• Bulletin of the Korean Chemical Society
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• v.22 no.6
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• pp.559-564
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• 2001

A method for calculating the main characteristics of a potentiometric titration curve in a carboxylic ion exchanger has been investigated. The potentiometric titration curves of simple electrolyte and ion exchangers (polyelectrolytes) showed a great difference between them. The acidity parameters of the ion exchangers, the thermodynamic constant (pK0), apparent equilibrium constant (K), and correction for the apparent equilibrium constant (b), were introduced and used to express the characteristics of the carboxylic ion exchanger. A characteristic equation related to the acidity parameters of the ion exchangers systems was derived. A fibrous carboxylic cation exchanger was used and potentiometric titration curves at different concentrations of the supporting electrolyte were obtained . To prove the validity of the characteristic equation, the concentration of the supporting electroyte was varied. In the present study, good agreement between the data points and the fitted curves was found in all the cases. The g (number of moles of alkali to 1 g of ion exchanger) of carboxylic ion exchanger was calculated from the concentration of supporting electrolyte (C), pH of the solution, and degree of neutralization of ion exchanger (x).

• Applied Chemistry for Engineering
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• v.10 no.7
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• pp.969-973
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• 1999

In this work, we studied the degree of hydrolysis of ion exchanger in $NH_4OH$ solution and sorption characteristics of $NH_3$ by potentiometric titration curves with using carboxylic acid ion exchanger Fiban K-4. We knew that the theoretical pH values agreed with the experimental pH values on the $NH_4OH$ concentrations in various concentrations of supporting electrolyte $(NH_4)_2SO_4$. The sorption values of $NH_3$ using the ion exchanger can be calculated from equivalent sorption curves for various pH. Also, the degree of hydrolysis increased with decreasing concentration of supporting electrolyte and pH. In order to obtain the mono ion form below 0.01 M as the decreasing concentration of supporting electrolyte, the pH values should be increased. From these results, therefore, the concentrations of supporting electrolyte and pH values were determined.

• YAKHAK HOEJI
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• v.46 no.5
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• pp.320-323
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• 2002

A method for the determination of acidic drug, mefenamic acid and ibuprofen with ion-selective electrode(ISE) using Fe(II)-di-2-pyridyl ketone oxime complex as a counter ion were developed. Benzyl-2-nitrophenyl ether(BNPE) plasticized membrane was more selective and sensitive than the other tested membranes. The acidic drug selective electrode exhibits a linear response for 10$^{-2}$ M 510$^{-5}$ M of acidic drugs, mefenamic acid and ibuprofen with a slope of -55.9 and -56.3 mV/dec. in borate buffer solution (pH 8.9). Potentiometric selectivity measurements revealed negligible interferences from aromatic and aliphatic carboxylic acid salts. The electrodes were found to be useful for the direct determination of mefenamic acid and ibuprofen in pharmaceutical preparations.

• Resources Recycling
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• v.2 no.4
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• pp.27-32
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• 1993

A process has been studied to recover gallium from steelmaking dust which had several hundreds ppm of gallium. Aqueous solution containing 38 mg/l gallium was obtained by leaching of dust with 2.25 mol/l sulfuric acid. The leach liquor contained iron and zinc about 1,000 times greater than gallium. Gallium was then concentrated by ion exchanger of chelating resin with functional group of amino carboxylic acid after reduction of ferric ion to ferrous ion and pH adjustment. Gallium was concentrated to be 13 g/l in the resulting eluate by double ion exchanges. The liquor was further treated to remove impurities by solvent extraction technique empolying TOMAC as extractant. The galluim with 99% purity was finally obtainable.

• Analytical Science and Technology
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• v.14 no.1
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• pp.59-63
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• 2001

A PVC membrane electrodes based on Fe(II)-dipyridyl-mefenamic acid ternary complex as ion exchanger were prepared using o-nitrophenyl octyl ether as a plasticizer. The 2,2'-dipyridyl, 4,4'-dipyridyl and 4,4'-dipyridyl-2,2'-dipyridyl were used as dipyridyl derivative ligand. The electrode dxhibits a fast stable and linear response for $10^{-5}-10^{-3}mol/L$ mefenamate with an anionic slope of -55.98, -49.47, -59.35mV/decade in pH 8.9 borate buffer solution respectively. Potentiometric selectivity measurements revealed negligible interferences from aromatic and aliphatic carboxylic acid salts.