氨基功能化磁性CoFe2O4/氧化石墨烯去除电镀废水中Cr(Ⅵ)的研究

使用改良的hummers法制备出的氧化石墨烯为载体,采用共沉淀法制备出磁性CoFe2O4/氧化石墨烯(MGO),再使用三乙烯四胺(TETA)对磁性CoFe2O4/氧化石墨烯进行氨基功能化,制备出氨基功能化磁性CoFe2O4/氧化石墨烯吸附剂.采用X-射线衍射仪(XRD)、傅里叶变换红外光谱仪(FT-IR)和扫描电子显微镜(SEM)对TETA-MGO的物相、化学组成和微观形貌进行表征,以TETA-MGO作为吸附剂去除电镀废水中Cr(Ⅵ),探讨吸附性能和吸附机理,分析TETA-MGO在外加磁场下的液固分离和再生吸附性能.结果表明纳米级立方尖晶石相磁性CoFe2O4均匀生长于氧化石墨烯的表面和片层之间,TETA通过C-N键与磁性氧化石墨烯(MGO)相连,氨基功能化成功,活性吸附位点增点.室温下,pH =2时吸附效果最佳,吸附120 min时达到吸附平衡,平衡吸附量约为48.66 mg·g-1,TETA-MGO对Cr(Ⅵ)的吸附动力学和吸附热力学可分别使用拟二级动力学模型和Langmuir等温吸附模型描述,吸附过程主要属于化学吸附控制的单分子层吸附,使用外加磁场可以对TETA-MGO实现简单的固液分离,TETA-MGO经过6次再生吸附后,对Cr(Ⅵ)的吸附量仅下降19.67;,说明具有良好的循环再生吸附能力.     

高岭石基介孔复合材料的二氧化碳吸附性能

碳排放量的快速增长所引起的全球气候变暖问题越来越受到各国的关注,因此研发制备可行高效的二氧化碳(CO₂)捕获材料具有极其重要的意义。本文以高岭石为原材料,采用煅烧-碱活化-酸刻蚀的方法,制备出介孔氧化硅载体(KNH),再将KNH经过五乙烯六胺(PEHA)修饰后制备出介孔复合材料(KNH-PEHA)。通过X射线衍射(XRD)、傅里叶变换红外光谱(FT-IR)、扫描电子显微镜(SEM)、N₂物理吸附等方法对样品进行表征,并进一步对样品进行CO₂吸附性能研究。结果表明,PEHA的浸渍修饰并未改变载体的结构,但显著提高了介孔复合材料对CO₂的吸附能力。吸附温度为25 ℃,KNH的CO₂吸附量为147.39 cm³/g,而PEHA质量分数为30%的KNH(KNH-P-30)平衡时的CO₂吸附量达到389 cm³/g,远高于未经PEHA修饰的KNH的吸附量,同时提出了该固体吸附剂对CO₂的吸附机理,为高岭石在气体吸附领域的应用提供一个新思路。     

超支化聚合物对石墨烯的功能化研究进展

石墨烯高分子化在发展高性能聚合物基纳米功能材料方面备受关注.追踪近几年与超支化聚合物/石墨烯复合材料相关的文献,针对超支化聚合物对石墨烯的共价和非共价功能化改性方法进行了综述.将共价功能化细分为表面功能化和边缘功能化,以及非共价功能化分为通过π-π作用超支化聚合物吸附在石墨烯表面和通过疏水作用超支化聚合物对石墨烯的剥离这两种情况.并简单介绍了超支化聚合物功能化的石墨烯基复合材料的性能和应用,对其存在的问题和未来的发展方向进行了展望.     

氧化石墨烯/二氧化硅复合材料的制备及其在吸附领域应用研究进展

近十年来,氧化石墨烯(GO)基复合材料日益引起研究者的广泛兴趣,而氧化石墨烯和二氧化硅的复合材料是其中的一个研究热点.本文介绍了氧化石墨烯/二氧化硅(GO/SiO2)复合材料的制备及其在吸附领域的应用.其制备方法包括非共价键法和共价键法,在非共价键法中,包括阳离子表面活性剂法和二氧化硅表面改性法;在共价键法中,包括形成酰胺键(-CO-NH-)、硅酯键(-COOSi-)、碳氧硅键(-C-O-Si-).吸附领域的应用包括对重金属离子、有机物的吸附.最后,我们对氧化石墨烯/二氧化硅复合材料将来的发展进行了展望.     

