Determination of RH‐5849 and indoxacarb in rice straw,rice husk,brown rice and soil using liquid chromatography–tandem triple quadrupole mass spectrometry following extraction with QuEChERS method

A fast and simple analytical method was developed for the simultaneous determination of RH‐5849 and indoxacarb in soil, rice straw, rice husk and brown rice. QuEChERS (quick, easy, cheap, effective, rugged and safe) method was used for extraction, and liquid chromatography with tandem triple quadrupole mass spectrometry was used for quantification. The matrix‐matched calibration plots were linear in the range between 25 and 5000 μg/L for soil, rice straw, rice husk and brown rice samples. All determination coefficients (R²) were ≥0.9962. The limits of detection and quantification were 1.5 and 5 μg/kg, respectively. Recoveries at three fortification levels ranged between 79.5 and 97.9% with relative standard deviations <11%. The developed method was validated and applied for the analysis of dissipation study samples. For field experiments, the half‐lives of RH‐5849 and indoxacarb in rice straw were 11.93 and 5.83 days, respectively. The method was demonstrated to be reliable for the routine monitoring of RH‐5849 and indoxacarb in rice samples. Copyright © 2016 John Wiley & Sons, Ltd.     

Synthesis of Mesoporous Silica Immobilized with 3-[(Mercapto or amino)propyl]trialkoxysilane by a Simple One-pot Reaction

Sodium silicate from rice husk ash (RHA) was transformed to functionalized silica with 3‐(mercaptopropyl)‐trimethoxysilane (MPTMS) or 3‐(aminopropyl)triethoxysilane (APTES) via a simple sol‐gel technique in a one‐pot synthesis to give RHAPrSH and RHAPrNH₂. The ²⁹Si MAS NMR of RHAPrSH and RHAPrNH₂ showed the presence of T¹, T², T³, Q², Q³ and Q⁴ silicon centers. The ¹³C MAS NMR showed that RHAPrSH had chemical shifts at δ 16.59, 32.73, consistent with two of the carbon atoms of the MPTMS moiety, while the ¹³C MAS NMR of RHAPrNH₂ had chemical shifts at δ 14.58, 26.13, 47.87, consistent with the three carbon atoms of the APTES moiety. The presence of carbon, silicon, sulfur and nitrogen in RHAPrSH and RHAPrNH₂ was determined by a combination of elemental analysis and EDX study.     

Lithium‐Doped Silica‐Rich MIL‐101(Cr) for Enhanced Hydrogen Uptake

Metal‐organic frameworks (MOFs) show promising characteristics for hydrogen storage application. In this direction, modification of under‐utilized large pore cavities of MOFs has been extensively explored as a promising strategy to further enhance the hydrogen storage properties of MOFs. Here, we described a simple methodology to enhance the hydrogen uptake properties of RHA incorporated MIL‐101 (RHA‐MIL‐101, where RHA is rice husk ash—a waste material) by controlled doping of Li⁺ ions. The hydrogen gas uptake of Li‐doped RHA‐MIL‐101 is significantly higher (up to 72 %) compared to the undoped RHA‐MIL‐101, where the content of Li⁺ ions doping greatly influenced the hydrogen uptake properties. We attributed the observed enhancement in the hydrogen gas uptake of Li‐doped RHA‐MIL‐101 to the favorable Li⁺ ion‐to‐H₂ interactions and the cooperative effect of silanol bonds of silica‐rich rice‐husk ash incorporated in MIL‐101.     

Rice Husk Ash: A New,Cheap, Efficient,and Reusable Reagent for the Protection of Alcohols,Phenols, Amines,and Thiols

Abstract

A mild, efficient, and eco-friendly protocol for the protection of alcohols and phenols as trimethylsilyl ethers has been developed using rice husk ash as a reagent. This reagent is also able to catalyze the acetylation of alcohols, phenols, thiols, and amines with acetic anhydride. All reactions were performed under mild conditions in good to high yields.

[Supplementary materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements for the following free supplemental files: Additional text, tables, and figures.]     

