碳酸盐活化稻壳制备高比表面积多孔炭

本文采用碳酸盐作为活化剂,活化稻壳,制备出具有介孔结构的高比表面积多孔炭。利用孔径分布、氮气吸附-脱附曲线以及透射电子显微镜表征了多孔炭的孔结构及形貌。碳酸钾活化稻壳制备出的多孔炭比表面积高达1860m2/g,孔径呈单分布,大小为2～3nm。同时通过活化条件和热重分析曲线探讨了碳酸盐的活化机理。     

聚乙二醇-400中磺化稻壳灰催化2-取代苯并噁唑的合成

以邻氨基苯酚（1）和芳醛（2a~2i）［或脂肪醛（2j, 2k）］为原料,聚乙二醇(PEG-400)为溶剂,稻壳灰负载氯磺酸（AC）为固体酸催化剂,采用超声辅助的“一锅法”合成了11个2-取代苯并噁唑(3a~3k),其结构经¹H NMR, IR和元素分析确证。以3a和3j的合成为例,优化了反应条件。结果表明：在最优合成条件［1 1 mmol, 2 1.2 mmol, AC 10 mol%, PEG-400 5 mL,于200 W超声30 min(3a)或60 min(3j)］下,3a和3j收率分别为92.4%和82.4%。 AC重复使用5次,3a收率84.7%。 PEG-400回收率约79%。     

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.]     

Preparation,Characterization and Antimicrobial Properties of Nanosized Silver-Containing Carbon/Silica Composites from Rice Husk Waste

Rice husk, one of the main side products in the rice production, and its sustainable management represent a challenge in many countries. Herein, we describe the use of this abundant agricultural bio-waste as feedstock for the preparation of silver-containing carbon/silica nano composites with antimicrobial properties. The synthesis was performed using a fast and cheap methodology consisting of wet impregnation followed by pyrolysis, yielding C/SiO₂ composite materials doped with varying amounts of silver from 28 to 0.001 wt %. The materials were fully characterized and their antimicrobial activity against ESKAPE pathogens, namely E. faecium, S. aureus, K. pneumoniae, A. baumannii, P. aeruginosa, and E. coli, and the pathogenic yeast C. albicans was investigated. Sensitivities of these strains against the prepared materials were demonstrated, even with exceptional low amounts of 0.015 m% silver. Hence, we report a straightforward method for the synthesis of antimicrobial agents from abundant sources which addresses urgent questions like bio-waste valorization and affordable alternatives to increasingly fewer effective antibiotics.     

Iron Carbonyl Thiourea Hybrid Material Based on Functionalised Silica from Rice Husk Ash for Oxidation of Limonene

Iron carbonyl thiourea, RHACP1Fe was successfully immobilized onto inorganic silica support from rice husk ask via chloropropyltriethoxysilane (CPTES) and the resulting catalyst was labelled as RHACP1Fe. This mesoporous organic-inorganic hybrid catalyst showed a specific surface area of 245.0 m²g^-1. The ²⁹ Si MAS NMR solid state spectrum showed the presence of Q⁴, Q³, T³ and T² silicon centres in RHACP1Fe. The oxidation of limonene with H₂O₂ was studied using RHACP1Fe. A moderate selectivity to the desired product (limonene peroxide) of 67% and a maximum limonene conversion of 60% was achieved. RHACP1Fe could be reused several times without losing its catalytic activity.     

Synthesis,Characterization, and Catalytic Behavior of Bamboo Rice Husk Ash

In this paper, we report the use of bamboo rice husk ash as an efficient, greener, reusable, and biodegradable heterogeneous catalyst for the synthesis of tetrahydro‐4H ‐chromene‐3‐carbonitriles via the one‐pot three‐component reaction of malononitrile with aromatic aldehydes and dimedone or 1,3‐cyclohexanedione. The formation of bamboo rice husk ash‐silica has been confirmed by several analytical techniques.     

