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Rice hulls

January 09, 2023

Rice hulls (or rice husks) are the hard protecting coverings of grains of rice. In addition to protecting rice during the growing season, rice hulls can be put to use as building material, fertilizer, insulation material, or fuel. Rice hulls are part of the chaff of the rice.

Rice husk

Production

Rice hulls are part of the rice seed. The hull protects the grain during the growing season from pests. The hull is formed from hard materials, including opaline silica and lignin. The hull is hard to eat or swallow (unless finely ground) and mostly indigestible to humans because of its enriched fibre components. However, during times of food scarcity in ancient China, a common daily meal was a pastry made from rice husks, wild vegetables, and soybean powder. This led to the idiom "meals of cereal, hulls, and vegetables for half a year," indicating poverty and food insecurity.[citation needed] Testing and commercialization of human grade anti-caking agents were done in the early 2000s. The material is approved for use in USDA Certified Organic products to replace silicon dioxide.

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

 
The temples of the Batujaya Archaeological Site in Indonesia (5th century AD) were built with bricks containing rice hulls.

Ash

Combustion of rice hulls affords rice husk ash (acronym RHA). This ash is a potential source of amorphous reactive silica, which has a variety of applications in materials science. Most of the ash is used in the production of Portland cement.[1] When burnt completely, the ash can have a Blaine number of as much as 3,600 compared to the Blaine number of cement (between 2,800 and 3,000), meaning it is finer than cement. Silica is the basic component of sand, which is used with cement for plastering and concreting. This fine silica will provide a very compact concrete. The ash also is a very good thermal insulation material. The fineness of the ash also makes it a very good candidate for sealing fine cracks in civil structures, where it can penetrate deeper than the conventional cement sand mixture.

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.

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]

Toothpaste

In Tamilnadu & Kerala, India, charcoal from Rice husks (Umikari in Tamil & Malayalam) were majorly used for over centuries in cleaning teeth, before toothpaste replaced it.

Rice bran oil

Main article: 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.

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.

Fertilizer and substrate

Rice hulls can be composted, but their high lignin content can make this a slow process. Sometimes earthworms are used to accelerate the process. Using vermicomposting techniques, hulls can be converted to fertilizer in about four months.

Rice hulls that are parboiled (PBH) are used as a substrate or medium for gardening, including certain hydrocultures. The hulls decay over time. Rice hulls allow drainage,[7] and retain less water than growstones.[8] It has been shown that rice hulls do not affect plant growth regulation.[7]

Fireworks

Rice hulls are coated with fine-grained gunpowder and used as the main bursting charge in aerial fireworks shells.

Fuel

 
Rice hulls can be pressed into logs for use in cooking fires instead of wood

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.[9]

Rice chaff being put to a brickmaking kiln in Mekong delta

Traditional brickmaking kilns in Mekong Delta are using rice hulls as fuel.

Juice extraction

Rice hulls are used as a "press aid" to improve extraction efficiency of apple pressing.[10]

Pet food fiber

Rice hulls are an inexpensive byproduct of human food processing, serving as a source of fiber that is considered a filler ingredient in pet foods.[11]

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.

Insulating material

Rice hulls themselves are a class A thermal insulating material because they are difficult to burn and less likely to allow moisture to propagate mold or fungi.[12] It is also used as roofing after mixing it with mud and water.

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.[13]

Geopolymers

Due to high amorphous silica content, the RHA (rice husk ash) can be used as a precursor material for geopolymer concrete.[14]

Rice concrete

To achieve the best pozzolanic properties the combustion of the husks has to be carefully controlled by keeping the temperature below 700°C and to create conditions to minimize carbon formation by feeding sufficient air.[15][16] 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.[17] 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.[18]

