Removing organic compounds such as crude oil from industrial effluents is one of the crucial issues in the oil and gas industries. A well-known and effective method for removing pollutants from wastewater is adsorption. One of the novel materials used for adsorption is activated carbon obtained from biodegradable materials. This study aimed to investigate the adsorption and removal of crude oil from wastewater using activated carbon made from oak seed husk. Obtained biocarbon was activated by phosphoric acid and pyrolyzed at 450 °C. Due to the effect of various parameters on the adsorption rate, including the initial concentration of crude oil, the amount of adsorbent, and contact time, several experiments were designed by the Box–Behnken method to minimize the tests and achieve optimal conditions. Under optimal conditions (initial oil concentration of 30 ppm, an adsorbent dosage of 2.5 g l−1, and a contact time of 50 min), oil adsorption of 98% was achieved. FTIR, FESEM, EDX, and BET analyses were performed to determine the adsorbent characteristics. The isotherms and kinetics of oil adsorption on activated carbon have been investigated. Three models of Langmuir, Freundlich, and Temkin isotherms were used to analyze the experimental adsorption data. Pseudo-first-order and pseudo-second-order models were also used to investigate the kinetics of the process. The chemical recovery method was applied to regenerate the activated carbon. The recovery efficiencies of acetone and hexane were examined during four recovery steps, and the efficiencies of acetone and hexane were 84% and 77%, respectively.
