共查询到20条相似文献,搜索用时 15 毫秒
1.
Clark MD Subramanian S Krishnamoorti R 《Journal of colloid and interface science》2011,354(1):144-151
Dispersions of multi-walled carbon nanotubes (MWNTs) assisted by surfactant adsorption were prepared for a number of ionic and non-ionic surfactants including sodium 4-dodecylbenzenesulfonate (NaDDBS), hexadecyl(trimethyl)azanium bromide (CTAB), sodium dodecane-1-sulfonate (SDS), Pluronic? F68, Pluronic? F127, and Triton? X-100 to examine the effects of nanotube diameter, surfactant concentration, and pH on nanotube dispersability. Nanotube diameter was found to be an important role in surfactant adsorption rendering single-walled carbon nanotube studies as unreliable in predicting MWNT dispersive behavior. Similar to other reports, increasing surfactant concentrations resulted in a solubility plateau. Quantification of nanotube solubility at these plateaus demonstrated that CTAB is the best surfactant for MWNTs at neutral pH conditions. Deviations from neutral pH demonstrated negligible influence on non-ionic surfactant adsorption. In contrast, both cationic and anionic surfactants were found to be poor dispersing aids for highly acidic solutions while, CTAB remained a good surfactant under strongly basic conditions. These pH dependent results were explained in the context of nanotube surface ionization and Debye length variation. 相似文献
2.
Yuanzhao Chen Zhenxia Li Yang Zhao 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2016,90(13):2619-2624
In this paper, the pristine multi-walled carbon nanotubes (P-MWCNTs) were purified either by the high temperature treatment (HT-MWCNTs) or by concentrated acid treatment (CA-MWCNTs). The HT-MWCNTs were prepared by heating at 500°C, while the CA-MWCNTs were treated by the mixture of concentrated nitric and sulfuric acids taken in a volume ratio of 3: 1. Ultrasonic processing and surfactants were utilized to achieve homogenous MWCNTs suspensions. The HT-MWCNTs and CA-MWCNTs were characterized by thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FT-IR). Among these three MWCNTs, the prepared homogeneously dispersed MWCNTs suspensions were characterized by UV–Vis absorbency and transmission electron microscopy (TEM). Finally, the dispersion mechanism was discussed. The results showed that both high temperature treatment and concentrated acid treatment can be used for purification of the P-MWCNTs, removing the amorphous carbon and other impurities. In these suspensions, the purified MWCNTs showed a better dispersibility in aqueous solution. The high temperature treatment was a kind of physical purification treatment method and it just burned the amorphous carbon away and strengthened the structure of MWCNTs, while the concentrated acid treatment was a chemical purification treatment method and this chemical treatment method grafted more effective groups to improve the dispersibility of MWCNTs. 相似文献
3.
Chunlai Qu Fang Cheng Hui Su Yang Zhao 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2016,90(11):2230-2236
Multi-walled carbon nanotubes (MWCNTs) are widely applied in development of composite materials. However, their properties are directly influenced by the degree of uniformity of dispersion of MWCNTs in the material’s matrix. In this paper, the dispersing of raw MWCNTs (R-MWCNTs) and decorated MWCNTs (D-MWCNTs) was studied in aqueous solution. The D-MWCNTs were obtained by chemical modification method by treatment of initial MWCNTs with the mixture of concentrated nitric and sulfuric acids (3: 1 vol/vol). To achieve a good dispersion of the MWCNTs, a method utilizing ultrasonic processing and surfactant (polyvinylpyrrolidone, PVP) was employed. MWCNTs were characterized by Fourier transform infrared spectroscopy (FT–IR) and X-ray diffraction (XRD). The prepared MWCNTs suspensions were investigated by UV spectroscopy, zeta potential measurements, surface tension and transmission electron microscopy (TEM). The D-MWCNTs have better dispersibility in aqueous solution; this attributed to the functional groups formed on their surface during chemical modification. The PVP surfactant in a certain concentration of 0.6 g/L has the maximum dispersing effect on MWCNTs in aqueous solution, the optimum concentration ratio of PVP and MWCNTs was 3: 1. 相似文献
4.
