Enhanced Elimination of Methyl Orange and Recycling of an Eco-Friendly Adsorbent Activated Carbon from Aqueous Solution

Azoic dyes are known as toxic contaminants. Methyl orange is one of these dyes, is removed from wastewater principally through biological, chemical or physical processes. This article will describe the removal of the methyl orange from the water by adsorption onto activated carbon. This material is characterized before and after use in adsorption by various techniques. The methyl orange adsorption efficiency was studied varying contact time, the mass of activated carbon, pH, initial solution concentration, and temperature. The adsorption was found fast attainment equilibrium in 30 min with better performance for the sorbent and appears to be enhanced by low pH. Kinetic data for methyl orange was found to follow pseudo-second order model and the Langmuir model better describes the adsorption process. A maximum amount of methyl orange adsorbed was registered at 113.63 mg/g. The influence of temperature on adsorption and the thermodynamic study showed that free energy and the enthalpy exhibit negative and positive values, respectively, which shows that the methyl orange adsorption on the activated carbon is a spontaneous and endothermic process. The desorption/regeneration process was studied by using different percentages of ethanol and distilled water and it appears to be the best desorption to regenerate methyl orange. The use of 90% ethanol gave a rate of adsorbed methyl orange regeneration close to 89%. On other hand, these results indicate the significance of activated carbon as new support for the elimination of the methyl orange.