Mediating the reactivity and selectivity of nanoscale zerovalent iron toward nitrobenzene under porous carbon confinement

Synchronously mediating the reactivity and selectivity of nanoscale zerovalent iron (nZVI/nFe(0)) toward target contaminant is of great significance but challenging. Herein, the nZVI confined under the porous carbon (i.e., PC@Fe) was successfully developed via a one-step carbothermal reductive strategy using the renewable hydrochar and and Fe (NO3)(3) as the precursors. The physicochemical properties of PC@Fe composites were systematically characterized by multiple morphological, structural and electrochemical methods, e.g., SEM, TEM, FTIR, XRD, Raman, and LSV, etc.. When the carbothermal temperature was >= 600 degrees C, it was found that the well-dispersed iron onto the hydrochar could be reduced in situ into iron nanoparticles. Accompanied by the evolution of the porous carbon (PC) with excellent adsorptivity, the removal of the nitrobenzene (NB) by the PC@Fe composite was increasingly enhanced from 4.7% to 74.3% at 6 h with increasing the carbothermal temperature from 300 degrees C to 800 degrees C. Especially for the PC@Fe-800 (i.e., carbothermal temperature is 800 degrees C), the NB was mainly adsorbed by PC@Fe-800 in first 6 h and subsequently reduced to aniline (AN) over next 18 h. Besides, the PC@Fe-800 exhibited hydrophobicity with a water contact angle (WCA) of 131.4 degrees that was higher than the commercial nZVI with a WCA of 37.1 degrees. The PC introduction could enhance the corrosion resistance of nFe(0) with the nontarget H2O/O-2, hence the reducing-equivalent of PC@Fe-800 for reduction of the target NB was improved. In general, the carbon-based confinement should be a promising alternation to improve the reactivity and selectivity of nZVI-based technology for water decontamination.