Adsorption behavior of some aromatic compounds on hydrophobic magnetite for magnetic separation

Abstract In this study, a hydrophobic magnetite coated with an alkyl chain or a phenyl group on the surface was prepared and used as an adsorbent to investigate the adsorption behavior of aromatic compounds having various values of log  P ow (phenol 1.46, benzonitrile 1.56, nitrobenzene 1.86, benzene 2.13, toluene 2.73, chlorobenzene 2.84 and o -dichlorobenzene 3.38) onto hydrophobic magnetite. The hydrophobic magnetites were modified with stearic acid and phenyltrimethoxysilane, and the modification amounts were 9.84 × 10 −3 and 4.17 × 10 −2  mmol/g, respectively. The aromatic compounds used in this study were divided into 3 groups depending on the log  P ow : 1  P ow P ow P ow . The adsorption amounts of above each group on the magnetite at an initial concentration of 100 ppm were 3.62 × 10 −3 (nitrobenzene), 1.92 × 10 −2 (phenol), 1.13 × 10 −1 (chlorobenzene), 2.42 × 10 −1 (benzene), and 3.10 × 10 −1  mmol/g (dichlorobenzene), respectively. This indicates that the adsorption behaviors depend on the strength of hydrophobicity of aromatic compounds. The adsorption mechanism for 2  P ow P ow is hydrophobic interaction and that for 1  P ow