3.3. Cr(VI) removal evaluation
Foam samples were subjected to column tests to determine their
Cr(VI) adsorption efficiency under realistic water treatment conditions.
Each experimental cycle lasted more than a month in order to collect
statistically significant results concerning residual Cr(VI) concentrations
at various pH values. It is worth noting that during this long-term procedure
there were no indications that the reducing efficiency of the
Cu-foam decreased. This is explained by the corrosion mechanism
occurring during reduction of Cr(VI) oxyanions (CrO4
2−) by Cu, which
results in the gradual dissolution of Cu2+ into the treated water and
the regeneration of metal's surface with zero-valent copper. Under
these conditions, the mechanism of Cr(VI) immobilization potentially
proceeds through the adsorption onto the freshly-formed Cu0 sites.