Sorption of naphthalene and 1-naphthol by biochars of orange peels with different pyrolytic temperatures.

Biochars, derived from biomass, are increasingly recognized as an environmental-friendly sorbent to abate organic pollutants. Sorption variations of biochars with their pyrolytic temperatures are evaluated. Nine biochars of orange peels with different pyrolytic temperatures (150-700 degrees C, referred as OP150-OP700) were characterized via elemental analysis, BET-N(2) surface area, and Fourier transform infrared spectroscopy. Sorption of naphthalene and 1-naphthol by the biochars in water are compared. Sorption isotherms varied from linear to Freundlich with increasing pyrolytic temperature. The respective contributions of adsorption and partition to total sorption were correlated with biochars' structural parameters. For OP150-OP600, sorption of 1-naphthol was significantly larger than naphthalene due to the former owning additional specific interactions. For 1-naphthol with high concentrations, the OP200 exhibited the maximal sorption capacity due to its largest partition and high adsorption among nine biochars. For 1-naphthol with low concentrations and naphthalene, the OP700 displayed the maximal sorption capacity. These observations provide a reference to the use of biochars as engineered sorbents for environmental applications.