膨润土纳米复合材料的制备、表征及吸附性能研究

用有机螯合剂(CA)和十六烷基三甲基溴化铵(HDTMAB)共同改性膨润土(IMB)，制得一系列膨润土纳米复合材料IMB-HDTMA-CA。X射线衍射(XRD)、热分析(TG-DTA)、红外光谱(FTIR)以及N₂-吸附脱附技术等研究发现，HDTMA⁺和CA已稳定柱撑在膨润土的片层结构中，其层间距增大、比表面积减小而疏水性增强。吸附实验表明，IMB-HDTMA-CA能协同吸附水中有机物对硝基苯酚(PNP)和重金属镉(Cd²⁺)。对水中对硝基苯酚的吸附源于PNP在膨润土层间有机相中分配作用的增加，其吸附容量和膨润土内有机碳含量和层间距大小一致，而与比表面积无关，依次为IMB-HDTMA-TEPA>IMB-HDTMA-TETA>IMB-HDTMA-En>IMB-HDTMA 》IMB；FTIR图谱显示，IMB-HDTMA-CA吸附Cd²⁺后的N-H吸收峰向低频方向移动，其吸附能力和所形成配合物的稳定性一致。     

有机膨润土吸附水中重金属和有机污染物的性能及机理研究

螯合剂柱撑有机膨润土IMB-TMA-Am能有效吸附水中有机物对硝基苯酚(PNP)和重金属离子Cu2 ,其中IMB为内蒙膨润土;CTMA为溴化十六烷基三甲基季铵盐阳离子;Am分别为有机螯合剂乙二胺(En)、三乙烯四胺(TETA)和四乙烯五胺(TEPA)。实验结果表明:螯合剂柱撑有机膨润土对有机污染物的吸附主要表现为有机物在长碳链疏水介质中的分配,其吸附能力和膨润土内有机碳、氮含量一致;对水中重金属离子的吸附机理是Cu2 和进入膨润土层间的有机螫合剂Am形成了配合物,其吸附能力和所形成配合物的稳定性一致。     

有机膨润土的吸附性能研究

有机膨润土处理水中有机物的研究已有报道［1－4］，但尚无就改性所用的表面活性剂对有机膨润土吸附性能的影响及规律的系统研究，对有机膨润土与不同有机物间作用机理的报道也甚少［1］．本文用3种不同的阳离子表面活性剂改性膨润土，并从等温吸附线的特征和有机物的辛醇－水分配系数较系统地研究了有机膨润上对几种有机物的吸附性能和作用机理．1实验部分1．1材料原士为钠基膨润土，经测定其阳离子交换容量为7464meg／100g土；澳化十六烷基王甲铰（CTMAB）为分析纯，溪化十二烷基三甲铰（DTMAB，95％），演化十八烷基三甲按（OTMAB…     

表面活性剂改性的螯合剂有机膨润土对水中有机污染物和重金属的协同吸附研究

采用季铵盐阳离子(CTMA+)和有机螯合剂(Am)复合改性膨润土(IMB), 制得一系列螯合剂柱撑膨润土IMB-CTMA-Am. 利用X射线衍射(XRD)分析、差热-热重(TG-DTA)分析、比表面积测定(N2-BET)以及元素分析等手段对吸附剂样品进行了表征. 结果表明, CTMA+和Am已柱撑进入膨润土层间. 吸附实验结果表明, IMB-CTMA-Am能同时有效地去除有机污染物对硝基苯酚(PNP)和重金属铅(Pb2+), 其对水中对硝基苯酚的强吸附能力来源于分配作用的增加和层间距的增大, 而与比表面积无关. 傅里叶变换红外光谱(FTIR)显示, IMB-CTMA-Am吸附Pb2+后的N—H吸收峰向低频方向移动, 表明Pb2+和膨润土层间的Am形成了稳定的配合物. 有机螯合剂Am和Pb2+所形成配合物的稳定性越大, IMB-CTMA-Am对Pb2+离子的吸附能力也就越强.     

