基于正交实验法的高岭土前驱体的制备

实验采用超声波插层与机械加热搅拌插层相结合,利用二甲基亚砜、尿素、甲酰胺和乙酸钾对高岭土进行一次插层;利用丙烯酰胺、乙酸铵、三已醇胺对高岭土进行二次插层改性。采用正交实验设计,通过改变高岭土及一次二次插层剂的添加剂量、超声反应温度、插层时间等,得到16组样品。利用红外光谱仪、X射线衍射仪及扫描电镜等对样品进行表征,发现经过改性后的高岭土前驱体的插层效果较好,其中高岭土3g时,一次插层剂为甲酰胺,二次插层剂为三乙醇胺时对高岭土改性在增加层间距以及结构稳定性方面的效果最好。     

层剥离高岭土改性煤沥青的结构与热稳定性

在超声波作用下,以二甲基亚砜(DMSO)插层处理高岭土,通过熔融复合法改性煤沥青。采用XRD、FTIR、SEM、TEM、TG、DSC表征测试了插层高岭土的层间距、层间相互作用、层分散形态,以及改性煤沥青的热稳定性。结果表明,DMSO削弱了层间铝羟基与硅氧键间的氢键作用,插层高岭土的层间距由0.716 nm增加至1.124nm,插层率达到98.57%;熔融复合后,高岭土发生层剥离,(001)衍射峰消失,以薄片形态分散于煤沥青中。薄片形态的高岭土通过延缓空气传输速率的方式改善了煤沥青的热稳定性,当插层高岭土掺杂质量分数为6%时,插层高岭土改性煤沥青的最大失重速率所对应温度为650℃,对应的失重为78.04%,而最大失重速率处原煤沥青失重85.41%。原煤沥青失重50%时的温度为490℃,而改性煤沥青达到550℃。未掺杂高岭土时,煤沥青软化点为42.3℃,改性煤沥青软化点增加到45.4℃,继续增加高岭土质量分数,软化点上升幅度减小。     

插层反应前高岭土的超声酸活化实验研究

以苏州高岭土为原料,在插层反应前用超声波和盐酸对其活化,制备了高岭土/DMSO插层复合物.通过比表面积(SSA)、FTIR和XRD等表征,探讨了超声时间和盐酸浓度对高岭土物性变化以及超声酸活化对插层反应的影响.结果表明:高岭土的比表面积随着盐酸浓度的增加和超声时间的延长而增人;超声处理未造成高岭土的晶化和层状结构的破环,不影响四面体匀称性;超声酸活化过程中,高岭土发生了一定程度的层离和层间距的增加,提高了插层率.     

碱法生产甲醇钠生产工艺的优化

目前制取甲醇钠主要有钠法和碱法两种方法,钠法工艺简单,转化率高,但有很大的危险性,碱法工艺因其强可逆性,转化率较低,同时又需要不断移除反应生成的水,但其成本低,在实际生产中通过反应精馏装置来生产。氢氧化钠与甲醇反应生成甲醇钠和水,这个反应的影响因素主要是反应温度,甲醇与氢氧化钠的质量比,反应时间。在本篇论文中,利用单因素实验法研究反应随影响因素的变化情况。实验结果表明,温度升高,甲醇与氢氧化钠的质量比越大,反应时间越长,甲醇钠的质量分数越高。从而确定了最优的反应条件。     

超声法制备高岭土/二甲基亚砜插层复合物的影响因素

以苏州高岭土为原料,采用超声波法快速制备了高岭土/二甲基亚砜插层复合物,用X射线衍射和红外光谱进行了表征.通过正交实验分析了反应时间、超声波强度、含水量和反应温度等因素对插层率的影响.结果表明:反应时间从1 h增加到5h可使插层率增加53.44%,影响最为显著;超声波强度次之;由于实验用高岭土含水量较多,使得水的影响弱化;而超声波提供的局部高温高压的特殊环境,使温度对反应的影响最小.最优化条件为:反应时间4h,超声波强度为200 W,含水量10%、温度为90℃,在此条件下,插层率达到92%以上.     

插层高岭土改性煤沥青的抗老化性能

在二甲基亚砜(DMSO)插层处理的基础上,利用高岭土以熔融复合的方式改性煤沥青,并研究高岭土的结构状态、煤沥青的老化机理和改性煤沥青的抗老化性能.X射线衍射结果表明:熔融复合过程中高岭土实现了层剥离,透射电镜观察到高岭土在煤沥青基体中呈薄片分散状态.煤沥青氧化是老化的关键,高岭土可能以阻隔空气和延缓传输的方式减少并有效控制了老化反应.与原煤沥青相比,改性煤沥青老化后亚甲基含量增幅降低了42.8%,亚砜基含量增幅降低了32.4%.老化试验进一步证实了高岭土的改性效果,6.0%(质量分数)掺量下针入度比为50.4%,而未改性煤沥青的针入度比仅为35.3%.     

