共查询到18条相似文献,搜索用时 62 毫秒
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木薯羧甲基淀粉对铜离子的吸附性能 总被引:2,自引:0,他引:2
采用搅拌球磨机对木薯淀粉进行机械活化,以活化60 min的木薯淀粉为原料,干法合成羧甲基淀粉吸附剂。考察羧甲基淀粉的取代度、溶液的pH值、Cu2+的初始浓度、吸附时间、羧甲基淀粉的投加量等因素对羧甲基淀粉吸附Cu2+性能的影响。结果表明,该羧甲基淀粉对Cu2+有很好的吸附作用;用取代度为0.841的羧甲基淀粉处理含Cu2+的废水,在pH=7.0、羧甲基淀粉的投加量50.00 mg/L、吸附时间15 min时,羧甲基淀粉对废水中Cu2+的吸附率高达98.80%,处理后的水质达到国家污水综合排放标准(GB8978-1996)中一级标准要求。 相似文献
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以过硫酸铵为引发剂,N,N’-亚甲基双丙烯酰胺为交联剂,制备氧化淀粉―丙烯酸―丙烯酰胺高吸水性树脂,并采用红外光谱、X射线衍射等手段对产品的结构进行表征。通过单因素实验优化其制备工艺,最佳工艺条件为:氧化淀粉基体用量为50%,丙烯酸/丙烯酰胺质量比为4∶1,丙烯酸中和度为70%,引发剂过硫酸铵用量为0.5%,交联剂N,N’-亚甲基双丙烯酸胺用量为0.15%,反应温度为80℃,反应时间为3 h。此条件下,氧化淀粉基高吸水性树脂的吸水率达到972.4 g/g。 相似文献
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"氧化还原"认知结构的重建 总被引:1,自引:1,他引:0
针对氧化还原的教学现状,依据有关理论,重新设计了氧化还原的认知结构和实施过程,并通过具体实践和效果评估进行了试验研究,以教学设计的校本研究方式呈现了研究结果。 相似文献
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木质素脱甲基化改性及产物结构表征 总被引:1,自引:0,他引:1
通过对不同催化剂、催化剂量、反应温度和反应时间等反应条件下得到的改性木质素与甲醛反应活性的研究,确定了木质素脱甲基化反应条件,并通过FT-IR半定量、GPC1、H NMR对木质素脱甲基化前后结构进行表征。FT-IR半定量表明木质素甲氧基由反应前的0.990降至0.765,酚羟基由1.174增至1.529;GPC表明木质素脱甲基化后大分子木质素发生了降解,分子量小于2000的木质素含量由由改性前的38%增至改性后的51%;1H NMR表明木质素改性后脂肪族侧链与苯环分离,同时大量-βO-4醚键裂解。 相似文献
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M. S. Balathanigaimani Wang‐Geun Shim Chan Kim Jae‐Wook Lee Hee Moon 《Surface and interface analysis : SIA》2009,41(6):484-488
A novel corn grain precursor was used for the preparation of activated carbon by chemical activation. The detailed investigation of the porosity development in the prepared activated carbon was done by altering the various activation conditions such as the activation temperature, activation time and ratio between the powdered form of carbonized corn grain char and KOH. The surface characteristics including the surface roughness of all the activated carbon samples were evaluated from the analysis of nitrogen (N2) adsorption isotherm data. At the maximum of 2978 m2/g, a super surface area having the corn grain‐based activated carbon (CG‐AC) was synthesized by using the following conditions: 1/4 ratio of powdered form of carbonized corn grain char/KOH; 800 °C; and 4 h. The possibility of preparing highly porous activated carbons with controlled porosity by varying different activation conditions was found from the pore size distribution results. In particular, the domination of the ratio between the powdered form of carbonized corn grain char and KOH on the porosity development was high compared to the activation temperature and activation time. In addition, the surface roughness calculated from the surface fractal dimension indicates the decrease of surface roughness with increasing activation conditions. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
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Alfonso Totosaus Ismael A. Godoy Teresita J. Ariza-Ortega 《International Journal of Polymer Analysis and Characterization》2020,25(7):517-528
Abstract Recent regulations restricting the use of one-use-plastics open the possibility to develop starch-based edible packaging material. The objective of this work was to determine the effect of three different modified starches on starch and dextrin composite edible films by a mixture design approach on edible films’ mechanical properties. The amylose content of chemically modified starches influenced their swelling capacities, where higher amylose content was inversely related to water-power uptake and directly related to film thickness. CMS3 Nifrastarch-TS edible films, with higher amylose content, presented higher puncture force and tensile strength, but lower puncture deformation and elongation, related to a less smooth surface, according to atomic force micrographs. The use of CMS1 Gelamil-100, with lower amylose content, decreased stiffness but increased films’ stretching, presenting higher surface smoothness film topography. The use of commercial chemical modified starches in combination with starch and dextrin will allow to control of edible film thickness and hence, mechanical properties, depending on food covering necessities. 相似文献
