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

Abstract

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.

Effect of Rice Husk on Fired Ceramic Shell Strength

“…The existence of the ZrSiO 4 phase in the fired ceramic shell mould are due to the formation of amorphous fused silica after firing rice husk at low temperature (below 1000 ºC) in air. In fact, the amorphous fused silica also was proved can combine and harden the brittle ceramic structure [7,19]. Although similar results were obtained in works by Javed et.…”

“…Although similar results were obtained in works by Javed et. al, the silica were found to be in crystalline form which is stable until up to 1700 ºC [19][20]. ZrSiO 4 phase is known to have low thermal expansion coefficient and is highly resistant to thermal shock [21].…”

Comparison between Properties of Biochar Produced by Traditional and Controlled Pyrolysis

“…In all biomaterials, a peak is observed within the ranges from 15° to 30°, indicating disordered structure. XRD analysis of the feedstock and biochars confirmed the presence of amorphous silica as indicated by the heap at 2θ ~ 22.5 o idue to amorphous silica and quartz amorphous silica, which is a major constituent of these biomaterials, can be present in form of disordered cristobalite (SiO 2 ) (Singh et al, 2008 andSrivastava et al, 2006). Chemical properties: Table 2 shows that, on the average, the pH value of SCBBs lower than in the RHBs.…”

Synthesis of the Coumarin-Containing Porous Silica as Column Packing Material

“…The X-ray spectrum of the prepared silica structures shows a single, broad peak at 2h = 21°-22° [25]. This broad peak was indicated that the silica framework is amorphous [26,27]. X-ray diffraction patterns of functionalized silica indicate that the structure of amino functionalized silica and coumarin based silica showed also a typical porous and amorphous structure.…”