丁腈橡胶的XeF2表面氟化改性研究

丁腈橡胶表面经ＸｅＦ２处理后，介质性能有显著的提高，摩擦系数降低６～８倍．用ＸＰＳ法研究了氟化处理的丁腈橡胶表面结构，并用曲线拟合分峰技术对Ｃ１ｓ谱进行数学处理．结果表明，随着氟化时间延长，橡胶表面氢被氟取代逐步生成—ＣＨ２—ＣＨＦ—ＣＨ２—、—ＣＨＦ—ＣＨ２—ＣＨＦ—和—ＣＨＦ—ＣＨＦ—ＣＨＦ—等．ＳＥＭ照片显示氟化膜厚度可达８～９μｍ．     

Properties of Natural Rubber/Recycled Chloroprene Rubber Blend: Effects of Blend Ratio and Matrix

The present study investigated the effects of two types of natural rubber and different blend ratios on the cure, tensile properties and morphology of natural rubber/recycled chloroprene rubber blends. The blends of natural rubber/recycled chloroprene rubber were prepared by using laboratory two-roll mill. The result showed that the cure time prolonged with the addition of recycled chloroprene rubber (rCR). Comparability, natural rubber/recycled chloroprene rubber (SMR L/rCR) blendcured rapidly than epoxidized natural rubber/recycled chloroprene rubber (ENR 50/rCR) blend. The addition of rCRalso caused a decrement in the tensile strength and elongation at break for both rubber blends. The SMR L/rCR blendsshowed higher tensile strength and elongation at break compared to those of ENR 50/rCR blends at any blend ratios.     

Chemical Modification of Upgraded Bentonite as Filler of Natural Rubber/Organobentonite Composite

Bentonite is an abundant natural resource that has great prospects for used as filler in natural rubber industry after certain modification, either through physical or chemical process. Reduction of mineral impurities in the bentonite was done to form upgraded bentonite by using hydrocyclone, and chemical modification of upgraded bentonite to form organobentonite was done by addition of commercially surfactant. Natural rubber/organobentonite composites made by melting compound technique at roll mill. The results showed that the reduction process of mineral impurities in the bentonite had been able to reduce the content of impurities, such as Fe₂O₃, CaO, and K₂O. Meanwhile, by using XRD dan FTIR analysis, an increase in the dose of surfactant on upgraded bentonite might increase the organic content and basal spacing of organobentonite. Low mineral impurities organobentonite was capable of producing natural rubber/organobentonite composite with faster vulcanization time and some better mechanical properties (such as elongation at break and modulus 100%) than natural rubber/carbon black composite.     

Hollow Reticular Shaped Highly Ordered Rice Husk Carbon for the Simultaneous Determination of Dopamine and Uric Acid

We have prepared activated porous carbon material through simple pyrolysis method from rice husks (rhAC) for sensitive detection of dopamine (DA) and uric acid (UA). The prepared rhAC material was thoroughly characterized using various spectroscopic, microscopic, and electroanalytical techniques. Analysis of the voltammetric data showed that the analytes followed a first order reaction kinetics while following a 2e^?/2H⁺ transfer process. We have discussed the possible oxidation mechanism for the analytes based on the results from our experimental analysis. The rhAC_GCE sensor was tested for interference, reproducibility, and stability. The sensor was also tested to evaluate its applicability in real life.     

Curing and Physical Properties of Natural Rubber/Wood Flour Composites

Natural rubber based composites were prepared by incorporating Wood flour of two different particle size ranges (250–300 µm) and (300–425 µm) and concentrations (15 and 30 phr) into the matrix, using a Banbury® internal mixer according to a base formulation. Curing characteristics of the samples were studied. Influence of particle size and loading of filler on the properties of the composites was analyzed. Results obtained show that the addition of wood flour to natural rubber increased scorch time and curing time and caused improvement in modulus at 300% strain and in tear properties. However, it decreased tensile strength and elongation at break. The particle size range of 300–425 µm was found to offer the best overall balance of mechanical and dynamic properties (tan δ and viscous torque). Swelling behavior of the composites in toluene was also analyzed in order to determine the rubber volume fraction and crosslinking density. Composites with the bigger particle size wood flour were found to have greater crosslinking density than the ones with smaller particle size, fact that could possibly indicate a better rubber-filler interaction in the former. Major percentage of filler increased slightly this interaction. Water absorption behavior of the composites with wood flour reached a maximum of 12% w/w when 30 phr of filler were incorporated; nonetheless, particle size did not affect this property. The ageing study in presence of air at 70 °C revealed that natural rubber composites with wood flour maintained the same classification cell with temperature as the pure rubber. A compound with 30 phr of carbon black was prepared for comparative purposes. Results obtained were as expected. Scorch time decreased and higher values of modulus at 300% strain and tensile strength were achieved, due to strongest interaction between filler and elastomer.     

