埃洛石纳米管表面结构对其吸附脱硫性能的影响

埃洛石纳米管是有广泛应用前景的新型纳米管材料,利用煅烧和酸处理等方法对埃洛石纳米管进行改性,研究改性后埃洛石纳米管表面结构对其吸附脱硫性能的影响,并利用X射线衍射（XRD）、红外光谱（FTIR） 和扫描电子显微镜（SEM）等手段进行表征和分析。研究发现,埃洛石纳米管热稳定性较高,高温煅烧后仍然保持其管状结构,随着煅烧温度的增加其羟基含量减少,脱硫性能改变。酸处理在一定程度上增加了煅烧后埃洛石纳米管的羟基含量,酸处理后样品的脱硫效果随羟基含量的增加而增加。因此表明埃洛石纳米管羟基含量是影响其脱硫效果的重要因素。     

埃洛石纳米管上基团种类吸附脱硫性能

通过有机后嫁接法对埃洛石纳米管进行系列氨基化与羧基化,研究改性剂表面基团与改性吸附剂孔容对油品中有机硫的脱除效果,并采用SEM、红外光谱、XRD与BET表征手段对改性材料进行分析表征。研究表明,表面基团与孔容对吸附脱硫具有一定影响：氨基化吸附剂脱硫率达到72.06%,较原吸附剂提高19.47%,羧基化吸附剂脱硫率仅提高8.42%;随着改性吸附剂孔容增大,脱硫率增大。     

金属组分引入对埃洛石纳米管吸附脱硫性能的影响

通过等体积浸渍法将金属组分引入到埃洛石纳米管（HNTs）上,研究金属组分对HNTs吸附脱硫性能的影响。采用X射线衍射（XRD）、吡啶吸附红外光谱（Py-IR）和N₂吸附-脱附测试对改性材料进行表征和分析。研究发现,3种金属组分在HNTs上主要以氧化物的形式存在,而且Co₃O₄、NiO和CuO的引入均能提高HNTs的吸附脱硫性能,其中负载量为10% NiO的HNTs脱硫率提高最多,由原管的30.10%提高到47.51%。金属氧化物的引入使HNTs表面的Lewis酸量增加,进而提高了HNTs的吸附脱硫性能。因此表明HNTs表面的Lewis酸量是影响其吸附脱硫性能的重要因素。     

Mn_(0.8)Cu_(0.2)Fe_2O_4/埃洛石纳米管的制备及其对次甲基蓝的吸附研究

采用溶胶凝胶法,以埃洛石纳米管、硝酸铁、硝酸锰、氯化铜为原料,制备磁性埃洛石纳米管,并采用扫描电镜,对Mn0.8Cu0.2Fe2O4/埃洛石纳米管磁性复合材料的形貌及结构进行分析,并对其吸附次甲基蓝废水进行研究。结果表明,磁离子很好的负载到埃洛石纳米管的表面,当投加量为0.1 g时,初始浓度为50 mg/L的溶液,去除率在90%以上,吸附量为11.61 mg/g,温度和浓度对磁性复合材料的吸附性能也有一定影响,吸附量随温度的升高及浓度的增大都呈增大趋势。     

用埃洛石负载氨基磺酸胍制备阻燃丁腈橡胶

以天然埃洛石纳米管（HNTs）作为载体,通过在其管内负载阻燃剂氨基磺酸胍（GAS）得到功能填料HNTs-GAS,以制备低烟无卤阻燃丁腈橡胶（NBR）。采用热重分析计算得到HNTs与GAS的投料质量比为1/3时可达到质量分数6%的最佳负载率。添加122.3份（质量,下同）HNTs-GAS和5.7份GAS的阻燃NBR复合材料的极限氧指数为28.3%,垂直燃烧达到V-1等级,烟密度为105,具有较好的阻燃性。HNTs-GAS的加入能有效提高NBR的力学性能,与添加相同用量HNTs和GAS的NBR相比,添加HNTs-GAS后NBR复合材料的拉伸强度、撕裂强度和扯断伸长率分别提高了47.5%、36.8%和67.1%。     

柚皮环氧树脂/埃洛石复合材料的制备及性能

以柚皮素为原料合成了新型柚皮环氧树脂,以埃洛石纳米管为改性剂、马来酸酐为固化剂采用浇注工艺制备了柚皮环氧树脂/埃洛石复合材料,考察了埃洛石纳米管用量对柚皮环氧树脂/埃洛石复合材料力学性能、动态力学性能、热稳定性的影响。结果表明:纯柚皮环氧树脂的冲击强度及玻璃化转变温度较双酚A型环氧树脂分别提高了3.05 kJ/m²,96℃;埃洛石纳米管能够显著提高柚皮环氧树脂/埃洛石复合材料的冲击强度,当埃洛石纳米管用量为0.8%(w)时,柚皮环氧树脂/埃洛石复合材料的冲击强度为5.50 kJ/m²,较纯柚皮环氧树脂提高了52.8%。     

埃洛石管内负载纳米四氧化三铁复合材料对亚甲基蓝的吸附性能

以柠檬酸铁为铁源,采用真空浸渍法和高温热分解法,在天然埃洛石纳米管(Hal)内成功负载了Fe3O4纳米粒子复合材料(A-Hal/Fe3O4),验证产物对染料分子的吸附性能提升效果。通过X射线衍射仪、Fourier转换红外光谱、X射线光电子能谱仪、透射电子显微镜以及振动样品磁强计对A-Hal/Fe3O4复合磁性材料的组成、结构、形貌、磁性进行表征,通过紫外-可见光谱检测了A-Hal/Fe3O4复合材料吸附亚甲基蓝的性能。结果表明:Fe3O4纳米颗粒已成功负载在HNTs管内,但有少量的Fe3O4表面被氧化成磁赤铁矿(γ-Fe2O3),造成样品呈黄色;制备的A-Hal/Fe3O4复合磁性材料对5 mg/L的亚甲基蓝的吸附性能良好,30 min内的吸附脱色率为98.99%;回收后再次吸附,30 min内的吸附脱色率为94.14%;相比于埃洛石原矿,A-Hal/Fe3O4产物在30 min时的脱色率提升20%以上。同时,负载在埃洛石管内的Fe3O4纳米粒子的比饱和磁化强度(Ms)可以达到4.7(A·m2)/kg,通过外加磁场的吸引作用,成功将吸附了有机染料分子的复合材料从模拟废水中快速分离。     

高岭土纳米管的制备及其脱硫性能的研究

高岭土纳米管是一种非常有前景的新型纳米管材料。以高岭土为原料采用插层法制备了高岭土纳米管,并对其脱硫性能进行了首次研究。利用静态实验研究了高岭土、高岭土-DMSO、高岭土纳米管及MCM-41对噻吩的吸附脱除性能。实验发现,高岭土纳米管对有机硫的脱除是有效的,并且其脱除噻吩的容硫量高达10.08 mg/g。通过分析,高岭土纳米管的比表面及孔径大小是影响脱硫率的关键。     

有机物改性对埃洛石纳米管吸附脱硫性能的影响

通过插层法和离子交换法对埃洛石纳米管（HNTs）进行有机物改性,研究了二甲基亚砜、甲醇以及十六烷基三甲基溴化铵改性对HNTs结构以及吸附脱硫性能的影响,考察了温度、时间和剂油比对吸附剂脱硫性能的影响。采用X射线衍射、红外光谱、透射电子显微镜与N₂吸附-脱附测试等对吸附剂进行分析表征。结果表明,有机物改性后HNTs的基本管状结构并未破坏,但层间距和管径有一定变化,吸附脱硫能力有所提高,其中HDTMA改性的埃洛石在温度为30℃、时间为4 h、剂油比为1∶20的条件下容硫量达到9.42 mg/g,脱硫率由未改性HNTs的29.62%提高到58.85%。     

埃洛石改性苯并噁嗪的制备及表征

采用硅烷偶联剂γ-氨丙基三乙氧基硅烷(KH550)对埃洛石纳米管(HNTs)进行表面改性,制得了改性埃洛石(mHNTs),并利用红外光谱和热重分析对其表征,测得KH550在埃洛石上的接枝率为6%。通过溶剂法合成了苯胺型苯并噁嗪单体(BOZ),然后将mHNTs分散在BOZ中,得到了改性埃洛石掺杂质量分数为0、1.7%、5%、7%、10%的5种埃洛石型苯并噁嗪体系,依次为1-BOZ、2-BOZ、3-BOZ、4-BOZ、5-BOZ。用红外光谱、热重分析和扫描电镜对其进行了表征。结果表明:mHNTs均匀地分散在单体中,提高了苯胺型苯并噁嗪的耐热性和热稳定性,固化温度也明显地降低。其中mHNTs的添加量为7%时,残炭率提高了8%,热分解温度升高了7℃,固化温度降低了10.6℃。     

硅烷偶联剂改性埃洛石纳米管的表征和增强丁苯橡胶的研究

采用双-[γ-（三乙氧基硅）丙基]-四硫化物（Si69）对埃洛石纳米管（Halloysite nanotubes．HNTs）进行表面改性,通过一系列测试方法（TGA,XPS,接触角测定）对改性效果进行表征,同时采用直接共混法制备了丁苯橡胶（SBR）／改性埃洛石（m—HNTs）复合材料,并对m—HNTs对混炼胶硫化特性和硫化胶力学性能的影响进行了研究。结果表明：m—HNTs的改性效果显著,可以缩短硫化时间,提高复合材料的力学性能,说明Si69改性的HNTs可以有效改善橡胶基体与填料之间的界面结合。     

Synergistic effect of plasma‐modified halloysite nanotubes and carbon black in natural rubber—butadiene rubber blend

