Efficient adsorption of a mixture of polycyclic aromatic hydrocarbons (PAHs) by Si–MCM–41 mesoporous molecular sieve

Abstract

This work describes the synthesis of Si–MCM–41 mesoporous adsorbent by a hydrothermal method and its characterization using FTIR, XRD, N2 adsorption/desorption, SEM, TGA, and EDX analyses. The mesoporous Si–MCM–41 was used as an adsorbent to remove the PAHs benzo[b]fluoranthene (B[b]F), benzo[k]fluoranthene (B[k]F), and benzo[a]pyrene (B[a]P) from aqueous media, and batch experiments were employed to determine the effects of initial adsorbate concentration and contact time. The Si–MCM–41 exhibited the hexagonal mesostructure typical of the M41S family, as confirmed by XRD, with type IV isotherms and type H1 hysteresis. The material showed a uniform mesopore size distribution, high surface area, thermal stability, and a high percentage of silica. The adsorption of B[b]F, B[k]F, and B[a]P reached equilibrium after ca. 60min (qe(exp)=18.35, 18.26, and 18.78μgg−1, respectively), and higher adsorbate concentrations were associated with increases in the percentage removal and the value of qe. The adsorption followed pseudo-second order kinetics, and the experimental data were fitted using the Langmuir isotherm model.