石墨球模板溶胶-凝胶法制备TiO2团聚空心球

以石墨球为模板,采用溶胶-凝胶法制备TiO2团聚空心球,在400～600℃煅烧制备的材料中生成锐钛矿相TiO2,在750℃煅烧则以金红石相TiO2为主.包围在石墨球外围的TiO2凝胶在煅烧过程中生成晶体,同时形成球形空心结构.适当温度的煅烧可以完全去除石墨球模板,并在材料中生成Ti—O—Ti键.当煅烧温度从400℃升高到750℃时,材料的比表面积从7.6 m2·g-1降低到4.0 m2·g-1,而平均孔径和总孔容出现较大的增加.煅烧温度低于600℃样品的光催化活性随温度升高而快速增强.     

常压干燥溶胶-凝胶法制备的TiO_2气凝胶织构和结构研究

以廉价的四氯化钛为前驱体,环氧丙烷为促凝剂,甲酰胺为干燥控制化学添加剂,有机配体丙酸为水解降速剂,采用正交实验设计以常压干燥-溶胶-凝胶法制备TiO2气凝胶,并用BET和XRD对样品的织构和结构进行表征。结果表明,以n(四氯化钛)∶n(去离子水)∶n(甲酰胺)∶n(丙酸)∶n(环氧丙烷)=1∶14∶2∶0.5∶10制备的TiO2气凝胶,比表面积为632.87 m2·g-1,平均孔径7.87 nm,孔容1.24 cm3·g-1;当平均孔径小、孔容大时比表面积较高,反之,比表面积很低;随着焙烧温度升高,晶化度增强,但仍未出现金红石相衍射峰,表明具有较好的热稳定性。TiO2气凝胶孔容较大时,锐钛矿相结晶度差,反之,结晶度好;孔容居中的TiO2气凝胶出现游离的无定型SiO2,而较低的丙酸含量有利于提高焙烧后样品的晶化度。     

常压干燥制备TiO_2-SiO_2复合气凝胶的结构与性能

以TiCl4和工业水玻璃为原料,采用溶胶-凝胶法,用三甲基氯硅烷/乙醇/正己烷混合溶液处理改性湿凝胶,通过常压干燥制备高比表面积和孔体积的TiO2-SiO2复合气凝胶。用扫描电镜、透射电镜、X射线衍射和Brunauer-Emmett-Teller法分析表征样品的形貌、微观结构和气凝胶孔的性能,研究复合气凝胶对罗丹明B(RhodamineB,RhB)的光催化降解性能,探讨二氧化硅含量对TiO2-SiO2复合气凝胶结构性能的影响。结果表明:随着硅含量的增加,所得TiO2-SiO2复合气凝胶的最可几孔径逐渐减小,比表面积和光催化活性先增大后减小;当摩尔比n(Ti):n(Si)=4:1时,制备的气凝胶比表面积为893m2/g,对30mL浓度为10-4mol/LRhB溶液的最终光催化降解率达到99%,优于锐钛矿TiO2粉末的。     

混合前驱体常压干燥制备SiO2气凝胶及其性能研究

本文以正硅酸乙酯(TEOS)和甲基三甲氧基硅烷(MTMS)作为混合硅源,通过两步溶胶-壤胶法和常压干燥工艺制备出轻质多孔的SiO2气凝胶,并采用凝胶时间的测定、扫描电镜(SEM)、傅里叶变换红外光谱(FTIR)和BET吸附等手段对SiO2气凝胶进行了表征,研究了水和前驱比(物质的量)、乙醇(EtOH)和前驱体比(物质的量)、碱浓度对溶胶-凝胶过程和SiO2气凝胶性能的影响.实验结果表明:前驱体:H2O∶ EtOH∶ HCl∶ HH4OH的物质的量为1∶4∶6∶1.8×10-3∶0.144时制备出的SiO2气凝胶性能最优,其密度、比表面积、孔容和平均孔径分别为0.15 g·cm-3、944m2 ·g-1、2.264cm3·g-1和9.592 nm.     

