Nature and reactivity of silica available in rice husk and its ashes

Rao, Golla Rama; Sastry, A. R. K.; Rohatgi, Pradeep K.

doi:10.1007/bf02744917

Cited by 26 publications

(8 citation statements)

References 4 publications

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“…Thus, the tendency of silica to retain carbon is eliminated, and white RHA is produced (Figure 1c,d). Lime reactivity was determined by a previously reported chemical method [23]. Table 2 gives the lime reactivity values of the ash samples prepared at different conditions.…”

Section: Resultsmentioning

confidence: 99%

“…The reactivity of the ash was determined according to a given chemical method [23]. Lime reactivity of the various ashes was determined by suspending a small quantity (approximately 0.3 g) of the ash in 50 mL of saturated lime solution at room temperature and by stirring after 18 h. The unused Ca was estimated by titration with a 0.001-M EDTA solution.…”

Section: Lime Reactivitymentioning

confidence: 99%

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Optimization of synthesis and characterization of nanosilica produced from rice husk (a common waste material)

et al. 2012

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Rice husk (RH), an inexpensive waste material, was used to produce nanosilica. Acid treatment of RH followed by thermal combustion under controlled conditions gave 22.50% ash of which 90.469% was silica. Various chemical treatments in varied conditions for controlled combustion were investigated in order to produce highly purified nanosilica. The structural properties (such as X-ray diffraction, Brunauer-Emmett-Teller, Fourier transform infrared spectroscopy, and transmission electron microscopy) of the silica were studied. The method was optimized, and the chemical composition of the product was determined by X-ray fluorescence and carbon, hydrogen, and nitrogen analysis. Lime reactivity of the ashes was determined. At optimized conditions, a nanosized, highly purified silica (98.8 mass percentage) was produced with a high surface area, high reactivity, and 99.9% amorphous in form. Strength and number of acidic sites were measured by potentiometric titration. This nanosilica showed strong and a large number of acidic sites in comparison with commercial silica, making it as a good support for catalysts. This economic technology, as applied to waste material, also provides many benefits to the local agro-industry.

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Section: Resultsmentioning

confidence: 99%

Section: Lime Reactivitymentioning

confidence: 99%

Optimization of synthesis and characterization of nanosilica produced from rice husk (a common waste material)

et al. 2012

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“…Studies of surface morphology, chemical reactivity and surface area measurements reveal the formation of amorphous silica during ashing. The reactivity was found to be the maximum at ashing temperature range of 400-600 o C and holding time of 6-12 h. However, it was found to decrease with ashing temperature and hold time [18]. After comparing the X-ray photoelectron spectroscopy peak widths of natural silica with those of rice husk ash, the difference in width has been attributed to variation in immediate chemical environment of silica and oxygen in the husk ash.…”

Section: Introductionmentioning

confidence: 94%

Synthesis and characterization of rice husk silica, silica-carbon composite and H3PO4 activated silica

Singh

Kumar

et al. 2008

Cerâmica

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This paper discusses synthesis and characterization of (i) rice husk based nanosilica, (ii) nanosilica carbon composite granules and (iii) phosphoric acid activated ash silica. These have been produced by burning husk in air, charring husk in hydrogen and activating husk silica with H3PO4 respectively. X-ray diffraction studies of these products reveal increasing peak width (amorphosity) with decreasing burning temperature. The activated rice husk silica transforms to crystalline product when burnt above 1000 ºC. The variation of surface area and pore volume with burning temperature show different behavior for air fired and hydrogen charred products. Activation energy associated with change in surface area for air fired and hydrogen charred samples have also been studied. Rate of variation in surface area with temperature indicate different trend. The validations of these products have been evaluated by decolorizing capacity of standard molasses and iodine solution. The adsorptive powers of these products have been found to be highest for activated silica and lowest for hydrogenated ash.

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“…Rice plants collect silica from the soil, which is stored as silicic acid inside the cellulose micro-compartments of the plant. The metal content varies according to the soil and manures used, but traces of potassium, calcium, magnesium, iron, sodium, manganese, aluminum, phosphorous and sulfur are found [14]. K is the main metal of RH (~2.7 mg/g), followed by Ca (~1.5 mg/g) and Mg and Mn (0.36 mg/g).…”

Section: Rice Husk As a Source Of Bio-energy And Sio2mentioning

confidence: 99%

Sustainable Harnessing of SiO2 Nanoparticles from Rice Husks: A Review of the Best Synthesis and Applications

Rodriguez-Otero,

Vargas,

Galarneau

et al. 2023

Processes

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The extraction of silica particles from rice husks has been extensively studied. This review aims to present the most efficient approach to harnessing rice husk biomass and converting silica into high-value-added materials for direct applications to address current challenges like water purification. Rice husks, as a residue from agriculture, had been largely used as a source of power through direct incineration in major rice-producing countries. However, rice husks present an intriguing opportunity as a renewable source of SiO2, offering a low-cost adsorbent with a high surface area and ease of functionalization that can be transformed into diverse mesoporous silica structures or composites, enabling applications in catalysis, drug delivery, water treatment, etc. This dual potential of rice husks can be harnessed by combining bio-oil and syngas production through pyrolysis with the efficient extraction of SiO2, ensuring the comprehensive utilization of the biomass. This review not only highlights the immense potential of silica nanoparticles but also serves as a roadmap for future investigations, with the ultimate aim of harnessing the full capabilities of this renewable and sustainable resource, contributing to the circular economy by yielding valuable by-products.

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Nature and reactivity of silica available in rice husk and its ashes

Cited by 26 publications

References 4 publications

Optimization of synthesis and characterization of nanosilica produced from rice husk (a common waste material)

Optimization of synthesis and characterization of nanosilica produced from rice husk (a common waste material)

Synthesis and characterization of rice husk silica, silica-carbon composite and H3PO4 activated silica

Sustainable Harnessing of SiO2 Nanoparticles from Rice Husks: A Review of the Best Synthesis and Applications

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