Adsorption Kinetics,Equilibrium, and Thermodynamics of Copper From Aqueous Solutions using Silicon Carbide Derived from Rice Waste

Adsorption of Cu(II) from aqueous solution on a novel adsorbent, silicon carbide ash (SiC ash), was studied using batch technique. The adsorbent was prepared by pyrolysis of Egyptian rice waste (rice straw and rice husk) and was characterized by scanning electron microscopy (SEM), energy-dispersive x-ray (EDX), Fourier-transform infrared (FTIR) spectroscopy, x-ray diffraction (XRD), and surface area analysis by Brunauer-Emmett-Teller (BET) Theory. The influence of pH, contact time, initial Cu(II) concentration, adsorbent dose, agitation speed, and temperature was investigated. Adsorption kinetics was analyzed using the pseudo-first-order, the pseudo-second-order, and intraparticular diffusion model. The adsorption process was found to follow a pseudo-second-order rate mechanism. The adsorption isotherm data could be well described by the Langmuir and Freundlich than the Dubinin–Radushkevich adsorption model. The adsorption capacity of 22.06 mg g^?1for SiC ash was obtained at pH = 5 and temperature of 298 K. Thermodynamic parameters, change in the free energy (ΔG°), the enthalpy (ΔH°), and the entropy (ΔS°), were also calculated. The overall adsorption process was exothermic, spontaneous in nature, and proceeds with decreased randomness as the entropy is negative value. Adsorption process was successfully applied to remove Cu(II) from an industrial wastewater sample.     

Rice husk ash as an adsorbent for methylene blue—effect of ashing temperature

Utilization of one waste material to control pollution caused by another is of high significance in the remediation of environmental problems. Rice husk, an abundantly available agricultural waste, can be used as a low cost adsorbent for dyes and heavy metals in effluent streams. The possible utilization of rice husk ash as an adsorbent for methylene blue dye from aqueous solutions has been investigated. Ash samples from husks of two origins were prepared at different temperatures and their physical, chemical spectroscopic and morphological properties were determined. XRD, FTIR and SEM were some of the techniques adopted for the characterization. The samples were also analyzed for bulk density, pH, nitrogen adsorption properties and lime reactivity. Experiments of methylene blue adsorption on the ash samples were conducted using batch technique and a comparative study was made. Results were analyzed using linear, Langmuir and Freundlich isotherms. The values of separation factor indicate that most of the ash samples do adsorb the dye molecules, but in varying quantities. Calcination at 900^∘C reduces the adsorption capacity of the ash to a great extent. Regression analysis shows that the experimental data fits both Langmuir and Freundlich isotherms for certain concentration limits. The adsorbate species are most probably transported from the bulk of the solution into the solid phase through intra-particle diffusion process. Kinetics of adsorption was found to follow pseudo second order rate equation with R ²∼ 0.99. The highest adsorption capacity (Q ₀) achieved is found to be ∼690 mg/g, which is even higher than the values reported for activated carbon from rice husk. The adsorption capacity of the ash samples are in good agreement with their surface area and pore volume.     

Characterization of rice husks and the products of its thermal degradation in air or nitrogen atmosphere

Rice husk is a by-product of rice milling process and are a major waste product of the agricultural industry. They have now become a great source as a raw biomass material for manufacturing value-added silicon composite products, including silicon carbide, silicon nitride, silicon tetrachloride, pure silicon, zeolite, fillers of rubber and plastic composites, adsorbent and support of catalysts. The bulk and true densities of raw rice husk with different moisture and sizes were determined. The rice husk was subjected to pyrolysis in fluidized-bed reactor in air or nitrogen atmosphere. The products obtained were characterized by thermogravimetric and X-ray powder analysis, IR-spectroscopy, scanning electron microscopy and nitrogen adsorption at 77 K. The specific surface area of the products is comparable with this of γ-Al₂O₃. The kinetics of H₂SeO₃ adsorption out of aqueous solutions at 298 K was studied. The adsorption capacity of white rice husks ash was found to be higher than that of black rice husk ash and the adsorption kinetics obeyed the second order kinetic equation.     

Effects of active silicon uptake by rice on 29Si fractionation in various plant parts

