碳纳米管/活性炭复合微球的制备及其对VB12的吸附应用

采用反相乳液法制备碳纳米管/壳聚糖复合微球(CNTs/CTS), 并对其进一步炭化、活化制得碳纳米管/活性炭复合微球(CNTs/AC). 以此复合微球为吸附材料, 探索了其对中分子代表物质VB12的吸附. 研究结果表明, 碳纳米管含量70%(w)的复合微球经水蒸气适当活化后球形度好、吸附性能优异, 其对VB12的吸附量达23.59 mg·g-1, 分别是活性炭和大孔吸附树脂的5.4和2.7倍. 分析表明这是由于碳纳米管/活性炭复合微球具有发达的中孔结构.     

无机纳米孔材料快速分离中成药中黄芪皂苷类成分

利用多壁碳纳米管(MWCNTs)等无机纳米孔材料快速吸附分离中成药中的黄芪皂苷类成分。基于高效液相色谱-三重四极杆质谱建立定性与定量分析方法,筛选SAPO-34、SAPO-11、ZSM-5、Y型分子筛、SBA-15、活性炭、MWCNTs等7种无机纳米孔材料吸附黄芪皂苷的活性,并用于分散固相萃取分离中成药中黄芪皂苷。MWCNTs分离黄芪皂苷的活性最佳,吸附和脱附平衡时间不超过2 min。黄芪皂苷的吸附率和回收率分别达到94.9%和92.1%。建立的方法能够快速分离黄芪颗粒和黄芪精口服液中的黄芪皂苷,且可有效降低散剂和口服液的基质效应,提高定量分析黄芪皂苷的准确度。     

基于多壁碳纳米管的人参皂苷快速分离

将多壁碳纳米管(MWCNTs)作为选择性吸附材料,用于快速分离人参提取物中的人参皂苷.人参经甲醇溶液超声提取后,提取物中主要为人参皂苷和糖类.人参中的糖类与人参皂苷的极性相近,是提取分离人参皂苷时的主要干扰物. MWCNTs可以快速吸附和脱附人参皂苷,但是对糖类无吸附作用.利用其选择性吸附性能,建立了MWCNTs快速分离人参提取物中人参皂苷和糖类的方法.在优化的分离条件下,MWCNTs对人参提取物中糖类的分离度高于90%,对8种主要人参皂苷[Rb1,Rb2,Rc,Rd,Re,Rg1,20(S)-Rf和Ro]的吸附容量为15. 0~24. 0μg/mg,回收率高于90%.进一步研究表明,人参皂苷在3 min内即可达到吸附和脱附平衡,并且人参皂苷的回收率受脱附溶剂极性的影响.相比于常规材料大孔树脂,MWCNTs可以更快速、简便地分离人参皂苷.     

乳化液膜清除未结合胆红素

高未结合胆红素症 (Ｈｙｐｅｒｂｉｌｉｒｕｂｉｎｅｍｉａ)是新生儿常见疾病 .胆红素在血液中的浓度过高 ,会伤害婴儿的大脑 (核黄疸 ) [1].肝昏迷患者的症状与胆红素在血液中含量过高也有直接关系 ,迅速有效地将其清除可使患者症状缓解[2 ],迄今为止 ,清除胆红素的研究主要集中在以吸附剂吸附为基础的血液灌流方法 ,所用的吸附剂主要有活性炭和大孔吸附树脂 ,活性炭的吸附选择性和血液相容性都比较差 ;大孔吸附树脂的吸附选择性和血液相容性等方面有待进一步提高[3],特别是在吸附未结合胆红素时 ,清除率低、清除速度慢 ,难以满足临床方面…     

磺化碳纳米管/活性炭复合微球的制备及其对低密度脂蛋白的吸附性能

采用悬浮聚合、炭化、活化制得碳纳米管/活性炭复合微球; 而后利用重氮盐偶合法将对氨基苯磺酸接枝到此复合微球上, 得到磺化碳纳米管/活性炭复合微球; 将其用于吸附血清中的低密度脂蛋白(LDL). 结果表明: 所制备的磺化碳纳米管/活性炭复合微球球形度好, 表面光洁, 中孔发达, 并且接枝有对氨基苯磺酸. 此复合微球对LDL的吸附量随着碳纳米管加入量的增加而逐渐增大; 当碳纳米管加入量为45% (w)时, LDL吸附量达6.564 mg·g^-1, 是未添加碳纳米管的3.3倍. 此复合微球在作为血液灌流LDL吸附剂方面有较好的应用前景.     

