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 (2-60 mg L(-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 24 h of contact between adsorbent and PAHs. FTIR, XRD, BET, and SEM techniques were used for the characterization of the adsorbent material.

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The capacity of a periodic mesoporous organosilica (PMO) to adsorb the aromatic compounds benzene, toluene, o-, and p-xylenes (BTX), which are usually present in produced waters, was investigated under both column and batch processes. The PMO was synthesized by condensation of 1,4 bis(triethoxisilyl)benzene (BTEB) under acidic conditions by using structure-directing agent (SDA) Pluronic P123 in the presence of KCl. Thermogravimetric analysis showed that the presence of the surfactant decreases the thermal stability of the PMO. The small-angle X-ray diffraction pattern, as well as the nitrogen adsorption/desorption isotherm measurements, revealed that the synthesized material has a crystalline structure, with hexagonally-ordered cylindrical mesopores. The adsorption kinetics study indicated an adsorption equilibrium time of 50 min and also showed that the data best fitted the pseudo-first order kinetic model. The intraparticle diffusion model was also tested and pointed to the occurrence of such process in all cases. Both Langmuir and Temkin models best represented the adsorption isotherms of toluene; Langmuir and Redlich-Peterson models best represented the data obtained for the other compounds. Adsorption capacity decreases in the order benzene>o-xylene>p-xylene>toluene. Satisfactory results were observed in the application of the synthesized PMO for the removal of BTX from aqueous solution.

Ethylenediaminetetraacetic acid (EDTA) functionalized silica spheres were used to remove metal ions from aqueous solutions. The adsorption kinetics of Cu 2+ , Zn 2+ , and Cd 2+ (60 mg•L −1 , pH 5.5) were fitted to the pseudosecond order model. Adsorption equilibria were reached within 20 min, indicating that chemisorption may be the limiting step in the adsorption process. Adsorption isotherms were analyzed with nonlinear models by considering the ERRSQ error function and the determination coefficient R 2 . The data with monoion solutions (10 mg•L −1 to 300 mg•L −1 ) were tested with Langmuir, Freundlich, and Redlich−Peterson isotherm models. The best fit was found with the Langmuir model, and maximum adsorption capacities followed the order: Cu 2+ > Zn 2+ > Cd 2+ . Breakthrough curves were obtained using filled columns. The adsorbed ions were quantitatively recovered on elution with hydrogen chloride (0.10 M). After three adsorption−recovery cycles, the metal ions could still be recovered almost quantitatively, which demonstrates the good performance of the EDTA-functionalized silica spheres.

The use of polyethylene terephthalate (PET) as a support material for TiO 2 films in advanced oxidation processes (AOPs) for water treatment was investigated. A green, low-cost immobilization procedure was developed and the amount of deposited photocatalyst ranged from 0.036 to 0.202 mg per cm 2 PET. Photocatalytic activity of the films was evidenced by degrading paracetamol solutions under UV radiation. The highest kinetic constants were observed for at least 0.09 mg TiO 2 per cm 2 PET. Scan electron microscopy (SEM) and energy-dispersive X-ray (EDX) analyses indicated 0.15 mg TiO 2 per cm 2 PET as enough to provide complete covering of the PET support. Characterization analyses were also performed with a film after 30 h of use in a UV/TiO 2 /O 3 reactor. According to SEM analyses, the photocatalyst was not detached from the PET support, while EDX and gravimetric data indicated the possibility of the TiO 2 to have been contaminated by compounds present in the solution during the treatment. V C 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40175.