Organic Dye Solutions Research Articles

Hollow mesoporous titania microspheres: New technology and enhanced photocatalytic activity

Hollow titania microspheres (HTS) were fabricated via a sol–gel process by coating the hydrolysis product of titanium tetrabutoxide (TBOT) onto the amino (–NH2) modified porous polystyrene cross-linked divinyl benzene (PS-DVB) microspheres under changing atmospheric pressure, followed by calcination in nitrogen and air atmosphere. Particularly, the atmospheric pressure was continuously and regularly changed during the formation process of PS-DVB@TiO2 microspheres. Then the TiO2 particles were absorbed into the pores and onto the surface of PS-DVB as well. The resultant HTS (around 2μm in diameter) featured a high specific surface area (84.37m2/g), anatase crystal and stable hollow microsphere structure, which led to high photocatalysis activity. The photocatalytic degradation of malachite green (MG) organic dye solution was conducted under ultraviolet (UV) light irradiation, which showed a high photocatalytic ability (81% of MG was degraded after UV irradiation for 88min). Therefore, it could be potentially applied for the treatment of wastewater contaminated by organic pollutants.

Fe(III)/H2O2-Like System for Removal of Azo Dye from Aqueous Solution

Fe(III)/H2O2 system is an effective method for separating the organic compounds from aqueous solution, whereas it is often investigated under lower pH conditions. In order to improve performance of the system, a Fe(III)/H2O2-like system that was composed of iron-based coagulant and H2O2 was developed, which has the combined effect of flocculation and oxidation. The system when used for decolorization of an organic azo dye solution, Procion Red MX-5B, under wider pH range, indicated higher decolorization efficiency. Parameters affecting the decolorization such as coagulant dosage, H2O2 concentration, initial solution pH, temperature, and initial dye concentration were examined in this study. The results indicated that with appropriate coagulant dosage, H2O2 concentration, and pH, it was more effective for the decolorization, especially in a weak alkaline environment (pH = 7-8); the pseudo-first-order kinetics could express the azo dye concentration as a function of the reaction time. This study further illustrated that the azo dye solution was degraded to a degree with 53.22% TOC removal at an initial total TOC concentration of 14.92 mg/L. Overall, the established system in this study was favorable to the decolorization of soluble azo dye.

Thermo photo-electrochemical effect in n-InP/aqueous solution of orange dye/C cell

The effect of light and heat is studied on the electrical properties of an electrochemical n-InP/aqueous solution of orange dye/C cell. The cell is investigated under the light and heat of filament bulb. The n-type indium phosphide and carbon plates are used as electrodes. The aqueous solution of organic material orange dye (C H N O ) in distilled water is served as electrolyte at 1, 3 and 5 wt. % concentration. The cell is assembled in sealed organic glass box with dimensions 35 × 13 × 14 mm. The open circuit voltage (V ) and short circuit current (I ) of the cell are observed by illuminating and heating the samples. The temperature is raised up to 60°C from 25°C when light intensity is increased from dark condition to 425 W/m . It is observed that the relationship between light intensity and temperature is approximately linear for all cases. The V and I increase 100% and 300% respectively by increasing the light. The reported n-InP/ aqueous solution of orange dye/C cell can be considered as small converter of light and heat into electric power.

Enhancing the light utilization efficiency of microalgae using organic dyes

Solar radiation is composed of wide light spectrum including the range which cannot be utilized for microalgae. To enhance the light utilization efficiency, organic dye solutions of rhodamine101 and 9,10-diphenylanthracene were used as wavelength converters. Each dye affected cell growth and lipid accumulation differently, based on the response of each to different light spectrum. Under a light intensity of 50W/m2, maximum cell growth (1.5g/L) was obtained with the red organic dye rhodamine101, whereas best lipid content (30%) with the blue type 9,10-diphenylanthracene. These two separate and complementary traits could be combined by simple mixing, and in so doing optimal growth (1.5g/L) as well as lipid accumulation (30%) was achieved: lipid productivity was 2.3 times greater than without the organic dye. This study proved that certain organic dye solutions could convert useless wavelengths to be useful for algae cultivation, thereby increasing the productivity of biomass and lipids.

Supercapacitor devices for energy storage and capacitive dye removal from aqueous solutions

Capacitive behavior of electrodes and devices in solutions of organic dyes was investigated for capacitive dye removal.

