Fabrication of ZIF-8 in porous biochar by a novel Zn-activation combined in-situ growth strategy for enhanced Pb removal

ZIF-8-decorated biochar hold great potential for heavy metal contaminated wastewater remediation due to the superior adsorption performance of ZIF-8. However, the inevitable blockage of nature pore during preparation restricted the enhancement of adsorption performance and further practical applications. Herein, a novel Zn(NO 3 ) 2 activation-combined in-situ growth strategy was established for porous ZIF-8-decorated biochar (AI-BC@ZIF-8) preparation, this strategy enables the synergistic promotion of porous structure and distribution of ZIF-8 for adsorbent. The AI-BC@ZIF-8 exhibited an excellent adsorption capacity of 249.63 mg/g for Pb, achieving removal efficiency of 99.8% for conventional 50 mg/L Pb-containing wastewater. The adsorption process conforms to the pseudo-second-order kinetic model and the Langmuir isothermal model, indicating the monolayer chemical adsorption mechanism. The results of FTIR, BET and XPS analyses indicate that the adsorption mechanism of AI-BC@ZIF-8 is electrostatic interaction, N-coordination, precipitation, ion-exchange and pore-filling. Overall, this adsorbent demonstrates outstanding adsorption performance, showing its great potential in efficient and low-cost water purification. This work provides a viable strategy for the synthesis of highly porous and efficient ZIF-8-decorated biochar for heavy metal removal from wastewater.