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Potentiality of white sand for the purification of wet process phosphoric acid from some metallic elements (U, Zn, Cd)

Mohamed F.Cheira, Ibrahium H.Zidan, Elsayd A.Manaa

The potentiality of applying white sand for the purification of wet process phosphoric acid via adsorption of metallic impurities has batchwise been studied across U(VI), Zn(II) and Cd(II). Besides representing a low cost procedure for acid purification fromhazardousmetals, possible recovery of the adsorbed uranium would represent an important added value. The relevant adsorption factors are studied together with both the corresponding thermodynamic characteristics and equilibrium isotherms. From the latter, the Langmuir isotherm was found to be better in interpreting the obtained data. Thus, the theoretical capacities estimated for the studied metal cations U(VI), Zn(II) and Cd(II) uponAbu Zeneima white sand have been found to attain 0.87, 2.23 and 0.14 mg/g while the practical capacities at the studied optimum conditions have attained 0.44, 1.59 and 0.11 mg/g respectively. The thermodynamic parameters have shown that the exothermic nature of the study system due to the obtained negative enthalpy (ÄH) whereas the negative entropy (ÄS) reflects the affinity of the white sand towards the studied metal cations.