Utilization of biochar prepared by invasive plant species Alternanthera philoxeroides to remove phenanthrene co-contaminated with PCE from aqueous solutions

In this study, a novel and environmental-friendly biochar prepared by alien species, Alternanthera philoxeroides ( AP ) under a temperature range of 300–700˚C (BC300-BC700), was applied to remove phenanthrene (PHE), perchloroethylene (PCE), and PHE/PCE bi-contaminant from aqueous solutions. Interestingly, the maximum adsorption capacity of AP biochar changed nonlinearly as the pyrolysis temperature increased, with BC400 and BC300 having the highest maximum adsorption capacities of 2.83 and 2.13 mg/g, respectively, followed by BC700, BC500, and BC600. The sorption kinetics of PHE and PCE on BC300 under single- and bi-contaminant conditions can be described by pseudo-second-order and pseudo-first-order kinetic models, respectively. In addition, it was observed that PHE and PCE could be removed simultaneously by BC300, and the presence of PHE inhibited the maximum sorption capacity of PCE onto AP biochar. Furthermore, this study revealed that the functional groups of C-O, C = O, and C = C played a key role in the removal of PHE/PCE from bi-contaminant solutions. These findings suggested that pyrolysis of invasive plants can be an option to control invasive plants and also contribute to the adsorption of organic contaminants for contaminant remediation. Graphical abstract