多壁碳纳米管-炭复合泡沫材料的制备和吸附性能

通过在聚氨酯泡沫模板中沉积多壁碳纳米管，用炭的预制体酚醛树酯将碳纳米管粘接固定在一起，经过高温碳化过程制备了碳纳米管-炭复合泡沫材料。红外光谱结果表明利用浓硫酸和浓硝酸的混合溶液处理可以使复合泡沫表面活化形成羧基和羟基，从而使复合泡沫具备较强的分子吸附能力。扫描电镜和氮吸附实验表明这种复合泡沫同时具备大孔和介孔，大孔能够满足流体自由流动的通畅性，介孔可以满足中分子的吸附需要。对标定物维生素B12的吸附实验证明这种复合泡沫对中分子量的生化分子具有有效的吸附能力。这种宏观尺寸的泡沫材料与传统的颗粒状活性炭相比具有简化工艺，提高吸附效率的应用潜力。     

新型蛋白结合类毒素血液灌流吸附剂的制备及吸附性能

蛋白结合类毒素(PBUT)在尿毒症并发症的发生发展中起着重要作用, 现有血液净化模式对其清除效果较差, 开发用于高效清除尿毒症患者体内PBUT的血液灌流吸附材料已成为迫切的临床需求. 本文首先采用悬浮聚合法制备了咪唑基改性低交联聚苯乙烯微球P(St-DVB-VMZ); 然后通过小分子外交联剂的一步法傅克烷基化后交联反应, 制备出血液灌流用含咪唑基超高交联聚苯乙烯多孔树脂吸附剂HCP(St-DVB-VMZ). 利用傅里叶变换红外光谱(FTIR)、 X射线光电子能谱(XPS)、 扫描电子显微镜(SEM)及N₂吸附-脱附分析等表征了吸附树脂的化学结构和微观孔结构. 结果表明, HCP(St-DVB-VMZ)具有丰富的孔结构, 比表面积达到709 m²/g. 尿毒症毒素吸附实验结果表明, HCP(St-DVB-VMZ)对蛋白结合类毒素[对硫酸吲哚酚(IS)、 对甲酚硫酸盐(PCS)和吲哚乙酸(IAA)]和中大分子毒素[甲状旁腺激素(PTH)、 β₂-微球蛋白(β₂M)及白细胞介素6(IL-6)]均具有优异的吸附性能并展示出较好的血液相容性, 有望实现全血灌流临床应用.     

电化学间接测量法研究谷胱甘肽在多壁碳纳米管和活性炭上的吸附

选取谷胱甘肽(GSH)作为小分子代表物,利用Cr(VI)与GSH的相互作用,即K2Cr2O7/H2SO4溶液加入GSH前后Cr(VI)还原峰电流值的差异,通过差分脉冲伏安法(DPV)的测定,可以间接测出GSH的含量.尝试将这种电化学间接测量法应用于研究多壁碳纳米管(MWCNTs)与商业活性炭(AC)对GSH的吸附行为.利用该方法可以确立GSH在二者的吸附量(Q)与吸附平衡浓度(Ce)的关系,绘制吸附等温曲线.根据Langmuir方程和Freundlich方程的拟合分析,证明了与商业活性炭相比,GSH在MWCNTs上的吸附更倾向Freundlich模型,即多分子层吸附.利用扫描电子显微镜(SEM)和透射电子显微镜(TEM)进行形貌表征,发现MWCNTs具有发达的堆积孔结构,有利于GSH小分子内扩散和吸附,与实验结果一致.     

氢在多壁碳纳米管上吸附行为研究

根据热力学平衡原理推导了通用吸附等温方程.通过比较氢在碳纳米管和炭狭缝孔上的高阶维里吸附系数，分析了77～297 K温度区间，温度、管径(孔宽)对碳纳米管、炭狭缝孔吸附空间储氢容量的影响，并由氢在石墨平面上的最大吸附容量计算了本次试验多壁碳纳米管(MWCNTs)在各平衡温度时的最大氢吸附容量.运用确定参数后的吸附等温方程，线性回归分析了氢在本次试验MWCNTs上的吸附数据.结果表明，在160～180 K温度区间，管内被吸附氢分子之间由于吸附受压产生的排斥能出现极大值；随着温度升高，氢分子之间以吸引力为主，提高氢气压力后才发生明显吸附.     