金刚石膜表面氨等离子体处理研究

本文尝试采用微波等离子体CVD技术,实现金刚石膜的制备以及金刚石膜表面的氨等离子体处理,实现氨基功能化修饰金刚石膜的制备.通过扫描电子显微镜(SEM)、拉曼光谱(Raman)、X射线光电子能谱(XPS)以及水接触角等对氨等离子体处理前后的金刚石膜进行检测分析.结果表明,采用微波等离子体CVD技术,可以在金刚石膜表面植入氨基实现功能化修饰,从而提高金刚石膜表面活性.同时,金刚石膜的整体品质未出现显著变化.     

改性羟基磷灰石制备及除氟特性研究

为了提高羟基磷灰石(HAP)的除氟容量,利用羟基铝(Al-OH)改性HAP制备羟基铝-羟基磷灰石复合材料(Al-OH-HAP),通过红外光谱(FTIR)、扫描电镜(SEM)、X-射线粉末衍射(XRD)和N2吸附-脱附曲线等方法对样品进行表征分析,结合吸附热力学和动力学模型拟合,探讨Al-OH-HAP对水溶液氟离子的吸附特性.实验结果表明:Al-OH改性后Al3+和OH-进入HAP晶格中,且改性后HAP的衍射峰更尖锐,结晶度增大.Al-OH改性后HAP的比表面积分别从106.75 m2/g增加到220.45 m2/g,且大部分孔为介孔结构.吸附拟合模型表明Al-OH-HAP对氟离子的吸附更加遵循Langmuir模型,说明Al-OH-HAP对F-的吸附更趋近于单层吸附,吸附过程中化学吸附占主导地位.热力学参数吸附吉布斯自由能(ΔGo)小于0、焓变(ΔHo)和熵变(ΔSo)大于0,说明Al-OH-HAP对F-的吸附是一个自发吸热的熵增过程,Al-OH-HAP对F-的吸附更符合拟二级反应动力学过程.Al-OH-HAP可以成为一种有潜力的饮用水除氟剂.     

Fe3O4/LDHs复合结构的制备及吸附性能研究

分别采用两种方式(一步合成法和二步合成法)在Fe3O4表面生长层状双金属氢氧化物(LDHs),得到了Fe3O4/LDHs复合材料.利用X-射线衍射、电子显微分析、红外光谱和交变梯度磁强计等测试方法研究了LDHs和Fe3O4的复合方式对复合材料形貌、粒径、结晶性、磁性能和吸附性能的影响.同时对比分析了LDHs和Fe3O4/LDHs复合材料对Cr(Ⅵ)离子的平衡吸附规律.结果表明,采用一步合成法制备的Fe3O4/LDHs复合材料具有良好的磁性能和吸附性能.     

n-n异质结Ag3PO4/Bi2WO6的制备及其增强的可见光活性

以片状Bi2 WO6为前驱体,采用沉淀法制备n-n异质结Ag3 PO4/Bi2 WO6复合材料.通过多种技术,像X射线衍射(XRD)、X射线光电子能谱(XPS)、N2吸附-脱附、扫描电镜(SEM)、透射电镜(TEM)和紫外-可见漫反射吸收光谱(UV-vis/DRS)考察所制备样品的组成、结构、形貌和光吸收性质.Ag3 PO4/Bi2 WO6复合材料由球形Ag3 PO4和片层Bi2 WO6相互交织组成,形成n-n异质结.随后,以染料罗丹明B(RhB)和苯酚(Phen)为模型分子来评价光催化剂Ag3 PO4/Bi2 WO6的可见光催化性能.与单体相比,Ag3 PO4/Bi2 WO6复合材料显示出增强的可见光催化活性.n-n异质结的形成可扩宽可见光吸收范围,促进光生电子-空穴对的分离,进而提高复合材料的可见光催化效率.     

多孔BaTiO3的制备及多孔BaTiO3/PVDF复合材料性能研究

采用溶胶凝胶法,以聚环氧乙烷-聚环氧丙烷-聚环氧乙烷三嵌段共聚物(P123)为模板剂,经80℃反应制备了BaTiO3溶胶,向溶胶中加入100 nm实心BaTiO3得到多孔BaTiO3前驱体,经550℃煅烧得到多孔BaTiO3,用偶联剂改性多孔BaTiO3;用溶液浇铸法制备BaTiO3/PVDF复合材料.采用TEM、氮吸附比表面测试仪、精密阻抗分析仪和超高压耐压测试仪表征粉体形貌及复合材料性能.实验结果表明:多孔BaTiO3颗粒直径为120 nm,比表面积46 m2·g-1,当多孔BaTiO3添加量10vol;时,复合材料介电常数达到21.4,场强达到261 kV/mm,该复合材料在高储能电容器材料具有应用潜力.     

