This medium allocation proposal aims to continue our on-going research efforts enabled by previous allocations SNIC 2018/3-454, SNIC 2017/1-369 and SNIC 2016/1-375, investigating the molecular organization and mobility of small inorganic solutes and organics in zeolites and sheet silicate interlayers (i.e. in lamellar pores between 1nm thick clay layers). Zeolite and smectite silicate clays have nanoporous structures and an extremely high surface area, enabling intercalation of large quantities of molecular substances leading to nanomaterials with novel and/or improved properties.
Using primarily molecular dynamics simulations we will study adsorption and interaction behavior of these nanoporous minerals with a range of inorganic and organic molecules, using methods developed during our previous (and ongoing) work of similarly hydrated systems, such as calculation of theoretical XRD diffractograms, vibrational powerspectra as well as free energy perturbation and umbrella sampling methods, see:
Holmboe+Bourg, J. Phys. Chem. C 2014, 118, 1001−1013
Tinnacher+Holmboe et al, 2016 Geo. et Cosm. Acta 177 (2016) 130–149
Tournassat+Holmboe et al, 2016, Clays and Clay Min. 64, 4, 374–388
Hellrup+Holmboe et al, Langmuir 2016, 32, 13214−13225
Holmboe et al., Langmuir 2016, 32, 12732−12740
Yang+Holmboe, Journal of Chem. Phys. 2017, 147, 084705
Yeşilbaş+Holmboe+Boily, ACS Earth Space Chem. 2018, 2, 38−47
Yeşilbaş+Holmboe+Boily, Residence times of nanoconfined CO 2 in layered aluminosilicates
Deconvolution of Smectite Hydration Isotherms, Jerry Lindholm, Jean-François Boily, and Michael Holmboe*, under review in ACS Earth and Space Chemistry.
Michael Holmboe, atom: A Matlab package for manipulation of molecular systems, submitted in Aug 2019 to special edition of Clay Minerals, Teaching Clay Science.
Our group at Umeå University have implemented two clay-specific forcefields, Clayff (Cygan, 2004) and the charmm-like INTERFACE ff (Heinz, 2005, 2013) for Gromacs. As an initial benchmarking study, we are studying i) smectite solvation (of clay surfaces + counter-cations) of pure alcohol and mixed water/alcohol mixtures, to find the dependence on clay basal spacings versus loading, to aid interpretation of experimental XRD diffraction data on the corresponding systems.
In a new project, we are using MD to study interactions of different aminoacids with zeolites, in the context of organic-N-fertilizers, in a new collaboration with the SLU start-up Arevo (www.arevo.se) and Prof. Torgny Näsholm.
In yet another project, we also collaborate with US researchers on uranykcomplex diffusion through compacted Bentnite clay, as highlighted in the national press: