Dye concentration

Dye adsorption from solution may be used to estimate the surface area of a powdered solid. Suppose that if 3.0 g of a bone charcoal is equilibrated with 100 ml of initially 10 Af methylene blue, the final dye concentration is 0.3 x 10 Af, while if 6.0 g of bone charcoal had been used, the final concentration would have been 0.1 x Qr M. Assuming that the dye adsorption obeys the Langmuir equation, calculate the specific surface area of the bone charcoal in square meters per gram. Assume that the molecular area of methylene blue is 197 A. ... 

There are many dyes available, each of which can be used over a 20-30 nm range and which, together, cover a wavelength range from about 365 nm in the ultraviolet to about 930 nm in the near-infrared. Dye concentrations are low, typically in the range 10 mol 1 to 10 mol 1. ... 

Effect of pH, dye concentration, size of pores of paper filters and their hydrophobic characteristics, filtration rate, nature and hydrocarbon radical length cSurf on sensitivity of their determination was studied. 

The times t are in minutes and the dye concentrations [dye] are in milliliters of stock dye solution per 100 ml of the reactant mixture. The stock dye solution was 7.72 x 10 molar. Use these data to fit a rate expression of the form... 

To evaluate the sorption capacity of the biomass, biosorption isotherms of R016 were obtained at different solution pHs. The initial concentration was varied from 0 to 5000 mg L, which resulted in different final dye concentrations after the sorption equilibrium was achieved. 

On integration of the above system of differential equations until B has been completely consumed U, W, and Z values are obtained. Monoazo dyes concentrations are then calculated using Ekjns. (5.4-175) and (5.4-176). The concentration of 1-naphthol is calculated knowing its surplus for the reaction and the concentration of bisazo dye S can be determined from any of the mass balances ... 

FIG. 4 SHG intensity from the dye eosin B adsorbed at the air-water interface as a function of the pH of the bulk aqueous solution. The aqueous dye concentration is 30 /xM and the fundamental wavelength is 532 nm. 

Example 5.7 We have to design a servo-controller for a mixing system. A blue dye for making denim is injected into a stream of water. The injected dye is blended into the pipe flow with the aid of in situ static mixers. A photodetector downstream is used to monitor the dye concentration. The analog output of the detector is... 

The block diagram is shown in Fig. E5.7b, where the dye concentration is denoted by C and the set point by R. The flow rate is one probable source of disturbance. 

In order to determine the liquid exchange mass flux at the interface due to the droplet deposition and the liquid reentrainment, Quandt (1962) measured the dye concentration in an isothermal annular flow. His steady-state model is similar to Vanderwater s as shown in Figure 5.22, except for his assumption that VId — Vh, = Vr Hence, the concentration balance of dye can be expressed as... 

These equations can be solved simultaneously, using the boundary conditions that at z = 0, Cf = CQ and Cd — 0, where Ca is the initial dye concentration introduced into the liquid. The solutions are... 

Wang, X. F., Y. Koyama, H. Nagae, Y. Yamano, M. Ito, and Y. Wada. 2006. Photocurrents of solar cells sensitized by aggregate-forming polyenes Enhancement due to suppression of singlet-triplet annihilation by lowering of dye concentration or light intensity. Chem. Phys. Lett. 420 309-315. 

Figure 10.13 Exhaustion rates of Cl Disperse Violet 1 on untreated wool in dyeing using liposomes at different lipid concentrations and constant dye concentration [58]...

A major drawback of synthetic thickeners when used with dyes is their sensitivity to electrolytes. Most soluble dyes behave as highly ionised electrolytes and disperse dyes contain anionic polyelectrolyte dispersing agents unless they have been formulated with nonionic systems specifically for use with acrylic thickeners. Consequently there is a loss of viscosity this can be quite pronounced although it depends on circumstances, particularly on the dye concentration. As already mentioned, this can be alleviated to some extent by copolymerisation with acrylamide during manufacture. Otherwise it is necessary to try to eliminate all electrolytes from the system or to increase the concentration of thickener. Such measures have their limitations in practice, however. Alternative synthetic thickening... 

In the final stage, the electrolyte and unfixed dye concentrations are low but further changes of liquor must take place until almost all the unfixed dye molecules are desorbed. 

A slug of dye is placed in the feed stream to a stirred reaction vessel operating at steady state. The dye concentration in the effluent stream was monitored as a function of time to generate the data in the table below. Time is measured relative to that at which the dye was injected. 

Red shift of fluorescence band with the increase of dye concentration due to directed nonradiative energy homotransfer (DHT) (owing to FRET mechanism) from the blue to the red centers of sample (see panel b in Fig. 5). 

A different approach to design a self-calibrating dye was proposed [70], in which a viscosity-sensitive molecular rotor (2-cyano-3-(4-dimethylaminophenyl) prop-2-enoic acid) was covalently linked to a reference dye, 7-methoxycoumarin-3-carboxylic acid, which exhibited no viscosity sensitivity (40, Fig. 13). A ratiometric measurement, that is, rotor emission relative to reference emission, was shown to be widely independent of dye concentration [70]. However, the design of such a ratiometric dye poses some challenges because of resonance energy transfer from... 

Noise can be also introduced by biochemical heterogeneity of the specimen. This can be a major cause of uncertainty in biological imaging. The high (three-dimensional) spatial resolution of fluorescence microscopy results in low numbers of fluorophores in the detection volume. In a typical biological sample, the number of fluorophores in the detection volume can be as low as 2-3 fluorophores for a confocal microscope equipped with a high NA objective at a fluorescent dye concentration of 100 nM. This introduces another source of noise for imaging applications, chemical or molecular noise, related to the inherent randomness of diffusion and the interaction of molecules. 

The stability of a wide variety of certified dyes in tablets has been evaluated upon exposure to various illumination conditions [20-22], In these works, more detailed studies of dye concentration, exposure time, and irradiation light intensity were performed, and the data analyzed more rigorously. The effect of varying tablet excipients was also investigated with respect to the decomposition kinetics. This work ended with the development of a systematic approach for the testing of color stability, and the investigators developed a ranking of colorant stabilities in tablets [22],... 

Pseudomonas luteola Reactive azo dyes, Direct azo dyes and leather dyes The 59-99% color removal after 2-6 days static incubation, at dye concentration of 100 mg L 1, monoazo dyes showing fastest rate of decoloration [78]... 

Acid Orange 7 Granular activated carbon-biofilm configured packed column With initial 500 mg L-1 dye concentration, a complete decolorization was achieved in all runs although the cosubstrates added into the BGAC-packed column system reduced until to zero [177]... 

Direct Black 38 Granulated anaerobic sludge mixed culture The dye was degraded and decolorized throughout the experimental period of 300 h. The batch anaerobic tests indicated that once reduced environments were established with glucose, decolorization occurs even at high dye concentrations [181]... 

Procion navy blue, Procion green, Direct blue, and a mixture of azo dyes Consortium comprised of three bacterial strains A high efficiency for dye degradation was observed even at high dye concentrations [159]... 

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