Evaluation of the use of loofa activated carbons as potential adsorbents for aqueous solutions containing dye

Abstract

In this study, two activated carbons were prepared from loofa, loofa carbon-1 (LC1) and loofa carbon-2 (LC2). The surface structure of LC1 and LC2 were analyzed by scanning electronic microscopy (SEM). The ability of LC1 and LC2 to remove reactive orange (RO) dye from aqueous solutions by adsorption has been studied. A series of experiments were conducted to assess the effect of system variables such as initial pH, initial metal ion concentration and temperature. The results showed that the adsorption of dye was maximal at the lowest value of pH (pH =1) and the most suitable sorption temperature was 25°C with maximum capacities of 38.3 and 50 mg/g for LC1 and LC2 respectively. Langmuir, Freundlich, Dubinin–Radushkevich (D–R), Temkin and Harkins–Jura isotherms were used to analyze the equilibrium data at different temperatures. The adsorption kinetics was found to follow a pseudo-first-order rate kinetic model. In addition, various thermodynamic parameters, such as standard Gibbs free energy (▵ G 0), standard enthalpy (▵ H 0), standard entropy (▵ S 0), and activation energy ( E a) have been calculated. The sorption process of reactive orange (RO) dye onto different activated carbons prepared from loofa was found to be spontaneous and exothermic process.