超声波辅助插层-剥离法制备煤系高岭土微粉的研究

我国煤系高岭土储量丰富,为满足造纸、纺织等行业个性化的需求,通常要对其进行深加工。以山西朔州煤系高岭土为原料,分别在恒温磁力搅拌和超声波作用下探究了煤系高岭土/二甲基亚砜(DMSO)插层复合物制备的最佳条件,在插层复合物的基础上对煤系高岭土进行超声辅助剥离,制备得到高岭土微粉,并利用XRD、SEM、BET、TG-DSC等方法分析表征样品。正交实验结果表明在磁力搅拌条件下DMSO用量、插层时间以及插层温度均对插层率具有一定的影响,引入超声波有利于高岭土插层率的提升。插层复合物经超声辅助剥离后晶粒厚度明显减小,高岭土片层状结构大体上呈现碎片化,仅保留少部分大的片状结构,其边缘碎化,整体上也出现碎裂的趋势。剥离样品的比表面积和孔径均大幅度增加,为硬质高岭土的剥离和超微细粉体的制备提供了新的思路。     

高岭土/NR插层纳米复合材料的结构和阻燃性能研究

采用两步插层法制备高岭土／NR插层纳米复合材料，并对其结构和阻燃性能进行研究。结果表明，在二甲基亚砜以及带有环氧基团的改性剂的分别作用下，NR大分子链实现了对高岭土的插层，高岭土片层以纳米尺寸均匀分散在NR中；与NR和填充型高岭土／NR复合材料相比，高岭土／NR插层纳米复合材料的热释放速率和质量损失均减小，阻燃性能得到改善。     

高岭土插层与剥离影响因素的研究

采用混合-静置法制备了高岭土/乙酸钾插层复合物,考察了含水量和温度对插层反应的影响,同时研究了不同剥离方式和插层率对插层复合物剥离效果的影响。结果表明,插层反应体系中少量的水有利于插层反应的进行,在20℃下反应24 h即可达到91%以上的插层率,无需搅拌和高温等其他能耗。高温水洗法和超声水洗法剥离效果较好,插层率越高的复合物剥离后晶粒厚度越小。     

高岭土插层改性研究进展

本文系统地分析了高岭土的结构、插层机理和插层改性的手段,着重探讨了插层高岭土固相插层和液相插层的制备工艺,以及采取FTIR、XRD、NMR和TG-DTA等测试方法对插层效果进行表征,最后对今后插层改性高岭土的发展和应用提出了展望。     

2,3,4,5-四甲氧基甲苯的合成研究

提出了一条以对甲酚为起点的合成2,3,4,5-四甲氧基甲苯更利于工业化的路线。通过Fe催化对甲酚制得2,3,6-三溴-4-甲基苯酚,再以甲醇钠作为甲氧基化试剂,在CuCl催化下,得到2,3,4,5-四甲氧基甲苯。     

Electrokinetic potential of kaolinite clay in the presence of polystyrene sulfonate

The determination of the electrokinetic potential of clay is very important in many applications. Therefore, this work was aimed at studying the effect of poly(4‐ sodium styrene sulfonate) on the electrokinetic potential and the sedimentation behavior of kaolinite clays at different pH values and/or in the presence of sodium or calcium chlorides. At pH values lower than the point of zero charge (PZC) of the kaolinite clay, the zeta potential of Na‐ or Ca‐kaolinite in CaCl₂ solutions was higher than that in NaCl solutions at the same concentration. Above the PZC, the zeta potential of Na‐ or Ca‐kaolinite in NaCl solution was higher than that in CaCl₂ at the same electrolyte concentration. These results reflect the ability of calcium cations to compress the double layer of the kaolinite clay better than sodium cations. Also, below the PZC and at low concentrations of poly(4‐sodium styrene sulfonate), the zeta potential of the kaolinite clay suspensions had low value, while the sediment volumes had higher values. On the other hand, above the PZC at increasing polymer concentrations, the zeta potentials increased but the sediment volumes had lower values compared to those produced below the PZC. The data showed the zeta potential of Na‐kaolinite suspensions are higher than Ca‐kaolinite, producing lower sediment volumes of Na‐kaolinite compared to Ca‐kaolinite at the same concentrations of polymer and/or pHs. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1705–1711, 2006     

Production of bio-diesel fuels by transesterification of rice bran oil

Transesterification of rice bran oil was investigated to produce the bio-diesel oil. Experimental conditions included molar ratio of rice bran oil to alcohol (1:3, 1:5 and 1 :7), concentration of catalyst used (0.5, 1.0 and 1.5 wt%), types of catalysts (sodium methoxide, NaOH and KOH), reaction temperatures (30, 45 and 60°C) and types of alcohols (methanol, ethanol and butanol). The conversion of rice bran oil increased with the alcohol mixing ratio and with the reaction temperature. Sodium methoxide was the most effective among the catalysts. The conversion was increased with the concentration of catalyst, but slightly increased over 1.0 wt%. The best conversion was obtained using methanol with sodium methoxide. In that case, 98% conversion was achieved within 1 hr. The physical properties of rice bran oil for diesel fuel can be significantly improved by transesterification reaction.     

