对磷矿中二氧化硅测定方法的初步评价

<正> 根据资料报导,测定二氧化硅含量的方法不少,主要有盐酸脱水重量、法硫酸——氢氟酸处理酸不溶物重量法、动物胶凝聚重量法、CTAB(季胺盐)凝聚重量法、高氯酸脱水重量法、氟硅酸钾容量法以及硅钼兰比色法等等。目前我国对磷矿中二氧化硅的测定多采用     

影响煤灰中二氧化硅测定结果的因素

介绍了影响动物凝聚重量法测定煤灰中二氧硅含量的主要因素,提出了提高重量法测定结果粗度的方法,如再将此结果与用硅钼兰比色法回收的滤液中二氧化硅的测定结果相复合,可使煤灰中二氧化硅的测定结果更准确。     

水泥及原材料中SiO2测定方法对比浅析

水泥行业化学分析测定二氧化硅的方法较多,但各种检测方法的适用性不尽相同。本文通过对三种常用分析方法（氯化铵重量法、氟硅酸钾容量法和动物胶凝聚法）进行试验和对比,探讨了三种方法的差异和优缺点,为不同材料中二氧化硅测定方法的选择提供参考。     

动物胶凝聚重量法测定二氧化硅的改进

岩矿样品中二氧化硅的测定通常以银(镍)坩埚碱熔,动物胶凝聚为例行分析方法。它虽比纯典法快速,但仍有以下缺点:(1)以动物胶凝聚硅酸时,需加热70至80℃,既费电、操作又不便;(2)硅酸的复容量较大,即使严格掌握操作条件,滤液中残留的二氧化硅仍有0.5%左右,使分析结果偏低,为此,在例行分析中必须以钼兰法将其回收,不但手续冗长,且耗试剂费0.3元左右;增加了测试成本。本文采用热解石墨坩埚(核工业部五所     

高氯酸脱水重量法测定矿石中高含量硅

阐述了采用“高氯酸脱水重量法”测定矿石中高含量硅基本原理、试验方法和试验步骤,并将动物胶脱水重量法与高氯酸脱水重量法分别测定二氧化硅的结果进行了对照,结论是后者完全可以取代前者。     

微波在动物胶法测磷矿石中硅含量的应用

动物胶凝聚重量法测定磷矿石中硅,先用微波炉碱熔分解试样,生成沉淀用玻璃砂芯坩埚过滤,再用微波炉恒重坩埚和沉淀,与经典方法对照,结果无明显差异。该方法简单准确,省时省电,具有一定实用价值。     

重量法测定湿法磷酸中的二氧化硅

一、前言湿法磷酸中二氧化硅含量测定方法报导极少。困难之处在于湿法磷酸中五氧化二磷含量约30％左右,而二氧化硅含量仅为1％左右,即有大量磷存在的这一特定条件下,用比色法测定二氧化硅,则要消除大量磷的干扰并非易事。用经典的二次脱水法测定二氧化硅是不可能的,由于磷酸脱水生成偏磷酸而腐蚀烧杯,造成极大的正误差。动物胶重量法对于测定低含量二氧化硅时,回收率极低造成负误差。据报导使用阳离子表面活性剂长碳链季胺盐与动物胶在溶液性质上极为类似,动物胶在酸性溶液中所形     

砂岩矿中二氧化硅的快速测定

用钼蓝光度法测定砂岩矿中高含量的二氧化硅，克服了传统重量法的手续繁琐、时间冗长、所用试剂种类多等缺点，建立了一种光度法测定高含量二氧化硅的新方法。该方法简单快速，经济实用，能够满足生产控制分析的需要。该方法相对标准偏差在0．98％以内，同时适用于硅铁的控制分析。     

硅酸盐中二氧化硅的快速容量测定

一、緒言关于硅酸盐的分析,随着生产发展的需要,經典法已經远远不能滿足要求,近几年来各有关方面提出不少关于硅酸盐快速化学分析方案,大大的提高了工作效率。这些方案綜合起来大体上都是将試样以强碱熔融,用酸中和,稀釋至一定体积,然后分別取出一定体积測定各个項目。通常是采用“动物胶法”,“硅氟酸鉀法”和“钼黄”及“钼藍”比色法測定二氧化硅。用EDTA法测定氧化铁、氧化鋁、氧化鈣、氧化鎂。用过氧化氫比色洼測定二氧化二钛。本文只談談关于二氧化硅的測定。前面談到的三个測定方法,其中“动物胶法”虽准确     