Molecularly imprinted particle for bisphenol A (BPA-MIP) was prepared using the surface molecular imprinting technique with a sol-gel process on the surface of silica nanoparticles. The dosages of diethylenetriaminepentaacetic acid (DTPA) as a functional monomer and teraethyl orthosilicate (TEOS) as a cross-linker were optimized, respectively. The prepared BPA-MIP was characterized by scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), Fourier transform infrared spectrometer (FTIR), thermogravimetric analysis (TGA), and a standard Brunauer-Emett-Teller (BET) analysis. Moreover, the proper binding and selective recognition ability were also investigated by a single batch binding experiment. The equilibrium data fitted well to the pseudo-second-order kinetic and the Langmuir model for BPA binding onto BPA-MIP, respectively. The saturate binding capacity of BPA-MIP was found to be 30.26 μmol g(-1), which was three times higher than that of BPA non-molecular imprinted particle (BPA-NIP). The satisfactory results demonstrated that the obtained BPA-MIP showed an appreciable binding specificity toward BPA than similar structural compounds in water phase. The BPA-MIP could serve as an efficient selective material for determining or removing BPA from water environment. 相似文献
5.
B Koh G Kim HK Yoon JB Park R Kopelman W Cheng 《Langmuir : the ACS journal of surfaces and colloids》2012,28(32):11676-11686
DNA short oligo, surfactant, peptides, and polymer-assisted dispersion of single-walled carbon nanotube (SWCNTs) in aqueous solution have been intensively studied. It has been suggested that van der Waals interaction, π-π stacking, and hydrophobic interaction are major factors that account for the SWCNTs dispersion. Fluorophore and dye molecules such as Rhodamine B and fluorescein have both hydrophilic and hydrophobic moieties. These molecules also contain π-conjugated systems that can potentially interact with SWCNTs to induce its dispersion. Through a systematic study, here we show that SWCNTs can be dispersed in aqueous solution in the presence of various fluorophore or dye molecules. However, the ability of a fluorophore or dye molecule to disperse SWCNTs is not correlated with the stability of the fluorophore/dye-SWCNT complex, suggesting that the on-rate of fluorophore/dye binding to SWCNTs may dominate the efficiency of this process. We also examined the uptake of fluorophore molecules by mammalian cells when these molecules formed complexes with SWCNTs. The results can have potential applications in the delivery of poor cell-penetrating fluorophore molecules. 相似文献
6.
Jang Jiseon Miran Waheed Lee Dae Sung 《Journal of Radioanalytical and Nuclear Chemistry》2018,316(2):691-701
Journal of Radioanalytical and Nuclear Chemistry - Amino-functionalized multi-walled carbon nanotubes (MWCNTs) were synthesized by a simple, cost-effective method using 3-aminopropyltriethoxysilane... 相似文献
7.
Z. H. He G. B. Gao Y. M. Zhang 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2014,88(7):1191-1195
In the present work, the decorated purified raw multi-walled carbon nanotubes (R-MWCNTs) were obtained by chemical modification (CM) by treatment with concentrated sulfuric acid and concentrated nitric acid mixture with a certain volume ratio of 1: 3. The R-MWCNTs and CM-MWCNTs samples were investigated by X-ray Diffraction (XRD) analysis and Fourier transform infrared spectroscopy (FT-IR). The prepared MWCNTs were homogeneously dispersed in water using a commercial surfactant (Polyvinyl pyrrolidone, (PVP)) and ultra-sonication. The dispersion of MWCNTs was obtained by UV-Vis analysis. The results show that chemical modification purified MWCNTs and more effective functional groups were attached on the surface of MWCNTs. Meanwhile, R-MWCNTs and CM-MWCNTs were uniformly distributed in aqueous PVP solution and the dispersion of CM-MWCNTs in water was better. 相似文献
8.
