Development of Nanoporous Inorganic Carbonates for Pharmaceutical and Environmental Applications

Abstract: Mesoporous magnesium carbonate (MMC) is a highly porous, anhydrous material which can be synthesized without the use of templates. This thesis shows how post- and in synthesis modification of MMC can create porous inorganic carbonates suitable for different pharmaceutical and environmental applications. Controlled release of IBU was achieved by loading IBU onto amine modified MMC (aMMC). The amine coverage was varied and there was a clear correlation between the release rate of IBU and the amine coverage, the higher the amine coverage the slower the release rate. aMMC was also used to load salicylic acid (SA). SA was then released within 15 minutes in a phosphate buffer (pH 6.8). The cytotoxicity of aMMC was evaluated and it was found non-toxic for human dermal fibroblast cells with particle concentration up to 1000 µg/mL for 48 h of exposure.  aMMC also showed a high adsorption capacity for three different types of anionic azo dyes;  acid red 183, amaranth and reactive black 5. The addition of amine groups to the surface of MMC significantly increased the uptake of the three dyes tested. Composite materials were synthesized by combining the synthesis of MMC and the synthesis of highly porous amorphous calcium carbonate. The calcium magnesium carbonate composite materials were evaluated for their CO2 sorption capacity (at 650 °C) and their CO2 cyclic stability. Addition of Al(NO3)3 to the best performing composite further improved its cyclic stability and the composite maintained a high CO2 uptake over 23 sorption/desorption cycles. Composite materials were also made by adding Al2O3 and SiO2 nanoparticles to the synthesis liquid of MMC.  This resulted in materials with Al2O3 and SiO2 incorporated into the porous MMC structure. The MMC materials with Al2O3 and SiO2 nanoparticles was then impregnated with Ni(NO3)2, calcined and used for catalytic conversion of syngas to natural gas. The material containing Al2O3 nanoparticles performed the best and had a CO conversion of close to 100% at 350°C as well as a high CH4 yield and selectivity.In this thesis porous inorganic carbonates have been developed and evaluated for their performance in different pharmaceutical and environmental applications.