Rice (Oryza sativa L.) accumulates large amounts of silicon which improves its growth and health due to enhanced resistance to biotic and abiotic stresses. Silicon uptake and loading to xylem in rice are predominantly active processes performed by transporters encoded by the recently identified genes Lsi1 (Si influx transporter gene) and Lsi2 (Si efflux transporter gene). Silicon deposition in rice during translocation to upper plant tissues is known to discriminate against the heavier isotopes ²⁹Si and ³⁰Si, resulting in isotope fractionation within the plant. We analyzed straw and husk samples of rice mutants defective in Lsi1, Lsi2 or both for silicon content and δ²⁹Si using isotope ratio mass spectrometry (IRMS) and compared these results with those for the corresponding wild‐type varieties (WT). The silicon content was higher in husk than in straw. All the mutant rice lines showed clearly lower silicon content than the WT lines (4–23% Si of WT). The δ²⁹Si was lower in straw and husk for the uptake defective mutant (lsi1) than for WT, albeit δ²⁹Si was 0.3‰ higher in husk than in straw in both lines. The effect of defective efflux (lsi2) differed for straw and husk with higher δ²⁹Si in straw, but lower δ²⁹Si in husk while WT showed similar δ²⁹Si in both fractions. These initial results show the potential of Si isotopes to enlighten the influence of active uptake on translocation and deposition processes in the plant. Copyright © 2009 John Wiley & Sons, Ltd.     

稻壳灰负载FeCl2·2H2O:一个温和高效的多相催化剂用于Friedlnder杂成环反应合成多取代喹啉（英文）

Rice husk ash was used as a new, green, and cheap adsorbent for FeCl3. Characterization of the obtained reagent showed that rice husk ash supported FeCl2·2H2O was formed. This reagent is efficient at catalyzing the synthesis of multisubstituted quinolines by the Friedl鋘der heteroannulation of o‐aminoaryl ketones with ketones or β‐diketones under mild reaction conditions. This methodology allows for the synthesis of a broad range of substituted quinolines in high yields and with excellent regioselectivity in the absence of a solvent.     

A review on recent advances in the comprehensive application of rice husk ash

Research on Chemical Intermediates - Rice husk ash, which is rich in non-crystalline silica, is a by-product material obtained from the combustion of rice husk. Because rice husk ash is available...     

Ionic conductivity enhancement in the solid polymer electrolyte PEO9LiTf by nanosilica filler from rice husk ash

Rice husk ash is a cheap raw material available in abundance in rice-growing countries. It contains around 85–90 % amorphous silica. Rice husk ash, when subjected to a simple chemical precipitation method, will produce nanosilica which can be used for many industrial and technological applications. In this work, we have successfully synthesized nano-sized silica from local rice husk ash and prepared the nanocomposite solid polymer electrolyte, PEO₉LiTf:SiO₂. The resulting electrolyte has been characterized by X-ray diffraction, differential scanning calorimetry, atomic force microscopy, Fourier transform infrared spectroscopy, and complex impedance spectroscopy. The electrolyte shows about a 12-fold increase in ionic conductivity at room temperature due to the silica filler. In the nanocomposite electrolyte, nanosilica particles obtained from rice husk ash behaved very similarly to the commercial grade nanosilica and had a size distribution in the 25- to 40-nm range. As already suggested by us and by others, the O^2? and OH^? surface groups in the filler surface interact with the Li⁺ ions and provide hopping sites for migrating Li⁺ ions through transient H bonding, creating additional high-conducting pathways. This would contribute to a substantial conductivity enhancement through increased ionic mobility. An additional contribution to conductivity enhancement, particularly at temperatures below 60 °C, appears to come from the increased fraction of the amorphous phase, as evidenced from the reduced crystallite melting temperature and the reduced enthalpy of melting due to the presence of the filler.     

Production of High Purity Amorphous Silica from Rice Husk

Combustion of the rice husk produces rice husk ash, which consists of mainly silica. High purity silica can be produced by controlled combustion after acid treatment. In this study, leaching of rice husk with hydrochloric acid and sulfuric acid were carried out prior to combustion to obtain purer silica. It was found that pre-treatment of the rice husk with sulfuric acid had accelerated the hydrolysis and decomposition of organic components as revealed by thermogravimetry (TG) and Scanning Electron Microscopy (SEM) analyses. In a systematic study, the combustion of un-leached, hydrochloric acid-leached and sulfuric acid-leached rice husks were performed in a muffle furnace at 500, 600, 700, 800 and 900^oC for 2 h. Results demonstrated that all the samples produced amorphous silica (SiO₂) and the average particle size were in the range of 0.50 to 0.70 μm. The effect of combustion at different temperatures between 500^oC and 900^oC on the silica production is very small, particularly at temperature above 600^oC. Thus, amorphous silica with purity above 99% as confirmed by X-Ray Fluorescence (XRF) analysis can be produced by hydrochloric and sulfuric acids leaching of the rice husk, followed by controlled combustion at 600^oC for 2 h. The BET surface area of the silica produced after leaching the rice husk with hydrochloric acid was higher (218 m²/g) than with sulfuric acid (209 m²/g). The silica obtained has potential application as filler in plastics and rubber compounding.     