Ashish Kumar Singha Deb B. N. Mohanty P. Ilaiyaraja K. Sivasubramanian B. Venkatraman 《Journal of Radioanalytical and Nuclear Chemistry》2013,295(2):1161-1169
Multi-walled carbon nanotubes (MWCNTs) were functionalized with diglycolamide (DGA) through chemical covalent route. The adsorption behavior of the DGA-functionalized-MWCNTs (DGA-MWCNTs) towards thorium from aqueous solution was studied under varying operating conditions of pH, concentration of thorium, DGA-MWCNTs dosages, contact time, and temperature. The effective range of pH for the removal of Th(IV) is 3.0–4.0. Kinetic data followed a pseudo-second-order model. The equilibrium data were correlated with the Langmuir, Freundlich, Dubinin-Radushkevich and Temkin models. The equilibrium data are best fitted with Langmuir model. The equilibrium Th(IV) sorption capacity was estimated to be 10.58 mg g?1 at 298 K. The standard enthalpy, entropy, and free energy of adsorption of the thorium with DGA-MWCNTs were calculated to be 8.952 kJ mol?1, 0.093 kJ mol?1 K?1 and -18.521 kJ mol?1 respectively at 298 K. The determined value of sticking probability (0.072) and observed kinetic and isotherm models reveal the chemical adsorption of thorium on DGA-MWCNTs. 相似文献
9.
Tang C Zhou T Yang J Zhang Q Chen F Fu Q Yang L 《Colloids and surfaces. B, Biointerfaces》2011,86(1):189-197
Ultrasonication is often used to disperse nano-particles in aqueous solution. However, a good dispersion of nano-particles in aqueous solution is not always achieved, due to the fact that incoming ultrasonicwaves in liquid are usually reflected and damped at the gas/liquid interface. In this work, we report a so-called wet-grinding assisted ultrasonication (GU) method, in which wet-grinding of multi-walled carbon nanotubes (MWCNTs) in chitosan solution is carried out before ultrasonication. The dispersions of MWCNTs were characterized by visual comparison, UV/vis spectroscopy, and scanning electron microscopy (SEM). The results demonstrate that the dispersion quality of chitosan/MWCNT suspension prepared by wet-grinding assisted ultrasonication is much better than that by ultrasonication or wet-grinding alone. It was found that wet-grinding could improve the water wettability of MWCNTs and eliminate the barrier of air layer around MWCNTs to ultrasonicwaves. Meanwhile, the composite from the chitosan/MWCNTs suspension prepared by GU method has an obvious improvement in mechanical property compared to pure chitosan. This simple method for integrating MWCNTs and biocompatible chitosan into a homogeneous dispersion may have great potential application in biotechnology, such as preparing composite materials for medicine, bio-fiber, biosensor, antibacterial coating, and cell cultivation. 相似文献
10.
Ashish Kumar Singha Deb P. Ilaiyaraja D. Ponraju B. Venkatraman 《Journal of Radioanalytical and Nuclear Chemistry》2012,291(3):877-883
Diglycolamide functionalized multi-walled carbon nanotubes (DGA-MWCNTs) were synthesized by sequential chemical reactions
for removal of uranium from aqueous solution. Characterization studies were carried out using FT-IR spectroscopy, XRD and
SEM analysis. Adsorption of uranium from aqueous solution on this material was studied as a function of nitric acid concentration,
adsorbent dose and initial uranium concentration. The uranium adsorption data on DGA-MWCNTs followed the Langmuir and Freundlich
adsorption isotherms. The adsorption capacity of DGA-MWCNTs as well as adsorption isotherms and the effect of temperature
on uranium ion adsorption were investigated. The standard enthalpy, entropy, and free energy of adsorption of the uranium
with DGA-MWCNTs were calculated to be 6.09 kJ mole−1, 0.106 kJ mole−1 K−1 and −25.51 kJ mole−1 respectively at 298K. The results suggest that DGA-MWCNTs can be used as efficient adsorbent for uranium ion removal. 相似文献
11.