Halloysite nanotubes (HNTs) were investigated concerning their suitability for rubber reinforcement. As they have geometrical similarity with carbon nanotubes, they were expected to impart a significant reinforcement effect on the rubber compounds but the dispersion of the nanofillers is difficult. In this work, HNTs were surface‐modified by plasma polymerization to change their surface polarity and chemistry and used in a natural rubber/butadiene rubber blend in the presence of carbon black. The aim of the treatment was to improve the rubber–filler interaction and the dispersion of the fillers. A thiophene modification of HNTs improved stress–strain properties more than a pyrrole treatment. The surface modification resulted in a higher bound rubber content and lower Payne effect indicating better filler–polymer interaction. Scanning electron microscopy measurements showed an increased compatibility of elastomers and fillers. As visualized by transmission electron microscopy, the thiophene‐modified HNTs formed a special type of clusters with carbon black particles, which was ultimately reflected in the final mechanical properties of the nanocomposites. The addition of HNTs increased loss angle. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Modification of halloysite nanotubes with poly(styrene–butyl acrylate–acrylic acid) via in situ soap‐free graft polymerization

Halloysite nanotubes (HNTs) were grafted with poly(styrene–butyl acrylate–acrylic acid) (P‐SBA) via an in situ soap‐free emulsion polymerization. To introduce double bonds into the HNTs, N‐(β‐aminoethyl)‐γ‐aminopropyl trimethoxysilane was first used to modify the HNTs and render amino groups, and then, the double bonds were anchored through an amidation reaction between acryloyl chloride and amino groups. P‐SBA chains were grafted onto HNTs because of participating of double bonds in the copolymerization of styrene, butyl acrylate, and acrylic acid. Fourier transforms infrared spectroscopy, transmission electron microscopy, specific surface area measurements, and thermogravimetric analysis were used to characterize the HNTs grafted with P‐SBA. The results indicate that 25.21% of P‐SBA was grafted onto the outer walls of the HNTs and filled into the inner spaces of the HNTs. The modification dramatically decreased the surface area of the HNTs. The property study of the HNTs grafted with P‐SBA focused on the dispersion behavior in the biphase system. The results show that the grafted HNTs dispersed stably in the water/cyclohexane biphase system and were a potential emulsifier. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Electrophoretically deposited halloysite nanotubes coating as the adsorbent for the removal of methylene blue from aqueous solution

Halloysite nanotubes (HNTs) coatings were prepared by electrophoretic deposition (EPD) from different alcoholic suspensions using polyethyleneimine (PEI) as the dispersant. The results of conductivity, zeta potential, FTIR and thermal analysis showed that PEI is protonated in alcoholic suspensions and then adsorbed on the surface of HNTs enhancing their zeta potential and so colloidal stability. Optimum concentration of PEI decreased with molecular size of alcohol due to the more adsorption of PEI on HNTs. Kinetics of EPD was the fastest from the suspensions with the highest zeta potential. HNTs coatings exhibited high resistance against cracking during their drying due to the self-reinforcement provided by long HNTs and the presence of PEI in their composition which acts as the binder. The coating (6cm²) deposited from ethanolic suspension with 0.5?g/l of PEI (optimum suspension) removed 36% of MB from its aqueous solution (concentration: 5?mg/l and volume: 30?ml) within 2?h.     

Application of MnOx/HNTs catalysts in low-temperature NO reduction with NH3

Halloysite (HNTs) was firstly adopted as a carrier to develop manganese based SCR catalysts. Supporting of manganese oxides (MnO_x) on halloysite was carried out via a simple in-situ reaction of Mn(AC)₂ and KMnO₄ on the surface of halloysite. The obtained MnO_x/HNTs catalyst was estimated for selected reduction of NO by NH₃. It was found that the SCR activity of the catalyst is perfectly high with a nearly 100% NO conversion at temperatures from 60 to 250 °C. Results showed that the adoption of Halloysite as carrier and the in-situ preparation method jointly play key function for the performance of the catalyst.     

Chemical reactions affecting halloysite dispersion in epoxy nanocomposites

Halloysite nanotubes (HNTs) have attracted a technologic and scientific attention as reinforcements of epoxy-based nanocomposites. However, their reported interaction with epoxy matrices is varied and the controlled dispersion of HNTs is still a challenge. In this work, we study the effect of chemical reactions taking place in the dispersion process of halloysite and their possible influence in the composite's properties. HNTs' surface was modified through an alkaline treatment and by grafting two aminosilanes with different chain lengths and functionality numbers. Evidence of homopolymerization and degradation reactions was found, depending on the surface treatment. The rheological study indicated that an interconnected network can be achieved in epoxy/HNTs blends depending on the surface chemical characteristics of the nanofillers and the blending method. The better dispersion was accomplished when ultrasonicating with the aid of a solvent. Nevertheless, the mechanical properties of the nanocomposites are not warranted by selecting a dispersion method. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47979.