Rice Hull Ash as Metal Polish

Abstract

In rice-producing countries, one of the byproducts of rice is its hull which is obtained from the rice milling process. Its agricultural use ranges from being cattle and swine feed component, fertilizer and gardening medium. Moreover, it is used as an energy source for small applications and as steel and concrete additive. However, it is also regarded as waste and when not properly utilized, may impose threat to the environment. The end product of rice hull used in energy applications is rice hull ash which has no commercial value and whose disposal may cause environmental pollution and health problems. This research investigated the potential use of rice hull as metal polish. The rice hulls were washed with water to eliminate dust and dried at room temperature for one day. The hulls were then put under uncontrolled combustion at low temperature for an hour and was further heated to a higher temperature for an hour. The rice hulls combusted in an open area yielded black carbonized ash while the hulls that were subjected to higher temperature resulted in white ash. Part of the resulting ashes of both conditions was ground finely while the rest remained coarse. All setups of ash were tested on different metals such as aluminium, copper, and stainless steel. It was observed that the rust and tarnish in all setups were removed through rubbing after which a shining or polishing effect on the metals was observed. The findings indicate that rice hull has the greatest amount of silica among all plant materials. Its silica ranges from 15-20%. Silica in rice hull ash is a common material in metal polish due to its hardness and abrasive properties (Mohs 6).