钛硅复合气凝胶的制备工艺与光催化能力研究

采用溶胶-凝胶工艺,经乙醇为溶剂的超临界干燥路线制备二氧化钛-二氧化硅复合气凝胶.对不同组成、不同煅烧温度和时间制备的气凝胶的光催化能力进行比较后,得出最佳工艺条件:二氧化钛与二氧化硅物质的量比为1:1,超临界干燥后600 ℃煅烧2 h.形成的复合气凝胶网络结构完善,有均匀的纳米多孔结构;比表面积达355.6 m2/g,孔容为0.32 mL/g,最可几孔半径为0.82 nm,平均孔半径为2.52 nm;其中二氧化钛为锐钛矿型,二氧化硅为无定形.     

SiO2气凝胶的非超临界干燥法制备与表征

以聚二甲基硅烷为原料,采用聚合物超临界法制备了SiO2气凝胶.聚合物超临界法制备的SiO2气凝胶除碳前为疏水性气凝胶,比表面积为27.68 m2/g,孔体积为0.103 7 cm3/g,平均孔径约为15 nm;除碳后为亲水性气凝胶,比表面积为500.6 m2/g,孔体积为0.404 3 cm3/g,平均孔径为3.23 nm.对聚合物超临界法制备SiO2气凝胶的反应机理进行了初步探讨.     

SiO_2气凝胶/短切石英纤维多孔骨架复合材料的制备与性能

以短切石英纤维、硅溶胶、B4C粉烧结制备多孔刚性骨架,以正硅酸乙酯、去离子水和乙醇配制SiO2溶胶,多孔骨架浸渍SiO2溶胶后经超临界干燥制备了SiO2气凝胶/多孔骨架复合材料.对隔热瓦的高温热导率、比表面积和孔径分布进行了测试并且观察了微观形貌.结果表明:SiO2气凝胶复合的石英纤维刚性隔热瓦具有纳米孔结构,平均孔径为39.5nm,在600℃和800℃,其热导率分别仅为0.033 5 W/(m·K)和0.0404W/(m·K),与未复合气凝胶的刚性骨架相比,高温热导率下降了40%～50%.此外,SiO2气凝胶填充了隔热瓦骨架中的大部分的宏孔,抗弯强度提高了30%,并且使刚性隔热瓦的脆性有一定改善.     

常压干燥法制备SiO2气凝胶粉体

以工业硅溶胶为原料,通过凝胶过程与干燥条件的控制,采用常压干燥法制备了SiO2 气凝胶粉体,并考察了老化液中正硅酸乙脂(TEOS)含量和干燥控制化学添加荆甲酰胺的添加对气凝胶粉体堆积密度、比表面积和孔径分布的影响.结果表明:所得气凝胶粉体具有纳米多孔结构,组成气凝胶结构的基本粒子呈圆球形,粒径为10～25 nm,由基本粒子连接而成的网络结构具有5～50 nm的孔径分布;随着热处理温度从常温升至1 100℃,SiO2气凝胶从最初的无定形态转化为方石英;在,TEOS的醇溶液中老化,有利于增强凝胶骨架的强度;添加甲酰胺可以改善气凝胶粉体的孔径分布,提高其比表面积.     

纳米二氧化钛光催化材料研究进展

综合评述了TiO2光催化材料的掺杂改性和大比表面积气凝胶制备和性能等方面的国内外研究进展.     

疏水SiO2气凝胶的制备及表征

以正硅酸乙酯(TEOS)为硅源,三甲基氯硅烷(TMCS)为改性剂,经老化、表面疏水改性,常压干燥制备了高比表面积疏水SiO2气凝胶.用傅立叶变换红外光谱仪(FT-IR)、扫描电镜(SEM)、比表面及孔径分布仪、热重分析仪(TG-DSC)对其疏水特性及结构进行表征.结果表明:疏水SiO2气凝胶与水的接触角达145°,在空气中的热稳定温度为269 ℃;且比表面积达1035 m2/g,具有典型的气凝胶结构特征,孔径尺寸和密度分别达9.7 nm和0.129 g/cc,骨架颗粒尺寸小于30 nm.     

