Rhodamine 6G In Water Research Articles

Application of dispersive liquid–liquid microextraction and spectrophotometric detection to the rapid determination of rhodamine 6G in industrial effluents

A rapid and effective preconcentration method for extraction of rhodamine 6G was developed by using a dispersive liquid–liquid microextraction (DLLME) prior to UV–vis spectrophotometry. In this extraction method, a suitable mixture of acetone (disperser solvent) and chloroform (extractant solvent) was injected rapidly into a conical test tube containing aqueous solution of rhodamine 6G. Therefore, a cloudy solution was formed. After centrifugation of the cloudy solution, sedimented phase was evaporated, reconstituted with methanol and measured by UV–vis spectrophotometry. Different operating variables such as type and volume of extractant solvent, type and volume of disperser solvent, pH of the sample solution, salt concentration and extraction time were investigated. The optimized conditions (extractant solvent: 300 μL of chloroform, disperser solvent: 3 mL of acetone, pH: 8 and without salt addition) resulted in a linear calibration graph in the range of 5–900 ng mL −1 of rhodamine 6G in initial solution with R 2 = 0.9988 ( n = 5). The Limits of detection and quantification were 2.39 and 7.97 ng mL −1, respectively. The relative standard deviation for 50 and 250 ng mL −1 of rhodamine 6G in water were 2.88% and 1.47% ( n = 5), respectively. Finally, the DLLME method was applied for determination of rhodamine 6G in different industrial waste waters.

Heterogeneous Fenton-like degradation of Rhodamine 6G in water using CuFeZSM-5 zeolite catalyst prepared by hydrothermal synthesis

In this study, heterogeneous Fenton-like degradation of reactive azo dye Rhodamine 6G in water was investigated over a CuFeZSM-5 zeolite catalyst prepared by hydrothermal synthesis. At initial pH of 3.4, a color removal of 100% was achieved after a reaction time of 45 min. TOC elimination was measured to be 51.8% after 2 h of oxidation. Initial decolorization rate was described by an equation of − r A 0 = 4.56 × 10 2 e − 24.83 / R T C R6G , 0 C H 2 O 2 , 0 0.35 where R is in kJ/mol. The leaching of iron and copper cations from zeolite structure into the solution during oxidation was dependent on pH strongly. The regulation of pH from 6.5 (dye solution pH) to 3.4, increased leaching for iron from 0.7 to 0.8 mg/dm 3 and for copper from 1.4 to 2.1 mg/dm 3. The copper was totally leached from the catalyst during the process at pH 3.4.

Staining and peeling of the internal limiting membrane using a fluorescent dye (Rhodamine 6 G)

Aim:To assess whether low concentrations of a fluorescent dye such as Rhodamine 6G would help the unaided human eye visualise the vitreous and the internal limiting membrane (ILM) under standard...

Both Rotor and Stator Subunits Are Necessary for Efficient Binding of F1 to F0 in Functionally Assembled Escherichia coli ATP Synthase

In F1F0-ATP synthase, the subunit b2delta complex comprises the peripheral stator bound to subunit a in F0 and to the alpha3beta3 hexamer of F1. During catalysis, ATP turnover is coupled via an elastic rotary mechanism to proton translocation. Thus, the stator has to withstand the generated rotor torque, which implies tight interactions of the stator and rotor subunits. To quantitatively characterize the contribution of the F0 subunits to the binding of F1 within the assembled holoenzyme, the isolated subunit b dimer, ab2 subcomplex, and fully assembled F0 complex were specifically labeled with tetramethylrhodamine-5-maleimide at bCys64 and functionally reconstituted into liposomes. Proteoliposomes were then titrated with increasing amounts of Cy5-maleimide-labeled F1 (at gammaCys106 and analyzed by single-molecule fluorescence resonance energy transfer. The data revealed F1 dissociation constants of 2.7 nm for the binding of F0 and 9-10 nm for both the ab2 subcomplex and subunit b dimer. This indicates that both rotor and stator components of F0 contribute to F1 binding affinity in the assembled holoenzyme. The subunit c ring plays a crucial role in the binding of F1 to F0, whereas subunit a does not contribute significantly.

