Action ◽  
Glass Electrode ◽  
Intragastric Ph ◽  
Morning Dose ◽  
Experimental Conditions ◽  
Duodenal Ulcers ◽  
Ph Values ◽  
Antisecretory Activity ◽  
Single Blind

A comparison was made of the antisecretory activity of orally administered nizatidine and ranitidine by measuring intragastric pH under basal conditions and during and after pentagastrin stimulation. Intragastric pH values were measured with a bipolar glass electrode in 10 patients with healed duodenal ulcers treated with nizatidine or ranitidine according to a randomized single-blind design. The antisecretory activity of the two drugs was similar during the 4 h of monitoring following drug administration. Nizatidine, however, showed a more rapid inhibitory action than ranitidine, producing a significantly greater increase in pH with respect to basal values during pentagastrin infusion. In the period following infusion the pH values observed with ranitidine were higher than with nizatidine, but not significantly so. Under these experimental conditions, therefore, the antisecretory activity of nizatidine was shown to be more rapid than that of ranitidine and equally effective.

Slip Factors of Centrifugal Slurry Pumps

1987 ◽  
Vol 109 (3) ◽  
pp. 313-318 ◽  
Author(s):  
K. K. Sheth ◽  
G. L. Morrison ◽  
W. W. Peng
Keyword(s):  
Flow Rate ◽  
Glass Bead ◽  
Power Flow ◽  
Mixture Density ◽  
Slip Factor ◽  
Friction Factors ◽  
Through Flow ◽  
Data Correlations ◽  
Power Measurements ◽  
Made In

Experiments have been carried out in order to determine the effects on slip factor due to the various parameters affecting the performance characteristics of a centrifugal slurry pump. The experiments were conducted with water, sand slurry, and a glass bead slurry at three different pump speeds. Measurements of power, flow rate, head developed by the pump and the density of the slurry were made in order to obtain the characteristic curves of the pump. Using Euler’s equation, equations were derived for calculating the slip and friction factors of the flow. The deduced slip factors for centrifugal slurry pump can be correlated well with suggested non dimensional groups. It shows a consistent trend of decreasing slip factor with increasing slurry mixture density and impeller rotation, or with a decreasing through flow rate. The sizes of the sand and glass bead particles are significantly different (0.71 mm versus 0.09 mm), however, the data correlations do not suggest its effect on the slip factors significantly as the other parameters. The slip factors deduced from head-flow rate curves are more reliable than those deduced from power-flow rate curves, since the shut-off power measurements are likely subjected to errors associated with the particles settling, or the transient effect if the measurements are taken momentarily.

scholarly journals Mechanism of the process of decomposition of apatitis with phosphoric acid

2019 ◽  
Vol 81 (1) ◽  
pp. 294-297
Author(s):  
R. F. Sabirov ◽  
A. F. Makhotkin ◽  
Yu. N. Sakharov ◽  
I. A. Makhotkin ◽  
I. Yu. Sakharov
Keyword(s):  
Phosphoric Acid ◽  
Ph Value ◽  
Batch Reactor ◽  
Experimental Studies ◽  
Hydrogen Ions ◽  
Experimental Conditions ◽  
Monocalcium Phosphate ◽  
Ph Values ◽  
Whole Process ◽  
Proportional Increase

Experimental studies of the kinetics and mechanism of the process, decomposition of apatite by phosphoric acid, in the Apatite-H3PO4-H2O system without the addition of sulfuric acid have been performed. The study of the decomposition process of Kovdorsky apatite with certain particle sizes was carried out in a batch reactor with a volume of 1 dm3 with stirring of the reaction mixture, and an initial concentration of phosphoric acid of 17% by weight, at a temperature of 78–82 °C. Observation of the process was carried out by determining the concentration of phosphoric acid and the concentration of monocalcium phosphate. The acidity of the reaction mixture was determined by the pH meter readings (pH-105 MA with a glass combined-ESC-10603 electrode). It was shown that during the whole process a constant smooth increase in the pH value of the reaction mixture to pH 6 occurs. Comparison of the pH values of the reaction mixture during the actual at the time of determining the concentration of phosphoric acid and pH of phosphoric acid of the corresponding concentration in the aqueous solution shows that the pH value of the reaction mixture is significantly affected by the presence of monocalcium phosphate gel. During the process, during the first thirty minutes, the concentration of phosphoric acid decreases from 17 to 10% by weight, the corresponding quantitative formation of monocalcium phosphate gel and a proportional increase in the pH of the reaction mixture. Then, as the concentration of phosphoric acid decreases, the process slows down and does not proceed to the end under the experimental conditions. The dependence of the concentration of hydrogen ions in the reaction mixture on the time of the process of decomposition of apatite in phosphoric acid, which is presented in logarithmic coordinates, shows that the mechanism of formation of hydrogen ions during the whole process does not change. Thus, it is shown that the process of decomposition of apatite by phosphoric acid in the Apatite-H3PO4-H2O system proceeds with the formation of an intermediate product - monocalcium phosphate gel. When this occurs, a corresponding significant change in the pH values of the reaction mixture occurs. During the whole process there is a constant decrease in the concentration of phosphoric acid.

scholarly journals Simultaneous electrochemical determination of acetaminophen and metoclopramide at electrochemically pre-treated disposable graphite pencil electrode

2016 ◽  
Vol 6 (3) ◽  
pp. 265 ◽  
Author(s):  
Shreekant M Patil ◽  
Vijay P Pattar ◽  
Sharanappa T Nandibewoor
Keyword(s):  
Simultaneous Determination ◽  
Differential Pulse ◽  
Electrochemical Determination ◽  
Experimental Conditions ◽  
Positive Direction ◽  
Oxidation Potentials ◽  
Voltammetric Behavior ◽  
Pulse Voltammetry ◽  
Apparent Shift

<p class="PaperAbstract"><span lang="EN-US">A sensitive and economic voltammetric method was developed for the simultaneous determination of acetaminophen (AMP) and metoclopramide (MCP) using pre-treated graphite pencil electrode (PTGPE). Compared to a graphite pencil electrode, the pre-treated electrode showed an apparent shift of the oxidation potentials in the positive direction and a notable enhancement in the current responses for both AMP and MCP. Cyclic voltammetry (CV) was used to study the voltammetric behavior of the drugs, while differential pulse voltammetry (DPV) was used to determine AMP and MCP simulta­neously. The dependence of the current on scan rate, pH and concentration was investi­gated to boost the experimental conditions for simultaneous determination. The calibra­tion curves were obtained over the range of 0.1</span><span lang="EN-US">×</span><span lang="EN-US">10<sup>-7</sup> to 1.1</span><span lang="EN-US">×</span><span lang="EN-US">10<sup>-7</sup> M, the concentration of each of both the drugs was varied by keeping the other constant, and achieved lower detection limit of 3.25 nM for AMP and 1.16 nM for MCP. The developed method was found to be selective and rapid for the simultaneous determination of AMP and MCP. The proposed method was applied simultaneously in real samples and pharmaceutical samples, with satisfactory results.</span></p>

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