PROTOTYPING OF PHOTOCATALYTIC MICROREACTOR AND TESTING OF PHOTODEGRADATION OF ORGANIC DYE

A photocatalytic microreactor is defined as a microfluidic device, which is integrated with a photocatalytic coating of TiO2 deposited on the inner surface of microchannels. This device is capable of degradation of organic dye solution in water in a continuous flow under the action of ultraviolet light. The objectives of this work were to present a rapid and economically viable approach for the prototyping photocatalytic microfluidic devices and to evaluate their photodegradation capability for organic dyes by ultraviolet-visible spectrophotometry. Prototyping of polydimethylsiloxane PDMS/TiO2/glass microreactors includes several procedures such as mold preparation, microchannel confection on PDMS surface, deposition of TiO2 on these microchannels, O2 plasma treatment of PDMS/TiO2 and glass surface for sealing these two parts. The efficiency of the photocatalytic microreactors was evaluated by fluxing two organic dye solutions, rhodamine B and methylene blue, with different flow rates of between 2 and 4 mL h-1. When the flow rate at 2 mL h-1was applied, discoloration of ~ 65% was achieved for both dye solutions, while PDMS/glass microchannels, without TiO2 film, demonstrated much lower discoloration of between 24 and 42% for rhodamine B and methylene blue, respectively. This confirmed that TiO2 was successfully deposited onto PDMS microchannels.

Large gain for crystalline thin films of thiophene/phenylene co-oligomer by photopumping with femtosecond laser pulses

We have evaluated the emission behaviors of crystalline thin films of thiophene/phenylene co-oligomers. Crystalline films of 2,5-bis(4-biphenylyl)thiophene (BP1T) were prepared on a substrate by vapor deposition followed by thermal treatment. The BP1T films contained crystalline domains several hundred micrometers in size. We examined the emission behavior of crystalline BP1T thin films by femtosecond laser excitation. Very high gains of over 500cm−1 were obtained for the crystalline BP1T film. Furthermore, the emission cross section of the crystalline BP1T film was on the order of 10–16cm2, rivaling that of dilute solutions of organic laser dyes.

Design and evaluation of a device for fast multispectral time-resolved fluorescence spectroscopy and imaging

The application of time-resolved fluorescence spectroscopy (TRFS) to in vivo tissue diagnosis requires a method for fast acquisition of fluorescence decay profiles in multiple spectral bands. This study focusses on development of a clinically compatible fiber-optic based multispectral TRFS (ms-TRFS) system together with validation of its accuracy and precision for fluorescence lifetime measurements. It also presents the expansion of this technique into an imaging spectroscopy method. A tandem array of dichroic beamsplitters and filters was used to record TRFS decay profiles at four distinct spectral bands where biological tissue typically presents fluorescence emission maxima, namely, 390, 452, 542, and 629 nm. Each emission channel was temporally separated by using transmission delays through 200 μm diameter multimode optical fibers of 1, 10, 19, and 28 m lengths. A Laguerre-expansion deconvolution algorithm was used to compensate for modal dispersion inherent to large diameter optical fibers and the finite bandwidth of detectors and digitizers. The system was found to be highly efficient and fast requiring a few nano-Joule of laser pulse energy and <1 ms per point measurement, respectively, for the detection of tissue autofluorescent components. Organic and biological chromophores with lifetimes that spanned a 0.8-7 ns range were used for system validation, and the measured lifetimes from the organic fluorophores deviated by less than 10% from values reported in the literature. Multi-spectral lifetime images of organic dye solutions contained in glass capillary tubes were recorded by raster scanning the single fiber probe in a 2D plane to validate the system as an imaging tool. The lifetime measurement variability was measured indicating that the system provides reproducible results with a standard deviation smaller than 50 ps. The ms-TRFS is a compact apparatus that makes possible the fast, accurate, and precise multispectral time-resolved fluorescence lifetime measurements of low quantum efficiency sub-nanosecond fluorophores.

ChemInform Abstract: Low‐Temperature Spectroscopy of Organic Molecules in Solid Matrices: From the Shpol′skii Effect to Laser Luminescent Spectromicroscopy for All Effectively Emitting Single Molecules

AbstractReview: 175 refs.

Application of temperature-dependent fluorescent dyes to the measurement of millimeter wave absorption in water applied to biomedical experiments.

Temperature sensitivity of the fluorescence intensity of the organic dyes solutions was used for noncontact measurement of the electromagnetic millimeter wave absorption in water. By using two different dyes with opposite temperature effects, local temperature increase in the capillary that is placed inside a rectangular waveguide in which millimeter waves propagate was defined. The application of this noncontact temperature sensing is a simple and novel method to detect temperature change in small biological objects.

