Characterization of Silica Produced from Rice Husk Ash: Comparison of Purification and Processing Methods

Abstract

As a byproduct of the combustion of rice husk to generate energy, rice husk ash (RHA) is formed by silica and carbon, apart from small amounts of other constituents. Several treatments can be used to increase the purity of the silica obtained, or even produce pure silica. The present study tested the efficiency of different techniques to obtain silica, characterizing and comparing the silicas obtained from RHA. A literature review was conducted, and then selected techniques were used to produce silica, which was characterized by XRF, XRD, particle sizing, specific weight, specific surface area, total carbon, and SEM. The literature review showed that most techniques include a pretreatment like acid or alkaline leaching followed by thermal treatment to increase the amount of silica produced by reduction of carbonaceous materials. The results showed that it is possible to produce silica from RHA using simple methods, and that these produced silica with purity above 98%. The treatments that afforded the best results were acid leaching followed by thermal treatment at 800ºC, and alkaline extraction at low temperature, with silica purity of 99.3% and 99.6%, respectively.

Biosilica Properties from Rice Husk using Various HCl Concentrations and Frequency Sources

“…The surface morphologies of all silicon dioxides are not uniform, although there is a tendency that the higher concentration will leads to the lower grain formation. This morphology in accordance to Fernandes et al [25] which reported that the silicon dioxide particles from their treatments were irregular and jagged. Azmi et al [26] also showed that silicon dioxide from rice husk were in irregular geometry.…”

“…Maximum peaks of HCl 1%, 3%, and 5% are in 2θ = 21.91 °, 21.65 °, and 21.77 °, respectively, with the same hkl plane (101). These peaks in line with Fernandes et al [25] which presented that silicon dioxide from rice husk using temperature of 800 °C has amoruphous phase. Azmi et al [26] and Johan et al [28] also reported silicon dioxide from rice husk at 700 -1100 °C and 700 -1000 °C, respectively, were in amorphous with cristobalite phase and have peaks at 2θ of 20 -22 °.…”

Comparative study using different external sources of aluminum on the zeolites synthesis from rice husk ash

“…According to the figure 4(A), RHA (from burning in the pulverized form) presents morphology and characteristics similar to other studies [33,34,83,84]. The micrographs of these samples are shown with respect to 1000× magnification.…”

“…Rice husk produces a black residue containing about 15% carbon and the remainder of silica on an average during burning [33]. In some places RHAs are disposed of in landfills, causing air and water pollution [34][35][36][37][38].…”

The Ability of Crystalline and Amorphous Silica from Rice Husk Ash to Perform Quality Hardness for Ceramic Water Filtration Membrane

“…Analysis of X-ray diffractometer (XRD) Figure 5 and 6 presented the diffractograms of the samples analysed. Previous studies had conducted an experiment using different time and temperature conditions to induce the existence of amorphous and crystalline silica [13]. In Figure AS 1 showed a single diffuse broad peak at about 2θ = 20.79° while the AS2 showed the single diffuse broad peak at about 2θ =22°.…”