粘土中二氧化硅的差示分光快速测定

粘土中二氧化硅的含量一般在50％左右,通常采用重量法或容量法测定。近年来,对采用硅钼蓝比色法的研究工作已取得了不少进展,并已逐渐被应用到较高二氧化硅含量的样品分析中。本文对硅钼黄显色的酸度、体积、温度等影响又作了进一步的研究,提出了在pH=1时,在小体积内进行硅钼黄显色,继后用抗坏血酸将其还原成硅钼蓝,且用差示分光法测定粘土中二氧化硅的快速方法。本法具     

明胶/XNBR复合膜的制备及其性能的研究

采用水溶液共混法制备明胶XNBR复合膜。对该膜制备条件的研究表明:在明胶、XNBR质量分数比为10:1,反应温度70℃,反应时间90min的条件下所得膜的力学性能较好。对明胶/XNBR复合膜和明胶/壳聚糖复合膜进行了对比研究,结果表明,明胶/XNBR复合膜较明胶/壳聚糖复合膜有更好的力学性能。     

Synthesis of poly(acrylic acid)–Fe3+/gelatin/poly(vinyl alcohol) triple‐network supramolecular hydrogels with high toughness,high strength and self‐healing properties

Hydrogels with good mechanical and self‐healing properties are of great importance for various applications. Poly(acrylic acid)–Fe³⁺/gelatin/poly(vinyl alcohol) (PAA‐Fe³⁺/Gelatin/PVA) triple‐network supramolecular hydrogels were synthesized by a simple one‐pot method of copolymerization, cooling and freezing/thawing. The PAA‐Fe³⁺/Gelatin/PVA triple‐network hydrogels exhibit superior toughness, strength and recovery capacity compared to single‐ and double‐network hydrogels. The mechanical properties of the synthesized hydrogels could be tailored by adjusting the compositions. The PAA‐Fe³⁺/Gelatin/PVA triple‐network hydrogel with 0.20 mmol Fe³⁺, 3% gelatin and 15% PVA could achieve good mechanical properties, the tensile strength and elongation at break being 239.6 kPa and 12.8 mm mm^?1, respectively, and the compression strength reaching 16.7 MPa under a deformation of about 91.5%. The synthesized PAA‐Fe³⁺/Gelatin/PVA triple‐network hydrogels have good self‐healing properties owing to metal coordination between Fe³⁺ and carboxylic groups, hydrogen bonding between the gelatin chains and hydrogen bonding between the PVA chains. Healed PAA‐Fe³⁺(0.20)/Gelatin3%/PVA15% triple‐network hydrogels sustain a tensile strength of up to 231.4 kPa, which is around 96.6% of the tensile strength of the original samples. Therefore, the synthesized triple‐network supramolecular hydrogels would provide a new strategy for gel research and expand the potential for their application. © 2019 Society of Chemical Industry     

相关参素对微乳液化学剪裁制备Ni-Fe复合磁性纳米微粒组成及粒径分布的影响

用XRD、TEM、EDS研究了微乳液化学剪裁制备明胶包裹的复合纳米量级Ni Fe超细微粒时 ,微乳液的水池半径和镍 /铁比对微粒组成和粒径的影响 ,结果表明 :水池半径不同 ,不但微粒的粒径不同 ,而且微粒的组成也有差异。同时表明 ,微粒为明胶包裹的球形超细微粒。微球的平均粒径为 4 8～ 136nm ,单个微粒的粒径 2 3～ 3 4nm ,每个复合微球中约有2 1～ 4 0个铁 镍粒子 ,X 射线衍射和X 射线能谱分析表明 ,主要成分为NiFe2 O4 和FeNi3。     

乳化法明胶亚微米粒子的制备

以A型明胶为原料,石蜡油为油相,采用乳化化学交联方法制备了明胶亚微米粒子. 用扫描电子显微镜(SEM)观察了明胶亚微米粒子的形貌和粒径. 研究了影响微球粒径的多种因素,包括明胶溶液浓度、乳化搅拌速度、乳化温度、乳化剂和固化剂. 结果表明,采用戊二醛为固化剂、增加明胶的浓度、提高乳化搅拌速度、使用混合性的乳化剂都有利于降低明胶粒子的粒径. 此外,对制备工艺进行了优化,并在7000 r/min左右高速搅拌的条件下,得到了成球性较好的粒径约为450 nm的明胶亚微米粒子.     