乙烯酮(双乙烯酮)下游产品废水的治理技术

乙烯酮(双乙烯酮)是十分重要的化工中间体,其下游产品较多。江苏某化工厂开发生产乙烯酮(双乙烯酮)下游产品三十多个,年生产规模三万多吨,是国内以乙烯酮(双乙烯酮)为中间体生产精细化学品的综合骨干企业。针对乙烯酮(双乙烯酮)下游产品废水特点,该厂结合企业实际,开展了产品优化,结构调整,清洁生产,资源循环利用,节水降耗等工作,从源头削减了污染物的生产。同时投资二千多万元新建预处理装置三套,6000m3/d废水生化处理装置一套,使全厂乙烯酮(双乙烯酮)下游产品的废水得到了有效的治理。     

A study of miscibility of blends of polybutadienes of varying microstructure

The miscibility of various amorphous polybutadienes with mixed microstructures of 1,4 addition units (cis, 1,4 and trans 1,4) and 1,2 addition units have been investigated. The studies here involved optical transparency, differential scanning calorimetry, and small angle light scattering. It was found that a 90 percent (cis) 1, 4 addition polybutadiene was immiscible with high (91 percent) 1,2 addition polybutadiene. Reduction of the 1,2 content to 71 percent induced an upper critical solution temperature (UCST) with the cis 1,4 polymer. Polybutadienes with 50 percent and 10 percent 1,2 contents were miscible above the crystalline melting temperature of the cis 1,4 polybutadiene. Immiscibility of the 91 percent 1,2 addition polymer was also found with a 10 percent 1,2 polybutadiene. The latter polymer also exhibits an UCST with the 71 percent 1,2 polymer. The results are used to interpret the characteristics of blends of polybutadienes of varying microstructure.     

几种乙炔加压设备性能的比较

阐述并比较了几种加压设备在乙炔加压清净过程中的性能和特点。     

粉煤灰中烧失量检测的不确定度分析

以F类粉煤灰为例,详细介绍了测定粉煤灰中烧失量的步骤、计算数学模型、影响测量不确定度的因素以及各项测量不确定度分量评定,人员、设备、材料、方法、环境都是影响测量不确定的因素。     

生物油的成分分析及物性测定

以添加FeCl2的ZnCl2-KCl混合熔盐裂解纤维素和秸秆,制得生物油。采用傅立叶变换红外光谱法和气相色谱-质谱法分析生物油的成分。结果表明,生物油中成分复杂,含有氧元素、多种有机化合物,主要包括酮类、醛类、酚类及羧酸类等。测定了20～80℃生物油的密度和粘度,发现生物油的密度与温度呈较好线性关系,而生物油的粘度均大于水的粘度,且不同熔盐体系对秸秆生物油的粘度无较大影响。     

分解炉扩径的技术改造

我厂3号回转窑(Φ4m×60m)生产线在1996年年底由SP窑(产量912t/d)改为NSP窑(产量1320t/d),预分解系统为四级旋风预热器带离线式分解炉     

Process of acceleration of filtration of viscose

Conclusions It is significant that the purification on a single passage of viscose through porous ceramic corresponds to the result of a two-stage filtration of it in industrial filter-presses with standard fillings.Kiev Combine. Kiev Technological Institute of Light Industry. Translated from Khimicheskie Volokna, No. 3, pp. 20–22, May–June, 1969.     

Effect of degree of deacetylation of chitosan on the kinetics of ultrasonic degradation of chitosan

The objective of the study was to explore the effect of the degree of deacetylation (DD) of the chitosan used on the degradation rate and rate constant during ultrasonic degradation. Chitin was extracted from red shrimp process waste. Four different DD chitosans were prepared from chitin by alkali deacetylation. Those chitosans were degraded by ultrasonic radiation to different molecular weights. Changes of the molecular weight were determined by light scattering, and data of molecular weight changes were used to calculate the degradation rate and rate constant. The results were as follows: The molecular weight of chitosans decreased with an increasing ultrasonication time. The curves of the molecular weight versus the ultrasonication time were broken at 1‐h treatment. The degradation rate and rate constant of sonolysis decreased with an increasing ultrasonication time. This may be because the chances of being attacked by the cavitation energy increased with an increasing molecular weight species and may be because smaller molecular weight species have shorter relaxation times and, thus, can alleviate the sonication stress easier. However, the degradation rate and rate constant of sonolysis increased with an increasing DD of the chitosan used. This may be because the flexibilitier molecules of higher DD chitosans are more susceptible to the shear force of elongation flow generated by the cavitation field or due to the bond energy difference of acetamido and β‐1,4‐glucoside linkage or hydrogen bonds. Breakage of the β‐1,4‐glucoside linkage will result in lower molecular weight and an increasing reaction rate and rate constant. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3526–3531, 2003