GMMT复合材料的制备及吸附性能研究

采用直接插层法对钠基膨润土进行改性,制备了明胶/膨润土(简称GMMT)复合材料;研究了明胶插层复合改性膨润土的工艺条件;通过测定明胶插层复合前后膨润土的比表面积等的变化,探讨了GMMT复合材料的吸附性能.     

两种有机物改性膨润土对Cu2+和Zn2+的吸附-解吸研究

选用天然有机物料(猪粪降解液)和有机化学试剂[十六烷基三甲基溴化胺(HDTMA)]对钠基膨润土进行表面改性,比较了膨润土对两类有机物的吸附特性,以及两种有机物改性膨润土对Cu2+、Zn2+吸附-解吸性能的差异。结果表明,膨润土对HDTMA和猪粪降解液是优惠吸附,且前者最大吸附量为382.4mg/g,是后者的4.19倍。HDTMA改性膨润土对Cu2+、Zn2+的最大吸附量均大于猪粪降解液改性膨润土,前者分别为后者的1.12倍(Cu2+)和1.09倍(Zn2+),且两种吸附剂对Cu2+的最大吸附量和吸附速率均大于Zn2+。Zn2+在两种改性膨润土上的解吸率均高于Cu2+,且Cu2+、Zn2+在猪粪改性膨润土上的解吸率均要高于在HDTMA改性膨润土的。两种有机物改性的钠基膨润土对重金属离子具有良好的吸附性能,可以用于含重金属废水的处理和重金属污染土壤的钝化修复,而猪粪降解液改性膨润土是环境友好的重金属钝化剂。     

复合改性膨润土对2,4,6-三氯苯酚和Pb~(2+)的吸附行为研究

本文主要以钠基膨润土为原料,用十六烷基二甲基苄基氯化铵和乙二胺四乙酸二钠盐对膨润土进行复合改性,制得改性膨润土,用XRD对其结构进行表征,研究了改性后的膨润土对2,4,6-三氯苯酚和Pb~(2+)的吸附行为,结果表明,改性后的膨润土对2,4,6-三氯苯酚和Pb~(2+)的吸附性能明显提高,吸附等温线较好地符合Langmuir模型,改性膨润土对2,4,6-三氯苯酚和Pb~(2+)的最大吸附量分别为238.1mg/g和191.20mg/g,吸附动力学符合准二级反应动力学方程,其二级反应速率常数为分别为8.34×10~(-5)g/mgámin和5.62×110~(-5)g/mgámin,改性膨润土对2,4,6-三氯苯酚的吸附为吸热反应,而对Pb~(2+)的吸附为放热反应。     

功能化碳质材料的制备及其对水中重金属的去除

重金属污染是目前最为严峻的环境问题之一,我国的重金属污染问题尤为突出。活性炭、纳米碳管和石墨烯等环境友好型碳质材料由于其比表面积大,吸附能力强等优点而被应用于水中重金属的去除,而进行官能团功能化改性后其吸附效果可以明显提高。本文重点阐述了活性炭、纳米碳管、石墨烯及生物质炭等碳质材料的巯基化(-SH)、氨基化(-NH₂)等功能化改性方法及其应用,考察了功能化碳质复合材料对水中重金属离子的去除效果和影响因素,最后展望了功能化碳质复合材料对水中重金属污染物去除研究的发展方向。     

多孔氧化物块体材料的制备及其对重金属离子吸附研究进展

目前去除重金属离子的方法较多,其中吸附法因操作简单、经济性好而被广泛使用。多孔氧化物块体材料作为新兴的吸附材料具有比表面积高、机械强度高及可回收性好等特点,但吸附选择性差以及孔结构单一的缺陷限制了其在水体重金属处理中的应用。本文详细叙述了多孔氧化物块体材料的多种制备方法,并分别讨论了各方法的优势及其不足。介绍了近几年研究较多的多孔氧化物块体材料及其制备方法与特性。最后,对多孔氧化物块体材料对 Pb、Cd及 Cr等重金属离子吸附性能的影响因素及改善措施方面进行了总结分析,并指出多种材料的复合、材料表面的接枝改性及分级多孔结构的构建会增强对重金属离子的吸附性能。期望本文为多孔氧化物块体材料的制备及其在重金属离子吸附方面的应用提供参考。     

