ABSTRACT
In this paper, the dehydration of xylose to furfural was carried out under atmospheric pressure and at the boiling temperature of a biphasic mixture of toluene and an aqueous solution of xylose, with sulfuric acid as catalyst plus an inorganic salt (NaCl or FeCl(3)) as promoter. The best yield of furfural was 83% under the following conditions: 150 mL of toluene and 10 mL of aqueous solution of 10% xylose (w/w), 10% H(2)SO(4) (w/w), 2.4g NaCl , and heating for 5h. FeCl(3) as promoter was found to be more efficient than NaCl. The addition of DMSO to the aqueous phase in the absence of an inorganic salt was shown to improve the yield of furfural.
Subject(s)
Atmospheric Pressure , Chlorides/chemistry , Ferric Compounds/chemistry , Furaldehyde/chemistry , Sodium Chloride/chemistry , Sulfuric Acids/chemistry , Xylose/chemistryABSTRACT
Carbon black is a form of amorphous carbon that is produced by incomplete combustion of petroleum- or some plant-derived materials and has a number of industrial uses. A process consisting of hydrolysis, carbonization and pyrolysis of rice husk was developed. Under optimal hydrolysis conditions (72 wt.% sulfuric acid, 50°C, 10 min), a hydrolysis ratio of 52.72% was achieved. After carbonization of the hydrolysis solution by water bath, the solid carbon was further pyrolyzed. As the pyrolysis temperature was increased from 400 to 800°C, the carbon content increased from 83.41% to 94.66%, the number of O-H, C-H, CO, and CC surface functional groups decreased, and based on Brunauer-Emmett-Teller (BET) results, the specific surface area and pore volume of carbon black increased from 389 to 1,034 m(2)/g and from 0.258 to 0.487 cm(3)/g, respectively. X-ray diffraction pattern (XRD) and Raman spectroscopy analyses of samples pyrolyzed at 400-800°C showed a localized graphitic structure. It is possible that the hydrolysis/carbonization/pyrolysis process developed in this study could also be applicable to the preparation of carbon black from other types of biomass.
Subject(s)
Oryza/chemistry , Soot/chemistry , Hot Temperature , Hydrolysis , Spectrum Analysis, Raman , X-Ray DiffractionABSTRACT
Rice husk is an abundant agricultural byproduct. The research on comprehensive utilization of rice husk to prepare xylose, activated carbon and silica was carried out. The hydrolysis conditions of xylan in rice husk to produce xylose were as follows: the concentration of H(2)SO(4) was 3.6% (wt.%), the temperature was 100°C, the ratio of rice husk mass (g) to H(2)SO(4) solution (ml) was 1:5 and the time was 3 h. The hydrolysis degree of xylan reached 95.6%. The resulting residues were used to prepare activated carbons with the BET surface area of 1763 m(2)/g when 50% H(3)PO(4) was impregnated with rice husk with the ratio of 5:1 at 500°C for 0.5 h. The produced carbons had effective adsorption capability to purify the xylose solution. Furthermore, they exhibited good electrochemical performance. After adsorption, activated carbons were calcined to produce silica with the diameter of 30 nm.
Subject(s)
Oryza/chemistry , Xylose/chemical synthesis , Adsorption , Charcoal/chemistry , Coloring Agents/chemistry , Hydrolysis , Indicators and Reagents , Phosphoric Acids/chemistry , Porosity , Silicon Dioxide/chemistry , Temperature , X-Ray Diffraction , Xylans/chemistryABSTRACT
In the present work, a new route for preparation of high-performance porous carbons under mild conditions was reported. The high surface area (2700 m2/g) and large pore volume (1.98 cm3/g) porous carbons were prepared from hydrochars by conventional phosphoric acid activation method. The hydrochars described here can be obtained from sulfuric acid hydrolysis of rice husk via dehydration, polymerization and carbonization. A specific capacitance of 130 F g(-1) was achieved by using the porous carbon, indicating that the porous carbon prepared by this route has good electrochemical performance. Furthermore, the localized graphitic nature of the porous carbon was proved by X-ray diffraction pattern.
Subject(s)
Carbon/chemistry , Charcoal/chemistry , Phosphoric Acids/chemistry , Water/chemistry , Adsorption , Electrochemical Techniques , Nitrogen/analysis , Porosity , Surface Properties , Temperature , Time Factors , X-Ray DiffractionABSTRACT
In the present work, a green and sustainable route for preparation of hydrochars from sulfuric acid hydrolysis solution of rice husk under low temperature and atmospheric pressure was described. This route was achieved with the catalysis of sulfuric acid. The sphere-like carbon materials with regular size of about 500 nm were obtained at 95 degrees C for 6h when the acid concentration was 42% and 52%. The morphology of the hydrochars changed with sulfuric acid concentration increased. The surface of the materials contained a large number of functional groups. Furthermore, the localized graphitic nature of the materials was proved by X-ray diffraction pattern. High surface area porous carbons could be prepared from the hydrochars after activation, and they exhibited good electrochemical performance.
Subject(s)
Biotechnology/methods , Charcoal/chemical synthesis , Oryza/chemistry , Waste Products/analysis , Spectroscopy, Fourier Transform Infrared , Sulfuric Acids/chemistry , Temperature , Time Factors , X-Ray DiffractionABSTRACT
A novel mesoporous lignin/silica hybrid prepared from rice husks at different pH values was produced in situ using the sol-gel process. The optimum conditions for hybrid formation were 90 degrees C and pH 3 for 6h in the presence of 2 mol L(-1) H(2)SO(4). The lignin/silica ratio reached 2:3 (41.67% lignin, 58.33% silica). The hybrid with various pore structures was spherical with diameters of approximately 60 nm and a specific surface of 471.7 m(2)/g. Such lignin/silica hybrid material originating from rice husks can potentially be used to decontaminate environmental objects.
