Rice husk ash as an alternate source for active silica production

Della, Viviana Possamai; Kühn, Ingeborg; Hotza, Dachamir

doi:10.1016/s0167-577x(02)00879-0

Cited by 573 publications

(295 citation statements)

References 16 publications

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“…Ashes from long and high temperature pyrolysis of rice husk are known to contain silica in crystalline form and the silica can be dissolved in basic solution at lower rates and higher temperatures in comparison with the amorphous one. 6,12 At calcination temperatures above 1173 K, the SiO 2 in RHA would consist phases of cristobalite and some tridymite because of the melting of the surfaces of ash silica particles and bonding of particles together. 14 This behavior was demonstrated in the calcination applied here even though the as-received rice husk ash was found to be already in crystalline form according to its XRD spectrum ( Figure 1).…”

Section: Properties and Solubility Of Rhs And Rhasmentioning

confidence: 99%

“…%). 6 Upon leaching with mineral acid and calcination, silica with high purity in amorphous form could be extracted from RH. 4,7 In the past few years our group used rice husk silica (RHS) in the synthesis of different kinds of zeolites including NaY, BEA, MOR, and mesoporous MCM-41.…”

Section: Introductionmentioning

confidence: 99%

“…Being less carbonaceous, RHA could be easily coursed through heattreatment to extract amorphous silica. 6,7 In another couple of studies, RHA containing crystalline tridymite and α-cristobalite was used as an alternative silica source for the syntheses of BEA and ZSM-5 zeolites. 9 A work characterized the ash produced from combustion of rice husk in fluidized bed reactor showing speed and continuity of the process.…”

Section: Introductionmentioning

confidence: 99%

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Properties of silica from rice husk and rice husk ash and their utilization for zeolite y synthesis

2011

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Recebido em 21/12/10; aceito em 22/3/11; publicado na web em 10/6/11This study compared properties of silica (SiO 2 ) from rice husk (RH) and rice husk ash (RHA) extracted by acid-and heat-treatment. The SiO 2 from RH was in amorphous phase with nearly 100% purity while that from RHA was in crystalline phase with 97.56% purity. Both extracted SiO 2 were used in the synthesis of zeolite NaY but that from RH was better due to the efficiency in product recovery and simplicity of extraction. After the NaY was exchanged to NH 4 Y and calcined to convert to HY, the product did not carry over the textural properties of the parent NaY and NH 4 Y.

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Section: Properties and Solubility Of Rhs And Rhasmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Properties of silica from rice husk and rice husk ash and their utilization for zeolite y synthesis

2011

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“…Reported optimal temperatures for limiting the crystallisation of silica within the literature vary widely: < 725°C [10]; limited crystallisation at 700°C [11]; and < 900°C [12]. Crystal lisation is not merely a function of temperature.…”

Section: Mineralogymentioning

confidence: 99%

Valorisation of rice husks using a TORBED® combustion process

Blissett¹,

Sommerville

Rowson

et al. 2017

Fuel Processing Technology

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World production of rice exceeds 750 million tonnes per year of which a fifth is removed in the form of rice husk during the milling process. The use of rice husks as a source of sustainable and renewable energy is often hindered by lack of capital and a poor understanding of rice husk combustion characteristics. This results in the selection of poor quality technology which generates significant quantities of harmful crystalline silica waste. Despite previous work in the area, detailed characterisation of the combustion of rice husk ash in a TORBED reactor across a wide temperature range has not yet been attempted and little effort has been directed towards assessing the economic viability of generating quality rice husk ashes. The use of a TORBED reactor enables low residual carbon after combustion without the generation of harmful crystalline material. Rice husk was combusted in a 400mm reactor at temperatures between 700-950°C. In the subsequent characterisation studies the resulting materials were shown to be fully amorphous high purity silica (> 95%) and were readily digested in a series of alkaline digestion experiments. Complete silica conversion was only possible using uneconomic Na2O/SiO2 ratios and further optimisation of the combustion process to generate higher surface area material is necessary to increase the digestion rates further. Provisional economic analysis suggests that sales of the by-product enhance the returns from rice husk based power generation. TORBED reactors enable the combustion of rice husk with considerable operating flexibility and they generate products that could be used to displace resource intensive products and processes thus, added value from the by-products can be obtained by using TORBED reactor technology.

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“…1,2) Leaching of rice husks using various acid media at temperatures ranging from 100 to 120°C and at various time intervals has been conducted to remove metallic impurities and to produce silica with a large surface area. 1,3) Ultrafine SiO 2 has a host of applications in the electronics, ceramic, and polymer material industries. 4,5) Thus, SiO 2 from rice husk has been extensively studied for various industrial applications.…”

Section: Introductionmentioning

confidence: 99%

Improved Optical Degradation Characteristics of Eu Complex Encapsulated by High-Pressure Annealing

Kato¹,

Fukuda²,

Akiyama³

et al. 2011

Jpn. J. Appl. Phys.

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In this study, we explored the use of rice-husk-derived nanosilica (nSiO 2 ) as fillers in epoxy resins. The nSiO 2 was irradiated with a capacitively coupled 13.56 MHz radio frequency (RF) plasma using an admixture of argon (Ar) and hexamethyldisiloxane (HMDSO) or 1,7-octadiene (OD) monomers. The plasma-polymerized nSiO 2 was loaded at various concentrations (1-5%) into the epoxy matrix. Surface hydrophobicity of the plasma-treated nSiO 2 -filled composites increased, which is attributed to the attachment of functional groups from the monomer gases on the silica surface. Microhardness increased by at least 10% upon the inclusion of plasma-modified nSiO 2 compared with pristine nSiO 2 -epoxy composites. Likewise, hardness increased with increasing loading volume, with the HMDSO-treated silica composite recording the highest increase. Elastic moduli of the composites also showed an increase of at least 14% compared with untreated nSiO 2 -filled composites. This work demonstrated the use of rice husk, an agricultural waste, as a nSiO 2 source for epoxy resin fillers.

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Rice husk ash as an alternate source for active silica production

Cited by 573 publications

References 16 publications

Properties of silica from rice husk and rice husk ash and their utilization for zeolite y synthesis

Properties of silica from rice husk and rice husk ash and their utilization for zeolite y synthesis

Valorisation of rice husks using a TORBED® combustion process

Improved Optical Degradation Characteristics of Eu Complex Encapsulated by High-Pressure Annealing

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