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.     

稀土化合物改性炭黑/天然橡胶复合材料的制备与性能

用铕（Eu）、钬（Ho）、饵（Er）和镝（Dy）4种稀土（Ln）氧化物（Ln2O3）制备了稀土氢氧化物改性炭黑，然后加入天然胶乳（NRL），采用凝聚共沉法制备了粉末状的稀土改性炭黑，天然橡胶复合材料P[NR／HAF-Ln（OH）3]。研究了稀土种类和用量对P[NR／HAF-Ln（OH）3]的粒径分布及其硫化胶物理机械性能的影响。结果表明，稀土可以提高NRL与乳化炭黑构成的粉末体系的成粉率，当Ho，Er的用量为1．0％或Dy的用量为0．5％时均可使粒径小于0．9mm的产物达100％；稀土的存在可显著提高P[NR／HAF-Ln（OH）3]硫化胶的拉伸强度和撕裂强度，而Er和Dy还可明显降低硫化胶的永久变形；SEM分析表明，HAF-Dy（OH）3以团粒形态存在于NR基体中，团粒表面覆盖一层NR膜，团粒与NR构成的界面模糊，说明HAF-Dy（OH）3与NR基体结合紧密，这是P[NR／HAF-Ln（OH）3]具有较好物理机械性能的主要原因。     

稻壳基二氧化硅/碳复合材料的表面改性及对天然橡胶的影响

以稻壳基二氧化硅/碳复合材料(SiCB)作为天然橡胶(NR)的补强填料, 采用表面化学改性的方法将天然乳胶(NRL)接枝到SiCB表面, 改善其与NR基体的相容性. 研究了不同处理方法对接枝NRL效率的影响, 以及填料填入NR后对硫化橡胶力学性能的影响. 结果表明, 经过硝酸和γ-(甲基丙烯酰氧)丙基三甲氧基硅烷(γ-MPTMS)预处理, NRL能高效接枝在SiCB表面, 得到的样品SiCB_MR10比未处理的SiCB_P有更强的补强能力. 硫化胶NR/SiCB_MR10的拉伸强度、 300%定伸和撕裂强度较NR/SiCB_P分别提高了61.06%, 27.15%和15.90%, 与传统炭黑产品N774填充的硫化胶NR/N774的力学性能相近. 经过NRL接枝改性的SiCB_MR10具有替代商业炭黑的应用前景.     

Effect of Electron Beam Irradiation on the Properties of High Styrene Rubber/Styrene Butadiene Rubber Blends

High styrene rubber (HSR)/styrene butadiene rubber (SBR) blends at different ratios were exposed to various doses of electron beam irradiation. The effect of irradiation dose and blend ratios on the mechanical properties and shape memory characteristics in terms of strain fixation) rate (R_f) and strain recovery rate (R_r) was investigated. The results revealed that rich styrene blends displayed higher tensile strength and hardness than low styrene content blends at all irradiation doses. However, elongation at break, and toughness were lower for rich styrene content. Also, it was observed that for most specimens, the tensile strength, elongation at break and hardness increases up to100 kGy. Increasing irradiation doses resulted in slight deterioration in some mechanical properties only for low styrene content at150 kGy. According to the normalized tensile stress at 25% elongation, it was found that the contribution of irradiation in enhancing the mechanical properties is higher for rich butadiene blends. On the other hand, it was observed that rich styrene content blends possess higher R_f and R_r at all the irradiation doses and stretching temperatures. However, the increase of irradiation dose decreases R_f values; the extent of this decrease depends on the blend ratios. Conversely, for all blends, R_r were increased by increasing irradiation dose and styrene content ratios.     

Effect of the Coating of the Polymer Blend (Polyacrylamide/PEG 6000) on the Efficiency of Rice Husk as a Pesticide Carrier

In recent years the utilization of fibers and powders derived from agricultural sources has become a subject of interest. However, they have been exploited only from an engineering point of view, and the strong ability of agricultural wastes as a carrier for agrochemical formulations has been ignored. A study has been made on the possibility of using such an agrochemical waste, namely rice husk, which is readily available and biodegradable, as a carrier for pesticide formulation. The solid formulations were prepared by adsorbing deltamethrin on the rice husk. The deltamethrin‐adsorbed rice husk is then coated with the polymer blend of Polyacrylamide and PEG 6000 in varying ratios between the deltamethrin‐adsorbed rice husk and the polymer blend. The formulations were characterized by analytical methods such as FTIR and XRD techniques. Important physical properties from the formulation standpoint, such as solubility, dispersion stability, and wettability, were studied.     

