An environmentally friendly and economically effective process to produce silica and activated carbon form rice husk ask simultaneously has been developed in this study. An extraction yield of silica of 72-98% was obtained and the particle size was 40-50 nm. The microstructures of the as-obtained silica powders were characterized by X-ray diffraction (XRD) and infrared spectra (IR). The surface area, iodine number and capacitance value of activated carbon could achieve 570 m(2)/g, 1708 mg/g, 180 F/g, respectively. In the whole synthetic procedure, the wastewater and the carbon dioxide were collected and reutilized. The recovery rate of sodium carbonate was achieved 92.25%. The process is inexpensive, sustainable, environmentally friendly and suitable for large-scale production.
"Silica (SiO 2 ), consisting of two of the most abundant elements in the earth's lithosphere, is an extremely important inorganic material that has been extensively utilized in a wide range of applications, such as glasses, optical fibers, food additives, electric and thermal insulators , absorbents, pharmaceutical products  . The common process to manufacture silica involves reacting minerals, such as quartz sand, with sodium carbonate at above 1000 °C, which demands significant energy input for not only the purification of minerals but also the high temperatures . In contrast, low temperature extraction of amorphous silica from biomass has presented to be an eco-friendly and costeffective alternative to the high energy processing of the inorganics . "
[Show abstract][Hide abstract] ABSTRACT: White ash, containing majority of SiO2 with trace amounts of Al2O3, CaO, MgO, K2O, P2O5, etc., was successfully produced by heating rice straw at 10 °C/min and holding at 250, 325 and 575 °C to facilitate decomposition and gasification of the organics while avoiding auto-ignition. Highly pure amorphous silica was derived from the resultant rice straw ash by a base dissolution and acid precipitation process at a 90.8% yield (or 11.47% from rice straw). The SiO2 chemical composition was confirmed by EDS and FTIR and the amorphous nature by XRD. Freeze-drying of silica gel produced mesoporous silica powders with a 5.8 nm average pore size (2 to 22 nm pore size distribution) and very high specific surface (509.5 m2/g BET and 637.0 m2/g BJH) and pore volume (0.925 cm3/g). These silica powders were dispersible in water and shown to consist of nano-disks with an average 172 nm diameter and 3.09 nm thickness as measured by TEM and AFM, respectively.
[Show abstract][Hide abstract] ABSTRACT: An alternative approach to the utilization of lignocellulosic biomass is reported in this paper. It was the first time that rice husk was used as carbon source to synthesize carbon coated silica particles. Rice husk was hydrolyzed and mixed with silica powder, then biochar coated silica particles were simply in situ synthesized. The coating morphology was similar to those who used pure chemicals or glucides as carbon source, while the mild reacting conditions could keep some organic functional groups on the particle surface and make the modification easier. Acid could be recycled to form a semi-closed reaction system. The composite was designed as one of the bases for the preparation of activated carbon shell. Thus, this paper may provide a low-cost and simple method to prepare functional materials.
Colloids and Surfaces A Physicochemical and Engineering Aspects 02/2012; 395:157–160. DOI:10.1016/j.colsurfa.2011.12.023 · 2.75 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A novel mesoporous silica spherical particle, MSP (AS) was facilely prepared using photonic industrial waste powder as the silica source via salt-templated aerosol spray approach. As an alternative to expensive mesoporous silica materials in prior works, the obtained MSP (AS) possesses advantages of simple and rapid synthesis with low manufacturing costs. The characteristics of the MSP (AS) material were investigated by the XRD, N2 adsorption–desorption measurement, SEM, TEM and TG/DTG analyses. The results clearly demonstrated the presence of mesoporous siliceous material with high specific surface area (585 m2/g), mesopore size (9.1 nm) as well as large pore volume (1.24 cm3/g). Furthermore, the MSP (AS) is evaluated as the support of adsorbent in terms of CO2 adsorption. It is observed that the amine-functionalized MSP (AS) adsorbent (TEPA-MSP (AS)) which possessed larger pore diameter and pore volume tends to have a higher adsorption capacity of 127 mg CO2/g adsorbent. This is superior to those of TEPA-SBA-15 (117 mg CO2/g adsorbent), TEPA-MCM-41 (112 mg CO2/g adsorbent) and TEPA-NaY (96 mg CO2/g adsorbent) under the same test condition. The results clearly suggest that the MSP (AS) synthesized using photonic industrial solid wastes via salt-templated aerosol route can be a potential and cost-effective adsorbent for CO2 capture.
Chemical Engineering Journal 07/2012; 197:215–222. DOI:10.1016/j.cej.2012.04.103 · 4.32 Impact Factor
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