Y Boyjoo | PubMed Health

PubMed2005

A comparative study of dye removal using fly ash treated by different methods.

The effect of different methods for fly ash treatment using conventional chemical, sonochemical and microwave method on dye adsorption in aqueous solution was investigated. Three basic dyes, methylene blue, crystal violet and rhodamine B, are employed for adsorption testing. It is found that fly ash shows different adsorption capacity depending on type of dyes. Chemical treatment using HCl will increase the adsorption capacity. The adsorption capacity of HCl treated fly ash varies with the preparation conditions. Microwave treatment is a fast and efficient method while producing the sample with the highest adsorption capacity. Solution pH and inorganic salts in dye solution can significantly influence the adsorption. The adsorption data have been analysed using Langmuir, Freundlich and Redlich-Peterson isotherms. The results indicate that the Freundlich and Redlich-Peterson models provide the better correlations with the experimental data.

Carbon↗

PubMed2005

Removal of dyes from aqueous solution using fly ash and red mud.

Fly ash and red mud have been employed as adsorbents for the removal of a typical basic dye, methylene blue, from aqueous solution. Heat treatment and chemical treatment have also been applied to the as-received fly ash and red mud samples. It is found that fly ash generally shows higher adsorption capacity than red mud. The raw fly ash and red mud show adsorption capacity at 1.4 x 10(-5) and 7.8 x 10(-6) mol/g, respectively. Heat treatment reduces the adsorption capacity for both fly ash and red mud but acid treatment by HNO(3) induces a different effect on fly ash and red mud. Nitric acid treatment results in an increase in adsorption capacity of fly ash (2.4 x 10(-5) mol/g) while it decreases the adsorption capacity for red mud (3.2 x 10(-6) mol/g). The adsorption data have been analysed using Langmuir, Freundlich and Redlich-Peterson isotherms. The results indicate that the Redlich-Peterson model provides the best correlation of the experimental data. Isotherms have also been used to obtain the thermodynamic parameters such as free energy, enthalpy and entropy of adsorption. For fly ash and red mud, adsorption of methylene blue is endothermic reaction with DeltaH(0) at 76.1 and 10.8 kJ/mol, respectively.

Adsorption↗