The air–solid photocatalytic degradation of organic dye films Acid Blue 9 (AB9) and Reactive Black 5 (RBk5) is studied on Pilkington Activ™ glass. The Activ™ glass comprises of a colorless TiO2 layer deposited on clear glass. The Activ™ glass is characterized using atomic force microscopy (AFM) and X-ray diffraction (XRD). Using AFM, the TiO2 average agglomerate particle size is 95 nm, with an apparent TiO2 thickness of 12 nm. The XRD results indicate the anatase phase of TiO2, with a calculated crystallite size of 18 nm.
Dyes AB9 and RBk5 are deposited in a liquid film and dried on the Activ™ glass to test for photodecolorization in air, using eight UVA blacklight-blue fluorescent lamps with an average UVA irradiance of 1.4 mW/cm2. A novel horizontal coat method is used for dye deposition, minimizing the amount of solution used while forming a fairly uniform dye layer. About 35–75 monolayers of dye are placed on the Activ™ glass, with a covered area of 7–10 cm2. Dye degradation is observed visually and via UV–vis spectroscopy.
The kinetics of photodecolorization satisfactorily fit a two-step series reaction model, indicating that the dye degrades to a single colored intermediate compound before reaching its final colorless product(s). Each reaction step follows a simple irreversible first-order reaction rate form. The average k1 is 0.017 and 0.021 min−1 for AB9 and RBk5, respectively, and the corresponding average k2 is 2.0 × 10−3 and 1.5 × 10−3 min−1. Variable light intensity experiments reveal a p = 0.44 ± 0.02 exponent dependency of initial decolorization rate on the UV irradiance. Solar experiments are conducted outdoors with an average temperature, water vapor density, and UVA irradiance of 30.8 °C, 6.4 g water/m3 dry air, and 1.5 mW/cm2, respectively. For AB9, the average solar k1 is 0.041 min−1 and k2 is 5.7 × 10−3 min−1. 相似文献
Temperature sensing membranes using Nafion® as the polymeric support matrix have been prepared incorporating common pH indicators and stains as visible indicators. These simple systems depend on the temperature sensitivity of the acid–base equilibria between the indicator and the acidic Nafion®. The films are able to sense temperature change through a change in film colour resulting from the equilibrium shift between different forms of the indicating dye. The dyes (phenolphthalein, methylene blue, safranin-O and crystal violet) studied covered a temperature range from 4 to 70 °C. 相似文献
Adsorption of industrially important dyes namely bromophenol blue, alizarine red-S, methyl blue, methylene blue, eriochrome black-T, malachite green, phenol red and methyl violet from aqueous media on activated charcoal has been investigated. The effect of shaking time, pH and temperature on the adsorption behaviour of these dyes has been studied. It was noted that adsorption of all the dyes on activated charcoal decreases with an increase in the pH and the temperature. The adsorption isotherms at different temperatures were found to be of L-type. Adsorption data was fitted to Freundlich, BET and Langmuir isotherms and various adsorption parameters have been calculated. The thermodynamic parameters such as DeltaG, DeltaH and DeltaS were calculated from the slopes and intercepts of the linear variation of lnK against 1/T, where K is the adsorption coefficient obtained from Langmuir equation, was used. The calculated values for the heat of adsorption and the free energy indicate that adsorption of dyes is favored at low temperatures and the dyes are chemisorbed on activated charcoal. 相似文献
Batch and column kinetics of methylene blue adsorption on calcium chloride, zinc chloride, magnesium chloride and sodium chloride treated beech sawdust were simulated, using untreated beech sawdust as control, in order to explore its potential use as a low-cost adsorbent for wastewater dye removal. The adsorption capacity, estimated according to Freundlich's model, the Langmuir constant K(L) and the adsorption capacity coefficient values, determined using the Bohart and Adams' bed depth service model indicate that salts treatment enhanced the adsorption properties of the original material. Since sawdust is an industrial waste/byproduct and the salts used can be recovered as spent liquids from various chemical operations, this process of adsorbent upgrading/modification might be considered to take place within an 'Industrial Ecology' framework. 相似文献
It is desirable to make effective use of solid wastes, as well as waste liquors, of the dye house generated from leather processing. The present study deals with the adsorption of Acid red 26 (Xylidine ponceau) dye using leather fibre waste (buffing dust) as substrate matrix by the means of ultrasound, magnetic stirring and conventional heating. The research examined the effect of various process parameters: ultrasonic power, concentration of dye, temperature and time. The dye uptake data have been fitted with Freundlich and Langmuir isotherms, indicating a useful dye adsorption process. A mechanism for dye adsorption in leather fibres has also been proposed. This study shows that it is possible to remove dyes from dye house effluent streams using leather waste fibres of buffing dust by means of ultrasound. Two different toxic wastes produced by the same industry can be effectively contained. This ‘Intra wastes interaction’ approach could reduce the burden of discarding wastes of other materials in the leather industry. 相似文献