The Experts below are selected from a list of 312 Experts worldwide ranked by ideXlab platform
A Y Ng - One of the best experts on this subject based on the ideXlab platform.
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column study on the sorption of cr vi using quaternized Rice Hulls
Bioresource Technology, 1999Co-Authors: A Y NgAbstract:The potential of quaternized Rice Hulls in removing Cr(VI) from synthetic solution, chrome electroplating waste and wood preservative waste was investigated in column experiments. Increase in column bed depth resulted in a longer service time at CtCo = 0.5 breakthrough. The presence of SO2−4, which is commonly present in the wastes, interfered with the sorption process and resulted in earlier breakthrough. The sorption process was flow-rate independent within the scope of this study. In the regeneration study, Cr(VI) could be recovered almost quantitatively by eluting with a 0.5 M NaOH solution and the column could be used repeatedly for at least five cycles.
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chromium vi sorption on quaternized Rice Hulls
Journal of Environmental Science and Health Part A-toxic\ hazardous Substances & Environmental Engineering, 1997Co-Authors: A Y NgAbstract:Abstract The sorption of Cr(VI) from synthetic solution and electroplating waste by quaternized Rice Hulls was investigated under laboratory conditions to assess its potential in removing Cr(VI). The results show that quaternized Rice Hulls provided higher sorption capacity and a more workable pH range as compared to the untreated Rice Hulls. From the Langmuir isotherm the maximum sorption capacity of Cr(VI) was 32.3 mg/g at pH 4.82 at 25° C. Column studies showed that Cr(VI) and Cu(ll) from electroplating waste could be successfully removed or reduced using a combination of untreated and quaternized Rice Hulls. The effect of different anions on the sorption capacity of quarternized Rice Hulls was discussed.
Maharajapuram V Ravichandran - One of the best experts on this subject based on the ideXlab platform.
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structural analysis of inclusions in β silicon carbide whiskers grown from Rice Hulls
Journal of the American Ceramic Society, 2005Co-Authors: Kevin M Knowles, Maharajapuram V RavichandranAbstract:Microcrystalline inclusions in the core of {beta}-SiC whiskers derived from the pyrolysis of Rice Hulls have been studied by transmission electron microscopy using conventional bright-field and dark-field imaging. The electron diffraction patterns from the whiskers show extra reflections arising from these inclusions. Dark-field images from these reflections are consistent with the presence of three different variants of inclusions, all of which are oriented with their [001] axes parallel to the heavily faulted [111] growth axis of the whiskers. A structural model for these inclusions is proposed which accounts satisfactorily for the extra reflections in the electron diffraction patterns.
Pemiah Brindha - One of the best experts on this subject based on the ideXlab platform.
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Antioxidant property of solvent extract and acid/alkali hydrolysates from Rice Hulls
Food bioscience, 2015Co-Authors: Vellingiri Vadivel, Pemiah BrindhaAbstract:Abstract In the present study, the extracts were prepared from Rice Hulls using solvent, acid and alkali hydrolysis treatments and their in vitro antioxidant potential was evaluated. Among various solvent extraction methods used to recover the polyphenolic extract, grinding in morter and pestle with 75% ethanol yielded maximum total phenolic concentration (240.14 mg FAE/L). Between acid and alkali treatments, alkali hydrolysis (932.14 mg FAE/L) is more effective than acid hydrolysis (674.29 mg FAE/L) in recovering phenolic compounds. Moreover, alkali hydrolysate exhibited higher antioxidant potential in terms of radical scavenging against DPPH (78.96%), superoxide (85.22%), hydroxyl (71.54%) radicals and hydrogen peroxide (78.64%). Further, the ferric reducing power (0.739 absorption units) and phosphomolybdate assays (1458 AEAA/mg sample) also indicated the high antioxidant activity of alkali hydrolysate of Rice Hulls when compared to acid hydrolysate and solvent extract. Hence, alkali hydrolysis treatment could be recommended for the maximum recovery of total phenolic compounds from Rice Hulls.
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antioxidant property of solvent extract and acid alkali hydrolysates from Rice Hulls
Food bioscience, 2015Co-Authors: Vellingiri Vadivel, Pemiah BrindhaAbstract:Abstract In the present study, the extracts were prepared from Rice Hulls using solvent, acid and alkali hydrolysis treatments and their in vitro antioxidant potential was evaluated. Among various solvent extraction methods used to recover the polyphenolic extract, grinding in morter and pestle with 75% ethanol yielded maximum total phenolic concentration (240.14 mg FAE/L). Between acid and alkali treatments, alkali hydrolysis (932.14 mg FAE/L) is more effective than acid hydrolysis (674.29 mg FAE/L) in recovering phenolic compounds. Moreover, alkali hydrolysate exhibited higher antioxidant potential in terms of radical scavenging against DPPH (78.96%), superoxide (85.22%), hydroxyl (71.54%) radicals and hydrogen peroxide (78.64%). Further, the ferric reducing power (0.739 absorption units) and phosphomolybdate assays (1458 AEAA/mg sample) also indicated the high antioxidant activity of alkali hydrolysate of Rice Hulls when compared to acid hydrolysate and solvent extract. Hence, alkali hydrolysis treatment could be recommended for the maximum recovery of total phenolic compounds from Rice Hulls.
