Fig. 6
a Cr(VI) immobilization efficiency by S-nZVI and GRSO4 (0.25 mM [Cr(VI)in]). A control experiment with no added reducing agent is also shown. Each measurement represents one batch reaction (note that x-axis is not linear). b Cr(VI) breakthrough curves in S-nZVI (triangles) and GRSO4 (circles) amended sand columns as a function of flow rates: 0.25, 1 and 3 ml/min ([(Cr(VI)0] = 0.25 mM and pH 7.0). The black dotted lines mark the breakthrough (C/C0 = 0.05) and exhaustion (C/C0 = 0.9) points on each curve. BTCs (C/C0 vs PV) for the tracer test at different flow rates are identical