High surface area Eucalyptus wood biochar for the removal of phenol from petroleum refinery wastewater

Abstract

The presence of phenolic compounds in petroleum refinery wastewater is a matter of significant environmental concern. Its removal is achieved through various methods, among which adsorption is an efficient and economically viable option. This study reports the development of activated biochar (EABC) from Eucalyptus wood pyrolytic biochar (EPBC) to remove phenols from petroleum refinery wastewater. The best activation strategy involved ball-milling of KOH and EPBC in the ratio 3:1, followed by annealing at 800 °C under an N2 atmosphere. The activated biochar (EABC-3–800) exhibited high phenol adsorption capacity (308.9 mg/g), attributed to the presence of heterogeneous pores, corroborated by large BET surface area (2048 m2 /g). As determined through HPLC, the EABC-3–800 could remove nearly 95% phenol (C0=114 ppm) from the wastewater of the delayed coking unit of a petroleum refinery. The best-fitting of the adsorption results in the Freundlich isotherm model substantiates the hypothesis of pore-based adsorption of phenol compared to the surface-adsorption-based Langmuir isotherm. The phenol adsorption kinetics followed the pseudo-second-order model, indicating weak chemical interactions between phenol and activated biochar. The regeneration and reuse of EABC-3–800 for a minimum of five operational cycles demonstrate its potential for industrial wastewater remediation. © 2021 The Author(s)