Treatment of organic dye solutions by electrodialysis

Laboratory tests were performed to determine the efficiency of dye solution desalination by electrodialysis. The study involved anionic dye and mineral salt recovery by obtaining two streams from a salt and dye mixture - dye-rich solution and salt solution. A standard anion-exchange and cation-exchange membranes or monovalent selective anion-exchange membranes were used in the ED stack. It was found that the separation efficiency was strongly dependent on the dye molecular weight. The best results for standard ion-exchange membranes were achieved for the desalination of Direct Black solution. Furthermore, the obtained results implied that the application of monovalent selective anion-exchange membranes improved the recovery of dye and salt solutions - the dye concentration in the diluate remained constant irrespective of the molecular weight of anionic dyes, whereas the salt recovery remained very high (99.5%).

Preparation and properties of silicon- and titanium-containing hybrid nanocomposite films based on ethyl cellulose

Nanocomposite hybrid films containing silicon and titanium compounds in the polymer matrix are prepared through the sol-gel method via the hydrolytic polycondensation of Si and Ti alkoxides (tetraethoxysilane and titanium tetrabutoxide) in the THF solution of a hydrophobic polymer, ethyl cellulose. Their structure and properties are studied with the use of a complex of physicochemical methods. During the hydrolysis of tetraethoxysilane and the subsequent polycondensation of the reaction products, silicon atoms are incorporated into the polymer and form -O-Si-O-bonds involving hydroxyl groups of ethyl cellulose. In the sol-gel method, titanium alkoxide yields nanosized particles of titanium dioxide that play the role of fillers in the polymer matrix. Titanium-containing films show solubility in THF and, after prolonged contact with the solvent, precipitate titanium dioxide from the solution. Hybrid films containing silicon are insoluble owing to the formation of a chemical network between polymer molecules and Si-OH groups of the products of hydrolysis of silicon alkoxide, as confirmed by the IR data. It is shown that the amounts and types of alkoxides and the diameters of the structures formed in the polymer matrix via the sol-gel procedure affect the hydrophilicity levels of ethyl cellulose hybrid films and their abilities to swell in water and aqueous solutions of organic dyes (brilliant blue and methylene blue). Ethyl cellulose hybrid films are hydrophilic, and they facilitate the removal of dye molecules from aqueous solutions. The best properties are featured by the films containing nanosized particles of titanium dioxide in the polymer matrix.

Low-temperature spectroscopy of organic molecules in solid matrices: from the Shpol'skii effect to laser luminescent spectromicroscopy for all effectively emitting single molecules

Sixty years ago, in 1952, Prof. E V Shpol'skii and his colleagues were the first to see quasilinear spectra from complex organic compounds in specially selected solvents at low temperatures. Twenty years later, in 1972, a team headed by Prof. R I Personov discovered laser fluorescence line narrowing in the solid solutions of organic dyes. These two discoveries served as the basis for the field of laser selective spectroscopy of impurity centers in solids. The work in this field culminated in the techniques of spectroscopy and luminescence imaging (microscopy) of single molecules in condensed matter. Today, optical spectroscopy of impurity centers in solid solutions has become one of the most popular tools for solving a wide variety of interdisciplinary problems in physics, physical chemistry, optics and spectroscopy, biophysics, quantum optics, and nanotechnology. In this article, the development of this field is briefly reviewed, potentials of the developed methods are discussed, and some research results are highlighted.

Plasma-assisted oxidative degradation of organic dyes in solution by the joint action of underwater discharge and ozone

Data on the degradation kinetics of two organic dyes in a mixture by the action of electrical underwater discharges and ozone are presented. It has been found that the rate of degradation by the to combined treatment of the both dyes with face discharge and ozone is five times the sum of degradation rates expected on the assumption of the additive effect of each of these factors.

Drop-drop Microextraction Enhanced by Two Opposite Surface Acoustic Waves

A droplet-droplet microextraction enhanced by two surface acoustic waves in opposite propagation directions is proposed. A 2×2 interdigital transducer array with 27.5MHz center frequency was fabricated on a 128 0 yx-LiNbO 3 piezoelectric substrate using micro-electric technology. Two surface acoustic waves in opposite propagation direction were generated when a RF signal was applied to diagonal interdigital transducers. The movement of extractive matter particles within microextraction solution was accelerated due to the radiation of the surface acoustic waves. Then, the mass transfer between two phases was enhanced. An ionic liquid and an organic dye (acid green-25) solution were used for extraction experiments. Results show that the extraction was greatly enhanced by two surface acoustic waves in opposite propagation directional, and almost finished within 160 seconds when the RF signal power was 27.8dBm.The stability of microextraction solution was also improved due to the two opposite surface acoustic waves. DOI: http://dx.doi.org/10.11591/telkomnika.v11i5.2502 Full Text: PDF