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V. Garcia P. Colonna D. Lourdin A. Buleon H. Bizot M. Ollivon 《Journal of Thermal Analysis and Calorimetry》1996,47(5):1213-1228
Order-disorder transitions were investigated in native cassava starch at intermediate moisture contents (35 to 60% wt. water), using Differential Scanning Calorimetry (DSC) and dynamic Wide Angle X-ray Diffractometry (WAXS) with a synchrotron radiation source.The gelatinization of granules occurs as a cooperative process, due to constraints induced in crystallites by the amorphous areas. Variations of water content (water volume fraction from 0.28 to 0.86) and heating rate (0.2–10C min–1) allowed access to equilibrium melting conditions. Cassava starch exhibits a higher melting temperature of the undiluted starch (T
m
o
) and an equivalent melting enthalpy of the repeating glucosyl unit (H
u), compared to other A-type starches. At intermediate water content (45% wt. water), a two-stage melting process is evidenced, with different kinetic rates below and above 75 C.We wish to thank F. Lavigne (URA, CNRS 1218, Chatenay Malabry) for valuable help with this work and C. Bourgaux from L.U.R.E. for helping us with dynamic X-ray diffraction experiments. The present study was supported by a grant from the European Communities (STD3-CT92-0110). 相似文献
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Droplet microfluidics is one of the most promising approaches that allows preparation of microparticles with tailored structure and composition. Various functional microparticles have been developed using microfluidics, where their controlled structure shows high potential for a wide range of applications. Among these, soft polymeric microparticles which exhibit low elastic modulus compared to ceramics and metals are extensively investigated in biomedical applications due to their biocompatibility, high surface-to-volume ratio, as well as soft and deformable nature. As the mechanical properties of soft microparticles play important role in determining how they function in each application, it is essential to adequately characterize them for the optimal design of functional microparticles. In this review, we mainly discuss the mechanical characterization methods of soft microparticles and their elastic property. A brief overview of the droplet microfluidics-assisted fabrication of microparticles is also provided before discussing the mechanical characterization techniques. We then describe the general characterization methods and models employed to determine the elastic properties of microparticles. In addition, we discuss the relationship between the physical parameters (size, composition, and structure) and the elastic properties of the microparticles, followed by the role of elastic properties in various applications including microcarrier, bioink, and self-healing to name a few. 相似文献
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A. M. B. Q. Habitante P. J. A. Sobral R. A. Carvalho J. Solorza-Feria P. V. A. Bergo 《Journal of Thermal Analysis and Calorimetry》2008,93(2):599-604
The aim of this work was to study the glass transition, the glass transition of the maximally freeze-concentrated fractions,
the ice melting and the gelatinization phenomenon in dispersions of starch prepared using glycerol-water solutions. The starch
concentration was maintained constant at 50 g cassava starch/100 g starch dispersions, but the concentration of the glycerol
solutions was variable (C
g= 20, 40, 60, 80 and 100 mass/mass%). The phase transitions of these dispersions were studied by calorimetric methods, using
a conventional differential scanning calorimeter (DSC) and a more sensitive equipment (micro-DSC). Apparently, in the glycerol
diluted solutions (20 and 40%), the glycerol molecules interacted strongly with the glucose molecules of starch. While in
the more concentrated glycerol domains (C
g>40%), the behaviour was controlled by migration of water molecules from the starch granules, due to a hypertonic character
of glycerol, which affected all phase transitions. 相似文献