Badal C Saha - One of the best experts on this subject based on the ideXlab platform.
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lime pretreatment enzymatic saccharification and fermentation of Rice Hulls to ethanol
Biomass & Bioenergy, 2008Co-Authors: Badal C Saha, Michael A CottaAbstract:Rice Hulls used in this study contained 35.6±0.1% cellulose and 12.0±0.7% hemicellulose. The maximum yield of monomeric sugars from Rice Hulls (15.0%, w/v) by lime pretreatment (100 mg g−1 Hulls, 121 °C, 1 h) and enzymatic saccharification (45 °C, pH 5.0, 72 h) using a cocktail of three commercial enzyme preparations (cellulase, β-glucosidase and hemicellulase) at the dose level of 0.15 ml of each enzyme preparation g−1 Hulls was 154±1 mg g−1 (32% yield). The lime pretreatment did not generate any detectable furfural and hydroxymethyl furfural in the hydrolyzate. The concentration of ethanol from lime-pretreated enzyme-saccharified Rice hull (138 g) hydrolyzate by recombinant Escherichia coli strain FBR5 at pH 6.5 and 35 °C in 19 h was 9.8±0.5 g l−1 with a yield of 0.49 g g−1 available sugars. The ethanol concentration was 11.0±1.0 g l−1 in the case of simultaneous saccharification and fermentation by the E. coli strain at pH 6.0 and 35 °C in 53 h.
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dilute acid pretreatment enzymatic saccharification and fermentation of Rice Hulls to ethanol
Biotechnology Progress, 2008Co-Authors: Badal C Saha, Michael A Cotta, Loren B Iten, Victor Y WuAbstract:: Rice Hulls, a complex lignocellulosic material with high lignin (15.38 +/- 0.2%) and ash (18.71 +/- 0.01%) content, contain 35.62 +/- 0.12% cellulose and 11.96 +/- 0.73% hemicellulose and has the potential to serve as a low-cost feedstock for production of ethanol. Dilute H2SO4 pretreatments at varied temperature (120-190 degrees C) and enzymatic saccharification (45 degrees C, pH 5.0) were evaluated for conversion of Rice hull cellulose and hemicellulose to monomeric sugars. The maximum yield of monomeric sugars from Rice Hulls (15%, w/v) by dilute H2SO4 (1.0%, v/v) pretreatment and enzymatic saccharification (45 degrees C, pH 5.0, 72 h) using cellulase, beta-glucosidase, xylanase, esterase, and Tween 20 was 287 +/- 3 mg/g (60% yield based on total carbohydrate content). Under this condition, no furfural and hydroxymethyl furfural were produced. The yield of ethanol per L by the mixed sugar utilizing recombinant Escherichia colistrain FBR 5 from Rice hull hydrolyzate containing 43.6 +/- 3.0 g fermentable sugars (glucose, 18.2 +/- 1.4 g; xylose, 21.4 +/- 1.1 g; arabinose, 2.4 +/- 0.3 g; galactose, 1.6 +/- 0.2 g) was 18.7 +/- 0.6 g (0.43 +/- 0.02 g/g sugars obtained; 0.13 +/- 0.01 g/g Rice Hulls) at pH 6.5 and 35 degrees C. Detoxification of the acid- and enzyme-treated Rice hull hydrolyzate by overliming (pH 10.5, 90 degrees C, 30 min) reduced the time required for maximum ethanol production (17 +/- 0.2 g from 42.0 +/- 0.7 g sugars per L) by the E. coli strain from 64 to 39 h in the case of separate hydrolysis and fermentation and increased the maximum ethanol yield (per L) from 7.1 +/- 2.3 g in 140 h to 9.1 +/- 0.7 g in 112 h in the case of simultaneous saccharification and fermentation.
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enzymatic saccharification and fermentation of alkaline peroxide pretreated Rice Hulls to ethanol
Enzyme and Microbial Technology, 2007Co-Authors: Badal C Saha, Michael A CottaAbstract:Abstract Rice Hulls used in this study contained 35.62 ± 0.12% cellulose and 11.96 ± 0.73% hemicellulose. Alkaline H 2 O 2 pretreatment and enzymatic saccharification methods were evaluated for conversion of Rice hull cellulose and hemicellulose to simple sugars. The yield of sugars from diluted alkaline peroxide pretreated (7.50% H 2 O 2 , v/v; pH 11.5; 35 °C; 24 h) Rice Hulls (15.0%, w/v) after enzymatic saccharification (45 °C, pH 5.0, 72 h) by three commercial enzyme preparations (cellulase, β-glucosidase, and xylanase) using 0.12 ml of each enzyme preparation per g Hulls was 428 ± 12 mg/g (90% yield). During the pretreatment, no measurable furfural and hydroxymethyl furfural were produced. The almost complete conversion (96%) of Rice Hulls to sugars was achieved by saccharifying the liquid and solid fractions separately after alkaline peroxide pretreatment. The concentration of ethanol from alkaline peroxide pretreated, enzyme saccharified Rice hull (39 g) hydrolyzate by recombinant Escherichia coli strain FBR5 at pH 6.5 and 35 °C in 24 h was 8.2 ± 0.2 g/l with a yield of 0.49 g/g available sugars (0.21 g/g Hulls). The ethanol concentration was 8.0 ± 0.2 g/l with a yield of 0.20 g/g Hulls in the case of simultaneous saccharification and fermentation by the E. coli strain at pH 6.0 and 35 °C in 48 h.
