Removal of organic pollutants from super heavy oil wastewater by lignite activated coke

Abstract

Extraction of organic pollutants from super heavy oil wastewater (SHOW) by lignite activated coke (LAC) is investigated. The factors studied include the exposure time, temperature, and different pollutant concentrations in the wastewater. The equilibrium adsorption data are analyzed by the Langmuir, Freundlich, Temkin and Dubinin–Radushkevich (D–R) isotherms. The best match is obtained by the Freundlich isotherm and a chemical mechanism is suggested based on the D–R model. The adsorption kinetics follows the pseudo second order model and the mass transfer model suggests that external and intra-particle diffusion influences the adsorption process. Thermodynamics studies show that adsorption of organic materials is spontaneous at high temperature (303 and 313K) but not so at lower temperature (293K) and reveals an endothermic process and increase in randomness during adsorption. The pilot dynamic adsorption test indicates that LAC can remove not only organic pollutants such as COD, NH3-N, oils, but also inorganic pollutants such as Mg2+, Ca2+, and salts.