See also

References

  1. ^ Otto W. Flörke, et al. "Silica" in Ullmann's Encyclopedia of Industrial Chemistry, 2008, Weinheim: Wiley-VCH, . doi:10.1002/14356007.a23_583.pub3.
  2. ^ Tichane, Robert (1998). Ash Glazes. Krause Publications. ISBN 0873416600.
  3. ^ 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
  4. ^ . Archived from the original on January 24, 2015. Retrieved February 9, 2015.
  5. ^ Goodyear Reaches Supply Agreements for Rice Husk Ash Silica (Online video) (YouTube). Goodyear Tire and Rubber Company. 2015-06-09. Retrieved 2016-05-26.
  6. ^ . 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.
  7. ^ a b Wallheimer, Brian (October 25, 2010). "Rice hulls a sustainable drainage option for greenhouse growers". Purdue University. Retrieved August 30, 2012.
  8. ^ "Growstones ideal alternative to perlite, parboiled rice hulls". (e) Science News. 2011-12-04. Retrieved 2013-06-06.
  9. ^ Olivier, Paul; Hyman, Todd (2012-03-27). "Biomass Gasification and the Benefits of Biochar" (PDF). Engineering, Separation and Recycling LLC. Retrieved 2013-06-06.
  10. ^ Press aids
  11. ^ "Ingredients to avoid". The Dog Food Project. Retrieved 2013-06-04.
  12. ^ "Rice hulls in construction - Appropedia: The sustainability wiki". Appropedia. 2013-02-23. Retrieved 2014-02-23.
  13. ^ Coxworth, Ben (28 May 2015). "Rice husks may find use in cheaper, greener, longer-lasting particleboard". New Atlas. GIZMAG PTY LTD 2017. Retrieved 4 December 2017.
  14. ^ Das, Shaswat Kumar; Mishra, Jyotirmoy; Singh, Saurabh Kumar; Mustakim, Syed Mohammed; Patel, Alok; Das, Sitansu Kumar; Behera, Umakanta (29 March 2020). "Characterization and utilization of rice husk ash (RHA) in fly ash – Blast furnace slag based geopolymer concrete for sustainable future". Materials Today: Proceedings. 33: 5162–5167. doi:10.1016/j.matpr.2020.02.870. S2CID 216202502.
  15. ^ "Effects of exposure to elevated temperatures on properties of concrete containing rice husk ash". researchgate.net. Retrieved 2022-10-10.
  16. ^ Umasabor, R. I.; Okovido, J. O. (2018). "Fire resistance evaluation of rice husk ash concrete". Heliyon. 4 (12): e01035. doi:10.1016/j.heliyon.2018.e01035. PMC 6299146. PMID 30582051.
  17. ^ "Rice concrete: characteristics and composition". concretersmelbourne.net. 5 March 2022. Retrieved 2022-10-10.
  18. ^ Al-Gburi, Majid; Yusuf, Salim A. (2022). "Investigation of the effect of mineral additives on concrete strength using ANN". Asian Journal of Civil Engineering. 23 (3): 405–414. doi:10.1007/s42107-022-00431-1. S2CID 247428142. Retrieved 2022-10-10.
  • Ma, Jian Feng; Kazunori Tamai; Naoki Yamaji; Namiki Mitani; Saeko Konishi; Maki Katsuhara; Masaji Ishiguro; Yoshiko Murata; Masahiro Yano (2006). "A silicon transporter in rice". Nature. 440 (7084): 688–691. Bibcode:2006Natur.440..688M. doi:10.1038/nature04590. PMID 16572174. 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. doi:10.1093/pcp/pci018. PMID 15695469.
  • Mitani, Namiki; Jian Feng Ma (2005). "Uptake system of silicon in different plant species". J. Exp. Bot. 56 (414): 1255–1261. CiteSeerX 10.1.1.543.3168. doi:10.1093/jxb/eri121. PMID 15753109.

External links

  • The Rice Hull House where rice hulls are used for insulation
  • Uses for rice husk ash, or RHA

