جستجوی مقالات مرتبط با کلیدواژه "ctab" در نشریات گروه "شیمی"

Magnetic iron oxide nanoparticles (Fe3O4 NPs) were synthesized by novel precipitation method as inverse spinel (Fe2O3. FeO). They are directly prepared without calcination under oxygen gas. The Fe3O4 NPs had been prepared by combining the iron sulfate solution with the aqueous mixture including sodium hydroxide and sodium nitrate, without and with using various surfactants such as sodium dodecyl sulfate (SDS), triton X100, cetrimonium bromide (CTAB) and cetramide (CT) as templates.  The FT-IR analysis demonstrated the Fe-O octahedral and tetrahedral bending at 744 cm-1 and 598 cm-1 respectively. The XRD analysis discovered  the mean crystal size of  Fe3O4 NPs is smaller than that presence of surfactants, and its value increment from 8.5 nm for Fe3O4 NPs to 21.55 nm, 22.53 nm, 27.66 nm, and 27.72 nm for Fe3O4 + Triton X-100, Fe3O4 + CT, Fe3O4 + SDS, and Fe3O4 + CTAB, respectively. SEM revealed their samples are nanoparticles and aggregated together like broccoli.  The possibility of using Fe3O4 NPs as magnetic adsorbents to remove the eosin yellow dye from aqueous solutions was successes and economy, due to collect by magnets without need for a long time to separate with centrifuge or filter paper. The maximum chemisorption of dye was 94.48 % using Fe3O4 NPs + CT at shaking 1hour, because CT has a positive part as a hydrophilic moiety and the used dye is acidic nature so will attract and dye easy removal, and the reuse reached to five times with efficiency depressed to 75.61 %.

The present work is mainly focused on the synthesis and characterization of surfactant-assisted Ir-Sn BMNP (bimetallic nanoparticles) using modified polyol method. CTAB (Cetyltrimethylammonium bromide), TSC (Trisodium citrate), and TX-100 (Triton X-100) as cationic, anionic, and nonionic surfactant respectively are used to study their effect on the particle size, morphology, and their stability. The synthesized particles are characterized by XRD, FE-SEM, EDAX, elemental mapping, TEM, HR-TEM, XPS and FT-IR, TGA, DTG, and DTA techniques. UV-Vis spectroscopy is used to monitor the synthesis of nanoparticles. The XRD patterns of all samples confirm that Ir-Sn BMNP are amorphous in nature. The influence of surfactant on the morphology and particle size of Ir-Sn BMNP samples was examined by the FE-SEM technique. The FE-SEM figures demonstrate that the particles of bimetal are in nano size, highly dispersed, and pseudo spherical in shape with smooth surfaces. The approximate crystallite (particle/grain) size of CTAB, TSC, and TX-100 assisted samples are ~1.39 nm (39 nm), ~2.2 nm (59 nm), and ~5.79 nm (89 nm) respectively, which are estimated from TEM and FE-SEM images. The presence and distribution of Ir and Sn elements in the BMNP is determined through EDAX and elemental mapping respectively. These techniques show that CTAB assisted Ir-Sn BMNP sample is in alloy form but TSC and TX-100 samples are in core-shell form, where the Ir core is surrounded by Sn shell. The XPS confirms the metallic state (Ir0), and the dual valence state of Sn (Sn2+ and Sn4+) is in the Sn 3d core level.

Hematite (α-Fe2O3) nanorods were synthesized by hydrothermal method using Cetyltrimethylammonium bromide (CTAB) as a surfactant agent. To study optical, nanostructural properties, and to control the morphology and shape of nanorods, 0.025 mol L-1, 0.05 mol L-1 and 0.1 mol L-1 concentration of CTAB were used. Moreover, the effect of interaction between bovine serum albumin (BSA) A9418-5G protein solution and hematite nanorods was investigated. Fourier transform infrared spectroscopy (FTIR), transmitting electron microscopy (TEM), X-Ray Diffraction (XRD), Energy Dispersive X-Ray Spectroscopy (EDS) and UV-vis spectroscopy were used to characterize α-Fe2O3 nanorods. The samples prepared by the interaction of BSA protein and hematite nanorods did not representa rod shape because the electrostatic interaction between CTAB and BSA would cause the nanorods to have a limited capacity for carrying protein. Hematite nanorods obtained from 0.025 mol L-1 of CTAB showed a maximum length of 25-30 nm. However, BSA protein solution falsification of rod shape particles increased. The results showed that BSA protein could affect the shape of hematite nanorods and their aggregation, and formspherical structures as well.

FeCe nanoparticles were synthesized by simple co-precipitation method using Iron chloride hexahydrate (FeCl3.6H2O) and cerium chloride (CeCl2•5H2O) as precursors in the presence of cetyltrimethylammonium bromide (CTAB) surfactant. The samples were characterized by high resolution transmission electron microscopy (HRTEM), field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), vibration sampling magnetometer (VSM), electron dispersive spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR) at different temperatures. The XRD results showed that Fe-doped CeO2 was single-phased with a cubic structure. SEM images showed the rod-shaped particles of as-prepared sample in the range size of 40-80 nm and annealed smallest one around 15 nm in diameter at 500oC for 3 h. The TEM studies revealed the squared-like shaped nanosized particles. The sharp peaks in the FTIR spectrum determined the element of Fe-Ce nanoparticles. The EDS spectra showed peaks of iron and cerium with less impurity in the prepared samples. The result of magnetic measurements showed a coercive field and saturated magnetization around 1650 G and 0.04 emu/g for as-prepared samples, respectively.