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Process for obtaining cellulose acetate from agricultural by-products
Carbohydrate Polymers, 2006Co-Authors: Atanu Biswas, R.l. Shogren, Badal C Saha, John W. Lawton, Julious L. WillettAbstract:Agricultural residues such as corn fiber, Rice Hulls and wheat straw can be used as abundant low-cost feedstock for production of fuel ethanol. However, the cost of cellulase enzymes to saccharify cellulose to glucose is a major hindrance. As an alternative, a novel process to obtain industrially important cellulose acetate from these by-products after removing hemicellulosic sugars was developed. Rice-straw, wheat hull and corn fiber were treated with dilute acid at a moderate temperature to hydrolyze the hemicellulose to monomeric sugars that can be fermented to ethanol. The cellulose was then treated with acetic anhydride and catalytic amount of sulfuric acid to make cellulose acetate. The production of cellulose acetate was confirmed by NMR analysis. The pretreatment used to hydrolyze the hemicellulose was also useful for cellulose acetate production. Without the pretreatment cellulose acetate conversions from wheat straw, corn fiber, and Rice Hulls were 0.5, 1.8 and 13.5, respectively. After pretreatment the conversion rate increased to about 25 wt% for all three agricultural residues used.
Takeshi Okutani - One of the best experts on this subject based on the ideXlab platform.
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Utilization of Silica in Rice Hulls as Raw Materials for Silicon Semiconductors
Journal of metals materials and minerals, 2020Co-Authors: Takeshi OkutaniAbstract:Highly pure silicon and silicon compounds are required in high technology products such as semiconductors and solar cells. Rice Hulls consist of 71 to 87wt% organic components such as cellulose and 13 to 29wt% inorganic components. In Rice Hulls, 87 to 97wt% of the inorganic components are silica (SiO 2 ). Rice plants absorb water-soluble siliceous ions via the roots. These ions are transported to stems, leaves and Rice Hulls by sap flow. In Rice Hulls, siliceous ions accumulate at the cuticle outside of the epidermis. The production of pure silicon compound (SiCl 4 ) and of silicon metal as the starting material for purification from Rice hull ash is proposed to utilize Rice hull SiO 2 in high technology industries. In one process, SiO 2 in Rice hull ash reacts with Cl 2 on the presence of C and is converted to SiCl 4 . SiO 2 + 2Cl 2 + 2C → SiCl 4 + 2CO The SiCl 4 is purified by distillation. The production of SiCl 4 from Rice hull ash is much more efficient than that from mineral SiO 2 . In another process, SiO 2 in Rice hull ash reacts with aluminum (Al) to synthesize Si and Al 2 O 3 .3SiO 2 + 4Al → 3Si + 2Al 2 O 3 The reactivity of Rice hull SiO 2 is higher than that of mineral SiO 2 . Although Rice Hulls are now utilized for agricultural materials and fuel, Rice hull SiO 2 also has high potential for use as industrial raw materials.
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synthesis of metallic silicon by reaction of silica in Rice Hulls with aluminum and its hydrochlorination
Journal of Solid State Chemistry, 2019Co-Authors: Takeshi OkutaniAbstract:Abstract Silica in Rice Hulls (Rice hull silica) reacted with aluminum to synthesize silicon and alumina at the temperature of 900–1225 °C. Rice hull silica contained about 20 wt% in Rice Hulls is amorphous and has high surface area with fine particles. Reactivity of Rice hull silica added potassium carbonate for aluminum was higher than Rice hull silica, silica sand and artificial amorphous silica because the addition of potassium carbonate caused the melt of Rice hull silica surface and improved the contact between Rice hull silica and aluminum melt. Si in the product of the reaction of Rice hull silica with aluminum at 1225 °C completely reacted with hydrogen chloride to form chlorosilanes without catalyst at 300 °C. The silicon and the unreacted aluminum existed as a eutectic alloy, Si7Al3, in the product. Since aluminum in the eutectic alloy first reacted with hydrogen chloride to sublimate as aluminum chloride, hydrogen chloride easily diffused in the eutectic alloy having empty aluminum sites, so that silicon in the eutectic alloy easily reacted with hydrogen chloride.
