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Methyl Orange (methyl + orange)
Selected AbstractsPhotocatalytic degradation of organic dyes in the presence of titanium dioxide under UV and solar light: Effect of operational parametersENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 3 2005Feryal Akbal The photocatalytic degradation of methylene blue and methyl orange have been studied in the presence of titanium dioxide powder illuminated with a 300-W UV lamp. The effect of hydrogen peroxide on the degradation process was also determined. It was found that the color removal efficiency was affected by the concentration of dye, amount of TiO2 added, and the pH of the solution. The degradation of dyes obeys first-order kinetics, with the apparent first-order rate constant increasing with decreasing dye concentration. The rate constants were evaluated as a function of the concentration of dye, amount of TiO2, and pH. © 2005 American Institute of Chemical Engineers Environ Prog, 2005 [source] ZnO Hierarchical Micro/Nanoarchitectures: Solvothermal Synthesis and Structurally Enhanced Photocatalytic Performance,ADVANCED FUNCTIONAL MATERIALS, Issue 7 2008Fang Lu Abstract A novel ZnO hierarchical micro/nanoarchitecture is fabricated by a facile solvothermal approach in an aqueous solution of ethylenediamine (EDA). This complex architecture is of a core/shell structure, composed of dense nanosheet-built networks that stand on a hexagonal-pyramid-like microcrystal (core part). The ZnO hexagonal micropyramid has external surfaces that consist of a basal plane (000) and lateral planes {011}. The nanosheets are a uniform thickness of about 10,nm and have a single-crystal structure with sheet-planar surfaces as {20} planes. These nanosheets interlace and overlap each other with an angle of 60° or 120°, and assemble into a discernible net- or grid-like morphology (about 100,nm in grid-size) on the micropyramid, which shows a high specific surface area (185.6,m2,g,1). Such a ZnO micro/nanoarchitecture is new in the family of ZnO nanostructures. Its formation depends on the concentration of the EDA solution as well as on the type of zinc source. A two-step sequential growth model is proposed based on observations from a time-dependent morphology evolution process. Importantly, such structured ZnO has shown a strong structure-induced enhancement of photocatalytic performance and has exhibited a much better photocatalytic property and durability for the photodegradation of methyl orange than that of other nanostructured ZnO, such as the powders of nanoparticles, nanosheets, and nanoneedles. This is mainly attributed to its higher surface-to-volume ratio and stability against aggregation. This work not only gives insight into understanding the hierarchical growth behaviour of complex ZnO micro/nanoarchitectures in a solution-phase synthetic system, but also provides an efficient route to enhance the photocatalytic performance of ZnO, which could also be extended to other catalysts, such as the inherently excellent TiO2, if they are of the same hierarchical micro/nanoarchitecture with an open and porous nanostructured surface layer. [source] Evaluation of the potential of polymeric carriers based on chitosan- grafted -polyacrylonitrile in the formulation of drug delivery systemsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2010A. A. Sarhan Abstract Graft copolymerization of chitosan with acrylonitrile (AN) was carried out by free radical polymerization using KMnO4 and oxalic acid as a combined redox initiator system. Graft copolymerization was confirmed by Fourier transform infrared spectra (FTIR), proton nuclear magnetic resonance spectra (1H-NMR), thermal gravimetric analysis (TGA) measurements, and wide angle X-ray diffraction (WAXD). In addition, further modification of the cyano groups of the grafted copolymers was performed by partial hydrolysis into carboxylic function groups with various extents. The extent of hydrolysis was monitored using FTIR spectroscopy. The potential of the hydrolyzed and unhydrolyzed grafted copolymers as polymeric carriers for drug delivery systems was extensively studied by preparation of tablets incorporated with methyl orange (MO) as a drug model. In vitro drug release was carried out in simulated gastric and intestinal conditions. The effects of grafting percentage (GP) and the extent of hydrolysis on the release kinetics were evaluated. Release continued up to 24 h for both hydrolyzed and unhydrolysed chitosan- g -PAN copolymers. The nature of drug transport through the polymer matrices was studied by comparing with power law or Kormeyer-Peppas equation. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Selecting significant factors by the noise addition method in principal component analysisJOURNAL OF CHEMOMETRICS, Issue 7 2001Brian K. Dable Abstract The noise addition method (NAM) is presented as a tool for determining the number of significant factors in a data set. The NAM is compared to residual standard deviation (RSD), the factor indicator function (IND), chi-squared (,2) and cross-validation (CV) for establishing the number of significant factors in three data sets. The comparison and validation of the NAM are performed through Monte Carlo simulations with noise distributions of varying standard deviation, HPLC/UV-vis chromatographs of a mixture of aromatic hydrocarbons, and FIA of methyl orange. The NAM succeeds in correctly identifying the proper number of significant factors 98% of the time with the simulated data, 99% in the HPLC data sets and 98% with the FIA data. RSD and ,2 fail to choose the proper number of factors in all three data sets. IND identifies the correct number of factors in the simulated data sets but fails with the HPLC and FIA data sets. Both CV methods fail in the HPLC and FIA data sets. CV also fails for the simulated data sets, while the modified CV correctly chooses the proper number of factors an average of 80% of the time. Copyright © 2001 John Wiley & Sons, Ltd. [source] Chemically modified porous silicon for laser desorption/ionization mass spectrometry of ionic dyesJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 8 2009I. V. Shmigol Abstract Desorption/ionization on silicon (DIOS) mass spectra of model ionic dyes methylene blue (MB+Cl,) and methyl orange (Na+MO,) were studied using p+ type-derived porous silicon (PS) free layers. As-prepared PS (PS-H), the PS thermally oxidized at 300 °C (PS-OX), PS with chemically grafted cation-exchanging alkylsulfonic acid (PS-SO3H) and anion-exchanging propyl-octadecyldimethylammonium chloride (PS-ODMA+Cl,) groups was tested as ionization platforms. Two mechanisms of the methylene blue desorption/ionization were found: (1) the formation of [MB + H]+, ion due to the reduction/protonation of MB+, which is predominant for PS-H and PS-OX platforms and (2) direct thermal desorption of the MB+ cation, prevailing for PS-SO3H. The fragmentation of the cation is significantly suppressed in the latter case. The samples of PS-SO3H and PS-ODMA+ Cl, efficiently adsorb the dyes of the opposite charge from their solutions via the ion-exchange. Consequent DIOS MS studies allow to detect only low fragmented ions (MB+ and MO,, respectively), demonstrating the potential of the ion-exchange adsorption combined with DIOS MS for the analysis of ionic organic compounds in solutions. Copyright © 2009 John Wiley & Sons, Ltd. [source] Facile Fabrication of Functional Polypyrrole Nanotubes via a Reactive Self-Degraded TemplateMACROMOLECULAR RAPID COMMUNICATIONS, Issue 21 2005Xiaoming Yang Abstract Summary: Polypyrrole nanotubes with high electric conductivity and azo function have been fabricated in high yield via an in-situ polymerization. During the process fibrillar complex of FeCl3 and methyl orange (MO), acting as a reactive self-degraded template, directed the growth of polypyrrole on its surface and promoted the assembly into hollow nanotubular structures. TEM image of uncompleted PPy nanotubes synthesized in MO solutions after reaction for 40 min. [source] A Cyclodextrin Microgel for Controlled Release Driven by Inclusion EffectsMACROMOLECULAR RAPID COMMUNICATIONS, Issue 22 2004Yu-Yang Liu Abstract Summary: A novel intelligent delivery system based on the environmental dependence of the inclusion effect of , -cyclodextrin (, -CD) with guest molecules, using a , -CD polymer (CDP) microgel as carrier, is proposed. Compared with smart hydrogels, which are driven by the phase-volume transition, controlled release from the CDP microgel is driven by "host-guest" inclusion effects. With the pH-dependent inclusion complexation of methyl orange (MO) with , -CD as a model system, the behavior of the controlled release of a CDP microgel was tested by changing the pH, showing that the mechanism is reasonable. Schematic illustration of the pH-dependent inclusion complexation of MO with , -CD in the CDP microgel. [source] Preparation of Bismuth Oxide Quantum Dots and their Photocatalytic Activity in a Homogeneous SystemCHEMCATCHEM, Issue 9 2010Prof. Hua Zhang Abstract Colloidal oil-soluble Bi2O3 quantum dots (QDs) are synthesized through an alcoholysis route in organic media. Water-soluble Bi2O3 QDs are then obtained from the initial oil-soluble QDs through phase transfer by surface modification with