title: Arsenate uptake by Al nanoclusters and other Al-based sorbents during water treatment.
abstract: In many parts of the world, arsenic from geogenic and anthropogenic sources deteriorates the quality of drinking water resources. Effective methods of arsenic removal include adsorption and coagulation with iron- and aluminum-based materials, of which polyaluminum chloride is widely employed as coagulant in water treatment due to its low cost and high efficiency. We compared the arsenic uptake capacity and the arsenic bonding sites of different Al-based sorbents, including Al nanoclusters, polyaluminum chloride, polyaluminum granulate, and gibbsite. Extended X-ray absorption fine structure (EXAFS) spectroscopy revealed that As(V) forms bidentate-binuclear complexes in interaction with all Al-based removal agents. The octahedral configuration of nanoclusters and the distribution of sorption sites remain the same in all types of removal agents consisting of nano-scale Al oxyhydroxide particles. The obtained distances for As(V)-O and As(V)-Al agreed with previously published data and were found to be 1.69 ± 0.02 Å and 3.17-3.21 Å, respectively. Our study suggests that As(V) binds to Al nanoclusters as strongly as to Al oxide surfaces. The As sorption capacity of Al nanoclusters was found to be very similar to that of Al clusters in a polyaluminum chloride. The most efficient Al-based sorbents for arsenic removal were Al nanoclusters, followed by polyaluminum granulate.
authors.affiliation: Institute of Biogeochemistry and Pollutant Dynamics (IBP), ETH Zürich, Universitätstrasse 16, 8092 Zürich, Switzerland; Eawag, Swiss Federal Institute of Aquatic Science and Technology, Überlandstrasse 133, 8600 Dübendorf, Switzerland. Electronic address: jasmin.mertens@env.ethz.ch.
authors.forename: Jasmin
authors.initials: J
authors.lastname: Mertens
authors.affiliation: CNRS, Aix-Marseille University, CEREGE, UMR 7330 (FR ECCOREV), 13545 Aix-en-Provence, Cedex 4, France; International Consortium for the Environmental Implications of Nanotechnology iCEINT, CNRS (France) - Duke University, NC, USA.
authors.forename: Jérôme
authors.initials: J
authors.lastname: Rose
authors.affiliation: Institute of Biogeochemistry and Pollutant Dynamics (IBP), ETH Zürich, Universitätstrasse 16, 8092 Zürich, Switzerland; Eawag, Swiss Federal Institute of Aquatic Science and Technology, Überlandstrasse 133, 8600 Dübendorf, Switzerland.
authors.forename: Bernhard
authors.initials: B
authors.lastname: Wehrli
authors.affiliation: Institute of Biogeochemistry and Pollutant Dynamics (IBP), ETH Zürich, Universitätstrasse 16, 8092 Zürich, Switzerland.
authors.forename: Gerhard
authors.initials: G
authors.lastname: Furrer
mesh_terms: D000327:Adsorption; D017607:Aluminum Compounds / Q000737:chemistry*; D001149:Arsenates / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D018508:Water Purification / Q000379:methods*; D056928:X-Ray Absorption Spectroscopy
chemical_list: D017607:Aluminum Compounds; D001149:Arsenates; D014874:Water Pollutants, Chemical
keywords: Al(13); Al(30); Arsenic; EXAFS; Sorption sites; Water treatment