Populus nigra leaf-derived biochar: an efficient and reusable low-cost carbon material for the ultrasonic-assisted remediation of oil spill.

Biochars are efficient materials for the adsorption of water pollutants. Moreover, the modification of biochars might enhance the adsorption potentials but increase the process cost. Therefore, the search for low-cost unmodified biochars with high adsorption capacity is needed. In this study, we prepared new biochar (PLBC) from low-cost Populus nigra leaves for oil sorption, in an attempt to search for unmodified biochar with high uptake capacity. The biochar was prepared by low-temperature pyrolysis at 350 °C in other to maintain a low process cost. The sorbent characterization revealed the presence of functional groups and surface pores on PLBC desirable for the sorption of oil. A decrease in the surface area of the biochar from 36.82 to 18.55 m²/g, the pore volume from 0.0372 to 0.0152 cm³/g, and the pore diameter from 4.434 to 3.276 nm was obtained after oil sorption. Elemental analysis of PLBC showed carbon content of 55.9% and a biochar yield of 58.6%. PLBC exhibited an oil uptake capacity of 4.634 g/g. The Freundlich and Pseudo-second-order models provided the best fit to the isotherm and kinetic evaluations, respectively, with the involvement of the intraparticle diffusion mechanism. Thermodynamics revealed a physicochemical, endothermic, feasible, and spontaneous oil uptake onto PLBC. High oil desorption (<92.5%) was achieved using petroleum ether as eluent, and PLBC exhibited good potentials for reuse. These investigations revealed the potential of PLBC as a viable low-cost sorbent for the treatment of oil spills. [ABSTRACT FROM AUTHOR]