Adsorption of polycyclic aromatic hydrocarbons over CuZnFeAl-LDH modified by sodium dodecyl sulfate

Abstract

Polycyclic aromatic hydrocarbons (PAHs) have received extensive attention due to being highly toxic, mutagenic, and carcinogenic organic pollutants. As a result, a series of adsorbents have been designed and developed to solve the problem. In this paper, CuZnFeAl-S has been explored as a highly efficient adsorbent for PAHs. First, CuZnFeAl-LDH was prepared using a coprecipitation method and then calcined at 500 °C to obtain CuZnFeAlO. Finally, CuZnFeAl-S was prepared by modifying CuZnFeAlO with sodium dodecyl sulfate (SDS). The physical and chemical properties of the adsorbents were characterized by XRD, N2 adsorption-desorption, SEM, ICP, FT-IR, TG-DSC, and IGC; subsequently their adsorption performance was investigated. The results show that the surface properties of CuZnFeAl-S changed from hydrophilic to hydrophobic after SDS modification, which enhanced the adsorption of PAHs obviously. The removal of naphthalene and phenanthrene on CuZnFeAl-S reached 97.3% and 90.3%, respectively. And the adsorption process of naphthalene and phenanthrene conforms to Langmuir adsorption and Freundlich adsorption, respectively. Besides, the adsorption thermodynamics indicate that the adsorption of PAHs was a spontaneous exothermic reaction. The highly efficient PAH adsorption performance of CuZnFeAl-S is the synergistic result of various molecule interactions, such as hydrogen bonding, π-π interactions, and electrostatic attraction.