Environmentally Benign Reuse of Agricultural Wastes to Prepare High-Purity Silica from Rice Husks

Umeda, Junko; Kondoh, Katsuyoshi; Michiura, Yoshisada

doi:https://doi.org/10.18910/9539

Environmentally Benign Reuse of Agricultural Wastes to Prepare High-Purity Silica from Rice Husks

Umeda, Junko; Kondoh, Katsuyoshi; Michiura, Yoshisada

Transactions of JWRI, 2007, 36(2), 17-21

Number of Access:587（2025-08-29 01:39 Counts）

Identifier to cite or link to this item: https://doi.org/10.18910/9539

Link to primary information

File	Format	Terms of use	Size	Views	Date.Available	Description	information
jwri36_02_017	pdf	None	690 KB	238	2012.09.22

Item Information

Output File Export EndNote Basic Export Mendeley

Title	Environmentally Benign Reuse of Agricultural Wastes to Prepare High-Purity Silica from Rice Husks
Creator	NRID 1000050345162 1000050345162 researchmap permalink umeda umeda Scopus Author ID 23478776500 23478776500 ORCID 0000-0001-8678-9708 0000-0001-8678-9708 CreatorName Umeda, Junko ; ウメダ, ジュンコ
	NRID 1000050345138 1000050345138 researchmap permalink kondoh kondoh Scopus Author ID 9942942300 9942942300 CreatorName Kondoh, Katsuyoshi ; コンドウ, カツヨシ
	CreatorName Michiura, Yoshisada ; ミチウラ, ヨシサダ
Subject	Rice Husk
	Silica
	Carboxylic Acid Leaching
	Hydrolysis
	Optimization Parameters
Abstract	Rice husk, one of main agricultural wastes in South-east Asia countries, is well known as renewable resource to produce both energy and high-purity silica (SiO₂), because it consists of 70% organics and 20% amorphous SiO₂. The conventional process of recovering silica originating from rice husks requires a leaching treatment by strong acid solutions, such as sulfuric acid (H₂SO₄), hydrochloric acid (HCl) and nitric acid (HNO₃), to remove metallic impurities from the rice husks before combustion. The use of these acid solutions, however, is hazardous to the environment and human life, and difficult for process-cost-saving in mass-production due to expensive and complicated disposal systems. In this study, an environmentally benign, harmless to human as well as economical process to produce high-purity amorphous SiO₂ powder originating from rice husks has been established without using strong acids. From the viewpoint of a harmless influence on human body, carboxylic acids such as a citric acid or oxalic acid are employed in the acid leaching treatment of rice husks. In this alkali impurities are effectively removed from husks via a chelate reaction between carboxyl (-COOH) and alkali elements. In the experiment, first of all, it was shown that the carboxylic acid leaching was effective in promoting the hydrolysis of organics by DTA and GCMS. From experimental results on the optimization of concentration and temperature of the carboxylic acid solution by DTA, XRF and ICP analysis, it was found that a concentration of 5% or more was enough to both increase SiO₂ purity over 99% and remarkably reduce alkali metal impurities in the rice husk ashes. Amorphous SiO₂ powder originating from rice husks has a porous structure, so that it was also easy to control its particle size by dry milling or a grinding process.
Publisher	大阪大学接合科学研究所
	オオサカダイガクセツゴウカガクケンキュウジョ
	Joining and Welding Research Institute, Osaka University
Source Title	Transactions of JWRI
Volume (Issue)	36(2)
Page	17-21
Date of Issued	2007-12
Language	English
Handle URL	https://hdl.handle.net/11094/9539
DOI	https://doi.org/10.18910/9539
PISSN	03874508
NCID	AA00867058
Access Rights	open access
oaire:version	Version of Record
Category	紀要論文 Departmental Bulletin Paper
Category	Transactions of JWRI / Vol.36 No.2 (2007-12)

Resource Type	departmental bulletin paper
Local Type	Departmental Bulletin Paper
DCMI Type	Text
DCTERMS.bibliographicCitation	Transactions of JWRI. 2007, 36(2), p. 17-21
DC.title	Environmentally Benign Reuse of Agricultural Wastes to Prepare High-Purity Silica from Rice Husks
DC.creator	Umeda, Junko
	ウメダ, ジュンコ
	Kondoh, Katsuyoshi
	コンドウ, カツヨシ
	Michiura, Yoshisada
	ミチウラ, ヨシサダ
DC.publisher	大阪大学接合科学研究所
	オオサカダイガクセツゴウカガクケンキュウジョ
	Joining and Welding Research Institute, Osaka University
DC.language' scheme='DCTERMS.RFC1766	English
DC.type' scheme='DCTERMS.DCMIType	Text
DCTERMS.issued' scheme='DCTERMS.W3CDTF	2007-12
DC.subject	Rice Husk
	Silica
	Carboxylic Acid Leaching
	Hydrolysis
	Optimization Parameters
DCTERMS.abstract	Rice husk, one of main agricultural wastes in South-east Asia countries, is well known as renewable resource to produce both energy and high-purity silica (SiO₂), because it consists of 70% organics and 20% amorphous SiO₂. The conventional process of recovering silica originating from rice husks requires a leaching treatment by strong acid solutions, such as sulfuric acid (H₂SO₄), hydrochloric acid (HCl) and nitric acid (HNO₃), to remove metallic impurities from the rice husks before combustion. The use of these acid solutions, however, is hazardous to the environment and human life, and difficult for process-cost-saving in mass-production due to expensive and complicated disposal systems. In this study, an environmentally benign, harmless to human as well as economical process to produce high-purity amorphous SiO₂ powder originating from rice husks has been established without using strong acids. From the viewpoint of a harmless influence on human body, carboxylic acids such as a citric acid or oxalic acid are employed in the acid leaching treatment of rice husks. In this alkali impurities are effectively removed from husks via a chelate reaction between carboxyl (-COOH) and alkali elements. In the experiment, first of all, it was shown that the carboxylic acid leaching was effective in promoting the hydrolysis of organics by DTA and GCMS. From experimental results on the optimization of concentration and temperature of the carboxylic acid solution by DTA, XRF and ICP analysis, it was found that a concentration of 5% or more was enough to both increase SiO₂ purity over 99% and remarkably reduce alkali metal impurities in the rice husk ashes. Amorphous SiO₂ powder originating from rice husks has a porous structure, so that it was also easy to control its particle size by dry milling or a grinding process.
DC.identifier	10.18910/9539
DC.format	9539
citation_title	Environmentally Benign Reuse of Agricultural Wastes to Prepare High-Purity Silica from Rice Husks
citation_author	Umeda, Junko
	Kondoh, Katsuyoshi
	Michiura, Yoshisada
citation_publisher	大阪大学接合科学研究所
citation_language	English
citation_date	2007-12
citation_journal_title	Transactions of JWRI
citation_volume	36
citation_issue	2
citation_firstpage	17
citation_lastpage	21
citation_public_url	https://hdl.handle.net/11094/9539
citation_doi_detail	10.18910/9539
citation_doi	https://doi.org/10.18910/9539

Environmentally Benign Reuse of Agricultural Wastes to Prepare High-Purity Silica from Rice Husks

Link to primary information

Item Information

Show details