Kinetics and thermodynamic study of aniline adsorption by multi-walled carbon nanotubes from aqueous solution 总被引:3,自引:0,他引:3
Multi-walled carbon nanotubes (MWCNTs) were used in the adsorptive removal of aniline, an organic pollutant, from an aqueous solution. It was found that carbon nanotubes with a higher specific surface area adsorbed and removed more aniline from an aqueous solution. The adsorption was dependent on factors, such as MWCNTs dosage, contact time, aniline concentration, solution pH and temperature. The adsorption study was analyzed kinetically, and the results revealed that the adsorption followed pseudo-second order kinetics with good correlation coefficients. In addition, it was found that the adsorption of aniline occurred in two consecutive steps, including the slow intra-particle diffusion of aniline molecules through the nanotubes. Various thermodynamic parameters, including the Gibbs free energy change (ΔG°), enthalpy change (ΔH°) and entropy change (ΔS°), were calculated. The results indicated that the spontaneity of the adsorption, exothermic nature of the adsorption and the decrease in the randomness reported as ΔG°, ΔH° and ΔS°, respectively, were all negative. 相似文献
12.
Mohamed Abdel Salam 《Arabian Journal of Chemistry》2012,5(3):291-296
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. 相似文献
13.
Yeong-Tarng Shieh Hong-Mao Wu Yawo-Kuo Twu Yi-Chang Chung 《Colloid and polymer science》2010,288(4):377-385
The dispersion of carbon nanotubes (CNT) in water of different pH and in chitosan aqueous solution of three acids, acetic
acid, formic acid, and hydrochloric acid, was investigated. Chitosan was soluble in water of pH ≤3 and could well disperse
untreated CNT and acid-treated CNT, both of which had poor dispersion in water of pH ≤3. With the presence of 0.1 wt% chitosan
in solution, particle sizes of the CNT dispersion were found to decrease with increasing COOH contents on the CNT. Particle
sizes of CNT, untreated and acid-treated, in the three acidic aqueous solutions were found to increase with increasing chitosan
contents in solutions. Among the three acids, hydrochloric acid gave the smallest particle size of the CNT dispersion. Without
chitosan, the dispersibility of the acid-treated CNT in aqueous solutions of three acids was in the order of acetic acid >
formic acid > hydrochloric acid. 相似文献
14.
In this work, silver (Ag) nanoparticles were deposited on multi-walled carbon nanotubes (MWNTs) by chemical reduction while Ag-decorated MWNTs (Ag-MWNTs)/polyaniline (PANI) composites were prepared by oxidation polymerization. The effect of the Ag incorporated into the interface of the composites on the electrochemical performance of the MWNTs/PANI was investigated. It was found that highly dispersed Ag nanoparticles were deposited onto the MWNTs, and the Ag-MWNTs were successfully coated by PANI. According to cyclic voltammograms, the Ag-MWNTs/PANI exhibited significantly increased electrochemical performances compared to MWNTs/PANI and the highest specific capacitance obtained of MWNTs/PANI and 0.15 M Ag-MWNTs/PANI was 162 F/g and 205 F/g, respectively. This indicated that Ag nanoparticles that were deposited onto the MWNTs caused an enhanced electrochemical performance of the MWNTs/PANI due to their high electric conductivity, which resulted in an increase of the charge transfer between the MWNTs and PANI by a bridge effect. 相似文献
15.
Novel films consisting of multi-walled carbon nanotubes (MWCNTs) were fabricated by means of the chemical vapor deposition technique with decomposition of either acetonitrile (ACN) or benzene (BZ) in the presence of ferrocene (FeCp2) which served as catalyst. The electrochemical response of the two different kinds of MWCNT-based films, further referred to as MWCNT-ACN and MWCNT-BZ, towards the oxidation of dopamine (DA) to dopamine-o-quinone (DAQ) was tested by means of cyclic voltammetry, differential pulse voltammetry, and electrochemical impedance spectroscopy. Both MWCNT-based films exhibit quasi-reversible response towards DA/DAQ with some slight kinetic differences; specifically, the charge-transfer process was found to be faster on MWCNT-ACN (k s?=?35.3?×?10?3 cm s?1) compared to MWCNT-BZ (k s?=?6.55?×?10?3 cm s?1). The detection limit of MWCNT-BZ for DA (0.30 μM) appears to be poorer compared to that of MWCNT-ACN (0.03 μM), but nevertheless, both MWCNT-based films exhibit greater detection ability compared to other electrodes reported in the literature. The sensitivities of MWCNT-ACN and MWCNT-BZ towards DA/DAQ were determined as 0.65 and 0.22?A M?1 cm?2, respectively. The findings suggest that the fabricated MWCNT-based electrodes can be successfully applied for the detection of molecules with biological interest. 相似文献
16.
