Fig. 4
a Cr(VI) breakthrough curves and b calculated Cr(VI) removal efficiencies (%) in GRSO4 amended packed sand columns as function of different flow rate (0.25, 1 and 3 ml/min) at different inlet Cr(VI) concentrations (C0 = 0.125, 0.25, 0.5 and 1 mM; pH 7.0). BTCs (C/C0 vs PV) for the tracer test at different flow rates are identical