酸化膨润土负载金催化剂用于CO氧化

用盐酸和硫酸对膨润土（Ben）进行改性处理,采用浸渍法（IMP）、沉积-沉淀法（DP）和阳离子吸附法(CA)制备改性膨润土负载的金催化剂,以CO氧化作为探针反应对催化剂的催化性能进行了研究,采用BET、XRD、TEM和TPD等对催化剂进行表征。 结果表明,经过简单的酸处理后的膨润土比表面积和孔体积有了大幅度的提高,硫酸酸化的膨润土作为载体较之盐酸酸化土更容易得到活性较高的金催化剂,XRD粒径计算结果和TEM观察结果证明,硫酸酸化的膨润土作为载体相比盐酸酸化土可以得到Au颗粒度更小的催化剂。 不同制备方法中,阳离子吸附法能较好的将Au负载于膨润土载体上,得到小颗粒的金催化剂,且在吸附48 h、450 ℃焙烧、150 ℃下H2还原的预处理条件下得到的催化剂活性最好。     

反相微乳液法制备纳米氧化铝

采用由环己烷、聚乙二醇辛基苯基醚(TritonX-100)、正丁醇与水溶液构成的反相微乳液体系, 合成了纳米Al2O3粉体. 采用X射线衍射、扫描电子显微镜、透射电子显微镜、比表面积分析仪等表征手段, 分别对产物的结构、形貌、比表面积和孔容进行了表征, 该纳米Al2O3比表面积约450 m2·g-1(随反应参数不同发生变化), 均属γ-Al2O3, 粒径均匀, 颗粒直径小于10 nm. 考察了微乳液体系中水与表面活性剂的物质的量之比r0、表面活性剂与助表面活性剂的体积比φ、焙烧温度等关键因素对产物比表面积等物理性质的影响. 结果表明, 当r0=20, φ=0.5, 焙烧温度为500 ℃时, 可以得到大比表面积、高孔容、分散性好及粒径分布均匀的γ-Al2O3粉体.     

Photocatalytic storing of O2 as H2O2 mediated by high surface area CuO. Evidence for a reductive-oxidative interfacial mechanism

CuO powders with a high specific surface area are shown to be able to produce H(2)O(2) in aqueous solution under simulated light irradiation. The highest rate of peroxide production was observed under mild experimental conditions using O(2) and a large surface area photocatalyst CuO irradiated with a solar simulator having light intensities between 60 and 90 mW/cm(2). The CuO employed had a specific surface area (SSA) of 64.8-70.1 m(2)/g and was prepared in a tubular furnace by controlled thermal decomposition of precipitated copper oxalate. The CuO particles produced were 1 mum cubes with primary particles around 15 nm. No peroxide was produced under the same conditions with commercial CuO, with SSA 200 times lower. The CuO synthesized during this work was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), specific surface area [Brunauer-Emmett-Teller (BET)], porosity, and X-ray photoelectron spectroscopy (XPS). From XPS, it was observed that only Cu(II) was present in the unused and used CuO. This indicates that the redox transient species involving other Cu oxidation states disappear very fast during the reaction, regenerating Cu(II) during H(2)O(2) production. Diverse experiments provided some evidence for the possible interfacial reaction mechanism leading to H(2)O(2), following the initial step of O(2)(-)(.) formation on the CuO surface under irradiation with photons, with energies exceeding the band gap of CuO. A photocatalyzed degradation of a concentrated 4-chlorophenol (4-CP) solution was observed under solar-simulated light in the presence of CuO.     

