Nanoclay

Nanoclay is one of the most affordable materials that have shown promising results in polymers. Nanoclay is made from montmorillonite mineral deposits known to have “platelet” structure with average dimension of 1 nm thick and 70 to 150nm wide.

Qualities

Montmorillonite clays possess several qualities that make them an excellent base for manipulation through nanotechnology. These qualities include stability, an interlayer space, high hydration and swelling capacity and a high chemical reactivity.

Clay characterization

Clays and their modified organic derivatives can be characterized using simple as well as modern tools which include determination of chemical compositions by gravimetric analysis, inductively coupled plasma (ICP) or XRF, cation exchange capacity (CEC) using standard ammonium acetate method, surface area measurement, Fourier transform infrared spectroscopy (FT-IR), powdered X-ray diffraction (PXRD) and others.The clays are also characterized by their cation exchange capacities, which can vary widely and depends on source and type of clay. The purity of the clay can affect the final nanocomposite properties; due to this it is very important to have montmorillonite with minimum impurities of crystalline silica (quartz), amorphous silica, calcite, kaolin etc. The technique mainly used for purification of clays includes hydrocyclone, centrifugation, sedimentation method and chemical treatment.

Nanoclay uses

Clays are inexpensive materials, which can be modified by ion exchange, metal/metal complex impregnation, pillaring and acid treatment to develop catalysts with desired functionality. Nanoclays are known to enhance properties of many polymers such as nylon 6, EVA, epoxy, PET, PE and PP leading to better clarity, stiffness, thermal stability, barrier properties to moisture, solvents, vapors, gases and flavors; reduced static cling and UV transmission in film and bottles; improved chemical, flame, scratch resistance, and dimensional stability in injection molded products. Plastic molded parts exhibit higher heat distortion temperatures, and better appearance when painted. Nanomer® and Cloisite® are the popular nanoclays available in the market. Nanomer® is a nanoclay product developed by Nanocor/AMCOL International Corporation, and Cloisite® nanoclays are produced by Southern Clay Products, Inc., of Texas, USA.According to a US Patent by Nanocor, the know-how of uniform dispersion of nanoclay (0.5 to 10% level) in polyolefins to produce concentrates that can be used in nanocomposites is claimed. The nanoclay dispersion is used to improve modulus and tensile strength, barrier properties, flame resistance, and thermal and structural properties of many plastics to extend their reach into areas dominated by metal, glass and wood.

Mycotoxin binder

Researchers at Olmix in France have developed a technique where the ulvans (a polysaccharide) contained in seaweed are used as pillars to increase the interlayer space of the montmorillonite clay by 10 times. This increase in the interlayer space allows even the larger-sized mycotoxins to enter, providing protection to the animal. This new product is called Amadite and has been patented worldwide.Research trials performed by the independent laboratory TNO in the Netherlands have shown the efficacy of nanoclay as a wide-spectrum mycotoxin binder. The binding ability of the nanoclay to the mycotoxins was maintained as the product passed through the stomach and small intestine. Studies showed that the new product reduced the level of DON (1 part per million) by 40% compared to control and of fumonisin B1 (2 ppm) by 50-60% when compared to control. Low inclusion rates of 1 kg per ton were used to obtain these adsorption levels, which add to the practical and economic usefulness of the product. In addition, the trials showed the inability of the nanoclay to adsorb carbohydrates, proteins and water-soluble vitamins, a concern with the use of other clay products.

Rheological modifier

Nanoclays made of synthetic layered silicates such as laponite, hectorite and saponite have been used as rheological modifiers in paints, inks, greases and cosmetics. Organoclays obtained by interaction of these layered silicates with ammonium or phosphonium salts act as thixotropic agent in the above applications. A small addition of nanoclays can greatly enhance the rheological properties of the paint system. These properties prevent pigment settling and sagging on vertical surfaces and gloss is minimally affected due to the low levels of addition. Thermal stability of grease is greatly enhanced by the addition of small amount of organoclays. Nanoclays provide colour retention as well as good coverage in cosmetics and inks. The organic binds to the ionic surfaces of layered silicates and converts it from a hydrophilic form to an oil wet, a hydrocarbon adsorbent material, ideal for water treatment applications.

Adsorption applications

When used for water treatment, organoclays are commonly utilized in the upstream sector of the petroleum industry for removing hydrocarbons from refinery process water, but it has seen little use in petroleum production. Organoclays have also been tested for treating ground and surface water and for other toxic organic chemicals from pharmaceuticals and pesticides industries. Organoclays can offer dramatic performance improvements in many other adsorption applications, including removing oil, grease, heavy metals, and polychlorinated biphenyl; organic matter, such as humic and fulvic acids; polynuclear and polycyclic aromatics; and sparingly soluble hydrophobic, chlorinated organics. Removing radionuclides, including pertechnetate, from water is another application with tremendous potential.

Drug vehicle

Nanoclays are potentially useful materials in the field of controlled release of therapeutic agent to patients, where it acts as a drug vehicle. MMT could adsorb dietary toxins, bacterial toxins associated with gastrointestinal disturbance, hydrogen ions in acidosis, and metabolic toxins such as steroidal metabolites associated with pregnancy. All these conditions result in a host of common symptoms, including nausea, vomiting and diarrhea, most of which are typical symptoms of the side effects caused by anticancer drugs.