The Mechanism of Alkali Metal Ion Sorption by Iron(III) Phosphate

Abstract

Alkali metal ion exchange (Li+, Na' and K') on irontlll) phosphate (FeP0 4) was studied potentiometricaIly as a function of temperature and metal ion concentration. The uptake behaviourof iron(llI) phosphate was inferred from a comparison of the K' ions sorbed and the loss of H' ions from the exchanger. Ff-IR spectroscopicstudiesand dissolutionstudiesof FeP0 4 confirmed the uptake mechanism of alkali metal cations as cation exchange. The potentiometric titrationdata were employedto evaluatethe apparentdissociationconstants of iron(lII) phosphate which were found to depend on the temperature of the system. The corresponding thermodynamic parameters i\Ho and i\So were also evaluated.

Sorption of divalent metal ions on CrPO4

“…The surface Cr/P molar ratio in the sample determined by the electron probe microanalysis method was observed to be 1.05, which is in accordance with the observations reported elsewhere [16].…”

“…The surface area of CrPO 4 was measured by the nitrogen adsorption method [15], using a surface area and pore size analyzer, Model ST-O3. The methods used for characterization were the same as reported earlier [16,17].…”

Iron phosphate as a novel sorbent for selective adsorption of chromium(iii) and chromium speciation with detection by ETAAS

“…The cation retention on iron phosphate has been previously reported to follow ion exchange mechanisms. 24,25 In order to elucidate the interaction mechanism of the present system, the effect of ionic strength on the adsorption of 5 mg L À1 Cr(III) by iron phosphate at pH 5.9 is carefully investigated. The experimental results show that when regulating the K + concentration in the sample solution within a wide range (0-900 mg L À1 ), Cr(III) adsorption efficiency remains at ca.…”

“…22,23 Iron phosphate can uptake alkali metal and divalent metal cations via cation exchange mechanism. 24,25 A fluoridized iron phosphate has been recently reported for the selective adsorption of specific protein species from human whole blood. 26 The unique local structures of iron phosphate have the potential for the adsorption of various species of environmental significance.…”

Structure, morphology, size and application of iron phosphate

“…Mustafa and Naeem et al studied the adsorption performance of iron phosphate on alkali metals (Li + , Na + , K + ), alkaline earth metals (Ca 2+ , Mg 2+ ) and divalent metal cations (Zn 2+ , Cu 2+ , Ni 2+ , Co 2+ ) [84][85][86][87][88]. They consider that the adsorption mechanism is related to the ion exchange between protons on the surface of iron phosphate and metal cations in the solution.…”