The sorption of chromium(III) onto Haro river sand has been investigated as a function of sorptive solution composition, amounts
of sorbent (10–500 mg) and sorbate (4.33·10−8–5.17·10−6 M), shaking time (I-60 minutes) and temperature (15–35°C). Maximum sorption has been achieved from 0.001 M HCI solution using
50 mg of the sand and 20 minutes shaking time. The sorption data followed Freundlich and D-R isotherms. The sorption capacity
of 0.4 μmole·g−1 and of sorption energy of 9.9 kJ·mole−1 have been computed from D-R parameters. Thermodynamic parameters ΔH=84.4 kJ·mole−1, ΔS=284.5 J·mole−1·K−1 and ΔG=−3.32 kJ·mole−1 at 298 K have been evaluated. Fe(II), Al(III), citrate, borate, oxalate, tartrate and carbonate ions reduce the sorption
significantly. Under similar experimental conditions Tc(VII), Re(VII), Sb(V) and Co(II) have very low sorption (<1%) and trivalent
Eu and Sm have large distribution ratios. Haro river sand can be used to preconcentrate or to remove micro or submicro amounts
of Cr(III) from very dilute solution and for the separation of Tc, Re and Sb from Cr, Eu and Sm.