The investigation of highly efficient chlorinated hydrocarbons removal based on metal nanoparticles carbonaceous synthetic particles: The degradation behavior and selective transformation mechanism

Abstract

Overconsumption in industrial manufacturing has led to critical emissions of chloroalkanes, posing a significant environmental threat. In this study, the innovative biochar (BC) particles containing nanocrystalline: NZVI, Fe/Pd, Fe/Ni were prepared by impregnation-liquid phase reduction using the pyrolysis of coconut husk as precursors to explore the degradation capabilities of chloroform (CF) via orthogonal experiment. The results indicated that when the pH value was 3, the temperature was 20 ℃, and the reaction time was 60 min, the CF removal efficiency of Fe/Ni-BC reached 80.38 ± 2.08 %, outperforming all other tested synthetic particles. Advanced characterization techniques showed that the abundant dispersed metallic nanoparticle sites would refresh the surface crystal morphology, improve the adsorption enrichment ability of biochar, enhance electron transfer capacity of synthetic particles, and further participate in reductive dechlorination by inducing an electrophilic attack of active hydrogen. Theoretical calculations verified that hydrogen activation and CF facile adsorption would be easily achieved after the introduction of metal nanoparticles, profiting from the multiple synergistic effects between special π-delocalized bond of biochar in carbon layer and multiple nanoparticles docking sites, and thus enhancing the specific CF catalytic selectivity of Fe/Ni as the active center. Collectively, the CF degradation on Fe/Ni-BC was a complex chemisorption process along with reductive hydrogenation decomposition, which achieved the parent CF reduction and promoted the conversion of the low-chlorinated benign products. These findings offer new insights into the developed multifunctional BC and their comprehensive assessment of CF sewage remediation.