Zinc oxide is an inorganic compound with the formula ZnO. It usually appears as a white powder, bigger than 150 nano meters, nearly insoluble in water and is widely used as an additive into numerous materials and products including plastics, ceramics, glasses, cement, rubber, lubricants, paints, oiniments, adhesives, sealants, pigments, foods as a source of Zn nutrient, batteries, ferrites, fire retardants, first aid tapes, exhibits anti-bacterial properties and is useful for pharmaceutical applications, etc.
It is well known that nanomaterials have very high surface area than the same mass of materials at the micro-scale. At nano scale, quantum effects are more predominant in determining the properties and characteristics of the material. This has led to the development of novel materials with distinctly different properties compared to their conventional forms. There are many interesting techniques and applications that are achievable with nanomaterials.
Nano Zinc oxide
The major difference between Nano and micro / fine Zinc Oxide powders is the level of opacity.Nano particle size powders are completely translucent and leave an invisible UV barrier and hence are used in sunscreen and unblock, lipstick, anti-bacterial lotions, rubber emulsions, UV stabiliser in plastics and as a catalyst in the chemical Industry.
Nano Zinc oxide synthesis
According to literature, nano zinc oxide can be prepared by direct precipitation method with zinc chloride (98% purity) and sodium carbonate (99.8% purity) anhydrous as raw materials.They are dissolved in water respectively and then sodium carbonate solution is dropped into zinc chloride solution which results in precipitation. The reaction is conducted at 60 deg C, under ultrasonic vibration and aged for several hours. In order to remove salt, as-burnt powders are filtered, then rinsed with distilled water and ethanol (99.7% purity). Finally the precursor is dried in oven at 80 deg C for 4 hours, and thermally treated for 3 hours at 450 deg C to obtain nano ZnO.
Aqueous dispersion
A stabilised aqueous dispersion of particulate zinc oxide comprises water, a stabilising agent and zinc oxide, the particles of which are coated with dense amorphous silica. Useful stabilising agents include cellulose ethers which contain quaternary ammonium groups and polyalkylene glycols. The dispersions have excellent stability at high concentrations of zinc oxide and are useful for preparing sunscreen formulations, cosmetics, sunblocks and veterinary products.