甲醇钠催化地沟油制备生物柴油研究

以浓硫酸为催化剂,高酸值地沟油与甲醇酯化反应降酸的最优工艺条件为:n(甲醇):n(地沟油)=9:1,m(浓硫酸):m(地沟油)=1.1％,反应温度60℃,反应时间5h.制备生物柴油的最优工艺条件为:以甲醇钠为催化剂,反应时间2h,反应温度65℃,n(甲醇):n(地沟油)=7:1,m(甲醇钠):m(地沟油)=0.8％.制...     

The reaction of kaolin with fluorides. II. Effect of aqueous hydrofluoric acid

The dissolution of kaolinite in aqueous solutions of hydrofluoric acid was investigated at different temperatures and fluoride concentrations. The percentage dissolution of kaolinite was greater than was to be expected from a theoretical consideration of the reaction. The percentage dissolution was less for Na-kaolinite than for a H-kaolinite under the same experimental conditions. Two reaction rates were observed. The relative intensities of the 001 and 002 basal reflections decreased with reaction time, temperature and hydrofluoric acid concentration. The decrease was probably due to an amorphous phase. Although kaolinite samples after treatment at the lower temperature showed very little change in their infra-red absorption spectra, a marked change in the spectra was observed at the higher temperature. The disruption of the kaolinite crystal lattice is believed to be due to the preferential extraction of aluminium from the lattice leaving an intermediate silica phase, which dissolves to form fluorosilicic acid.     

Adsorption characteristics of polyacrylamide and sulfonate-containing polyacrylamide copolymers on sodium kaolinite

Polyacrylamide and its copolymer containing 6.8 mole % 2-acrylamido-2-methylpropane sulfonic acid were prepared by an irradiation-initiated precipitation polymerization technique. The polymer was characterized by intrinsic viscosity under conditions similar to those used during adsorption measurements. Hydrolytic degradation of the polyacrylamide was found to be negligible under conditions used. The adsorption substrate, sodium kaolinite, was prepared by extensive ion exchange treatment. Equilibrium adsorption of the polymers on the sodium kaolinite was made as a function of polymer concentration, solution pH, ionic strength, and temperature.     

The reaction of kaolin with fluorides: I. Effect of neutral and acid sodium fluoride solutions

The reaction between kaolinite and neutral and acid sodium fluoride solutions was investigated at different temperatures and over the acid pH range. The stoicheiometric replacement of hydroxyls in the kaolinite crystal lattice by fluoride ions, as reported by earlier workers, was not confirmed. The release of hydroxyl ions into solution was due predominantly to the disruption of the kaolinite crystal lattice. In the presence of sodium ions and at pH < 7, sodium fluoro-silicate and cryolite were found as solid phases. At pH > 7, only cryolite was found as a solid phase. Small, spherical, particles were observed in all cases. These particles were believed to be amorphous silica, formed as an intermediate phase in the disruption process.     

Pyrophyllite as raw material for ceramic applications in the perspective of its pyro-chemical properties

General pyro-chemical properties of pyrophyllite were studied using one Indian variety as sample. In addition to normal routine analysis, thermal expansion, infrared spectroscopy, DTA, XRD and SEM studies were also employed to understand the pyro-chemical properties of the specimen at different temperatures. The results indicate that the specimen contains pyrophyllite as major phase with sericite, quartz and diaspore as minor phases. Unlike kaolinite, pyrophyllite contains low alumina and high silica which on heating mainly produces mullite and amorphous silica. Mullite crystallization from pyrophyllite is rather easy than that from kaolinite. The silica in turn yields large amount of viscous liquid at high temperature. It is suggested that pyrophyllite may be utilized in such compositions favourably where mullite is a desirable phase by partial replacement of china clay which is a viable alternative particularly in the background of depleting reserves of kaolinite and its continuous cost escalation. Additionally amorphous silica produced in the reaction system may acts as an in situ produced filler material that reduces the use of quartz in such system.     

N,N-二甲基乙酰胺二甲基缩醛的合成工艺优化

报道了一种优化的N,N-二甲基乙酰胺二甲基缩醛(DMACA)合成工艺。该工艺使用液体甲醇钠,蒸除甲醇后悬浮在正己烷中,再和亚胺络合物反应。甲醇钠和硫酸二甲酯的摩尔比为1.2∶1,-10℃滴加亚胺络合物,滴加时间为1 h,反应时间为1.5 h。本合成工艺产品收率高(由文献值25%~35%提高到75%~85%),纯度好(HPLC≥98%)。     

3-氨基-2-噻吩甲酸甲酯的合成工艺

文章研究了以甲醇钠为催化剂,巯基乙酸甲酯、2-氯丙烯腈为原料合成3-氨基-2-噻吩甲酸甲酯的工艺。考察了原料配比、反应温度、反应时间以及萃取剂对反应收率的影响,结果显示当2-氯丙烯腈、巯基乙酸甲酯和甲醇钠三者的摩尔比为1∶1.2∶3.3时,体系在25～30℃反应4 h,以三氯甲烷为萃取剂时,收率可达到88.2%。