Removal of Safranin Dye from Wastewater Using Khulays Natural Bentonite

Abstract

Khulays natural bentonite as low-cost adsorbent was investigated to be used to remove safranin dye from wastewater. The removal process was studied using batch adsorption experiments. The effect of different parameters on the adsorption process was investigated including contact time, initial safranin dye concentration, initial solution pH and Khulays natural bentonite dosage. Adsorption isotherms were applied to estimate the equilibrium characteristics of the adsorption process, evaluate the applicability of the process and suggest the appropriate design for the adsorption system. Adsorption kinetics were investigated using pseudo-first-order model and pseudo-second-order model to fit the experimental data. The results revealed that the adsorption process achieved equilibrium after 80 minutes. The removal process is initial solution pH dependent where the removal percentage of safranin dye gradually increased as the initial safranin dye solution pH increased. They also showed that as the initial safranin dye concentration increased the removal percentage decreased because of limited active sites on bentonite surfaces which consequently saturated with safranin dye. The experimental data was well fitted with Langmuir model more than with Freundlich model and the maximum adsorption capacity was equal to 294.1 mg/g. Moreover, the experimental results showed that the adsorption of safranin dye onto Khulays natural bentonite followed pseudo second-order model.