Clays: Colloidal Properties in Nanodomain

Abstract

The ever-growing application of clays in nanotechnology rests on fundamental principles of colloid chemistry. They make soils as nature’s great electrostatic chemical reactor. Highly anisotropic and often irregular particle shape, broad particle size distribution, different types of charges within the unit cells, heterogeneity of layer charges, pronounced CEC, dis-articulation and flexibility of layers, and different modes of aggregation make clays different from other colloidal materials. Their inseparable association with the genesis of life on Earth and evolutionary diversification of Neoproterozoic life is a safety-belt of nanotechnology.Nanotechnology promises to be the greatest technological breakthrough in history, doing for our control of matter what computers did for our control of information. The origins of nanoscience can be traced to clay mineralogy and crystallography when it was discovered that clay minerals were crystalline and of micrometer size. The unit cell dimensions of clay minerals are in nanometer scale in all three axes (x, y, and z). The advantages of clays are: (i) their ordered arrangements, (ii) their large adsorption capacity, (iii) their shielding against sunlight (ultraviolet radiation), (iv) their ability to concentrate organic chemicals, and (v) their ability to serve as polymerization templates. Clays protected organic matter from reoxygenation during the late Precambrian period, allowing a corresponding quantity of O2 to accumulate in the environment. The inseparable association of clays with lifeforms makes them most desirable in manufacturing nanoparticles. Clays have been extensively used in industry, but as concern for environmental sustainability grows, clay minerals find new takers from all conceivable forms of industries. Nanotechnology literature is flooded with clay-polymers for their possible use in high strength material manufacturing, for ecological life support system, removal of contaminants from water and wastes, and as catalysts in chemical reactions to reduce energy consumption.