Remediation of Phenanthrene Contaminated Soil by a Solid State Photo-Fenton Reagent Based on Mesoporous Magnetite/Carboxylate-Rich Carbon Composites and Its Phytotoxicity Evaluation

Abstract

An environment-friendly soil remediation method based on solid state photo-Fenton reagent was developed for remediation of the phenanthrene contaminated soil. The soil remediation process of solid state photo-Fenton reagent is different from the conventional homogeneous and heterogeneous Fenton reagents (or photo-Fenton reagents). A solid state photo-Fenton reagent, mesoporous magnetite/carboxylate-rich carbon (MMCRC) composite, has been one step fabricated at a relative low carbonization temperature. In the porous structure of MMCRC, carbon serves as not only the binder to connect Fe3O4 nanoparticles and form the pore structure of MMCRC but also the supporter to solidify the carboxylate groups. Carboxylate groups solidified into carbon can coordinate with Fe3O4 nanoparticles and form the ferricarboxylate complexes. The excellent visible light absorption ability and photocatalytic activity of MMCRC originate from the ferricarboxylate complexes. Phenanthrene was chosen as a model to investigate the degradation of polycyclic aromatic hydrocarbons (PAHs) by MMCRC. Without using any other chemical agents, MMCRC can be activated by visible light irradiation and release O2•– by itself to degrade phenanthrene in soil at circumneutral pH, which make the soil remediation process extremely simple. The effects of soil remediation method based on MMCRC on contaminated soil were evaluated by using phytotoxicity test of lettuce cultivation. The phytotoxicity of phenanthrene contaminated soil was significantly reduced after treated by MMCRC and no obvious differences could be observed between noncontaminated soil and phenanthrene contaminated soil treated by MMCRC in terms of the lettuce growth indexes. The soil remediation method based on MMCRC is technologically feasible and has huge potential in the domain of remediation of persistent organic pollutant contaminated soil.