Development of novel magnetic bentonite based adsorbents combined with different carbon sources for removal of oil content from produced water

Abstract

Water scarcity is a challenge faced worldwide due to depleting sustainable good quality water resources. Produced water, associated with the production of gas and oil, usually comes as oil contaminated water, creating real problems in water resources' management. Therefore, removing oil content from produced water is crucial to meet the discharge limits set by governmental legislation. Compared to the current state of produced water treatment technologies, adsorption is envisaged as a promising technique due its simplicity, and ease of operation. For that, the development of adsorbents with high removal capability, good stability, high recoverability, inexpensive, and environmentally friendly nature is the most important step in adsorption process. Bentonite is a type of clay minerals that is inexpensive, non-toxic, and naturally occurring that have been utilized in water remediation applications. Thus, the aim of this work is to develop novel magnetic bentonite-based adsorbents combined with different carbon sources (reduced graphene oxide, and multiwall carbon nanotubes) for oil content removal. The developed adsorption composites were characterized using XRD, TGA, SEM, EDX, TEM, and BET analysis techniques. Furthermore, the adsorptive behavior of the developed composites was compared to magnetic bentonite under the same experimental conditions examining the effect of various parameters on the adsorption capability. The experimental data were analyzed using three isotherm models including Langmuir, Freundlich and Sips models using non-linear regression fitting and were compared using Akaike Information Criterion statistical model. The results showed that developed composites attained enhanced adsorption capacity and had shorter equilibrium times compared to magnetic bentonite. Furthermore, the oil content removal performances of all synthesized composites reported in this study were investigated in a fluidized bed reactor and a possible adsorption mechanism was proposed. Overall, this work confirms the feasibility of the proposed adsorbents for oil removal in industrial adsorption process.