Green hybrid zeolite coatings for on-orbit molecular decontamination

Abstract FAU-type and MFI-type green hybrid zeolite coatings were developed for on-orbit molecular decontamination application by using a mixture of an organic binder (silicone resin) and an inorganic binder (suspension of colloidal silica nanoparticles). The zeolite content in the final dry coatings varies from 80 to 85 wt % whereas the total amount of binders varies from 15 to 20 wt %. This amount of binder was sufficient to give the zeolite coating interesting adhesion and cohesion properties. In fact, by using an equal amount of each binder, homogeneous films without significant cracks were obtained on an aluminum alloy substrate which is the main constituent of satellites. Nitrogen adsorption-desorption measurements revealed almost no loss of micropore volume of zeolite coatings. Adsorption experiments of an organic pollutant were carried out using n-hexane as probe molecule. The n-hexane adsorption capacities of FAU-type hybrid zeolite coatings (136–143 mg/ganhydrous zeolite) are lower than that of pure FAU-type zeolite (180 mg/ganhydrous zeolite) due to water co-adsorption. The n-hexane adsorption capacities of MFI-type zeolite coatings (103–106 mg/ganhydrous zeolite) are similar to that of pure MFI-type zeolite (110 mg/ganhydrous zeolite).