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以甲基三甲氧基硅烷(MTMS)和水玻璃通过共前驱体混合,并在常压干燥条件下制备得到自疏水SiO2气凝胶。通过对制备的SiO2气凝胶的表观密度、孔隙特征、疏水性能等进行表征测试,研究溶胶中水玻璃、MTMS和乙醇的摩尔比对其性能的影响。结果表明:当混合前驱体中的乙醇/MTMS/水玻璃的摩尔比为12:3:1时,制备的改性Si02气凝胶具有良好的物理性能,密度为0.097g/cm^3,比表面积为813.28m^2/g,疏水角为150.3°。 相似文献
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以正硅酸乙酯(tetraethoxysilane,TEOS)为硅源,甲基三甲氧基硅烷(methyltrimethoxysilane,MTMS)为改性剂,无水乙醇(ethanol,EtOH);为溶剂,通过溶胶-凝胶法制备了SiO2湿凝胶,并经过超临界干燥得到了SiO2气凝胶.利用N2吸脱附测试、红外光谱、热重-差热分析、扫描电镜,高分辨透射电镜、接触角测试等手段对气凝胶的基本性能、表面基团、热稳定性、微观形貌结构进行了研究.结果表明:以TEOS,MTMS,EtOH, H2O的摩尔比为1:0.3:15:4制得的改性气凝胶为轻质疏水块状固体材料,密度为0.1g/cm3,比表面积为1070m2/g,孔隙率为95.5%.经MTMS改性后SiO2气凝胶的比表面积、孔体积和孔隙率更大,密度吏低,其疏水耐温性从250℃提高到500℃以上. 相似文献
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以甲基三甲氧基硅烷(MTMS)和丙基三甲氧基硅烷(PTMS)为原料,通过二者的水解共缩聚反应制备了改性甲基硅树脂涂料,该涂料所形成的涂层具有良好的柔韧性.利用电导率仪着重研究了MTMS和PTMS的水解反应的条件,以使二者能够更好地水解共缩聚.研究了MTMS/PTMS的物质的量比、加水量、蒸馏反应温度和时间对涂层性能的影响.结果表明:当MTMS/PTMS物质的量比为3∶1、H2O/烷氧基硅烷物质的量比为4∶1时,将PTMS预水解15 min后再一次性加入MTMS进行水解共缩聚反应,得到的改性甲基硅树脂涂料具有良好的综合性能,涂膜固化后铅笔硬度为4H,附着力为2级,柔韧性2 mm. 相似文献
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以一甲基三氯硅烷(一甲)和甲醇为原料,采用塔式反应器连续合成甲基三甲氧基硅烷(MTMS),探讨了原料配比、下塔温度、上塔温度、反应塔压力、粗品回流比和甲醇含水量对MTMS收率及酸值的影响。结果表明:随着一甲与甲醇质量比的增大,MTMS收率先升后降,酸值先降后升;随着下塔温度的升高,MTMS收率升高并趋于稳定,酸值降低并趋于稳定;随着上塔温度的升高,MTMS收率先升后降,酸值降低;随着反应塔压力的升高,MTMS收率先升后降,酸值升高;随着粗品回流比的增大,MTMS收率和酸值均先升后降;随着甲醇含水量的升高,MTMS收率降低,酸值变化不明显;MTMS的较佳合成条件为:一甲与甲醇质量比1.5∶1,下塔温度85~90℃,上塔温度60~64℃,反应塔压力10~20 kPa,粗品回流比0.5~1,甲醇含水量≤500×10-6。 相似文献
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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. 相似文献
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离子液体及其在有机反应中的应用 总被引:1,自引:0,他引:1
简要介绍了离子液体的分类、组成、特性及其合成方法。综述了离子液体作为反应介质在各类有机反应中的应用。并对离子液体的工业化应用前景进行展望。 相似文献
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A. Venkateswara Rao Ravindra R. Kalesh D.P. Amalnerkar T. Seth 《Journal of Porous Materials》2003,10(1):23-29
The experimental results on the effect of adding trimethylethoxysilane (TMES) as a co-precursor on the hydrophobicity and physical properties of tetraethoxysilane (TEOS) based silica aerogels, are reported. The molar ratio of TEOS, ethanol (EtOH), water (0.001 M oxalic acid catalyst) was kept constant at 1:5:7 respectively, while the molar ratio of TMES/TEOS (A) was varied from 0 to 0.6. It has been observed that as the A value increases, the gelation time increases. The hydrophobicity was tested by measuring the contact angle, and the surface chemical modification was confirmed by the FTIR spectroscopy studies. The thermal stability of the hydrophobic aerogels was studied in the temperature range from 25 to 800°C. The hydrophobic nature of the aerogel could be maintained up to a temperature of 287°C and above this temperature the aerogels become hydrophilic. The bulk density and the optical transmittance of the aerogels have been found to decrease with increase in A value. The aerogels have been characterized by Fourier transform infrared spectroscopy (FTIR), Optical transmittance, Scanning electron microscopy (SEM), Differential thermal analysis (DTA) and Thermogravimetric analysis (TGA), and Contact angle measurements. 相似文献
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Zn-Al-CO_3水滑石晶粒尺寸控制与光屏蔽作用研究 总被引:2,自引:1,他引:2
在旋转液膜反应器中制备成核浆液 ,通过控制晶化温度制备了不同粒径且晶体结构完整的Zn Al CO3水滑石 (LDHs)。将不同粒径的Zn Al CO3LDHs配成质量分数为 0 0 2 %的水分散液 ,测定在紫外 -可见光范围的透过率 ,结果发现 ,随晶化温度的升高 ,LDHs粒径增大 ,样品对紫外及可见光的阻隔作用增强 ;Zn Al CO3LDHs在不同波长下的吸光度与晶体粒子在a轴和c轴方向的尺寸呈线性关系。由外推法求得了Zn Al CO3LDHs对各波长紫外 -可见光产生屏蔽作用的晶粒尺寸阈值。对波长分别为 2 90、3 2 0、40 0、60 0和 80 0nm光波能够产生屏蔽作用的Zn Al CO3LDHs ,其粒子尺寸在a轴方向需分别大于 3 2 92、3 3 77、3 4 77、3 5 5 6、3 5 79nm ;在c轴方向需分别大于 9 73、12 79、16 47、19 3 5、2 0 2 2nm。 相似文献
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《分离科学与技术》2012,47(8):1321-1328