大孔吸附树脂对尿毒症和烧伤毒血症血浆中分子物质体外吸附的研究

研究了大孔吸附树脂对尿毒症和烧伤毒血症患者血浆中分子物质的体外吸附,用Sephadex G15柱层析法对血浆中分子物质进行吸附前、后的组分分析,并进行了血浆模拟灌流实验,观察中分子物质的清除率,初步探讨了大孔吸附树脂孔结构对中分子物质的吸附机理。     

Effect of oxyfluorination on electromagnetic interference shielding of polyaniline-coated multi-walled carbon nanotubes

Highly conducting polyaniline (PANi)-coated multi-walled carbon nanotubes (MWCNTs) were prepared by in situ polymerization method for electromagnetic interference shielding. The thickness of the PANi coatings was controlled by the oxyfluorination treatment on the multi-walled carbon nanotubes and analyzed with both SEM and TEM. The oxyfluorination with higher oxygen content produced more hydrophilic functional groups on the surface of multi-walled carbon nanotubes. The functional groups led to the well distribution and coating of PANi on the multi-walled carbon nanotubes resulting in the higher interfacial affinity between them. The uniform coating of PANi on MWCNTs by controlling the oxyfluorination conditions also played a crucial role in increasing the electrical conductivity of nanocomposites. The improved interfacial affinity resulted in the higher electromagnetic interference (EMI) SE of 47.03?dB based on the synergistic combination of the conductive components. The EMI shielding mechanism of PANi on MWCNTs suggested that EMI was mainly shielded by adsorption to avoid secondary EMI.     

Fabrication of carbon nanotube sheets and their bilirubin adsorption capacity

Bilirubin adsorption on carbon nanotube surfaces has been studied to develop a new adsorbent in the plasma apheresis. Powder-like carbon nanotubes were first examined under various adsorption conditions such as temperatures and initial concentrations of bilirubin solutions. The adsorption capacity was measured from the residual concentrations of bilirubin in the solution after the adsorption process using a visible absorption spectroscopy. We found that multi-walled carbon nanotubes (MWCNTs) exhibit greater adsorption capacity for bilirubin molecules than that of single-walled carbon nanotubes (SWCNTs). To guarantee the safety of the adsorbents, we fabricated carbon nanotube sheets in which leakage of CNTs to the plasma is suppressed. Since SWCNTs are more suitable for robust sheets, a complex sheet consisting of SWCNTs as the scaffolds and MWCNTs as the efficient adsorbents. CNT/polyaniline complex sheets were also fabricated. Bilirubin adsorption capacity of CNTs has been found to be much larger than that of the conventional materials because of their large surface areas and large adsorption capability for polycyclic compound molecules due to their surface structure similar to graphite.     

Effect of oxidation treatment of multi-walled carbon nanotubes on the adsorption of pentachlorophenol from aqueous solution: Kinetics study

Multi-walled carbon nanotubes (MWCNTs) were oxidized using different oxidizing agents and the produced oxidized MWCNTs were characterized using different techniques. IR measurements showed the presence of carboxylic acid function groups especially for the MWCNTs oxidized with nitric acid and hydrogen peroxide. The adsorption of pentachlorophenol (PCP) to pristine and oxidized multi-walled carbon nanotubes (MWCNTs) has been studied. The results showed that the oxidation of the MWCNTs decreased their abilities to adsorb PCP compared with the pristine MWCNTs. The adsorption was studied kinetically and the results showed that the adsorption process occurs in two different steps. The first step involves the transfer of PCP to the surface of the oxidized MWCNTs, which was very fast due to the diffusion of PCP from the liquid phase to the solid phase. This step followed by a second slower step of adsorption could be due to intra-particle diffusion.     

Effects of solution chemistry on the adsorption of ibuprofen and triclosan onto carbon nanotubes

Single-walled carbon nanotubes (SWCNTs), multiwalled carbon nanotubes (MWCNTs), and oxidized MWCNTs (O-MWCNTs) were studied for the adsorption of ibuprofen (IBU) and triclosan (TCS) as representative types of pharmaceutical and personal care products (PPCPs) under different chemical solution conditions. A good fitting of sorption isotherms was obtained using a Polanyi-Manes model (PMM). IBU and TCS sorption was stronger for SWCNTs than for MWCNTs due to higher specific surface area. The high oxygen content of O-MWCNT further depressed PPCP sorption. The sorption capacity of PPCPs was found to be pH-dependent, and more adsorption was observed at pHs below their pK(a) values. Ionic strength was also found to substantially affect TCS adsorption, with higher adsorption capacity observed for TCS at lower ionic strength. In the presence of a reference aquatic fulvic acid (FA), sorption of IBU and TCS was reduced due to the competitive sorption of FA on carbon nanotubes (CNTs). Sorption isotherm results with SWCNTs, MWCNTs and O-MWCNTs confirmed that the surface chemistry of CNTs, the chemical properties of PPCPs, and aqueous solution chemistry (pH, ionic strength, fulvic acid) all play an important role in PPCP adsorption onto CNTs.     

