载铜蒙脱石的制备与表征

以蒙脱石和硫酸铜为主要原料,制备载铜蒙脱石。比较载铜前后蒙脱石的晶体结构和表面特性。结果表明：铜主要是以水合阳离子的形式,以离子交换的方式进入蒙脱石品格层间,还有少量铜以化学吸附的形式进入Si-O四面体和Al-O八面体的微孔中。与蒙脱石相比,载铜后的蒙脱石总比表面积、微孔比表面积、微孔体积减少,而离子交换容量、外比表面积、孔体积和孔径增大。另外,载铜蒙脱石的总电荷、层间电荷、端面电荷和zeta电位的绝对值均低于蒙脱石,表明所载铜降低了粘土矿物质的负电荷。     

蒙脱石的钠化改性

蒙脱石（MontmoriUonite）属于单斜晶系的含水层状硅酸盐矿物。其颗粒细小，具有胶体分散特性。蒙脱石属于2：1型结构单元层的二八面体型，单位晶胞由两片顶角朝里的Si-O四面体中夹一片AlO或Mg-O八面体形成一结构层。处于八面体空隙中的三价Al^3＋、Fe^3＋、和Cr^3＋离子常常被低价离子取代如Mg^2＋代替Al^3＋，Si^4＋常常被Al^3＋代替。由于部分高价阳离子被低价阳离子所取代，使结构层中的氧负电荷过剩。为了保证电荷平衡，水，交换性阳离子如Na^＋、Ca^2＋和有机液体可以进入层间结构，故蒙脱石具有5H离子交换能力。层间水分子在100-200℃时逐渐脱水，但并不破坏结构单元层的结构。脱水后的蒙脱石又可重新吸附水分子或其他极性分子进入层间。其化学式可表示为：     

蒙脱石八面体层中(Fe~(3+)+Mg~(2+))含量和晶胞参数b_0对蒙脱石-水体系电导的影响

蒙脱石八面体层中(Fe~(3+)+Mg~(2+))含量影响晶胞参数b_0亦影响蒙脱石的比亲水性,即影响蒙脱石结合水膜的厚度。结合水膜厚度的大小,影响蒙脱石层间交换性阳离子在蒙脱石-水体系中的电导。本工作通过对不同地区,不同类型蒙脱石-水体系电导测试,讨论了蒙脱石八面体层中(Fe~(3+)+Mg~(2+))含量和晶胞参数b_0的变化对电导率影响的规律。     

晶粒大小及孔结构对氧化铝陶瓷耐磨性的影响

利用扫描电子显微镜研究了氧化铝陶瓷中Al2O3晶体的大小、均匀程度和孔结构对氧化铝陶瓷耐磨性的影响,指出了采取有效措施控制Al2O3晶体长大和使微孔小而均匀是提高氧化铝陶瓷耐磨性的主要途径。     

酸处理后坡缕石的孔结构变化

在90℃,坡缕石分别用不同浓度的盐酸处理1.5h,对制得样品的物相、比表面积和微孔结构以及微观形貌进行了研究.结果表明:酸处理可以提高坡缕石的比表面积,改变坡缕石晶体的孔结构,随着酸浓度的改变,坡缕石的总比表面积、微孔比表面积和外比表面积都随之发生改变.当酸浓度小于等于3 mol/L时,坡缕石颗粒聚集体逐步被解离,溶蚀作用主要发生在孔道内,晶体结构能保持相对完整;当酸浓度大于3 mol/L时,部分颗粒被溶蚀掉.结果说明H 能进入到坡缕石的晶体孔道中产生作用,使晶体的孔道不断扩大,孔径最大可以达到0.62～0.75nm,但孔径超过0.62～0.75nm后晶粒会被破坏.     

凹凸棒石与酸反应产物和结构演化的研究

利用TEM，XRD研究了热液型和沉积型凹凸棒石与酸作用过程中产物、结构变化。结果表明：随着酸浓度增加，凹凸棒石与酸反应时间延长，凹凸棒石中八面体阳离子溶解增加，并在溶解的同时，四面体硅部分分解成硅酸或聚硅酸溶胶，部分四面体硅保持凹凸棒石纳米针状晶体形态假象，直至八面体阳离子完全溶解。八面体阳离子部分溶解并不破坏凹凸棒石的晶体结构，当八面体阳离子基本完全溶解时，凹凸棒石晶体转变为纳米棒状无定形活性SiO2。比较而言，热液型凹凸棒石比沉积型凹凸棒石更耐酸，除热液型凹凸棒石的晶体直径比沉积型凹凸棒石的晶体直径大之外，可能与热液型凹凸棒石八面体的有序度高有关。实验结果证实：酸处理后的凹凸棒石在镁盐溶液中没有发生成分和结构的恢复。     