mercaptopropionic acid. X-ray diffraction and transmission electron microscopy studies show that the crystallinity is enhanced and particles grow larger after phase transfer. The water-soluble Bi2O3 QDs exhibit excellent photocatalytic activity for the degradation of methyl orange at a wide range of pH values. After several cycles, the Bi2O3 QDs retain high degradation efficiency. Simulation according to the first-order reaction dynamics indicates that the degradation reaction may follow complicated quasi-homogeneous photocatalysis. [source] Photocatalytic Activity and Electronic Structure Analysis of N-doped Anatase TiO2: A Combined Experimental and Theoretical StudyCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 6 2009H. Gao Abstract N-Doped TiO2 photocatalysts were prepared by a hydrothermal method with tetra- n -butyl titanate (TTNB) and triethanolamine as precursors. The obtained samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and UV-visible diffuse reflectance spectra (DRS), respectively. Photocatalytic activities of the anatase products were investigated on the degradation of methyl orange (MO). The incorporation of nitrogen impurity in anatase TiO2 was studied by the first-principles calculations based on the density functional theory (DFT). The calculated electronic band structures for substitutional and interstitial N-doped TiO2 indicated the formation of localized states in the band gap, which lied above the valence band. Excitation from the impurity states of N 2p to the conduction band could account for the optical absorption edge shift toward the lower energies. It was consistent with the experimentally observed absorption of N-doped samples in the visible region. [source] Self-Assembled Supramolecular Nanocarrier Hosting Two Kinds of Guests in the Site-Isolation StateCHEMISTRY - A EUROPEAN JOURNAL, Issue 43 2009Xing-Long Lou Abstract Hyperbranched polyethylenimine (HPEI) was simply mixed with a solution of amphiphilic calix[4]arene (AC4), which possesses four phenol groups and four aliphatic chains, in chloroform. This resulted in the novel supramolecular complex HPEI,AC4 through the noncovalent interaction of the amino groups of HPEI with the phenol groups of AC4. The formed HPEI,AC4 supramolecular complexes were characterized by 1H,NMR spectroscopy and dynamic light scattering. The cationic water-soluble dye methyl blue (MB) and the anionic water-soluble dye methyl orange (MO) were used as the model guests to test the performance of HPEI,AC4 as a supramolecular nanocarrier. It was found that HPEI,AC4 could accommodate the anionic water-soluble MO guests into the HPEI core. The MO encapsulation capacity of HPEI,AC4 was pH sensitive, which reached maximum loading under weakly acidic conditions. The loaded MO molecules could be totally released when the pH value was reduced to be around 4.5 or raised to be around 9.5, and this process was reversible. HPEI,AC4 could not only accommodate the anionic MO with the HPEI core but could also simultaneously load the cationic MB molecules using the formed AC4 shell, thereby realizing the site isolation of the two kinds of functional units. The amount of MO and MB encapsulated by HPEI,AC4 could be controlled by varying the ratio of hydroxyl groups of AC4 to amino groups of HPEI. [source] Enhanced Stabilization of Reverse Micelles by Compressed CO2CHEMISTRY - A EUROPEAN JOURNAL, Issue 4 2005Dong Shen Dr. Abstract The effect of compressed CO2 on the solubilization capacity of water in reverse micelles of sodium bis(2-ethylhexyl) sulfosuccinate (AOT) in longer chain n -alkanes was studied at different temperatures and pressures. It was found that the amount of solubilized water is increased considerably by CO2 in a suitable pressure range. The suitable CO2 pressure range in which the solubilization capacity of water could be enhanced decreased with increasing W0 (water-to-AOT molar ratio). The microenvironments in the CO2 -stabilized reverse micelles were investigated by UV/Vis adsorption spectroscopy with methyl orange (MO) as probe. The mechanism by which the reverse micelles are stabilized by CO2 is discussed in detail. The main reason is likely to be that CO2 has a much smaller molecular volume than the n -alkane solvents studied in this work. Therefore, it can penetrate the interfacial film of the reverse micelles and stabilize them by increasing the rigidity of the micellar interface and thus reducing the attractive interaction between the droplets. However, if the CO2 pressure is too high, the solvent strength of the solvents is reduced markedly, and this induces phase separation in the micellar solution. [source] | |||||||||||||