Removal of Amido Black Dye by Adsorption with Zeolite Synthesized from Fly Ash

Abstract

Investigations have been undertaken to determine whether zeolite synthesized from fly ash hold promise in the treatment of wastewater from the textile industry. The initial findings indicate that zeolite synthesized from fly ash has high adsorptive capacity for dyes and it is relatively cheap. This work presents the experimental studies on the adsorptive removal of Amido Black 10 B dye using a low-cost zeolite synthesized from fly ash. Preparation methodology for zeolite involved mixing of fly ash with NaOH, fusion of the mixture at 600C, grinding, aging, curing, filtration, washing and drying. The synthesized zeolite was then used to study the effect of various parameters namely pH, temperature, agitation speed, adsorption time, zeolite loading and initial dye concentration on the dye removal efficiency. Then, the optimal process parameters for the dye–zeolite system were determined. Each experiment was carried out thrice and the average values were reported to ensure the consistency, repeatability and accuracy of the results. It was observed from the experimental analysis that the dye removal efficiency increases with increasing the adsorbent dosage, adsorption time as well as stirrer speed and the optimal values of zeolite dosage, adsorption time and stirrer speed were found to be 10 g/L, 6 h and 300 rpm respectively. On the other hand, the dye removal efficiency decreased with increasing the initial dye concentration in the solution as well as temperature, indicating that the adsorption process using zeolite is exothermic and is effective for the treatment of solutions with low concentrations of adsorbate. The effect of pH on the dye removal efficiency did not show any regular trend. A sudden drop in the removal efficiency from a pH of 6 to a pH of 8 was noticed. Maximum dye removal was obtained at low pH values (between 2–5) indicating the fact that the zeolite surface is positively charged. The spent adsorbent was regenerated by ultrasonic cleaning with surfactant solution followed by rinsing, drying and sintering. The regenerated zeolite performed in a way similar to the original zeolite with a little decrease in removal efficiency. Finally, the data were fitted with various equilibrium and kinetic models and the model parameters were obtained by curve fitting and regression analysis.