January 09, 2023
rice, hulls, rice, husks, hard, protecting, coverings, grains, rice, addition, protecting, rice, during, growing, season, rice, hulls, building, material, fertilizer, insulation, material, fuel, part, chaff, rice, rice, husk, contents, production, uses, toothp. Rice hulls or rice husks are the hard protecting coverings of grains of rice In addition to protecting rice during the growing season rice hulls can be put to use as building material fertilizer insulation material or fuel Rice hulls are part of the chaff of the rice Rice husk Contents 1 Production 2 Uses 2 1 Ash 2 2 Toothpaste 2 3 Rice bran oil 2 4 Brewing 2 5 Fertilizer and substrate 2 6 Fireworks 2 7 Fuel 2 8 Juice extraction 2 9 Pet food fiber 2 10 Pillow stuffing 2 11 Insulating material 2 12 Particle boards and cardboard 2 13 Geopolymers 2 14 Rice concrete 3 See also 4 References 5 External linksProduction EditRice hulls are part of the rice seed The hull protects the grain during the growing season from pests The hull is formed from hard materials including opaline silica and lignin The hull is hard to eat or swallow unless finely ground and mostly indigestible to humans because of its enriched fibre components However during times of food scarcity in ancient China a common daily meal was a pastry made from rice husks wild vegetables and soybean powder This led to the idiom meals of cereal hulls and vegetables for half a year indicating poverty and food insecurity citation needed Testing and commercialization of human grade anti caking agents were done in the early 2000s The material is approved for use in USDA Certified Organic products to replace silicon dioxide 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 Edit The temples of the Batujaya Archaeological Site in Indonesia 5th century AD were built with bricks containing rice hulls Ash Edit Combustion of rice hulls affords rice husk ash acronym RHA This ash is a potential source of amorphous reactive silica which has a variety of applications in materials science Most of the ash is used in the production of Portland cement 1 When burnt completely the ash can have a Blaine number of as much as 3 600 compared to the Blaine number of cement between 2 800 and 3 000 meaning it is finer than cement Silica is the basic component of sand which is used with cement for plastering and concreting This fine silica will provide a very compact concrete The ash also is a very good thermal insulation material The fineness of the ash also makes it a very good candidate for sealing fine cracks in civil structures where it can penetrate deeper than the conventional cement sand mixture 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 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 Toothpaste Edit In Tamilnadu amp Kerala India charcoal from Rice husks Umikari in Tamil amp Malayalam were majorly used for over centuries in cleaning teeth before toothpaste replaced it Rice bran oil Edit Main article 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 Brewing Edit 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 Fertilizer and substrate Edit Rice hulls can be composted but their high lignin content can make this a slow process Sometimes earthworms are used to accelerate the process Using vermicomposting techniques hulls can be converted to fertilizer in about four months Rice hulls that are parboiled PBH are used as a substrate or medium for gardening including certain hydrocultures The hulls decay over time Rice hulls allow drainage 7 and retain less water than growstones 8 It has been shown that rice hulls do not affect plant growth regulation 7 Fireworks Edit Rice hulls are coated with fine grained gunpowder and used as the main bursting charge in aerial fireworks shells Fuel Edit Rice hulls can be pressed into logs for use in cooking fires instead of wood 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 9 source source source source source source source source source source source source source source source Rice chaff being put to a brickmaking kiln in Mekong delta Traditional brickmaking kilns in Mekong Delta are using rice hulls as fuel Juice extraction Edit Rice hulls are used as a press aid to improve extraction efficiency of apple pressing 10 Pet food fiber Edit Rice hulls are an inexpensive byproduct of human food processing serving as a source of fiber that is considered a filler ingredient in pet foods 11 Pillow stuffing Edit Rice hulls are used as pillow stuffing The pillows are loosely stuffed and considered therapeutic as they retain the shape of the head Insulating material Edit Rice hulls themselves are a class A thermal insulating material because they are difficult to burn and less likely to allow moisture to propagate mold or fungi 12 It is also used as roofing after mixing it with mud and water Particle boards and cardboard Edit Rice hulls are also used to make particle boards and cardboard The silica in rice husk make the particle boards less attractive to termites 13 Geopolymers Edit Due to high amorphous silica content the RHA rice husk ash can be used as a precursor material for geopolymer concrete 14 Rice concrete Edit To achieve the best pozzolanic properties the combustion of the husks has to be carefully controlled by keeping the temperature below 700 C and to create conditions to minimize carbon formation by feeding sufficient air 15 16 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 17 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 18 See also EditRice hull bagwall construction Winnowing barnReferences Edit Otto W Florke et al Silica in Ullmann s Encyclopedia of Industrial Chemistry 2008 Weinheim Wiley VCH doi 10 1002 14356007 a23 583 pub3 Tichane Robert 1998 Ash Glazes Krause Publications 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 a b Wallheimer Brian October 25 2010 Rice hulls a sustainable drainage option for greenhouse growers Purdue University Retrieved August 30 2012 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 Ingredients to avoid The Dog Food Project Retrieved 2013 06 04 Rice hulls in construction Appropedia The sustainability wiki Appropedia 2013 02 23 Retrieved 2014 02 23 Coxworth Ben 28 May 2015 Rice husks may find use in cheaper greener longer lasting particleboard New Atlas GIZMAG PTY LTD 2017 Retrieved 4 December 2017 Das Shaswat Kumar Mishra Jyotirmoy Singh Saurabh Kumar Mustakim Syed Mohammed Patel Alok Das Sitansu Kumar Behera Umakanta 29 March 2020 Characterization and utilization of rice husk ash RHA in fly ash Blast furnace slag based geopolymer concrete for sustainable future Materials Today Proceedings 33 5162 5167 doi 10 1016 j matpr 2020 02 870 S2CID 216202502 Effects of exposure to elevated temperatures on properties of concrete containing rice husk ash researchgate net Retrieved 2022 10 10 Umasabor R I Okovido J O 2018 Fire resistance evaluation of rice husk ash concrete Heliyon 4 12 e01035 doi 10 1016 j heliyon 2018 e01035 PMC 6299146 PMID 30582051 Rice concrete characteristics and composition concretersmelbourne net 5 March 2022 Retrieved 2022 10 10 Al Gburi Majid Yusuf Salim A 2022 Investigation of the effect of mineral additives on concrete strength using ANN Asian Journal of Civil Engineering 23 3 405 414 doi 10 1007 s42107 022 00431 1 S2CID 247428142 Retrieved 2022 10 10 Ma Jian Feng Kazunori Tamai Naoki Yamaji Namiki Mitani Saeko Konishi Maki Katsuhara Masaji Ishiguro Yoshiko Murata Masahiro Yano 2006 A silicon transporter in rice Nature 440 7084 688 691 Bibcode 2006Natur 440 688M doi 10 1038 nature04590 PMID 16572174 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 doi 10 1093 pcp pci018 PMID 15695469 Mitani Namiki Jian Feng Ma 2005 Uptake system of silicon in different plant species J Exp Bot 56 414 1255 1261 CiteSeerX 10 1 1 543 3168 doi 10 1093 jxb eri121 PMID 15753109 External links EditThe Rice Hull House where rice hulls are used for insulation Uses for rice husk ash or RHA Rice hulls used in cutting tool industry Retrieved from https en wikipedia org w index php title Rice hulls amp oldid 1131503204 Ash, wikipedia, wiki, book, books, library,

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