新型亚磷酸铀的合成与表征

由于无机微孔晶体具有规则的孔道结构和丰富的结构类型,在吸附、分离、催化、主客体化学等领域的广泛应用,具有新颖结构的微孔晶体的合成一直备受关注。近年来,以假四面体的HPO3基团取代的四面体PO4基团构筑微孔晶体在超大孔微孔晶体的合成领域取得很多成果。ZZ-1的化学式为[C10H24N2][(UO2)2(HPO3)3].H2O,是以佛尔酮二胺为模板剂合成出的层状亚磷酸铀,其结构是由UO7五双角锥和HPO3假四面体连接形成的4,8元环的网络片层,这些片层的堆积形成了层状结构。层与层之间的嵌有顺式的异佛尔酮二胺阳离子和水分子。ZZ-1在266nm激光激发下发出强烈的绿光。     

苏皖沉积型坡缕石酸溶动力学研究

从坡缕石提纯入手,用分光光度法进行元素分析,对坡缕石的酸溶动力学进行研究。实验结果表明：坡缕石酸溶反应中八面体阳离子溶出率取决于阳离子在矿物中的含量、酸溶反应本身活化能和离子扩散速度。其酸溶动力学宜采用圆柱体一内扩散控制模型模拟,其浸出率x对反应时间t的关系可表示为(1-x) xlnx=kt。在实验条件下坡缕石八面体阳离子Fe^3 ,Al^3 和Mg^2 酸溶反应表观活化能分别为11．4,9．5kJ／mol和16．6kJ／mol。     

钙钠基蒙脱石铝柱撑的制备和表征

以山西大同的钙钠基蒙脱石为原料,制备了铝柱撑蒙脱石.通过XRD,FT-IR,N2吸附-脱附等测试手段,分析了产物的层间距、比表面、孔特征和结构变化.结果表明:钙钠基蒙脱石铝柱撑能获得比较好的柱撑效果,层间距为1.94nm,BET比表面为273.87m2/g,微孔容积为0.1174cm3/g,微孔孔径的最可几分布为0.738nm,中孔孔径的最可几分布为3.766nm.     

剥离型葡萄糖酸蒙脱石的制备及其表征

利用葡萄糖酸改性碱性钙基膨润土制备了一种与水溶性高分子材料亲合性较强的剥离型葡萄糖酸蒙脱石.通过单因素实验,分析了葡萄糖酸用量、反应温度、分散剂浓度等因素对葡萄糖酸蒙脱石剥离的影响,认为蒙脱石剥离可能是由于层间发生激烈的中和反应造成的.电子显微镜扫描表明这种剥离型蒙脱石为片状结构,纳米片的厚度为75～100 nm; DSC测定表明该葡萄糖酸蒙脱石的失水温度与葡萄糖酸钙相同,葡萄糖酸基团分布在纳米片的表面上;IR 扫描表明葡萄糖酸与蒙脱石的结合方式为化学键;XRD表征说明该葡萄糖酸蒙脱石仍为层状结构,为多层蒙脱石晶片组成.将该葡萄糖酸蒙脱石添加到木薯淀粉糊中,能使淀粉糊的黏性增加一倍.     

Adsorption of gaseous SO2 and structural changes of montmorillonite

Several montmorillonite samples after adsorption of gaseous SO₂ were analyzed to evaluate structural and textural changes. The equilibrium adsorption of the SO₂ gas was measured at 25 °C and 0.1 MPa. The samples were characterized by X-ray diffraction (XRD), infrared spectroscopy (IR), swelling index (SI), pH measurements, and N₂ adsorption–desorption isotherms. SO₂ adsorption increased with the specific surface area of montmorillonite. SO₂ retention decreased pH of the dispersed samples from 6 to 1 and released interlayer and octahedral cations from the structure, which increased the specific BET surface area and specific micropore surface similar to that of acid-activated montmorillonite.     

Sorption of Cyclohexylamine by Montmorillonites

Infrared spectra indicate that protonation of cyclohexylamine sorbed by montmorillonite depends upon the interlayer cations and the origin of the lattice charge. No protonation occurs with Cs and very little with Na, but with all the other interlayer cations studied cyclohexylammonium ions are formed. Protonation occurs more readily if the lattice charge originates in the octahedral layer. Various associations are inferred between interlayer hydroxides, hydrated cations, ionic and molecular cyclohexylamine and water. The sorption of cyclohexylamine is compared with that of aniline and the validity of the concept “surface acidity” is questioned.     