Adsorption of benzoic acid and reactive brilliant blue 4 (RBB4) by hypercrosslinked resins and macroporous resins was examined. Micropore areas were much higher in the hypercrosslinked resins than macroporous resins while the pore volume and average pore diameter of macroporous resins were superior to the hypercrosslinked resins. The investigation showed that the pore size distributions of the resins significantly influenced the adsorption capacity of adsorbents. Adsorption of benzoic acid was dominated by BET surface area and the micropore area while the adsorption of RBB4 shifted to a pore-size-dominant process. The maximum mol adsorption capacities of benzoic acid were all higher than those of RBB4 by the resins, showing the influence of the molecular dimension on adsorption. The adsorption thermodynamic parameters were calculated and it revealed that the adsorption was an exothermic, spontaneous, and more ordered process. Adsorption kinetics and elution processes were also investigated for establishing the appropriate adsorption conditions for purifying wastewater containing benzoic acid or RBB4. 相似文献
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为了解决天然沸石对废水中重金属吸附能力低的问题,制备出了六种改性沸石并考察了改性沸石对六价铬离子的吸附特性。在这六种改性沸石中,H2 SO4/CuSO4复合改性沸石对铬的吸附性能最佳,其对铬的吸附曲线符合Freundlich方程;其吸附强度是天然沸石的8倍;其吸附动力学曲线符合二级动力学模型,实测值十分接近理论值,这也证明在其对六价铬离子的吸附过程中离子交换起着十分重要的作用。 相似文献
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Martina Salzano de Luna Francesco Greco Raffaele Pastore Giuseppe Mensitieri Giovanni Filippone Paolo Aprea Domenico Mallamace Francesco Mallamace Sow-Hsin Chen 《International journal of molecular sciences》2021,22(11)
Chitosan (CS) is largely employed in environmental applications as an adsorbent of anionic dyes, due to the presence in its chemical structure of amine groups that, if protonated, act as adsorbing sites for negatively charged molecules. Efficient adsorption of both cationic and anionic dyes is thus not achievable with a pristine chitosan adsorbent, but it requires the combination of two or more components. Here, we show that simultaneous adsorption of cationic and anionic dyes can be obtained by embedding Linde Type A (LTA) zeolite particles in a crosslinked CS-based aerogel. In order to optimize dye removal ability of the hybrid aerogel, we target the crosslinker concentration so that crosslinking is mainly activated during the thermal treatment after the fast freezing of the CS/LTA mixture. The adsorption of isotherms is obtained for different CS/LTA weight ratios and for different types of anionic and cationic dyes. Irrespective of the formulation, the Langmuir model was found to accurately describe the adsorption isotherms. The optimal tradeoff in the adsorption behavior was obtained with the CS/LTA aerogel (1:1 weight ratio), for which the maximum uptake of indigo carmine (anionic dye) and rhodamine 6G (cationic dye) is 103 and 43 mg g−1, respectively. The behavior observed for the adsorption capacity and energy cannot be rationalized as a pure superposition of the two components, but suggests that reciprocal steric effects, chemical heterogeneity, and molecular interactions between CS and LTA zeolite particles play an important role. 相似文献
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Yujun Song Hongxiang Ou Weibai Bian Yunlei Zhang Jianming Pan Yan Liu Weihong Huang 《Journal of Inorganic and Organometallic Polymers and Materials》2013,23(6):1325-1334
Surface ion-imprinting technique combined with a sacrificial support process was applied to synthesize Sr2+ ion-imprinted polymers (Sr-IIPs) in which yeast cells were used as sacrificial supports. The synthesized polymers were characterized by Fourier transmission infrared spectrometry, scanning electron microscope, transmission electron microscope and nitrogen adsorption–desorption analysis. The results indicated that Sr-IIPs possessed a relatively good dispersion and large surface area. Batch mode adsorption experiments were carried out to investigate the specific adsorption equilibrium, kinetics and selective recognition properties of Sr-IIPs. Sr-IIPs exhibited a fast kinetics adsorption capacity and high selectivity for adsorption of Sr2+. Under optimal experimental conditions, the adsorption of Sr2+ onto Sr-IIPs followed the pseudo-second-order kinetics model and was well-described by the Langmuir isotherm model. The monolayer adsorption capacity at 318 K was 60.61 mg g?1 for Sr-IIPs, which is over three-times that of NIPs. Thermodynamic parameters confirmed that the adsorption of Sr2+ onto Sr-IIPs was a spontaneous and endothermic process within the studied temperature range (298–318 K). 相似文献