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

This work describes the synthesis of Si-MCM-41 mesoporous adsorbent by a hydrothermal method and its characterization using FTIR, XRD, N-2 adsorption/desorption, SEM, TGA, and EDX analyses. The mesoporous Si-MCM41 was used as an adsorbent to remove the PAHs benzolblfluoranthene (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. 60 min (q(e(exp)) = 1835, 18.26, and 18.78 mu g g(-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. (C) 2016 Elsevier B.V. All rights reserved.