Modification of Nanoclays for Crude Oil Absorption and Heat Storage Applications

The object of this research is studying the modification method and applications of nanoclays. The primary unit of MMT is comprised by layered stacks, and contains 8 to 10 sheets per stack. The dimension of nature clay, for example, montmorillonite (MMT) with layered structure is 1 x 100 x 100 nm3 for each sheet. There are large amounts of cations existing in clay layers, such as sodium ions, magnesium ions, calcium ions, and aluminum ions. The cationic exchange capacity of MMT is 1.2 mequiv./g. Hence, the MMT can be modified by acidifying organic ammonium salts and exchanging with sodium ions. After the organic ammonium salts intercalation, the d spacing of MMT could be expanded from 12 Å to 52 Å or to 74 Å. The organic intercalation would introduce the hydrophobic characteristic into clay layers and make the modified MMT has hydrophobic affinity which can absorb organic materials into clay spacing. In this case, the d spacing of intercalated MMT could be further expanded. Thus, the hydrophobic affinity and layered expandable characteristics make organoclay could be used as an organo-container to absorb and store organic materials. In this research, the organic modified MMT was treated as an organo-container to absorb crude oil and paraffin. For the crude oil absorption, the organoclay was intercalated by poly(oxyalkylene) amines. To compare with mono-amine or di-amine with different molecular weight, the highest crude oil absorption efficiency is the organoclay which was intercalated by mono-amine and the efficacy is up to 15 folds weight over organoclay. Except for the high absorption efficiency, there is another unique characteristic, lower critical solubility temperature (LCST) of these organoclays. The poly(oxyalkylene) ammonium salts intercalated organoclay could be homogeneously dispersed with crude oil and water under lower temperature, and aggregated into lumps and clearly separated from water phase that the crude oil could be removed easily. Furthermore, we used n-Octadecyl amine (ODA) to modify MMT and used to absorb crude oil. The absorption efficiency of ODA/MMT is 6 folds over organoclay. The ODA/MMT would be self-aggregated after absorbing crude oil and clearly separated from water phase under ambient temperature. The most important thing is that the ODA/MMT could be recovered from toluene extraction which the crude oil can be removed without destroying the structure of ODA/MMT. The ODA/MMT could be reused for several times with stably performance and the recovery was up to 90%. Thus, the ODA/MMT can be used as an environment friendly materials to remedy the water contaminant. In the third section, we used ODA/MMT as a heat storage organo-container. The ODA/MMT was used to absorb octadecane, a kind of phase change material (PCM). The absorption efficiency is 5.6 folds over organoclay when using 1.0 CEC intercalated ODA/MMT. The phase transition temperature of octadecane is about 25－29 °C, and the shape of octadecane could be fixed when absorbing by ODA/MMT. Moreover, the enthalpy transition of ODA/MMT/Paraffin reaches to 100%. Hence, the ODA modified organoclay is an excellent organo-container which can be used as a heat storing material.