Polymeric adsorbents for oil removal from water

Abstract

In this study, the application of four synthetic resins for the removal of emulsified oil from produced water was investigated. Key experimental parameters such as adsorbent dosage, contact time, initial oil concentration and pH were evaluated for Optipore L493, Amberlite IRA 958, Amberlite XAD 7 and Lewatit AF 5. Oil removal rates upwards of 98% were achieved using AF 5, XAD 7 and L493. IRA 958 recorded very modest removal rates of less than 25%. Isotherm data were further investigated and fitted using Langmuir, Freundlich, Toth, Flory Huggins and Dubinin-Radushkevich models. The results show that the adsorption onto XAD 7 and L 493 is a multilayer adsorption process over a heterogeneous surface that is best illustrated by the Freundlich and Toth models respectively. The Dubinin-Radushkevich best described the removal using AF 5 resin that assumes that the adsorption process occurs on a heterogenous surface with a gaussian energy distribution. Kinetic studies assessing the rate of removal for each resin were conducted. Experimental results were best fitted using pseudo second order kinetics. It is concluded that XAD 7 had the highest kinetics among all tested resins. Also, AF 5 exhibited the highest adsorption capacity. Overall, the study confirmed the applicability of the resins for the removal of oil from produced water.

Keywords: Adsorption; Adsorption isotherms; Oil water emulsions; Polymeric adsorbents; Produced water.