title: Magnetic orientation of nontronite clay in aqueous dispersions and its effect on water diffusion.
abstract: The diffusion rate of water in dilute clay dispersions depends on particle concentration, size, shape, aggregation and water-particle interactions. As nontronite clay particles magnetically align parallel to the magnetic field, directional self-diffusion anisotropy can be created within such dispersion. Here we study water diffusion in exfoliated nontronite clay dispersions by diffusion NMR and time-dependant 1H-NMR-imaging profiles. The dispersion clay concentration was varied between 0.3 and 0.7 vol%. After magnetic alignment of the clay particles in these dispersions a maximum difference of 20% was measured between the parallel and perpendicular self-diffusion coefficients in the dispersion with 0.7 vol% clay. A method was developed to measure water diffusion within the dispersion in the absence of a magnetic field (random clay orientation) as this is not possible with standard diffusion NMR. However, no significant difference in self-diffusion coefficient between random and aligned dispersions could be observed.
authors.affiliation: Applied Surface Chemistry, Department of Chemical and Biological Engineering, Chalmers University of Technology, Kemivägen 10, 412 96 Gothenburg, Sweden; SuMo Biomaterials, VINN Excellence Centre, Chalmers University of Technology, 412 96 Gothenburg, Sweden. Electronic address: abrahamc@chalmers.se.
authors.forename: Christoffer
authors.initials: C
authors.lastname: Abrahamsson
authors.affiliation: Applied Surface Chemistry, Department of Chemical and Biological Engineering, Chalmers University of Technology, Kemivägen 10, 412 96 Gothenburg, Sweden.
authors.forename: Lars
authors.initials: L
authors.lastname: Nordstierna
authors.affiliation: German Cancer Research Center, Medical Physics in Radiology, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany.
authors.forename: Matias
authors.initials: M
authors.lastname: Nordin
authors.affiliation: Department of Chemistry, KTH Royal Institute of Technology, Teknikringen 30, 100 44 Stockholm, Sweden; Laboratory of Biomolecular NMR, St. Petersburg State University, St. Petersburg 199034, Russia.
authors.forename: Sergey V
authors.initials: SV
authors.lastname: Dvinskikh
authors.affiliation: Ian Wark Research Institute, University of South Australia, Mawson Lakes Campus, Mawson Lakes, SA 5095, Australia.
authors.forename: Magnus
authors.initials: M
authors.lastname: Nydén
mesh_terms: D000538:Aluminum Silicates / Q000737:chemistry*; D000077215:Clay; D004058:Diffusion; D008280:Magnetics; D066244:Proton Magnetic Resonance Spectroscopy; D014867:Water / Q000737:chemistry*
chemical_list: D000538:Aluminum Silicates; D014867:Water; D000077215:Clay
keywords: Anisotropic microstructure; Bound water; Diffusion; Diffusion NMR; Exfoliated clay; Magnetic alignment; NMR 1D imaging; Nontronite clay; Permeability