Improved Degradation of Phenanthrene in Soil Washing Eluent by Photo‐Fenton Like Process With Citric Acid

Abstract Herein, improved degradation of phenanthrene (PHE), one of the common polycyclic aromatic hydrocarbons (PAHs), was explored in a citric acid (CA) photo‐Fenton like system under UVB irradiation. Degradation of PHE in soil washing (SW) eluent by the nonionic surfactant Tween 80 (TW80) using Fe(III)‐CA complex was compared with other iron complexes showing a faster degradation with a rate constant of 3.07 × 10 −2 min −1 . The stability as well as photochemical transformation of Fe(III)‐CA under UVB radiation was evaluated, followed by comparison of PHE oxidation with traditional Fenton or Fenton‐like process. Fe(III)‐CA complex was found to be stable in dark but quickly photo dissociated under irradiation. The system using Fe(III)‐CA was proved oxidizing PHE more efficiently than traditional Fenton reaction with a rate constant of 3.92 × 10 −3 min −1 and Fe(II)‐CA involved system with a rate constant of 1.74 × 10 −2 min −1 . A two‐stage pattern of PHE decay was observed in the UVB/H 2 O 2 /Fe(III)‐CA system. The effects of operational factors including Fe(III)‐CA dosage, Fe(III)/CA ratio, H 2 O 2 , and TW80 dosage on PHE degradation were explored. The checked parameters exhibited different influence on PHE degradation. This work provided a cost‐effective strategy for remediating soil pollutants in SW effluent with the presence of surfactant.