Rice hull
Rice hulls or husks are the hard protecting coverings of grains of
of the rice.Production
Rice
Winnowing, used to separate the rice from hulls, is to put the whole rice into a pan and throw it into the air while the wind blows. The light hulls are blown away while the heavy rice fall back into the pan. Later pestles and a simple machine called a rice pounder were developed to remove hulls. In 1885 the modern rice hulling machine was invented in Brazil. During the milling processes, the hulls are removed from the raw grain to reveal whole brown rice, which is then usually milled further to remove the bran layer, resulting in white rice.
Uses
Ash
Combustion of rice hulls affords rice husk ash (acronym RHA). This ash is a potential source of amorphous reactive
Rice husk ash has long been used in ceramic glazes in rice growing regions in the Far East, e.g. China and Japan.[2] Being about 95% silica, it is an easy way of introducing the necessary silica into the glaze, and the small particle size helps with an early melt of the glaze.[citation needed]
A number of possible uses for RHA include absorbents for oils and chemicals, soil ameliorants, a source of silicon, insulation powder in steel mills, as repellents in the form of "vinegar-tar" release agent in the ceramics industry, as an insulation material. More specialized applications include the use of this material as a catalyst support.[3]
Goodyear announced plans to use rice husk ash as a source for tire additive.[4][5]
Rice hulls are a low-cost material from which silicon carbide "whiskers" can be manufactured. The SiC whiskers are then used to reinforce ceramic cutting tools, increasing their strength tenfold.[6]
Tooth powder
In southern India, charred rice hull, known as Umikkari in Malayalam and Tamil, was traditionally used for cleaning teeth before the advent of toothpaste.[7]
Rice bran oil
Rice bran oil is the oil extracted from the hard outer brown layer of rice called chaff (rice husk). It is popular as a cooking oil in the Indian subcontinent and East Asian countries, including India, Nepal, Bangladesh, Indonesia, Japan, Southern China, and Malaysia.[citation needed]
Brewing
Rice hulls can be used in brewing beer to increase the lautering ability of a mash. Rice husk is also used in one step of traditional preparation processes of Kaoliang (Sorghum) liquid. After fermentation, rice husk can be added into the wine tank to increase the void, which is advantageous for distillation.[citation needed]
Fertilizer and substrate
Rice hulls can be
Rice hulls that are parboiled (PBH) are used as a substrate or medium for gardening, including certain
Fireworks
Rice hulls are coated with fine-grained gunpowder and used as the main bursting charge in aerial fireworks shells.[citation needed]
Fuel
With proper techniques, rice hulls can be burned and used to power steam engines. Some rice mills originally disposed of hulls in this way.[citation needed]
Unfortunately the direct combustion of rice hulls produces large quantities of smoke. An alternative is gasification. Rice hulls are easily gasified in top-lit updraft gasifiers. The combustion of this rice hull gas produces a blue flame, and rice hull biochar makes a good soil amendment.[10]
Traditional brickmaking
Juice extraction
Rice hulls are used as a "press aid" to improve extraction efficiency of apple pressing.[11]
Pet food fiber
Rice hulls are an inexpensive
Pillow stuffing
Rice hulls are used as pillow stuffing. The pillows are loosely stuffed and considered therapeutic as they retain the shape of the head.[citation needed]
Insulating material
Rice hulls themselves are a class A
]Particle boards and cardboard
Rice hulls are also used to make particle boards and cardboard. The silica in rice husk make the particle boards less attractive to termites.[14]
Geopolymers
Due to high amorphous silica content, the RHA (rice husk ash) can be used as a precursor material for geopolymer concrete.[15]
Rice concrete
To achieve the best
At a given water-cement ratio, the addition of small amounts of rice hull ash (2 to 3% of cement mass) may be useful to improve the workability of concrete mixtures by reducing the cement milk separation and segregation and increasing the strength and durability of concrete.[18] However, the introduction of large quantities of this additive may result in poor workability of the concrete mixture if strong water reducing additives are not used.[19]
See also
References
- ISBN 978-3-527-30385-4.
- ISBN 0873416600.
- ^ J. Chumee et al. "Characterization of platinum–iron catalysts supported on MCM-41 synthesized with rice husk silica and their performance for phenol hydroxylation" Sci. Technol. Adv. Mater. 9 (2008) 015006 free download
- ^ "Goodyear Converts Waste from Rice Harvest to Fuel-Efficient Tire Treads". Archived from the original on January 24, 2015. Retrieved February 9, 2015.
- ^ Goodyear Reaches Supply Agreements for Rice Husk Ash Silica (Online video) (YouTube). Goodyear Tire and Rubber Company. 2015-06-09. Retrieved 2016-05-26.
- ^ "SiC Whisker-Reinforced Ceramic Composites". Materials Science and Technology Division - Physical Sciences Directorate. Oak Ridge, TN, USA: Oak Ridge National Laboratory. Archived from the original on 2009-08-16. Retrieved 2013-06-06.
- ^ "ഉമിക്കരി ഉപയോഗിച്ച് പല്ല് തേക്കുന്നത് നല്ലതാണോ?". Samayam Malayalam (in Malayalam). Retrieved 2024-06-05.
- ^ a b Wallheimer, Brian (2010-10-25). "Rice hulls a sustainable drainage option for greenhouse growers". Purdue University. Retrieved 2012-08-30.
- ^ "Growstones ideal alternative to perlite, parboiled rice hulls". (e) Science News. 2011-12-04. Retrieved 2013-06-06.
- ^ Olivier, Paul; Hyman, Todd (2012-03-27). "Biomass Gasification and the Benefits of Biochar" (PDF). Engineering, Separation and Recycling LLC. Retrieved 2013-06-06.
- ^ "Press aids". Vincent Corp. Archived from the original on 2010-01-09.
- ^ "Ingredients to avoid". The Dog Food Project. Archived from the original on 2018-04-04. Retrieved 2013-06-04.
- ^ "Rice hulls in construction - Appropedia: The sustainability wiki". Appropedia. 2013-02-23. Retrieved 2014-02-23.
- ^ Coxworth, Ben (2015-05-28). "Rice husks may find use in cheaper, greener, longer-lasting particleboard". New Atlas. GIZMAG PTY LTD 2017. Retrieved 2017-12-04.
- S2CID 216202502.
- ^ "Effects of exposure to elevated temperatures on properties of concrete containing rice husk ash". researchgate.net. Retrieved 2022-10-10.
- PMID 30582051.
- ^ "Rice concrete: characteristics and composition". concretersmelbourne.net. 2022-03-05. Retrieved 2022-10-10.
- S2CID 247428142.
Bibliography
- Ma, Jian Feng; Kazunori Tamai; Naoki Yamaji; et al. (2006). "A silicon transporter in rice". Nature. 440 (7084): 688–691. S2CID 4330847.
- Mitani, Namiki; Jian Feng Ma; Takashi Iwashita (2005). "Identification of the silicon form in xylem sap of rice (Oryza sativa L.)". Plant Cell Physiol. 46 (2): 279–283. PMID 15695469.
- Mitani, Namiki; Jian Feng Ma (2005). "Uptake system of silicon in different plant species". J. Exp. Bot. 56 (414): 1255–1261. PMID 15753109.
External links
- The Rice Hull House where rice hulls are used for insulation
- Uses for rice husk ash, or RHA
- Rice hulls used in cutting tool industry