钛柱撑黏土的核磁共振和漫反射红外光谱

Pillared clays（Ti-PILCs）were synthesized from Na-type montmorillonite through intercalation with polymeric hydroxy-titanium.The mechanism of the pillaring course was studied by means of magic angle spinning nuclear magnetic resonance（MAS NMR）and diffuse reflectance infrared spectroscopy（DRIFTS）techniques.DRIFTS suggested that after Ti-pillaring,the silicon-oxygen tetrahedral Si—O—Si bond and aluminum oxide octahedral Si—O—Al bond were broken.Meanwhile,NMR also showed the change of the silicon-oxygen tetrahedral structure and aluminum oxide octahedral structure in the pillared clay.In the pillaring process,the titanium hydroxy-oligomeric cations entered the layers of the montmorillonite by ion-exchange,the Si—O—Al bond of the raw clays were broken,the silicon-oxygen tetrahedron structure were overturned,and the reactive oxygen species（structural hydroxyl）reacted with titanium hydroxy-oligomeric cations to form Si—O—M bond.This led to the incorporation of pillaring species of Ti in the layers of the clay.After further heat treatment,the TiO₂ pillars were formed in the layers to obtain Ti-PILCs.     

Adsorption of diuron on mechanically and thermally treated montmorillonite and sepiolite

The effects on montmorillonite (Mt) and on sepiolite (Sep) of mechanical (60 and 180 s grinding time) and further thermal treatments (TT) at 500 °C during 24 h, for removing diuron from aqueous solutions were evaluated. The adsorbents and complexes formed were characterised. The specific surface area (SSA), SEM, XRD and zeta potential of the clay mineral samples were determined. The SSA values showed an increase of 50% for ground Mt and a slight decrease for ground Sep. TT reduced SSA by 50% for the Sep samples, but similar values remained for the Mt samples. Both minerals showed a decrease in crystallinity with increasing grinding time and TT. The zeta potential showed an increased of the negative surface charge for the Mt ground samples, but no changes were noticed for the Sep ground samples. The Mt-TT samples showed a slight decrease whilst the Sep samples showed an increase of the negative surface charge in comparison to those without thermal treatment. The adsorption of diuron on Mt was lower than on Sep, and it decreased slightly after 60 and/or 180 s of grinding, despite the larger SSA values. This differences on the adsorption extent were probably due to the increased micropore surface. In contrast, thermal activation caused significantly increased adsorption, especially for the 180-s ground sample that was inversely correlated with the micropore surface, indicating that diuron was not adsorbed in micropores. Diuron adsorption on Sep was higher than on Mt due to its higher SSA. The adsorption capacity of Sep samples was increased by mechanical treatments (ground and sonicated). Moreover, thermal activation led to additional increases in adsorption probably due to changes in the Sep structure by the loss of OH structural groups leading to a more hydrophobic surface. Diuron adsorption on Mt-TT samples produced an increase in the negative surface charge compared to the original sample, whereas a decrease in the negative surface charge was observed for Sep.     

Main factors controlling the texture of zirconia and alumina pillared clays

The texture development has been studied of a saponite and a montmorillonite, intercalated with zirconium and aluminum oligomers, after calcination at 773 K. Remarkable differences were observed among the samples, depending on the source of the intercalating polycations and the parent material. On calcining, the alumina pillared clays suffered noticeable specific surface area and micropore volume losses, which were related to the pillar density of the samples. On the contrary, the zirconia pillared clays showed a slight surface area increase, which affected both the micropores and the mesopores and could be due to the combined effect of the thermal decomposition of the zirconium oligomers and the possible presence of mesoporous ZrO₂ particles. Horvath–Kawazoe and Cheng–Yang methods were both applied in order to obtain the micropore size distributions of the solids.     

非均匀多孔介质表面变压过程的分形特征

多孔物质的表面结构可以用分形维数D来表征,D与微孔结构存在对应的关系,不同的表面分形维数对应不同的微孔结构.详细讨论了分形维数和微孔结构随压力的变化规律.随着压力的增大,多孔介质表面形成更小的吸附微孔,孔径分布广,表面变得更粗糙,分形维数增大,至到趋于稳定值.分形维数表达表面结构简洁明了.     

非均匀多孔介质表面变压过程的分形特征研究

多孔物质的表面结构可以用分形维数D来表征,D与微孔结构存在对应的关系,不同的表面分形维数对应不同的微孔结构．详细讨论了分形维数和微孔结构随压力的变化规律．随着压力的增大,多孔介质表面形成更小的吸附微孔,孔径分布广．表面变得更粗糙,分形维数增大,至到趋于稳定值．分形维数表达表面结构简洁明了．