(679d) Atomic Layer Deposition Surface Functionalized Adsorbents for Adsorption of Metal Ions and Organic Pollutants

Ultrathin TiO₂ and Al₂O₃ films were deposited on 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. At pH 5, the 20 and 40 cycles of TiO₂ coated samples without heat treatment removed remarkable amount of As(V), Se(IV), V(V), Mo(VI), Pb(II), Sb(III), Ag(I), Cu (II), and Ba(II) from the solution simultaneously. The micron-sized adsorbent particles were separated easily from water due to their large particle size, making it practically suitable for trace contaminant remediation in water. 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 of Al₂O₃ coated biochar, respectively. The improvement of adsorption capacity after Al₂O₃ ALD coating was due to its improved hydrophilia.