Nano sulfated titania as solid acid catalyst in direct synthesis of fatty acid amides

Nanosized sulfated titania was prepared by a sol-gel hydrothermal process. X-ray diffraction (XRD), transmission electron, and scanning electron micrographs (TEM and SEM), FT-IR specific surface area, and BET N(2) adsorption were employed to characterize the properties of the synthesized sulfated TiO(2). The results indicate that both anatase and rutile TiO(2) are obtainable. This prepared sulfated titania showed high catalytic activity in direct amidation of fatty acids as well as benzoic acids with various amines under solvent-free conditions.     

高比表面积Cr2O3-α-AIF3催化剂的制备和应用

采用炭硬模板法制备了高比表面积Cr2O3-α-AIF3催化剂.该催化剂的合成过程主要包括三步:(1)将一定浓度的蔗糖溶液浸渍到Cr203-y-Al2O3中,然后经过热处理,使得蔗糖分解为炭;(2)将含炭的Cr2O3-y-Al2O3固体在400℃用HF气体进行完全氟化;(3)在高温下利用燃烧法除去炭硬模板.对所制备的催化剂进行了X射线衍射(XRD),氮气吸脱附曲线,氨气程序升温脱附(NH3-TPD),透射电镜(TEM),扫描电镜(SEM)和X射线能量散射(EDX)技术表征.结果表明,氟化过程对Cr2O3-α-AIF3催化剂比表面积有重要影响,在最佳实验条件下,能够得到比表面积为115 m2·g-1的催化剂.此催化剂对催化裂解二氟乙烷(HFC-152a)制备氟乙烯(VF)的催化活性明显高于直接氟化制备的Cr2O3-α-AIF3催化剂,这是因为高比表面积的Cr2O3-α-AIF3催化剂具有较大的酸量.     

原位法常压干燥制备疏水SiO2气凝胶及其热稳定性

在正硅酸乙酯(TEOS)酸碱两步催化的溶胶-凝胶过程中, 加入干燥控制化学添加剂(DCCA)N,N-二甲基甲酰胺(DMF)和三甲基氯硅烷(TMCS)的混合溶液, 进行原位疏水改性处理, 并结合常压干燥工艺制备了高比表面积的疏水SiO2气凝胶. 利用N2物理吸附, 全自动X射线衍射仪(XRD), 傅立叶变换红外光谱仪(FTIR), 扫描电子显微镜(SEM)等对样品的形貌结构进行了表征. 实验结果表明, 原位疏水改性比非原位疏水改性制备的SiO2气凝胶具有更大的比表面积, 可达979 m2·g-1, 气凝胶表面存在憎水性基团—CH3, 有良好的疏水性. 500 ℃热处理后, 气凝胶因失去大量的—CH3基团, 由憎水性转为亲水性; 800 ℃高温热处理后, 疏水SiO2气凝胶仍处于非晶态, 具有良好的热稳定性能.     

Synthesis and photocatalytic activity of TiO2 nanoparticles prepared by chemical vapor condensation method with different precursor concentration and residence time

Nanosized TiO(2) photocatalysts were synthesized using a chemical vapor condensation method under a range of synthesis conditions (precursor vapor concentration and residence time in a tubular electric furnace). X-ray diffraction showed that the prepared TiO(2) powders consisted mainly of anatase (>94%) with a small amount of rutile. The mean particle diameter from the Brunauer-Emmett-Teller surface area and transmission electron microscopy measurements ranged from 9.4 to 16.6 nm. The specific surface area (92.5-163.5 m(2) g(-1)) of the prepared TiO(2) powders was found to be dependent on the synthesis conditions. The content of hydroxyl groups on the surface of the prepared TiO(2) sample was higher than those on commercial TiO(2), resulting in increased photocatalytic oxidation. The photocatalytic activity of the TiO(2) samples prepared in a methylene blue solution was strongly dependent on the crystallinity and specific surface area, which were affected by the TTIP vapor concentration and residence time.     

