Investigation of gas oil separation from wastewater using a specific natural clay as adsorbent

In this study separation of gasoil from wastewater has been investigated by using three types of natural clays (NCs) and two commercial organoclays, cloisite 15A, and cloisite 30B. Initial results of gas oil adsorption by these clays showed that one of the NCs was much more attractive than the others because of its much better adsorption performance as well as its low cost and availability. This clay was called super adsorbent clay (SAC). Three NCs were characterized by X-ray diffraction (XRD), and it was shown that SAC mainly contains lead oxide. Adsorption performance of SAC was obtained at various temperatures (20-60 degrees C), pHs (3-12), mixing times (2.5-30min), mixing rates (50-600rpm), and different amounts of clay (0.1-1g). It was found that mixing time and rate of mixing were much more important factors. Isotherm models were applied for the system and it was found that the Freundlich isotherm can predict the adsorption of gasoil onto SAC more accurately, especially at higher concentrations. Finally, regeneration of gasoil-saturated SAC was studied at different temperatures. Results showed that saturated SAC can be regenerated completely at a temperature of 180 degrees C and at a time period of about 8min.