Chemical activation of vermiculite to produce highly efficient material for Pb2 + and Cd2 + removal

• Vermiculite was chemically activated by leaching with HCl or H2O2 solution.
• The expansibility factor was 2.5 and 14.83 for HCl and H2O2 activated samples.
• H2O2 activated sample showed high removal efficiency for Pb2 + and Cd2 + ions.
• The entry of Cd2 + or Pb2 + into V samples increases their thermal stability.

In this study vermiculite from Egypt was chemically activated by leaching with 0.5 M HCl solution or by treatment with 30% H2O2 solution. SEM and X-ray results showed that leaching of vermiculite with HCl solution results in partial transformation of its ordered layer structure into delaminated structure while its treatment with H2O2 solution results in high separation and fragmentation of the layers with no structure change. The expansibility factor, k was measured on the base of the changes in the internal layer space of raw and activated vermiculite and it was found to be 2.5 and 14.83 for samples activated by HCl and H2O2, respectively. As indicated from DSC tests, the chemically activated vermiculite treated with Cd2 + or Pb2 + ions showed higher thermal stability than that of raw vermiculite treated with the same ions. The removal efficiency of peroxide activated vermiculite was higher than that of the acid activated vermiculite for both cadmium and lead ions.