Adsorption of polycyclic aromatic hydrocarbons from aqueous solutions by modified periodic mesoporous organosilica

Structural formulas of the sources of silica (without CH2CH3 groups) BTEB (a), FTE (b), and idealized schematic of primary structure of mesoporous organosílicas (c). [Display omitted] ► A PMO is synthesized using Si sources and surfactants as structure-directing agents. ► PMO have structures that allow molecules to be held into their nanotubes. ► The viability of using the PMO for PAH removal from aqueous solution is presented. A novel procedure was developed for the synthesis of a periodic mesoporous organosilica (PMO), which was used to remove polycyclic aromatic hydrocarbons (PAHs) from aqueous solutions. Adsorption equilibrium isotherms and adsorption kinetics experiments were carried out in solutions of PAHs (2–60mgL−1), using the PMO as adsorbent. Adsorption models were used to predict the mechanisms involved. The adsorption kinetics data best fitted the pseudo-first-order kinetic model for naphthalene, and to the pseudo-second-order model for fluorene, fluoranthene, pyrene, and acenaphtene. The intraparticle model was also tested and pointed to the occurrence of such processes in all cases. The isotherm models which best represented the data obtained were the Freundlich model for fluoranthene, pyrene, and fluorene, the Temkin model for naphthalene, and the Redlich–Peterson model for acenaphtene. PAHs showed similar behavior regarding kinetics after 24h of contact between adsorbent and PAHs. FTIR, XRD, BET, and SEM techniques were used for the characterization of the adsorbent material.