Extraction of palladium from nitric acid medium by commercial resins with phosphinic acid,methylene thiol and isothiouronium moieties attached to polystyrene-divinylbenzene |
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Authors: | K A Venkatesan B Robert Selvan M P Antony T G Srinivasan P R Vasudeva Rao |
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Institution: | (1) Fuel Chemistry Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, India;(2) Fuel Chemistry Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, India;(3) Fuel Chemistry Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, India;(4) Fuel Chemistry Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, India;(5) Fuel Chemistry Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, India |
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Abstract: | Summary Commercially available polystyrene-divinylbenzene (PS-DVB) resins functionalized with isothiouronium (Tulsion CH-95), phosphinic
acid (Tulsion CH-96) and methylene thiol (Tulsion CH-97) moieties have been used for separating palladium from nitric acid
medium. Extraction of palladium has been studied as a function of time, concentration of nitric acid and palladium. The distribution
coefficients (Kd, ml/g) of palladium on sulfur based resins (Tulsion CH-95 and Tulsion CH-97) are higher (5000-104ml/g in 0.1M nitric acid) than on Tulsion CH-96 resin and decrease with increasing concentration of nitric acid. The initial
rate of extraction of palladium by Tulsion CH-95 and Tulsion CH-97 resins was very rapid and the time required for the establishment
of equilibrium was a function of palladium concentration in the aqueous phase. The rate data could be fitted by a second order
rate equation and the magnitude of rate constant for the extraction of palladium by these resins (~102M-1. min-1) decreased in the order of: Tulsion CH-95 > Tulsion CH-97 > Tulsion CH-96. The extraction isotherms of Tulsion CH-95 were
fitted by Langmuir adsorption model and the coefficients were obtained by regression. The extraction capacity of palladium
on Tulsion CH-95 was found to be ~20 mg/g at 3M nitric acid. Column experiments have been conducted and the data were fitted
using Thomas model. A column utilization of 75% was achieved for the extraction of palladium by Tulsion CH-95 resin. |
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