聚乙烯醇改性磷酸银的光催化活性研究

在制备的磷酸银表面吸附少量的聚乙烯醇(PVA),并通过热处理制备了DPVA/Ag3 PO4复合材料.使用傅立叶红外光谱法(FT-IR)和荧光光谱法(PL)对DPVA/Ag3 PO4复合材料进行表征.分析得知,经聚乙烯醇复合改性的DPVA/Ag3 PO4复合微粒中存在共轭结构,光生电子-空穴对复合率降低,光催化活性得到显著提高.研究了不同条件(复合比例、热处理温度、热处理时间)下制备的复合光催化剂在可见光下催化降解甲基橙的光催化性能.当PVA与Ag3 PO4质量比为1:4000,热处理温度为190℃,热处理1 h时光催化效果最好.     

离子液体改性白炭黑及性能表征

采用离子液体1-烯丙基-3-甲基氯化咪唑(AMI)改性白炭黑(SiO2).通过傅里叶红外光谱(FT-IR),X射线衍射(XRD),X射线光电子能谱(XPS),热失重分析仪(TGA),扫描电镜(SEM),接触角仪,BET比表面积和孔径分析仪,对改性前后白炭黑的微观结构以及性能进行表征.结果表明,经AMI改性后,白炭黑粒子间的相互作用明显减小,团聚倾向减弱,在橡胶复合材料基体中的分散性提高.AMI改性白炭黑疏水性增强,接触角由12.7°增加到80.5°,比表面积由67.84cm2/g增加到124.28cm2/g.改性前后,白炭黑晶型结构变化不大,仍为无定形态.     

高性能刷状ZnO介晶的制备及其对复合树脂性能的增强作用

无机填料作为齿科复合树脂的主要成分,对其性能影响最为显著。本文以阿拉伯胶为结构导向剂,用热水解法合成了多孔、分级结构的刷状ZnO介晶,其厚度和直径分别为1.2 μm和1.0 μm。通过微流控制法在其表面包覆了4~6 nm无定形SiO₂,以利于其表面硅烷化。通过场发射扫描电镜(FE-SEM)、X射线衍射仪(XRD)、热重分析仪(TGA)等对其进行了表征。对ZnO@SiO₂进行硅烷改性处理后,将其作为辅助填料,与改性纳米SiO₂主填料一起添加到Bis-GMA/TEGDMA树脂体系中,光固化得到齿科复合树脂。力学测试表明,ZnO@SiO₂填充质量分数控制在5%以内时可有效提高复合树脂力学性能。与单一二氧化硅填料的复合树脂相比,添加填充质量分数3% ZnO@SiO₂,复合树脂的力学性能表现最佳,其弯曲强度、弯曲模量和压缩强度分别提高了12.9%、6.6%和3.7%,同时还表现出优良的抗菌活性,对变异链球菌抗菌率达98.7%。此外,添加了ZnO@SiO₂介晶填料的复合树脂还具备更好的耐磨性。     

Characteristics of composites based on PMMA modified gel silica glasses

Gel silica glass prepared by the sol-gel process can be modified by incorporating an organic phase into the intrinsically porous inorganic gel matrix, which results in a composite material with much improved mechanical and optical properties. Characterisation of PMMA modified gel silica glass prepared by the in situ polymerisation method using FT-Raman spectroscopy, gel permeation chromatography and the nitrogen adsorption technique are reported. Some essential problems encountered in the preparation are discussed.     

HNTs/SiO2复合气凝胶制备及其性能研究

采用正硅酸乙酯(TEOS)为硅原,以硅烷改性的埃洛石纳米管(HNTs)为增强相,利用CO2超临界干燥技术制备具有优良力学和隔热性能的HNTs/SiO2复合气凝胶.利用傅立叶红外光谱、扫描电镜、比表面积与孔径分析仪、万能试验机和导热率测量仪等手段对HNTs改性后的表面状态、HNTs/SiO2复合气凝胶的微观形貌、孔结构、力学和导热性能进行了测试分析.结果表明:改性后的HNTs均匀分散到二氧化硅气凝胶基体中,并与SiO2纳米颗粒实现良好的结合,HNTs/SiO2复合气凝胶呈三维网络结构,当HNTs含量为15wt;时,平均孔径为10.47 nm;随着HNTs含量的增加,复合气凝胶的力学性能不断增强,同时其导热系数也不断增大,当HNTs含量为15wt;时,HNTs/SiO2复合气凝胶的抗压强度为0.85 MPa,导热系数为0.024 W/mK.     

