title: The role of counter ions in nano-hematite synthesis: Implications for surface area and selenium adsorption capacity.
abstract: Nano metal oxides are of interest for aqueous selenium (Se) remediation, and as such, nano-hematite (nα-Fe2O3) was examined for use as a Se adsorbent. The effect of surface area on adsorption was also studied. nα-Fe2O3 particles were synthesized from Fe(NO3)3 and FeCl3 via forced hydrolysis. The resulting particles have similar sizes, morphologies, aggregate size, pore size, and PZC. The nα-Fe2O3 from FeCl3 (nα-Fe2O3-C) differs from the nα-Fe2O3 from Fe(NO3)3 (nα-Fe2O3-N) with a ∼25±2m(2)/g greater surface area. Selenite Se(IV) adsorption capacity on nα-Fe2O3 has a qmax ∼17mg/g for the freeze-dried and re-suspended nα-Fe2O3. The Δqmax for nα-Fe2O3 from Fe(NO3)3 and FeCl3 that remained in suspension was 4.6mg/g. For selenate Se(VI), the freeze-dried and re-suspended particles realize a Δqmax= 1.5mg/g for nα-Fe2O3 from Fe(NO3)3 and FeCl3. The nα-Fe2O3 from Fe(NO3)3 and FeCl3 that remained in suspension demonstrated Se(VI) Δqmax=5.4mg/g. In situ ATR-FTIR isotherm measurements completed for Se(VI) at a pH 6 suggest that Se(VI) forms primarily outer-sphere complexes with nα-Fe2O3 synthesized from both salts.
authors.affiliation: Yale University, Department of Chemical and Environmental Engineering, Mason Lab, 9 Hillhouse Ave, New Haven, CT 06511, United States.
authors.forename: Amanda W
authors.initials: AW
authors.lastname: Lounsbury
authors.affiliation: Yale University, Department of Chemical and Environmental Engineering, Mason Lab, 9 Hillhouse Ave, New Haven, CT 06511, United States.
authors.forename: Jamila S
authors.initials: JS
authors.lastname: Yamani
authors.affiliation: University of Connecticut, Department of Civil and Environmental Engineering, Castleman Building, 261 Glenbrook Road, Storrs, CT 06269, United States.
authors.forename: Chad P
authors.initials: CP
authors.lastname: Johnston
authors.affiliation: Northeastern University, Department of Civil and Environmental Engineering, Snell Engineering Center, 360 Huntington Avenue, Boston, MA 02115, United States.
authors.forename: Philip
authors.initials: P
authors.lastname: Larese-Casanova
authors.affiliation: Yale University, Department of Chemical and Environmental Engineering, Mason Lab, 9 Hillhouse Ave, New Haven, CT 06511, United States; Yale University, School of Forestry and Environmental Studies, Kroon Hall, 195 Prospect St. New Haven, CT 06511, United States. Electronic address: julie.zimmerman@yale.edu.
authors.forename: Julie B
authors.initials: JB
authors.lastname: Zimmerman
keywords: Adsorption; Hematite; Iron oxide; Nanoparticles; Selenium