Removal of Color from Aqueous Solutions Containing Textile Dyes by Dolomite Wastes

The wastewaters of textile industries are large in volume and have different qualities. Therefore, their treatment is complicated. The main purpose of this research is to study the performance of dolomite wastes from stone industries, which are usually discharged into environment without being utilized, as an adsorbent for removal of dyes from textile industries wastewater. For this purpose, and because of wide usage of Acidic, Disperse and Reactive dyes in textile industries, color solutions containing C.I.Acid Red 88, C.I.Disperse Red 151 and C.I.Reactive Red 29 were used. For optimizing of different factors which affect the amount of adsorption, four factors of initial dye concentration, initial pH, stirring speed and adsorbent dosage were observed. In order to decrease the number of experiments, for minimizing the time and expenses, Taguchi method is utilized. Dolomite was incinerated at 800°C to increase adsorption capacity. The experiments were performed in batch reactors. In optimum conditions, the maximum color removal efficiencies for Acid Red 88 (initial concentrationof 50 mg/L, initial pH of 6, stirring speed of 200 rpm, adsorbent dosage of 8g/L), for Disperse Red 151 (initial concentration of 100 mg/L, initial pH of 4, stirring speed of 200 rpm, adsorbent dosage of 8g/L) and for Reactive Red 29 (initial concentration of 50 mg/L, initial pH of 2, stirring speed of 200 rpm, adsorbent dosage of 6g/L) were more than %99, that shows a high level of color removal performance by this adsorbent. Freundlich isotherm is the best model describing the adsorption process by charred dolomite in equilibrium condition for color removal.