绿色合成载银壳聚糖及其等温线、动力学及抑菌性

以吸附绿色合成法制备载银壳聚糖,采用X射线衍射(XRD)、场发射扫描电镜(FESEM)和热重分析研究其微观结构和热稳定性,并研究了壳聚糖对银离子的吸附模型,以此为抗菌材料,通过平板扩散板法评价载银壳聚糖的抗菌效果。实验结果表明:银离子在多糖结构中的引入影响了其原有的晶体结构,提升了其热稳定性。壳聚糖对银离子的吸附等温线与Langmuir和Dubinin-Radushkevich方程相一致,说明了壳聚糖中银离子的吸附过程符合单层吸附和化学吸附,并且根据Langmiur方程计算壳聚糖对银离子的最大吸附量为478.09 mg/g,含银量为32.34%,与Dubinin-Radushkevich计算结果一致。银含量饱和的载银壳聚糖对大肠杆菌(Escherichia coli)和金黄色葡萄球菌(Staphylococcus aureus)具有良好的抗菌性能,其最小抑菌浓度为80 μg/mL。     

Hydrophobic and thermal insulation properties of silica aerogel/epoxy composite

Silica aerogel/epoxy composite was prepared by dry mixing hydrophobic aerogels with epoxy powders and heat pressing method. The composite materials show a serviceability temperature up to 250 °C with low thermal conductivity (0.11–0.044 W/m k) and hydrophobic property (water contact angle of 117–140°). Transmission electron microscope photos proved that part of silica aerogels nanopores had been immersed by epoxy. Based on this phenomenon, an immersion model was build up to study the effect of immersion on the thermal insulation and hydrophobic properties. In addition a thermal conductivity prediction equation of aerogel/polymer system was obtained and confirmed by comparing the experimental data.     

Effect of pH and chitosan concentration on precipitation and morphology of hierarchical porous silica

Understanding the interaction between chitosan molecules and sodium silicate is one of the principal objectives for the development of new environmentally benign strategies for the synthesis of low-cost porous silica with hierarchical structure. In this work, we have explored two essential factors simultaneously: chitosan/silica ratios (0.1, 0.4, 0.8 and 1.6) and pH values of the mixture (3, 5 and 6). The obtained silica–chitosan composite and the calcined products were investigated by using thermal gravimetric analysis, N₂-physisorption, scanning electron microscopy, and transmission electron microscopy. Rapid precipitation of silica–chitosan composite occurred because of the initial pH values of the chitosan and sodium silicate solutions. The amount of precipitating silica–chitosan composite was increased with increasing pH value of the mixture and chitosan/silica ratios but it did not change with the decrease of pH value of the mixture. The as-synthesized products prepared at pH 3 and 6 showed macroscopic two-solid phases (consisting of silica-rich phase and chitosan-rich phase), while those prepared at pH 5 displayed liquid and solid phases. At pH 3, a unimodal porous structure was found for the calcined products obtained from the silica-rich phase while a hierarchical structure was found for those obtained from the chitosan-rich phase; meanwhile, a hierarchical structure occurred for all calcined products prepared at pH 6. Different hierarchical structures of the silica products could be obtained by changing pH value of the mixture and chitosan/silica ratios.     

Structure of bioactive mixed polymer/colloid aerogels

The structure of polymer/colloid mixed silica sono-aerogels has been studied by SAXS, N₂ adsorption–desorption and Hg porosimetry. The system is described as a composite in which the polymeric phase (sonogel) is the matrix. The structure of this phase prepared with ultrasounds is very fine consisting in aggregates of ∼5 nm radius formed by elementary particles of 1 nm radius. Including Ca(II) into the silica atomic network causes enlarging the average size of the particle more than three times with respect to its size in its pure silica counterpart. The stiffness increases as well by 50%. The size of the particles and pores is also affected by the ultrasound dose applied; the higher for the larger the particles. On the other hand, a low dose produces a rough particle surface.     

Cadmium ions adsorption in simulated wastewater using structured alumina–silica nanoparticles

Some results on the removal of cadmium ions from simulated industrial wastewater using sol–gel structured nanoparticles of silica and alumina are presented. Two different core-shell nanoparticles were prepared: Al–Si particles (alumina core surrounded by a silica shell) with a molar composition Al:Si of 1:5, and Si–Al particles (silica core and alumina shell) with a molar composition Si:Al of 1:5. Different amounts of cadmium ions were added and the flocculation process of these particles, induced by the ions adsorption, was followed using dynamic light scattering. The efficiency of the ions adsorption was determined using atomic absorption spectroscopy. The results show that it is possible to reduce the cadmium concentration from 140 ppm to less than 5 ppb using Si–Al particles, meeting some international regulations for this contaminant (New European Directive 98-83). The Al–Si particles were not so efficient because the cadmium was only reduced from 125 ppm to less than 90 ppb. The sol–gel technique allows to synthesize model nanoparticles with different morphologies to be used as a prototypes, allowing to choose the better morphology and scaling this knowledge to an industrial level using commercially available silica and alumina nanoparticles chemically modified on the surface.