A New Protocol for Ash Wood Modification: Synthesis of Hydrophobic and Antibacterial Brushes from the Wood Surface

The article presents the modification of ash wood via surface initiated activators regenerated by electron transfer atom transfer radical polymerization mediated by elemental silver (Ag⁰ SI-ARGET ATRP) at a diminished catalyst concentration. Ash wood is functionalized with poly(methyl methacrylate) (PMMA) and poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) to yield wood grafted with PMMA-b-PDMAEMA-Br copolymers with hydrophobic and antibacterial properties. Fourier transform infrared (FT-IR) spectroscopy confirmed the covalent incorporation of functional ATRP initiation sites and polymer chains into the wood structure. The polymerization kinetics was followed by the analysis of the polymer grown in solution from the sacrificial initiator by proton nuclear magnetic resonance (¹H NMR) and gel permeation chromatography (GPC). The polymer layer covalently attached to the wood surface was observed by scanning electron microscopy (SEM). The hydrophobic properties of hybrid materials were confirmed by water contact angle measurements. Water and sodium chloride salt aqueous solution uptake tests confirmed a significant improvement in resistance to the absorption of wood samples after modification with polymers. Antibacterial tests revealed that wood-QPDMAEMA-Br, as well as wood-PMMA-b-QPDMAEMA-Br, exhibited higher antibacterial activity against Gram-positive bacteria (Staphylococcus aureus) in comparison with Gram-negative bacteria (Escherichia coli). The paper presents an economic concept with ecological aspects of improving wood properties, which gives great opportunities to use the proposed approach in the production of functional hybrid materials for industry and high quality sports equipment, and in furniture production.     

粉煤灰漂珠负载Bi2WO6复合材料的制备及光催化性能研究

以工业固体废弃物粉煤灰漂珠(fly ash cenospheres, FACs)为载体, 采用水热法制备了新颖的漂珠负载Bi₂WO₆复合材料(Bi₂WO₆/FACs), 通过X射线衍射(XRD), 扫描电子显微镜(SEM), X-射线光电子能谱(XPS), 和紫外-可见漫反射光谱(DRS)技术对其进行了表征。XRD数据显示了正交相Bi₂WO₆的特征衍射峰。DRS结果证实了引入FACs后Bi₂WO₆对可见光的吸收增强。在可见光的照射下, 以亚甲基蓝溶液的光催化降解评价了Bi₂WO₆/FACs复合材料的光催化性能。结果表明：Bi₂WO₆/FACs的光催化性能优于纯Bi₂WO₆的, 其一级反应速率常数(k)为后者的2.4倍。尤其是由于漂珠质轻中空的特性, Bi₂WO₆/FACS复合光催化剂可长时间漂浮于水面, 既能充分吸收光能, 又有利于催化剂的回收和重复利用。     

粉煤灰漂珠负载Bi2WO6复合材料的制备及光催化性能研究

以工业固体废弃物粉煤灰漂珠(fly ash cenospheres,FACs)为载体,采用水热法制备了新颖的漂珠负载Bi2WO6复合材料(Bi2WO6/FACs),通过X射线衍射(XRD),扫描电子显微镜(SEM),X-射线光电子能谱(XPS),和紫外-可见漫反射光谱(DRS)技术对其进行了表征。XRD数据显示了正交相Bi2WO6的特征衍射峰。DRS结果证实了引入FACs后Bi2WO6对可见光的吸收增强。在可见光的照射下,以亚甲基蓝溶液的光催化降解评价了Bi2WO6/FACs复合材料的光催化性能。结果表明:Bi2WO6/FACs的光催化性能优于纯Bi2WO6的,其一级反应速率常数(k)为后者的2.4倍。尤其是由于漂珠质轻中空的特性,Bi2WO6/FACS复合光催化剂可长时间漂浮于水面,既能充分吸收光能,又有利于催化剂的回收和重复利用。