Application of biosurfactant surfactin on copper ion removal from sand surfaces with continuous flushing technique

The potential of using the biosurfactant surfactin to remove adsorbed metal ions from sand surfaces with continuous flushing approaches was evaluated. With the surfactin solution flushing approach, low removal efficiency of 2-15% for copper ions was detected due to the contact of surfactin with copper ions occurring mainly in the inter-particle pore region. The channeling effect also contributed to the low removal efficiency. By incorporating foam in the flushing operation, the contact of surfactin with copper ions was enhanced due to reduced channeling effect. More copper ions with outer-sphere interaction type were thus available and the removal efficiency was increased. Increasing the surfactin concentration could increase the dynamic foaming capacity and lead to improved removal efficiency of 40%. The results demonstrated that the foam-enhanced solution flushing approach was efficient with a low usage of surfactin.