engleski

Sorption of diazo dye on fly ash

The goal of this work was to investigate the application of fly ash as a sorbent for removal of toxic and cancerogenic diazo dye, Congo red, from aqueous solutions. Batch sorption process was performed in order to examine the removal of Congo red dye using fly ash by varying the initial dye concentration, contact time and temperature of the process. Langmuir, Freundlich and Dubinin-Radushkevich isotherms were used to analyze the equilibrium data at different temperatures. A linear regression method was used for comparison of the isotherms. The equilibrium data could be well described by the Langmuir isotherm. Three kinetic models (pseudo-first-order, pseudo- second-order and intra-particle diffusion) were used to predict the sorption rate constants. The sorption kinetic was found to follow pseudo-second-order rate kinetic model and the intra-particle diffusion was one of the rate determining steps. Thermodynamic parameters of sorption process (free energy, enthalpy, and entropy) were calculated. The negative values of free energy, enthalpy and entropy suggested that the sorption was spontaneous, exothermic and stable.

sorption ; fly ash

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