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In situ EXAFS study of Sr adsorption on TiO2(110) under high ionic strength wastewater conditions

DOI: 10.3390/min11121386 DOI Help

Authors: Arjen Van Veelen (University of Manchester; Los Alamos National Laboratory) , Paul C. M. Francisco (Hokkaido University) , Nicholas Edwards (University of Manchester) , J. Frederick W. Mosselmans (Diamond Light Source) , Tsutomu Sato (Hokkaido University) , Roy A. Wogelius (University of Manchester)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Minerals , VOL 11

State: Published (Approved)
Published: December 2021
Diamond Proposal Number(s): 4940

Open Access Open Access

Abstract: In order to provide important details concerning the adsorption reactions of Sr, batch reactions and a set of both ex situ and in situ Grazing Incidence X-ray Absorption Fine Structure (GIXAFS) adsorption experiments were completed on powdered TiO2 and on rutile(110), both reacted with either SrCl2 or SrCO3 solutions. TiO2 sorption capacity for strontium (Sr) ranges from 550 ppm (SrCl2 solutions, second order kinetics) to 1400 ppm (SrCO3 solutions, first order kinetics), respectively, and is rapid. Sr adsorption decreased as a function of chloride concentration but significantly increased as carbonate concentrations increased. In the presence of carbonate, the ability of TiO2 to remove Sr from the solution increases by a factor of ~4 due to rapid epitaxial surface precipitation of an SrCO3 thin film, which registers itself on the rutile(110) surface as a strontianite-like phase (d-spacing 2.8 Å). Extended X-ray Absorption Fine Structure (EXAFS) results suggest the initial attachment is via tetradental inner-sphere Sr adsorption. Moreover, adsorbates from concentrated SrCl2 solutions contain carbonate and hydroxyl species, which results in both inner- and outer-sphere adsorbates and explains the reduced Sr adsorption in these systems. These results not only provide new insights into Sr kinetics and adsorption on TiO2 but also provide valuable information concerning potential improvements in effluent water treatment models and are pertinent in developing treatment methods for rutile-coated structural materials within nuclear power plants.

Journal Keywords: rutile; Sr; in situ; EXAFS; tetradental; high ionic strength wastewater

Subject Areas: Materials, Chemistry, Environment

Instruments: I18-Microfocus Spectroscopy

Added On: 14/12/2021 09:54


Discipline Tags:

Desertification & Pollution Earth Sciences & Environment Radioactive Materials Physical Chemistry Chemistry Materials Science Nuclear Waste Inorganic Chemistry

Technical Tags:

Spectroscopy X-ray Absorption Spectroscopy (XAS) Extended X-ray Absorption Fine Structure (EXAFS)