|
|||||
|
|
Arsenic sorption on TiO2 nanoparticles: Size and crystallinity effects |
|
| Authors: | Gautham Jegadeesan Souhail R. Al-Abed Vijayakumar Sundaram Kirk G. Scheckel |
| Affiliation: | a Gradient Corporation, 20, University Road, Cambridge, MA 02138, USA b Pegasus Technical Services, Inc, 46, E. Hollister Street, Cincinnati, OH 45221, USA c National Risk Management Research Laboratory, U.S. Environmental Protection Agency, 26 W. Martin Luther King Dr., Cincinnati, OH 45268, USA d ECO: LOGIC Engineering, 3875, Atherton Road, Rocklin, CA 95765, USA e Department of Civil and Environmental Engineering, University of Cincinnati, Cincinnati, OH 45221, USA |
| Abstract: | Single solute As (III) and As (V) sorption on nano-sized amorphous and crystalline TiO2 was investigated to determine: size and crystallinity effects on arsenic sorption capacities, possible As (III) oxidation, and the nature of surface complexes. Amorphous and crystalline nanoparticles were prepared using sol-gel synthesis techniques. For amorphous TiO2, solute pH in the range of 4-9 had a profound impact on only As (V) sorption. As (III) and As (V) sorption isotherms indicated that sorption capacities of the different TiO2 polymorphs were dependent on the sorption site density, surface area (particle size) and crystalline structure. When normalized to surface area, As (III) surface coverage on the TiO2 surface remained almost constant for particles between 5 and 20 nm. However, As (V) surface coverage increased with the degree of crystallinity. X-ray absorption spectroscopic analysis provided evidence of partial As (III) oxidation on amorphous TiO2 rather than crystalline TiO2. The data also indicated that As (III) and As (V) form binuclear bidentate inner-sphere complexes with amorphous TiO2 at neutral pH. |
| Keywords: | Arsenic TiO2 Speciation |
| 本文献已被 ScienceDirect 等数据库收录！ | |