A one-pot co-pyrolysis of potassium/calcium carbonate with biowaste-derived hydrochar strategy was proposed to prepare hierarchical porous biochars (HPBs) for the first time. The pore structure, especially the pore size distribution, could be designed by adjusting the mass ratios of different carbonates. HPBs were hydrophobic, nitrogen doped, graphitized, and contained surface functional groups. HPBs showed unexpected sorption quantity for diethyl phthalate (DEP) that reached 657 mg g-1, which much higher than that of the reported sorbents. The sorption was multilayered and had multiple action modes, and was limited by the chemical sorption and the sorption quantity was dominated by the physical sorption. Lewis acid-base interaction, π-π stacking interaction, hydrogen bonding interaction, partitioning and pore filling were the potential sorption mechanisms. This work proposed a simple, environmentally friendly and low-cost method to convert biowaste into advanced HPBs and confirmed that produced HPBs represent ideal sorbents for the removal of organic pollutants.
Keywords: Biochar; Carbonate; Co-pyrolysis; Phthalate esters; Porous structure; Water treatment.
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