Luminiscent dye Rhodamine 6G doped monolithic and transparent TEOS silica xerogels and spectral properties

Sol–gel process was used for the preparation of Rhodamine 6G (R6G) doped silica xerogels, using tetraethylorthosilicate [TEOS, Si(OC2H5)4] as the precursor for the silica network. Silica alcosol was prepared by hydrolysis and polycondensation of ethanol (EtOH) diluted TEOS in the presence of citric acid (CTA) catalyst. The ethanolic R6G was added to the alcosol to trap R6G molecules inside the SiO2 gel network during the gelation of the TEOS alcosol. The effect of CTA/TEOS molar ratio on the gelation time of the R6G doped TEOS alcosol, transparency and monolithicity of the R6G doped silica xerogel was studied by varying the CTA/TEOS molar ratio from 1.2 × 10-4 to 180 × 10-4 by keeping the molar ratios of TEOS:EtOH:H2O:R6G constant at 1:5:7:9.2× 10-6, respectively. It was found that the minimum (<70 h) gelation time was observed at higher and lower CTA/TEOS molar ratios of 72 × 10-4 where as maximum (>180 h) gelation time was observed for CTA/TEOS molar ratio of 72 × 1024. While opaque and monolithic R6G doped SiO2 xerogels were obtained for <4.8 × 10-4 CTA/TEOS molar ratios, whereas cracked and transparent xerogels were obtained for >120 × 10-4 molar ratios of CTA/TEOS. Transparent, homogeneous and monolithic samples were obtained between 4.8 × 10-4 and 120 × 10-4 of CTA/TEOS molar ratios. Leaching out property was studied by using water, methanol and ethanol solvents for the R6G doped SiO2 xerogels of 9.2 × 10-6 and 12 × 10-4 of R6G/TEOS and CTA/TEOS molar ratios, respectively, and found that R6G molecules were trapped in the pores of the SiO2 network.Bleaching out phenomena of the R6G doped SiO2 xerogels was studied by focusing the high intensity light on some part of the samples for a period of 1 h and found that the pores were continuous in SiO2 network. Visible spectra of R6G in water, ethanol, SiO2 alcosol and xerogel were taken for 1.6 × 10-4 M R6G andobserved that there were two absorption peaks at 499 and 525 nm in the spectrum of R6G in water due to dimerization of R6G molecules and only one absorption peak at 530 nm in the spectra of ethanol, SiO2 alcosol and xerogel because of monomerization of R6G molecules. Visible spectra of the R6G doped silica xerogels for varying R6G/TEOS molar ratios from 9.2 × 10-8 to 9.2 × 10-5 were taken and found the red shift (5–10 nm) with increasing the R6G/TEOS molar ratio from 9.2 × 1028 to 9.2 × 10-5. The effect of temperature on these sample was studied by varying the temperature from 50 to 300 8C and found that the R6G doped silica samples were stable up to 200 8C. IR spectra were taken for pure R6G powder and R6G doped silica xerogels of 9.2 × 10-8 and 9.2 × 10-5 R6G/TEOS molar ratios and found that most of the peaks present in pure R6G powder spectrum were absent in the spectra of trapped R6G SiO2 xerogels. This shows that, the SiO2 network hinders the rotational and vibrational transitions of R6G when it is caged in the SiO2 network. The peaks related to bending motion in R6G molecules were not disturbed by the SiO2 network

Single-molecule analysis of ultradilute solutions with guided streams of 1-µm water droplets

We describe instrumentation for real-time detection of single-molecule fluorescence in guided streams of 1-microm (nominal) water droplets. In this technique, target molecules were confined to droplets whose volumes were comparable with illumination volumes in diffraction-limited fluorescence microscopy and guided to the waist of a cw probe laser with an electrostatic potential. Concentration detection limits for Rhodamine 6G in water were determined to be approximately 1 fM, roughly 3 orders of magnitude lower than corresponding limits determined recently with diffraction-limited microscopy techniques for a chemical separation of similar dyes. In addition to its utility as a vehicle for probing single molecules, instrumentation for producing and focusing stable streams of 1-2-microm-diameter droplets may have other important analytical applications as well.

