Conversion of rice husk into amorphous silica and combustible gas

Chakraverty, A.; Kaleemullah, S.

doi:10.1016/0196-8904(91)90116-z

Cited by 49 publications

(20 citation statements)

References 2 publications

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“…The XRD graph obtained for RHA is shown in Figure , which consists of a broad peak at 22.29° representing the amorphous nature of RHA leached using HCl. A similar result was reported by Chakraverty and Kaleemullah who observed that the ash samples treated with acid before calcination did not have any sharp peaks and reported that the sample was amorphous in nature. Yuvakkumar et al reported that broad peak at 2Θ angle of 22° denoted the amorphous nature of silica.…”

Section: Resultssupporting

confidence: 88%

Comparative assessment of chemical treatments on extraction potential of commercial grade silica from rice husk

Nayak

Nandi

Datta

2019

Engineering Reports

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In the present study, an attempt has been made to extract commercial grade amorphous silica nanoparticles from rice husk (RH) using four different chemicals (NaOH, KOH, Na2CO3, and K2CO3) and two washing solvents (water and ethanol). The elemental, structural, and morphological characterizations of the silica samples were carried out using scanning electron microscopy coupled with energy‐dispersive X‐ray spectroscopy (SEM‐EDS), atomic absorption spectrometry (AAS), X‐ray diffraction (XRD), and Fourier‐transform infrared spectroscopy (FTIR). The combined NaOH and water treatment was found to be the most efficient method in terms of recovery of silica sample, while combined Na2CO3 and water treatment was more suitable for obtaining pure silica. No significant difference in the percentage recovery of silica was observed between the two washing treatments at p < 0.05. Scanning electron micrographs of the Na2CO3‐cum‐water and K2CO3‐cum‐water treated samples showed nonagglomerated silica nanoparticles. The XRD analysis of silica obtained from these two treatments was also free from any sharp peaks illustrating pure amorphous structure of silica. EDS and AAS study of K2CO3‐cum‐water treated samples showed higher mineral impurities compared to Na2CO3‐cum‐water treated sample. It could be inferred that silica obtained from Na2CO3 and water washing treatment can be used for extraction of metallurgical grade silicon.

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Section: Resultssupporting

confidence: 88%

Comparative assessment of chemical treatments on extraction potential of commercial grade silica from rice husk

Nayak

Nandi

Datta

2019

Engineering Reports

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“…2. A lack of sharp, defined peaks indicates noncrystalline or amorphous material (Chakraverty and Kaleemullah 1991). Amorphous substances display an atomic arrangement that is either random or has very short-range order (Ladd and Palmer 1993).…”

Section: Preparation Of Silica Gel From Rice Hull Ashmentioning

confidence: 99%

“…The silica has been recovered by various methods. Chakraverty and Kaleemullah (1991) used an acid leaching process to remove silica. Luan and Chou (1990) recovered silica by the gasification of rice hull with a pilot flame in a modified fluidized bed.…”

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confidence: 99%

Silica Gel from Rice Hull Ash: Preparation and Characterization

1998

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Rice hulls, a waste coproduct of the rice industry, is composed of 20% silica. The objectives of this study were to develop a method to recover silica from rice hull ash and produce silica gel, and to determine the physical and chemical properties of the rice hull silica gel (RHSG) relative to Trisyl 300, a commercial silica gel. Rice hull ash consisting of 61% silica and 36% carbon was dispersed in sodium hydroxide to dissolve the silica and produce a sodium silicate solution. The latter was titrated to pH 7 with 1M sulfuric acid to obtain a gel at neutral pH. The RHSG was aged, washed, and dried under specific conditions to get a final product that was slightly basic and had a moisture content >65%. Energy dispersive X‐ray spectrometry indicated that silicon was the most abundant element present in RHSG and Trisyl 300. Elemental analyses by inductively coupled plasma emission spectroscopy indicated a greater concentration of sodium and sulfur in RHSG relative to that in Trisyl 300. RHSG surface area was 258 m2/g, which was slightly more than half that of Trisyl 300 particles; the particle pore diameter was 121 Å, which was more than twice that of Trisyl 300. Fourier transform infrared spectroscopy showed similarities in chemical structures for both the silica gel samples with respect to siloxane bonds, surface silanol groups, and adsorbed water. X‐ray diffraction patterns for both the samples showed a broad peak between 15 and 35° 2θ diffraction angle indicating their amorphous nature. Scanning electron micrographs revealed that RHSG particles ranged in sizes from <5 to >40 μm, whereas Trisyl 300 particles were smaller, ranging in sizes from <5 to 25 μm and had a more uniform appearance. Silica gel production from rice hull ash alleviates the ricehull waste disposal problem and creates a commercially viable value‐added product. RHSG has wide‐ranging applications in a variety of industries, such as vegetable oil refining, pharmaceuticals, cosmetics, and paints.

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“…However, the final disposal of the RHA after adsorption has not been reported. Recent studies have demonstrated that the RHA can be an economically available raw material for production of silica gels and powders [24][25][26][27][28]. While the classical method for the preparation of silica powders generally employs acid with sodium silicate, which is currently manufactured by smelting quartz sand with sodium carbonate at 1300 • C [29,30], or manufactured by NaOH extraction from RHA [31].…”

Section: Introductionmentioning

confidence: 99%