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[en] Spectrophotometric determination of cobalt(II), nickel(II) and copper(II) is carried out with 1-(2 pyridylazo)-2-naphthol as a complexing reagent in aqueous phase using non-ionic surfactant Tween 80. Beer's law is obeyed for Co(II), Ni(II) and Cu(II) over the range 0.5 - 4.0, 0.5 - 4.0 and 0.5 - 3.0 ngmL/sup -1/ with detection limit (2 σ) of 6.7, 3.2 and 3.9 ngmL/sup -1/. The max molar absorption, molar absorptivity, Sandell's sensitivity of Co(II), Ni(II) and Cu(II) are 580 nm, 570 nm and 555 nm; max (104 mol/sup -1/ cm /sup -1/) is 0.87, 1.8 and 1.6 and 6.8, 3.3 and 3.9 ng cm-2 respectively. The pH at which complex is formed for Co(II), Ni(II) and Cu(II) is 5, 5.5 and 6.5 respectively. The critical micelle concentration (CMC) of Tween 80 is 5%. The present method is compared with that of atomic absorption spectroscopy and no significant difference is noted between the two methods at 95% confidence level. The method has been applied to the determination of Co(II), Ni(II) and Cu(II) in industrial waste water and pharmaceutical samples. (author)
[en] Spectral luminescent characteristics of the dye acridine orange and eosin has been studied in reverse micellar solutions of sodium bis(2-ethyl-hexyl)sulfosuccinate. It was shown that the increase of the nucleus volume of reverse micelles. (author)
[en] GaCl 5,10,15,20-Tetra(1-pyrenyl)porphyrin (GaClTPyP) was successfully synthesised and encapsulated into Pluronic F127. The unmetallated 5,10,15,20-tetra(1-pyrenyl)porphyrin (H2TPyP) precursor was also encapsulated into Pluronic F127. The fluorescence quantum yield for GaClTPyP at 0.045 was lower than that of H2TPyP at 0.13 due to the heavy atom effect of Ga in the former which encourages intersystem crossing to the triplet state, lowering the fluorescence. Fluorescence quantum yield values increased when GaClTPyP or H2TPyP were encapsulated in Pluronic F127. GaClTPyP/Pluronic F127 showed higher values of the binding constant (Kb) as well as Stern-Volmer constant (Ksv) when compared to H2ClTPyP/Pluronic F127. It was determined from fluorescence quenching studies for GaClTPyP was located more in the inner core (hydrophobic) of Pluronic F127 and H2TPyP more on the outer region. Single oxygen quantum yields (ГђВ¤△) were determined to be 0.32 and 0.53 for GaClTPyP and GaClTPyP/Pluronic F127 respectively, an increase for the latter compared to the former.
[en] The production of nanoparticles from solution typically involves the use of complex solution additives or particle functionalization with organic ligands to prevent aggregation. Another approach would be to produce the particles within a nanoscale environment, such as inside a micelle. In this contribution, we produced indium tin oxide nanoparticles using the diblock copolymer reverse micelle approach. We examined different solution precursor routes without any additives. Additionally, we examined the role of the reaction sequence, either nanoparticle formation outside the micelles or using the micelle itself as a nanoreactor. (author)
[en] The conductometric studies of the solutions of cerium and thorium laurate in the mixture of 70/30 benzenemethanol (v/v) has been carried out at 25-40 deg C in order to determine the CMC, limiting molar conductance, dissociation constant and thermodynamic parameters for both dissociation and association processes. The results show that these soaps behave as a weak electrolyte in benzene-methanol and Debye-Huckel-Onsager's equation is not applicable to the solutions of these soaps and micellization process is favored over the dissociation process. (author)
[en] Micellar enhanced ultrafiltration (MEUF) is a separation technique which can be used to remove metals ions or dissolved organics from water. In this study MEUF has been carried out to investigate the retention of crystal violet (CV) (molecular weight 407.98), a cationic dye, from aqueous stream. Regenerated cellulose membrane of molecular weight cut-off 10 kDa was used in a cross-flow ultrafiltration unit. Sodium dodecylsulfate (SDS) and NaCl were used as surfactant and electrolyte, respectively. The removal of CV and permeate flux were studied as a function of dye and surfactant concentrations, ionic strength and pH. The ultrafiltration experiments showed that anionic surfactant SDS allowed retention of crystal violet in the order of 99 pour cent in the whole range of dye and surfactant concentrations considered. High retention was also obtained at pH range from 2 to 12. Permeate flux decreases when surfactant concentration or ionic strength increases.
[en] A selective and fairly sensitive automatic spectrophotometric method for the determination of indium by flow injection analysis (FIA) has been developed. Anionic micellar medium of sodium dodecyl sulfate has been used for the system Indium reacts with 1,5-diphenylthiocarbazone (dithizone) at ph 7.00 in micellar medium, to give red-violet chelate, which absorb at 5300 nm. The molar absorptivity and Sandell's sensitivity were found to be 6.7 x 10/sup 3/ l mol/sup -1/ cm/sup -1/ and 20 ng cm/sup 2/ of indium, respectively. Linear calibration graph was obtained for 0.25 to 6.0 micro gram ml/sup -1/ of indium. The reaction is instantaneous and absorbance remain stable for 45 h. Various analytical parameters, such as effect of pH, flow rate, sample volume, dispersion coefficient, time and reagent concentration were studied. The interference of over 40 anions, cations and complexing agents has been studied at 1 micro g ml/sup -1/. Method has been applied to determine indium in synthetic mixture and water samples. (author)
[en] Synthesis of metal nano-shells around organic micelles is achieved through radiolysis of aqueous solutions of surfactant self-assembled in spherical micelles and metal ions. The formation of the metal nano-shells is evidenced by UV-visible spectroscopy and Small Angle X-ray Scattering. (authors)