Synthesis and characterization of Fe(II)-silicate precipitation tube (FeIISPT) as a heavy metal adsorbent and its comparison with Fe(III)-silicate precipitation tube (FeIIISPT)

Micron sized Fe(II)-silicate precipitation tube (FeIISPT) synthesized through 'silica garden' route has been characterized by different analytical techniques. These tubes are hollow, porous and hierarchially built from smaller tubules of 5-10 nm diameter. Morphology and chemical composition at the interior and exterior surface of these tubes differ remarkably. FeIISPT comprises significant amount of physically and chemically bound moisture. The isoelectric point of FeIISPT may be observed at pH 4.01 indicating the surface bearing surplus negative sites. FeIISPT appears to be a potential adsorbent of Hg(II), Zn(II), Pb(II) and Cd(II). Physico-chemical properties of FeIISPT have been compared with FeIIISPT.