The trays, on their holders, were manually transferred to a freezer at -20 °C overnight and then to a Labconco vacuum cabinet attached to a freeze drier. The metal shelves of the cabinet were covered with open cell polymer foam to insulate the trays from the shelves and prevent thawing of the samples during drying. Each liquid aliquot dried to form a porous disc with a flat-bottomed face. This bottom face will subsequently be used for XRD analysis.