Oxidised, multi-walled, carbon nanotubes can be grafted with polystyrene molecules using an situ radical polymerisation reaction, thereby dramatically modifying their solubility and their suitability for nanocomposite applications. 相似文献
17.
The suspending behaviors of multiple-wall carbon nanotubes (MWNTs), including pristine MWNTs (p-MWNTs) and acid-mixture-treated MWNTs (MWNTCOOH), stabilized by cationic single-chain surfactant, dodecyltrimethylammonium bromide (DTAB), and cationic gemini surfactant hexyl-alpha,beta-bis(dodecyldimethylammonium bromide) (C 12C 6C 12Br 2) were studied systematically. The surfactant structure influences the suspendability of MWNTs dramatically as well as the surfactant adsorption behavior on the nanotubes. Although both the surfactants can disperse the MWNTs effectively, they actually show different stabilizing ability. DTAB is not capable of stabilizing these two MWNTs below critical micelle concentration (CMC). However, C 12C 6C 12Br 2 can suspend both the nanotubes effectively even well below its CMC. Moreover, the adsorption of these two surfactants reaches equilibrium at twice the CMC with the original MWNT concentration of 2 mg/mL, 2 mM for C 12C 6C 12Br 2, and 30 mM for DTAB. After the adsorption equilibrium, the maximum amounts of the two suspended MWNTs in C 12C 6C 12Br 2 solution are about twice as much as those in DTAB solution. The strong hydrophobic interaction among the C 12C 6C 12Br 2 molecules and between the C 12C 6C 12Br 2 molecules and the nanotubes as well as the high charge capacity of C 12C 6C 12Br 2 lead to its much stronger adsorption ability on the MWNTs and result in its superior stabilizing ability for the MWNTs in aqueous phase. The gemini surfactant provides a possibility to effectively stabilize the MWNTs in aqueous solutions even at very low surfactant concentration well below its CMC. 相似文献
18.
Asymmetric end-functionalization of carbon nanotubes was achieved by sequentially floating a substrate-free aligned carbon nanotube film on two different photoreactive solutions with only one side of the nanotube film being contacted with the photoreactive solution and exposed to UV light each time. The resultant nanotubes with different chemical reagents attached onto their opposite tube-ends should be very useful for site-selective self-assembling of carbon nanotubes into many novel functional structures for various potential applications. 相似文献
19.
Xinyan Yan Zhaolan Zhai Zhanqian Song Shibin Shang 《Journal of Dispersion Science and Technology》2013,34(12):1687-1695
Polymeric surfactants from natural rosin containing a unique tricyclic rigid structure were prepared and their structures were characterized by IR, 1H NMR and GPC. Their surface activities including hydrophile—lipophile balance values (HLB), emulsification properties, foaming properties, critical micelle concentration (CMC) and the minimum surface tension (γCMC) were evaluated. With the increase in ratio of hydrophobic to hydrophilic in polymeric surfactant, the CMC values of the surfactants decreased, and the emulsification and foaming properties of these surfactants increased, and the HLB values of them decreased. This type of polymeric surfactants was used to disperse single-walled carbon nanotubes (SWCNTs) in water, and their dispersal capacities were comparatively determined by UV-visible absorption spectroscopy. Thermogravimetric analysis (TGA) was used to quantify the amount of surfactant attached onto the nanotubes. More intuitive image of their dispersion states were obtained by transmission electron microscopy (TEM) and atomic force microscopy (AFM). The results showed that this type of polymeric surfactants had good dispersion capacity and dispersion stability to SWCNTs in water through strong hydrophobic attraction and weak van der Waals interactions. 相似文献