A sustainable route for the preparation of activated carbon and silica from rice husk ash
ABSTRACT 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.
- SourceAvailable from: You-Lo Hsieh[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.Powder Technology 07/2012; 225:149–155. DOI:10.1016/j.powtec.2012.04.002 · 2.27 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: Silica nanoparticles were synthesized from rice husk ash at room temperature by sonochemical method. The feeding rate of percipiteting agent and time of sonication were investigated. The nanostructure of the synthesized powder was realized by the FE-SEM photomicrograph, FT-IR spectroscopy, XRD and XRF analyses. These analytical observations have revealed that the nano-sized amorphous silica particles are formed and they are spheroidal in shape. The average particle size of the silica powders is found to be around 50 nm. The as-synthesized silica nanoparticles were subsequently modified with chlorosulfonic acid and prepared silica sulfuric acid nanoparticles, which were employed as an efficient catalyst for the acylation of alcohols and phenols with acetic anhydride in excellent yields under solvent-free conditions at room temperature. This reported method is simple, mild, and environmentally viable and catalyst can be simply recovered and reused over 9 times without any significant loss of its catalytic activity.Combinatorial chemistry & high throughput screening 08/2012; DOI:10.2174/138620712803519743 · 1.93 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: A new simple method to prepare acidic mesoporous sulfonated silica in situ without any surfactant is reported. The prepared catalysts were characterized by XRD, nitrogen adsorption, thermogravimetric analysis (TGA), and elemental analysis. The concentration of –SO3H groups was measured by titration, and FTIR was applied to confirm the successful incorporation of the strong acid sites. The in situ sulfonated silica (ISS) has a large surface area with a narrow range of mesoporosity and good thermal stability. Moreover, the preparation method has the advantage of easy control of the acid concentration and versatile synthesis. The ISS was used in catalytic hydrolysis and showed remarkable reusability even under very harsh conditions. The butylation of phenol was conducted over ISS to utilize the mesoporosity of the catalysts. Finally, the ISS catalysts might be used in various acid catalyses owing to the advantages of their simple/inexpensive preparation, reusability, and mesoporosity.Berichte der deutschen chemischen Gesellschaft 07/2014; 2014(21). DOI:10.1002/ejic.201402288