Homogeneously Dispersed Zerovalent Iron Nanoparticles Supported on Hydrochar-Derived Porous Carbon: Simple, in Situ Synthesis and Use for Dechlorination of PCBs

Herein, we have developed a simple and effective strategy for in situ preparation of nanoscale zerovalent iron (NZVI) supported on porous carbon (PC) using renewable hydrochar as the carbon precursor. Physicochemical properties of the resultant NZVI/PC composites were characterized by XRD, SEM-EDS, TEM, and BET, and the effectiveness of these composites was evaluated for the remediation of PCB-contaminated water. Results showed that the iron ions were uniformly dispersed within the hydrochar matrix and serve as an activation agent for the hydrochar during a subsequent pyrolysis process. The iron is reduced in situ to NZVI with diameters of 8.5-10 nm, without requiring an additional reducing agent. At temperatures of 600-800 degrees C, the well-dispersed NZVI catalyzes the transformation from amorphous carbon to graphitic carbon. The NZVI/PC composite prepared at 800 degrees C exhibited high efficiency for adsorption and dechlorination of PCBs in aqueous solution. This is attributed to the composites' high surface area, uniformly dispersed nanoscale iron, high degrees of graphitic porous carbon, and substantial amount of mesopores. The present study offers a simple and sustainable approach for the preparation of prospective NZVI/PC with high stability and reactivity from renewable resources.