Mineral surfaces

Task 2 – Selection, preparation and characterization of the minerals surfaces

Task leaders Frédéric Villiéras and Laurent Michot
Participants LIEC LRS PhENIx LGL

Objectives

Provide a set of relevant well-characterized mineral surfaces either magnesium- or iron-rich with well-controlled surface properties.

Description of work

  • The first objective of task 2 is to collect natural minerals available in collections or commercially and to perform the synthesis of the pure synthetic ones with controlled crystal-chemistry and shape. The next step consists in mineralogical purification of natural samples to remove accessory minerals in order to obtain nearly pure clay phases. When necessary, separation between different particle sizes will be performed to obtain sets of calibrated particles.
  • The analysis of crystal-chemistry then consists in XRD, chemical analyses, infrared, SEM, TEM, solid state NMR and thermal analysis (all task 2 partners) of purified and synthetic samples. For the well-known samples such as saponite and nontronite, the analyses will be limited to check for the representativity of the obtained batches. For the new samples, a complete characterization of the sample is planned and includes most of the above mentioned analyses in order to link crystal-chemistry and surface properties.
  • Surface properties will be performed with XPS and NAP-XPS (Tempo beamline at SOLEIL) to obtain qualitative and quantitative information on surface chemistry, with AFM and high-resolution gas adsorption to derive particle-shape as implemented by the DIS method developed at LIEC, and wiht CEC and Zetametry to get complementary information on particle charge and surface properties in aqueous conditions.

Role of participants

F. Villiéras and L. Michot: task leaders
M. Jaber: Synthesis of saponites and ferrous talcs
T. Georgelin: Synthesis of iron oxides, oxyhydroxides and sulfides
R. Gley : Purification and preparation of size selected clay minerals, CEC and chemical analyses
M. Pelletier: Gas adsorption experiments, surface characterization
I. Bihannic: structural properties and crystal chemistry, XRD
A. Razafitianamaharavo: Gas adsorption and AFM experiments.

Risks and contingency plan

Extremely limited
One difficulty could be the characterization by gas adsorption, classical and high-resolution methods for solids with low specific surface area. The use of complementary microscopic methods such as AFM or TEM methods should allow to obtain the information.

Deliverables / milestones

D2.1 – a series of reference minerals for further use in tasks 35
D2.2 – list of reference minerals, quantities, synthesis protocol
D2.3 – structural and physico-chemical properties of the referenced minerals, open access
M2.1 – full characterization of referenced minerals already available (m6)
M2.2 – full characterization of additional natural and synthesized minerals (m12)
M2.3 – characterization of the surface properties of hydrothermal chimneys (m18)