Purification of wet process phosphoric acid by decreasing iron and uranium using white silica sand.

Natural white silica sand as an adsorbent has been developed to reduce the concentration of iron and uranium ions as inorganic impurities in crude Egyptian phosphoric acid. Several parameters such as adsorbate concentration, adsorbent dose, volume to weight ratio and temperature, were investigated. Equilibrium isotherm studies were used to evaluate the maximum sorption capacity of adsorbent. Thermodynamic parameters showed the exothermic nature of the process and the negative entropy reflects the affinity of the adsorbent material towards each metal ion.

Effect of ionic strength on the adsorption of copper and chromium ions by vermiculite pure clay mineral.

It is important to assess the effects of ionic strength when studying adsorption of metal ions on clay mineral because the background salt may complex metals and compete for adsorption sites. The sorption behavior of vermiculite pure clay mineral has been studied with respect to copper and chromium as a function of ionic strength in single metal ion solutions. Background electrolytes used in these experiments were KCl, NaCl and NH4Cl. The studies were conducted by a batch method at temperature 25 degrees C. The adsorption capacity and adsorption energy for each metal ion were calculated from the Langmuir adsorption isotherm. Also the competitive adsorption behavior of some heavy metal ions such as Cr(III), Cu(II), Ni(II) and Co(II) by vermiculite pure clay mineral was studied. The result shows the competition between coexisting heavy metal cations for the same adsorption sites of an adsorbent. However, when trivalent metal was added to the solution it competitively replaced divalent ions that had been previously adsorbed onto the vermiculite pure clay mineral, resulting in the desorption of these metals into the solution.

Chromatographic separations and recovery of lead ions from a synthetic binary mixtures of some heavy metal using cation exchange resin.

A simple solid phase extraction procedure on cation exchange resin Purolite C100 is presented. The procedure based on a column technique for separation and recovery of lead ions from synthetic binary mixtures. Equilibrium distribution coefficient, k(d) for the different metal ions such as Al(III), Fe(III), Ba(II) and Pb(II) in the presence of nitric acid and ammonium acetate solutions of variable concentrations was determined at 25 degrees C. The values of separation factor, alpha were evaluated. Quantitative separation of lead ions from a synthetic binary mixtures are based on the fact that ammonium acetate is a good elute for lead ions but fails to elute the other cations.