Use of thermal lens spectrometry for the investigation of dimerization equilibria of rhodamine 6G in water and aqueous micellar solutions

The aggregation and the fluorescent properties of rhodamine 6G in aqueous solutions have been investigated using thermal lens spectrometry in addition to conventional absorption and fluorescence experiments. The results show that, when the compound is highly fluorescent, the photothermal method is very sensitive to detect the formation of dimers. It allowed the determination of the absolute fluorescence quantum yield of the monomer and of the dimerization constant. The experiments, carried out over a wide range of concentrations, show that while the non-active absorption by dimers is the main quenching process at low concentrations, the decrease in the fluorescence quantum yield of the dye at higher concentrations could also result from migrational quenching involving the non-radiative energy transfer from excited monomers to non-fluorescent dimers. Solubilization of rhodamine 6G into micellar solutions has a positive effect on the deaggregation of dimers for dye concentrations up to at least 4×10 −4 M. In solutions containing 2% and 10% of anionic SDS or nonionic Brij 35, respectively, dimers are absent and the fluorescence efficiency of the rhodamine is completely restored. On the contrary, in solutions containing 4% of cationic CTABr, the absolute fluorescence quantum yield of monomers is significantly decreased and dimerization still occurs to a small extent.

Fluorescence quantum yield of rhodamine 6G using pulsed photoacoustic technique

Experimental method for measuring photoacoustic(PA) signals generated by a pulsed laser beam in liquids is described. The pulsed PA technique is found to be a convenient and accurate method for determination of quantum yield in fluorescent dye solutions. Concentration dependence of quantum yield of rhodamine 6G in water is studied using the above method. The results indicate that the quantum yield decreases with increase in concentration in the quenching region in agreement with the existing reports based on radiometric measurements.

The spectroscopic behaviour of rhodamine 6G in polar and non-polar solvents and in thin glass and PMMA films

Absorption, fluorescence, quantum yields and lifetimes of rhodamine 6G in water, methanol, dichloroethane and chloroform were measured. From a comparison of these quantities with those for thin glass and plastic films conclusions are drawn about dimer formation and the stability of rhodamine 6G in these materials. The stability in the films is increased as compared with the solutions.

Absorption behaviour of methanolic rhodamine 6G solutions at high concentration

The optical constants of rhodamine 6G dissolved in methanol and of a solid rhodamine 6G film are determined. The concentration of the solutions is varied between 10 −5 and 0.66 mol/ℓ. Deviations from Beer's law at high concentrations are found. They are thought to be due to the mutual interaction of neighbouring molecules. The absorption behaviour of rhodamine 6G in methanol is compared with the absorption behaviour of rhodamine 6G in water.

Picosecond time dependent rotational diffusion of rhodamine 6G in micellar solution

The rotational diffusion time constants of rhodamine 6G in water, cetyldimethylbenzylammonium chloride, and sodium dodecylsulfate micellar solution has been determined with a picosecond phase fluorimeter in the temperature range 10°C to 80°C. Data analysis shows a strong micellar influence leading to anisotropic rotational diffusion in sodium dodecylsulfate micellar solution.

Effect of soap on the fluorescent lifetime and quantum yield of rhodamine 6G in water

Addition of the soap ammonyx LO to a solution of 2 × 10 -4 M rhodamine 6 G in water lengthens the fluorescent lifetime from 3.8 to 5 nsec, and increases the relative quantum yield by ≈ 1.5. Concentrations of soap and solute are those commonly used in cw rhodamine dye lasers. Comparisons are made with rhodamine 6G in ethanol solutions.

Rotational relaxation and triplet-state effects in the cw dye laser

In a cw dye laser apparatus we measure first the fluorescence depolarization in the usual manner, and then the ratio of laser threshold pump powers for the laser polarization parallel and perpendicular to the linearly polarized pump source. From these two measurements we can obtain the important triplet-state parameter KT ≡ kSTτTσT/ σe, as well as the rotational relaxation time for the dye. For Rhodamine 6G in water with Triton X-100, we find KT=0.35 ± 0.02, while with Ammonyx-LO KT=0.25 ± 0.02. These additives also slow down the rotational relaxation of the dye molecule by more than an order of magnitude compared to common organic solvents.

Cw OPERATION OF AN ORGANIC DYE SOLUTION LASER

A cw laser using a 2.5×10−4 M solution of rhodamine 6G in water containing a deaggregating agent (1.5% Triton-X100) is described. The laser consists of a 4.5-mm transverse-flow hemispherical cavity excited longitudinally by the 5145-Å output of a 1-W argon ion laser. With mirror reflectances of 97.5% and 99.5%, a 200-mW threshold excitation was measured. Power output was approximately 30 mW at 597 nm with 960 mW excitation power.