Detailed characterization of calcium silicate precipitation tube (CaSPT) as a multi-cation adsorbent in aqueous medium

Calcium silicate precipitation tube (CaSPT) produced through ‘silica garden’ route has been physico-chemically characterized as a multi-cation adsorbent in aqueous medium. Characterizations include phase identification, morphology, surface area, pore volume, iso-electric point and surface charge determination, thermogravimetric analysis, functional group identification and initial assessment as a multi-cation adsorbent. These tubes are hierarchically built from smaller interconnected tubes of about 20 nm diameter. Exterior and interior walls of the ‘as grown’ tubes, analyzed through SEM-EDAX, show different chemical composition. One of the prominent phases in ‘as grown’ tubes was identified as γ-Ca2SiO4. CaSPT has moderately high surface area. Iso-electric point (IEP) at pH 3.41 indicates the surface is suitable for adsorbing cationic species. Initial adsorption studies corroborate that CaSPT is a promising adsorbent for Cu(II), Cd(II), Zn(II), Pb(II) and Cr(III). CaSPT as an adsorbent is superior to conventional non tubular calcium silicate.