New insights in the treatment of real oilfield produced water: Feasibility of adsorption process with coconut husk activated charcoal

Naphthenic acids are water-soluble organic compounds (WSO), present in oilfield produced water (OPW), whose removal aims to comply with environmental legislation and ensure the correct disposal of OPW. In this study, the performance of the adsorptive process for the removal of WSO in synthetic (single- and multi-component) and real OPW was evaluated. It was observed that the lower the pH of the sample, the greater the adsorption capacity of WSO. Moreover, the kinetic parameters of adsorption followed the pseudo-second order model while the equilibrium parameters were represented by the isothermal BET (Brunauer, Emmett and Teller) model. In the desorption process followed the second-order model, and the aqueous solution of sodium hydroxide (0.3 and 0.1 M) showed the highest desorption efficiency (~70 %) in the synthetic and real systems, respectively. With this protocol, the adsorbent proved to be effective for the treatment of OPW, without significant loss of efficiency, for up to three consecutive cycles of adsorption-desorption. In addition, after treatment, the real effluent was classified within the legal parameters for offshore disposal, which enhances its industrial application. [Display omitted] •Coconut shell activated carbon with high adsorption capacity (up to 122.53 mg·g−1).•Adsorption capacity increases with lower pH values independent on the temperature.•Regeneration of up to 75.6 % of the adsorbent capacity with aqueous NaOH solution.•Adsorbent reuse for up to three consecutive cycles, without major changes.•Treatment of OPW by adsorption with high potential for industrial application.