(89b) Synthesis of Surface Functionalized Adsorbents for Adsorption of Metal Ions and Organic Pollutants By Atomic Layer Deposition (Invited)
Different thicknesses of TiO2 and Al2O3 films were applied on micron-sized silica gel particles and biochars by atomic layer deposition (ALD), respectively. TiO2 coated silica gel particles were used as adsorbents for adsorption of metal and metalloid ions; their adsorption ability for a mixture of 19 trace elements of heavy metals and other toxic elements, including As(V), Se (IV), Be(II), Al(III), V(V), Cr(III), Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Ba(II), Tl(I), Sb(III), Cd(II), Ag(I), Sr(II), Mo (VI), and Pb(II), from aqueous solutions was investigated. The removal efficiencies of As(V), Se(IV), V(V), Mo(VI), and Pb(II) were higher than 75% simultaneously in the mixed solution at pH 3 for 20 and 40 cycles of TiO2 coated silica gel particles without heat treatment. In contrast, the uncoated silica gel particles did not adsorb any ions under this pH condition. Al2O3 deposited biochars were used for removal of organic pollutants and the adsorption capacities were evaluated by adsorption of methylene blue (MB). The data fit well with the Langmuir isotherm and the maximum adsorption capacities were found to be 26.8 and 35.0 mg/g at 25 ºC for the uncoated biochar and 5 cycles Al2O3 (5Al) coated biochar, respectively. The adsorbed MB amount per square meter achieved 1.3 mg/m2 onto the 5Al biochar, and it was twice the amount on the uncoated biochar. The improvement of adsorption capacity after Al2O3 ALD coating was due to its improved hydrophilia.