Potential application of gelatin scaffolds prepared through in situ gas foaming in skin tissue engineering

Gelatin’s excellent foaming ability allows the application of in situ gas foaming as a preparation technique for porous scaffold development. Here, a new iterative experimental design for in situ gas foaming method is reported. The prepared scaffolds were studied for applying the findings to the future skin tissue engineering scaffolds. The thermal stability, mechanical properties, and pore structure of the scaffolds are reported and their degradation resistance by using collagenase enzyme and their cytotoxicity by using fibroblasts were studied. The results of this study demonstrated that gas foaming method can be modified to produce an interconnected porous structure with enhanced mechanical properties.     

Adsorption and recovery of nonionic polymers by neutralization of cellulose fiber surface charge via cationic polyamide‐epichlorohydrin resins

Gelatin‐based graft copolymers of polypropylene (PP), has been synthesized by chemical method using benzoyl peroxide (BPO), as radical initiator. Biodegradation studies of pristine PP and PP‐g‐Gelatin have been carried out by soil burial test in simple soil and soil enriched with nitrogenous content by adding urea. The microbial degradation was substantiated by the direct attack of the microbes on the grafted samples. The rate of degradation by the direct attack was fast in comparison to the degradation in soil burial studies. The biochemical tests performed on the organisms isolated from the soil, identified these organisms as Bacillus circulans, Kurthia gibsonii, and Flavobacterium sp. which helped biodegradation of PP‐g‐Gelatin samples. The degradation of the grafted samples was further confirmed by carrying out the physical characterization of the original samples and the degraded samples by SEM, XRD, and TGA. The XRD and thermal data indicate an increase in the crystallinity of the degraded samples. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

BaTiO3 nanocubes-Gelatin composites for piezoelectric harvesting: Modeling and experimental study

Flexible composites containing BaTiO₃ nanoparticles into Gelatin bio-polymer matrix were designed and investigated. Following the idea that the electric field concentration in corners/edges at the interfaces between dissimilar materials give rise to enhanced effective permittivity in composites, cuboid-like BaTiO₃ nanoparticles have been employed as nanofillers into Gelatin matrix by using an inexpensive solution-based processing method. As predicted by finite element method simulations developed for cubic-like inclusions into a homogeneous polymer matrix, the experimental permittivity of xBT-(1-x)Gelatin composites increases when increasing the high-permittivity filler addition. For the composition x = 40 wt% (corresponding to 12 vol% BaTiO₃ addition), permittivity reaches ε_r ～15.7 with respect to ε_r ～9.8 of pure Gelatine (measured at 10⁵ Hz), while the average piezoelectric coefficient d₃₃ as determined by piezoelectric force microscopy shows a remarkable increase up to 21 pm/V in composites with x = 40 wt%, in comparison to ～7 pm/V in pure Gelatin. By using the experimentally determined material constants, the simulated piezoelectric voltage output vs. time has shown a similar increase (about a doubling of its amplitude) of the harvesting signal in the composite with x = 40 wt% BT, with respect to one of the polymer matrix, thus demonstrating the beneficial role of embedding BT nanoparticles into the biopolymer for increasing the mechanical harvesting response.     

Gel-spinning and drawing of gelatin

Gelatin fibers can be prepared by the gel-spinning method using dimethyl sulfoxide as a solvent. The use of the method and the drawing in a gel state were effective in inducing segmental orientation in gelatin fiber. The fibers showed high values for the mechanical properties of tensile strength of 180 MPa and Young's modulus of 3.4 GPa.     

明胶对明胶/壳聚糖共混膜性能影响的研究

采用溶液共混法制备出了一系列明胶／壳聚糖共混膜,并考察了制备条件对膜性能的影响。结果表明：明胶的溶解方式对吸水率和溶胀比影响很小;随明胶分子量增加,共混膜的吸水率和孔洞体积增大;而随共混体系中明胶质量分数的增加,吸水率和孔洞体积亦增加,但溶胀比下降。     

三文鱼皮明胶的制备及其性能的研究

本文通过酸碱法对三文鱼皮进行预处理,制备了三文鱼皮明胶。研究分析了碱处理时间和浓度、酸处理时间和浓度对明胶产率和粘度的影响规律;测定了三文鱼皮明胶的成分、氨基酸组成、相对粘度。通过紫外光谱、红外光谱、X-射线衍射对其结构进行了分析。