Effect of thermal treatment of rice husk ash on the surface properties of hydrated lime-rice husk ash binders

Rice husk ash fired at different temperatures, 450, 700 and 1000°C, was mixed with different concentrations of lime (molar lime/silica ash ratio of 0.2, 0.5 and 1.0). Each dry mixture was first ground and hydrated in the suspension form (water/solid ratio = 10) for various time intervals within the range of 1 to 365 days. The surface properties of the unhydrated and hydrated samples were studied by means of nitrogen adsorption measurements. The results indicated that the surface areas and total pore volumes of unhydrated solid mixtures and hydrated lime-rice husk ash samples, prepared with lime/silica ash ratio of 1.0, decrease with increasing firing temperature of rice husk ash. The effect of varying the lime/silica ash ratio of the solid mixture on the surface area and pore structure was fully discussed. The results of surface area and pore volume measurements could also be related to the crystal structure of silica produced from rice husk ash.     

Nontargeted GC–MS approach for volatile profile of toasting in cherry,chestnut, false acacia,and ash wood

By using a nontargeted GC–MS approach, 153 individual volatile compounds were found in extracts from untoasted, light toasted and medium‐toasted cherry, chestnut, false acacia, as well as European and American ash wood, used in cooperage for aging wines, spirits and other beverages. In all wood types, the toasting provoked a progressive increase in carbohydrate derivatives, lactones and lignin constituents, along with a variety of other components, thus increasing the quantitative differences among species with the toasting intensity. The qualitative differences in the volatile profiles allow for identifying woods from cherry (being p‐anisylalcohol, p‐anisylaldehyde, p‐anisylacetone, methyl benzoate and benzyl salicylate detected only in this wood), chestnut (cis and trans whisky lactone) and false acacia (resorcinol, 3,4‐dimethoxyphenol, 2,4‐dihydroxy benzaldehyde, 2,4‐dihydroxyacetophenone, 2,4‐dihydroxypropiophenone and 2,4‐dihydroxy‐3‐methoxyacetophenone), but not those from ash, because of the fact that all compounds present in this wood are detected in at least one other. However, the quantitative differences can be clearly used to identify toasted ash wood, with tyrosol being most prominent, but 2‐furanmethanol, 3‐ and 4‐ethylcyclotene, α‐methylcrotonolactone, solerone, catechol, 3‐methylcatechol and 3‐hydroxybenzaldehyde as well. Regarding oak wood, its qualitative volatile profile could be enough to distinguish it from cherry and acacia woods, and the quantitative differences from chestnut (vanillyl ethyl ether, isoacetovanillone, butirovanillone, 1‐(5‐methyl‐2‐furyl)‐2‐propanone and 4‐hydroxy‐5,6‐dihydro‐(2H)‐pyran‐2‐one) and ash toasted woods. Copyright © 2014 John Wiley & Sons, Ltd.     

长治煤与生物质混合灰熔融特性研究

采用灰熔点测定仪、X射线荧光仪、X射线衍射仪和FactSage软件相结合对生物质（花生壳、稻壳）与高灰熔点长治煤混合灰的熔融特性及其熔融机制进行了研究。结果表明,两种生物质灰都可以降低长治煤的灰熔融温度,花生壳灰助熔效果优于稻壳灰,这主要与它们的化学组成和赋存形态有关。低熔点长石类矿物（钙长石、钠长石）和白榴石的生成是花生壳与长治煤混合灰熔融温度降低的主要原因;长石类矿物的生成及其与SiO₂结合生成的低温共熔物引起稻壳与长治煤混合灰熔融温度降低。热力学计算表明,在碱性氧化物Na₂O、CaO、K₂O存在时,SiO₂和Al₂O₃优先与其反应生成低熔点硅铝酸盐,一定程度上抑制了高熔点莫来石矿物的生成,从而起到助熔作用。混合灰的熔融过程可以分为含钾矿物熔融和含钙矿物熔融两个阶段,两类矿物熔融顺序：含钾矿物先于含钙矿物。     

Preparation,characterization and application of RHA/TiO2 nanocomposites in the acetylation of alcohols,phenols and amines

In this work, anatase-phase nano-titania was prepared by embedding in rice husk ash, and identified using a variety of techniques. The obtained nanocomposite (RHA/TiO₂) was used as a green and inexpensive catalyst for the promotion of the acetylation of alcohols, phenols and amines with Ac₂O at room temperature under solvent free conditions. The procedure gave the products in excellent yields during all reaction times. Also this catalyst can be reused for several times without loss of its catalytic activity.     