High-density growth of carbon nanotubes with catalytic sites activated on nickel substrate

We describe the growth of carbon nanotubes (CNTs) from catalytic nanoparticles formed on a nickel surface. For the growth of CNTs, a chemical vapor deposition (CVD) furnace was set up and ethanol was used as carbon source. Observation of SEM images shows that CNTs grew densely on the nickel surface and that nanoparticles play a key role in the growth of the CNTs. XRD and Raman analyses reveal that the obtained products have graphitic pattern of multi-walled carbon nanotubes (MWCNTs). Also HRTEM images confirm clearly that the product was a MWCNT and their diameter was in the range of 20–50 nm.     

Electrochemical production, characterization, and application of MWCNTs

The subject of this study is production of carbon nanotubes (CNTs) using an original procedure of reduction of lithium molten salts onto graphite cathode; their structural characterization and application as support material for electrocatalysts aimed for hydrogen evolution. As-produced CNTs were characterized by means of scanning and transmission electron microscopy (SEM and TEM), Raman spectroscopy, and thermogravimetric and differential thermal analysis (DTA). SEM and TEM images have shown that nanotubes are mostly of curved shape with length of 1–20 μm and diameter of 20–40 nm. Raman peaks indicate that the crystallinity of produced nanotubes is rather low. The obtained results suggest that formed product contains up to 80 % multiwalled carbon nanotubes (MWCNTs), while the rest being non-reacted graphite and fullerenes. DTA curves show that combustion process of the nanotubes takes place in two stages, i.e., at 450 and 720 °C. At the lower temperature, combustion of MWCNTs occurs, while at higher one, fullerenes and non-reacted graphite particles burn. As-produced MWCNTs were used as electrocatalyst’s support materials and their performance was compared with that of traditional carbon support material Vulcan XC-72. MWNTs have shown almost twice higher real surface area, and electrocatalyst deposited on them showed better catalytic activity than corresponding one deposited on Vulcan XC-72.     

A comparative study on properties of multi-walled carbon nanotubes (MWCNTs) modified with acids and oxyfluorination

In this study, the surface modification of multi-walled carbon nanotubes (MWCNTs) with acid and oxyfluorination has been examined. Acid treatment of multi-walled CNTs produces many functionalized groups on the surface of MWCNTs, such as C-N stretching and the asymmetric carboxylate group (-COO-). It can be concluded that nitrogen doping of the graphite sheets may take place and a C-N bond identical to the sp³-bonded carbon nitride may form during the acid treatment process. In addition, oxyfluorinated MWCNTs exhibit higher BET specific surface area and mesopore volume than those of the as-received and acid treated MWCNTs. Therefore, acid and oxyfluorination treatments are more effective methods for enhancing the chemical and textural properties of MWCNTs.     

Novel Dispersion of MWCNTs in Polystyrene Polymer Induced by the Addition of 3-Hydroxy-2-Napthoic Acid

This article reports an extensive investigation of the unique dispersion behavior of solutions with multi-walled carbon nanotubes (MWCNTs) and 3-hydroxy-2-napthoic acid (β-HNA) in tetrahydrofuran (THF) solvent, which results into a multifold enhancement in the electrical properties of polystyrene (PS). A number of solutions with 0.4% of MWCNTs (w/v) and β-HNA (0–1%, w/v) in THF were prepared separately. MWCNTs precipitated out in THF solvent shortly after the preparation and formed two distinct phase regions (2φ). Gratifyingly, addition of β-HNA solution to the MWCNTs solution offered an unprecedented enhancement in the dispersion of MWCNTs. Such dispersion in solutions with only 0.02% β-HNA (w/v) was found to be stable up to 2 weeks at room temperature. FTIR spectroscopy was incorporated to illustrate the adsorption of β-HNA onto the surface of carbon nanotubes (CNTs). After this successful dispersion, nanocomposites solutions comprising of 0.067% β-HNA (w/v), 6.7% PS (w/v), and varying concentrations of MWCNTs (0–0.33%, w/v) were prepared. A remarkable dispersion behavior of MWCNTs in the presence of polymer was also observed. Finally, thin films made up of consistent polystyrene/β-HNA concentrations and increasing amounts of MWCNTs were prepared by casting technique to investigate the influence of dispersion on the electrical properties of the film. The dispersion significantly affected the DC electrical conductivity and incorporation of 5% MWCNTs elevated the electrical conductivity up to 10 orders of magnitude with respect to neat PS.