Tailoring the structure of metal oxide nanostructures towards enhanced sensing properties for environmental applications

The present article reviews recent works in our laboratory about the sensing properties to toxic gases using nanostructured WO(3), TiO(2), FTiO(2), and CuO functionalized quartz crystal microbalance (QCM) sensors. WO(3) and TiO(2) functionalized QCM sensors have much shorter response time than those functionalized by conventional hydrogen-bond acidic branched copolymers for detection of dimethyl methylphosphonate (DMMP). FTiO(2) functionalized QCM sensors can improve the gas sensing characteristics by shortening the response time but at the price of partial irreversibility. The sensing mechanism was examined by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). Varied CuO nanostructures were synthesized by simple modulation of reaction conditions. All the as-prepared CuO was applied on QCM resonators and explored for HCN sensing. Surprisingly, responses of all the sensors to HCN were found to be in an opposite direction as compared with other common volatile substances, offering excellent selectivity for HCN detection. The sensitivity was very high, and the response and recovery were very fast. Comparison of the specific surface areas of CuO nanostructures showed that CuO of higher surface area is more sensitive than that of lower surface area, indicating that the specific surface area of these CuO nanostructures plays an important role in the sensitivity of related sensors. Based on experimental results, a sensing mechanism was proposed in which a surface redox reaction occurs between CuO and Cu(2)O on the CuO nanostructures reversibly upon contact with HCN and air, respectively. The CuO functionalized QCM sensors are considered to be a promising candidate for trace HCN gas detection in practical applications.     

Synthesis and characterization of crystalline nanosized MgF2 powder via microemulsion route

Nanosized MgF₂ was synthesized by precipitation in microemulsions of water in cyclohexane stabilized by polyethylene glycol tert-octylphenyl ether. The synthesized MgF₂ powder was characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), BET specific surface area, attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), and X-ray diffraction (XRD). The results showed that the synthesized powder was a MgF₂ powder with a crystallite size in the range of 9-11 nm and a specific surface area of 190 m²/g.     

Synthesis, characterization and adsorption performance of a novel post-crosslinked adsorbent

In this paper a post-crosslinked polymeric adsorbent PDHT-2 with high specific surface area was prepared by Friedel-Crafts reaction of the pendant vinyl groups without an externally added crosslinking agent. It was obvious that both the specific surface area and the pore volume of starting copolymer PDHT-1 increased significantly after post-crosslinking. Batch adsorption runs of phenol from aqueous solution onto adsorbent PDHT-1 and PDHT-2 were researched, and commercial macroporous resin XAD-4 was chosen for comparison purpose. Experimental results showed that the adsorption isotherms could be fitted by Langmuir model and Freundlich model and the adsorption capacity onto PDHT-2 was much larger than that onto PDHT-1 and XAD-4 with respect to phenol and phenolic compound, which possibly resulted from its larger specific surface area. The adsorption process for phenol onto the three adsorbents was proved to be exothermic and spontaneous in nature. The thermodynamic parameters such as Gibb's free energy (ΔG), change in enthalpy (ΔH) and change in entropy (ΔS) had been calculated. The adsorption kinetic curves obeyed the pseudo-second order model and the intraparticle diffusion process was the rate-controlling step.     

四种晶型MnO2超级电容器电极材料的电化学性能研究

用尽量简便的方法制备出δ、α、β及γ型4种MnO₂粉末. 通过X射线衍射（XRD）、场发射扫描电镜（FSEM）、热重分析（TGA）与比表面积测试（BET）等方法对样品粉末性质进行分析,并对4种不同粉末制成的电极进行循环伏安、恒流充放电及稳定性测试. 结果表明,4种MnO₂都具有良好的电容特性,其中α-MnO₂具有最高的比表面积与孔隙率,故其电极比容量最高,但其大电流放电时的倍率特性较差. 其余3种MnO₂比表面积相当,而β-MnO₂虽然比容量较低,但其简单的孔隙结构使其拥有最好的倍率特性与稳定性.