Thermal insulations from rice husk ash,an agricultural waste

Rice husk ash, an agricultural waste material, is available in large quantitaties in the rice paddy growing countries of the world at little or no cost. This ash is highly porous, mostly silica and possesses refractory and thermal insulation properties. It is therefore an attractive starting raw material for the manufacture of low to moderate cost thermal insulations for dryers, ovens, kilns and furnaces, including those employed in the ceramic industry. This paper deals with manufacture, properties and usage of a spectrum of low to high temperature thermal insulations and insulating refractories that can be made from rice husk ash, namely: (i) Calcium ferrite bonded porous silica refractory: (ii) Sodium silicate bonded porous silica refractory; (iii) Fired and chemically bonded forsterite insulating refractory; (iv) Hydraulic setting calcium silicate/silica thermal insulation.     

Fixation capability of recycling materials as potential additives for cesium immobilization in contaminated forest soil

The fixation capability of cesium on five recycling materials was compared through two sets of sorption experiments using the materials mixed with and without soil. The estimated Freundlich constant K and the distribution of sorbed cesium on the materials revealed a general order of the fixation capability as carbonized sludge > coconut shell biochar > incinerated sewage sludge ash > rice husk biochar > slag. Parametric strong positive correlations were found existent between the fixation capability of cesium and the property-related indexes of the materials such as cation exchange capacity, organic matter content and the potassium concentration.

     

Development and characterization of fully bio‐based polybenzoxazine‐silica hybrid composites for low‐k and flame‐retardant applications

In the present work, new classes of bio‐based polybenzoxazines were synthesized using eugenol as phenol source and furfurylamine and stearylamine as amine sources separately through solventless green synthetic process routes and were further reinforced with varying percentages (1, 3, 5, and 10 wt%) of silica (from rice husk) to attain hybrid composites. The molecular structure, cure behaviour, thermal stability, dielectric properties, and flame‐retardant behaviour of both benzoxazine monomers and benzoxazine composites were characterized using appropriate modern analytical techniques. The eugenol‐based benzoxazines synthesized using furfurylamine (FBz) and stearylamine (SBz) were cured at 223°C and 233°C, respectively. The differential scanning calorimetry (DSC) data reveal the glass transition temperatures (T_g) of FBz and SBz were 157°C and 132°C, respectively, and the maximum decomposition temperature (T_max) as obtained from thermogravimetric analysis (TGA), were found to be 464°C and 398°C for FBz and SBz, respectively. The dielectric constants for FBz and SBz obtained at 1 MHz were 3.28 and 3.62, respectively. Furthermore, varying weight percentages (1, 3, 5, and 10 wt%) of 3‐mercaptopropyltrimethoxysilane (3‐MPTMS) functionalized bio‐silica reinforced the composite materials as evidenced by their improved thermal stability and lower dielectric constant. Data obtained from thermal and dielectric studies suggested that these polybenzoxazines could be used in the form of adhesives, sealants, and composites for high performance inter‐layer low‐k dielectric applications in microelectronics.     

Preparation of super-hydrophobic white carbon black from nano-rice husk ash

Nano-rice husk ashes were prepared by burning rice husk with a self-propagating method. The white carbon black with high purity was prepared by an alkali dissolving–acid reaction method from nano-husk ash. The super-hydrophobic SiO₂ films were prepared by the sol–gel method using hexamethyldisilazane as a modifier. The effects of the pH and reaction time in the acid reaction process on the purity of the white carbon black, and the effect of the modifier on the hydrophobic property of SiO₂ films were studied. The performances were characterized by XRD, BET, SEM, IR, and contact angle analyzer. The results showed that the purity of white carbon black reached 98.48 % when the NaOH solution with the rice husk ash was heated for 2 h at 90 °C, then the pH of the solution was adjusted by sulfuric acid to 3, and the acid reaction time was 2 h. The contact angle of SiO₂ films was more than 160° when volume ratio of the modifier to silica–sodium hydroxide mixed solution was 0.15. The mechanism of the modifier on SiO₂ surfaces is a graft copolymerization. The hydrophobic groups in the modifier replace the hydroxy groups on SiO₂ surfaces and make SiO₂ surfaces present super-hydrophobicity.