Elucidating the effect of different desorbents on naphthalene desorption and degradation: Performance and kinetics investigation.

In this work, the effect of different desorbents (low molecular weight organic acids (LMWOAs), surfactants, and inorganic salts) on naphthalene (NAP) desorption in soil was investigated, and the results showed that NAP desorption pattern fitted the pseudo-second-order kinetics. The addition of LMWOAs, especially citric acid (CA), could stimulate the reactive oxygen species (ROS) generation and NAP degradation in Fe(II) activated persulfate (PS) system, while the presence of surfactants and CaCl 2 could inhibit the NAP removal due to the competitive consumption of ROS. The maximum removal of NAP was 97.5% within 120 min at the PS/Fe(II)/CA/NAP molar ratio of 15/5/1/1, and the pseudo-first-order kinetic constant of NAP removal increased from 0.0110 min−1 to 0.0783 min−1 with the addition of CA. Compared with surfactants and inorganic salts, LMWOAs, especially CA, were more suitable as desorbent in soil washing coupled with in situ chemical oxidation technique. Moreover, 1.86 mg L−1 desorbed amount and 36.1% removal of NAP from soil could be obtained with the presence of 1 mM CA. Finally, the significant removal of NAP and other contaminants (phenanthrene, fluoranthene, and benzene series) in actual groundwater could provide theoretical basis and technical support for the remediation of organic contaminated sites with desorbents. [Display omitted] This study systematically reported the performance and mechanisms of NAP desorption and degradation in the presence of three different kinds of desorbents. The kinetics of NAP desorption and degradation with desorbents were elucidated. The effect of different desorbents on NAP removal was compared and LMWOAs, especially CA, were evaluated to be the optimal desorbents in the soil washing coupled with ISCO process. The enhancement of LMWOAs for NAP degradation was further illuminated. The significant removal of NAP in actual groundwater and other contaminants (PHE, FLT, and BTEX) could provide technical support for the remediation of organic contaminated sites with desorbents. • Effect of different desorbents on NAP desorption and degradation was investigated. • The kinetics of NAP desorption and degradation with desorbents was elucidated. • SO 4 −• and HO• contributed to NAP degradation in PS/Fe(II) system with desorbents. • Effective removal of NAP in actual groundwater containing desorbents was achieved. [ABSTRACT FROM AUTHOR]