Cu and Ni ferrites as the semiconductor materials were synthesized by a microwave sol-gel auto-combustion method. Two cationic surfactants, sodium dodecyl sulfate (SDS) and cetyltrimethylammonium bromide (CTAB), were applied and the influence of surfactants on the properties of the Cu and Ni ferrite particles was studied. The samples were characterized by X-ray powder diffraction (XRD) pattern, scanning electron microscope analysis (SEM), Fourier transform infrared (FT-IR) spectroscopy and diffuse reflectance spectra (DRS). Powder XRD analysis and FT-IR spectroscopy confirmed the formation of ferrite spinel phase. The crystallite size was calculated to be 50-95 nm using Scherrer’s equation. The morphology and size of the synthesized nanoparticles have been observed by scanning electron microscopy. The particles were agglomerated without using surfactant. Using CTAB leads to the samples with layer shapes, and  using SDS leads to  the samples  with pyramidal shapes. The energy band gaps  calculated from UV–DRS absorption by using Kubelka-Munk equation were 1.68-1.77 eV, indicating that band gap of Cu ferrites becomes small and band gap of Ni ferrites becomes large in the presence of surfactant.

In this work, the glassy carbon electrode (GCE) was modified with multi-walled carbon nanotubes (MWCNTs) by drop casting process, and it was used as a working electrode for the electrochemical determination of 3,5-dinitrobenzoic acid (3,5-DNBA) in an electrolytic solution containing a cetyl trimethyl ammonium bromide (CTAB). This process was examined by using differential pulse voltammetry (DPV) and cyclic voltammetry (CV) techniques. The modified electrode showed an excellent electrocatalytic activity and sensitivity towards the investigation of 3,5-DNBA reduction behavior in the presence of CTAB. The electrochemical process was irreversible and was controlled by adsorption. The effect of pH, scan rate and concentration were studied at the surface of MWCNTs/GCE. The electrochemical behavior of 3,5-DNBA was studied in the presence and absence of CTAB at MWCNTs/GCE in PBS having pH 6.5. The LOD (limit of detection) and LOQ (limit of quantification) of 3,5-DNBA was found to be as 4.94×10-6 M, 1.65×10-5 M respectively. The surface coverage area concentration (Γ) of MWCNTs/GCE was calculated and was found to be as 1.3146×10-8 mole/cm2. By using electrochemical impedance spectroscopy (EIS), the interfacial electron transfer behavior of 3,5-DNBA was studied at different types of electrode surfaces.

In the present study, the application for the removal of phenylalanine by using two nano sorbents, namely, cetyltrimethylammonium bromide –Coated and BKC (benzal-conium chloride)-Coated Fe3O4 nanoparticles was investigated. Solid-phase extraction (SPE) and ultra violet–visible spectroscopy were used for studying the removal ability of each nano-sorbent in this study. Scanning Electron Microscopy, X-ray diffraction and Fourier infrared were used to characterize the synthesized magnetite nanoparticles. Batch adsorption studies were carried out to study the effect of various parameters, such as contact time, solution pH and concentration of phenylalanine. The equilibrium adsorption data of phenylalanine onto Fe3O4 nanoparticles (non-functionalized sample), cetyltrimethylammonium bromide -Coated and BKC -Coated were analyzed using Freundlich and Langmuir adsorption isotherms. The results indicated that adsorption of phenylalanine increased with increasing solution pH and maximum removal of phenylalanine was obtained at pH=9.0. Correlation coefficient were determined by analyzing each isotherm. It was found that the Freundlich equation showed better correlation with the experimental data than the Langmuir.

An electrochemical sensor for sensitive determination of isoniazid (INH) using multi-walled carbon nanotubes-cetyltrimethyl ammonium bromide (CTAB) surfactant composite on the surface of a glassy carbon electrode was developed. The peak current increased greatly compared with bare GCE and MWCNT/GCE electrode. The oxidation process was irreversible over pH range studied and exhibited a diffusion controlled behavior. The current response was found to be directly proportional to the concentration of INH in the concentration range of 1.0×10-7 M to 1.2×10-6 M with a limit of detection (LOD) of 2.14×10-9 M. The modified electrode showed good selectivity and reproducibility. The developed analytical method was successfully applied to isoniazid determination in human serum and urine samples. This method can be employed in clinical analysis, quality control and routine determination of drugs in pharmaceutical formulation.

Quaternary ammonium compounds (QACS) are employed both as disinfectants for manual processing lines and surfaces in the food industry, and in human medicine area. QACS also cause cell death by protein denaturation . One of the QAC is cetyl trimethyl ammonium bromide (CTAB) that appears to rapture the cell membrane. The primary site of action of CTAB has been suggested to be the lipid components of the membrane, causing cell lysis as secondary effect.
For these important roles of CTAB as a cationic surfactant, CTA (cetyl trimethyl ammonium) was studied as the main active site of CTAB. After optimization the values of thermodynamic functions, chemical shifts and Mulliken charges were obtained by calculation in Gaussian 98 program