Photocatalytic activity of PbMoO4 molybdate synthesized by microwave method

Lead molybdate powders (PbMoO4) with scheelite-type structure were successfully synthesized at low temperatures by using microwave irradiation (MW) in ethylene glycol medium. The resulting powders were characterized by X-ray powder diffraction (XRD), diffuse reflectance spectroscopy (DRS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and adsorption–desorption N2 isotherms (BET). PbMoO4 was tested as photocatalyst under UV irradiation for the degradation reaction of rhodamine B (rhB), indigo carmine (IC), orange G (OG), and methyl orange (MO). The bleaching of the organic dye solutions over PbMoO4 photocatalyst was quickly reached for rhB, IC, and OG with half-life times (t1/2) shorter than 7min. On the other hand, MO shows a recalcitrant behavior to photocatalytic degradation with t1/2=172min. Total organic carbon (TOC) analysis of samples irradiated revealed that mineralization of organic dyes by the action of PbMoO4 is feasible in 67% (rhB), 83% (IC), 55% (OG), and 60% (MO) after 96h of UV irradiation.

Single Step Formation of C-TiO2Nanotubes: Influence of Applied Voltage and Their Photocatalytic Activity under Solar Illumination

Self-aligned and high-uniformity carbon (C)- titania (TiO2) nanotube arrays were successfully formed via single step anodization of titanium (Ti) foil at 30 V for 1 h in a bath composed of ethylene glycol (EG), ammonium fluoride (NH4F), and hydrogen peroxide (H2O2). It was well established that applied voltage played an important role in controlling field-assisted oxidation and field-assisted dissolution during electrochemical anodization process. Therefore, the influences of applied voltage on the formation of C-TiO2nanotube arrays were discussed. It was found that a minimal applied voltage of 30 V was required to form the self-aligned and high-uniformity C-TiO2nanotube arrays with diameter of ~75 nm and length of ~2 μm. The samples synthesized using different applied voltages were then subjected to heat treatment for the conversion of amorphous phase to crystalline phase. The photocatalytic activity evaluation of C-TiO2samples was made under degradation of organic dye (methyl orange (MO) solution). The results revealed that controlled nanoarchitecture C-TiO2photocatalyst led to a significant enhancement in photocatalytic activity due to the creation of more specific active surface areas for incident photons absorption from the solar illumination.

Surface Acoustic Wave Enhancing Drop-Drop Microextraction with an Original Position Loop for Stabilizing Drops

A surface acoustic wave based drop-drop microextraction, in which an original position loop is used for stabilizing drops, is proposed. An interdigital transducer with 27.5 MHz center frequency was fabricated on a 128° yx-LiNbO3 piezoelectric substrate for exciting surface acoustic wave. Mass transfer of extractive matter between two liquid phases was enhanced due to acoustic streaming caused by radiation of surface acoustic wave. An original position loop, which was used to prevent extraction liquid from movement along the surface of piezoelectric substrate, was fixed on the substrate with 1 mm gap. An ionic liquid and an organic dye (acid green-25) solution were used for extraction experiments. Results show that the extraction time is greatly decreased due to surface acoustic wave radiation, and extraction process can be finished within two minutes at 30.0 dBm RF signal power.

Decolorization of organic dye solution by ozonation; Optimization with response surface methodology

Background: Ozone was used as a strong oxidant for decolorization of solution containing organic dyes. Three azo dyes, CI acid black 1 (AB1), CI acid yellow 19 (AY19) and CI acid orange 7 (AO7) which are widely used colorants in leather dyeing and finishing processes, were quantified with colorimetry. The effects of influential parameters including the ozone dosage, initial concentration of the dyes, initial pH of the solution, and temperature on the decolorization efficiency were studied. Central composite design (CCD) was applied to the optimization of decolorization of the dye solution by ozonation, and a second-order polynomial equation was proposed to predict the process efficiency. Results and discussion: Predicted results were found to be in good agreement with experimental values (R 2 = 0.9365, 0.9643, and 0.9296 for AB1, AY19, and AO7 respectively), which proves the suitability of the model employed and the success of CCD in optimizing the conditions of ozonation process. The variation of process efficiency as a function of independent variables was shown by graphical response surfaces. Conclusions: It was found that response surface methodology could effectively predict and optimize the performance of ozonation process for decolorization of solution containing organic dyes, AB1, AY19, and AO7. Also, the optimum values of the process variables to achieve the maximum decolorization efficiency could be calculated and verified experimentally.

Near-infrared photocatalyst of Er3+/Yb3+ codoped (CaF2@TiO2) nanoparticles with active-core/active-shell structure

A novel near-infrared (NIR) photocatalyst of Er3+/Yb3+-(CaF2@TiO2) was synthesized with optically active centers (Er3+/Yb3+) presented both in the CaF2 cores and TiO2 shells, and the corresponding upconversion luminescence properties increased greatly, which was helpful for the organic dye solution removal efficiency under NIR irradiation.