Nanoscale zero-valent iron@mesoporous hydrated silica core-shell particles with enhanced dispersibility, transportability and degradation of chlorinated aliphatic hydrocarbons

Nanoscale zero-valent iron@mesoporous hydrated silica core-shell particles (NZVI@mHS CSP) with improved dispersibility, transportability and dechlorination strength were successfully synthesized and tested for the removal of chlorinated aliphatic hydrocarbons from groundwater. The structural, electronic and textural features of the NZVI@mHS CSP were characterized by different techniques. The NZVI@mHS CSP depicted a specific surface area of 71 m(2).g(-1), significantly higher, compare to NZVI (12 m(2).g(-1)), with a mesoporous network due to the formation of a hydrated silica shell surrounding the NZVI particle. NZVI@mHS CSP showed an enhanced transportability in sand column compared with NZVI, related to the suspension stability, small aggregated particle size (< 1.3 mu m) and negative particle charge (- 12.11 mV) at neutral pH. NZVI@mHS CSP achieved higher degradation rates than NZVI for the dechlorination of 1,1,1-TCA in synthetic solution and CAHs in real groundwater samples. The dechlorination pathway of 1,1,1-trichloroethane was studied in detail, revealing the formation of 1,1-dichloroethane, ethylene and ethane as the main products. The results of this study prove the ability of NZVI@mHS CSP to transport through a sand column and degrade CAHs pollutants present in real groundwater.