Abstract
A new hybrid material for the removal of polycyclic aromatic hydrocarbons (PAH) from water was prepared by the polymerization of pentynyl beta-cyclodextrin (PyβCD) and silica micro-particles (SMP). Phenanthrene, being one of the important members of the PAH family and a potential risk for environmental pollution, was selected for this study. Results show that phenanthrene removal efficiency of the SMP was improved significantly after hybridization with PyβCD-polymer. Approximately 50% of the phenanthrene was removed in the first 60 min and more than 95% was removed in less than 7 h when 25 mL of the 2 ppm aqueous phenanthrene solution was incubated with the 100 mg of SMP-PyβCD-polymer material. Infrared spectroscopy and thermal gravimetric analysis show that the enhanced efficiency of the SMP-PyβCD-polymer compared to the unmodified SMP was due to the formation of the inclusion complexation of phenanthrene with the PyβCD. These results indicate that SMP-PyβCD polymers have a potential to be applied as molecular filters in water purification systems and also for waste water treatment.
Highlights
Polycyclic aromatic hydrocarbons (PAH) are considered one of the most toxic and widespread pollutants which cause severe health problems for human beings, and for other living organisms [1,2]
Scanning electron microscopy (SEM) images of the βCD (Figure 1a), Poly-βCD (1, Figure 1b), Poly-PyβCD (3, Figure 1c), and that of hybrid materials prepared by polymerization of PyβCD in the presence of silica micro-particles (SMP) (4, Figure 1e,f) show that morphological changes in the materials appeared at different stages. βCD in the SEM images appears as a flake-like crystalline (Figure 1a) that has the typical morphology of βCD powder [40]
This was probably due to the hydrophobic character induced by the pentynyl groups grafted on the βCD surface
Summary
Polycyclic aromatic hydrocarbons (PAH) are considered one of the most toxic and widespread pollutants which cause severe health problems for human beings, and for other living organisms [1,2]. ΒCD polymer is normally soluble in water and, not suitable for water purification systems to remove PAHs, while PyβCD-polymer is insoluble due to the hydrophobic character introduced by the pentynyl groups. 2 g of PyβCD (2) was added into 40 mL of water followed by the addition of 6.8βCD mL of wasinstirred at 60 °C until a clear solution was obtained. After 48 h, reaction was stopped and product was purified by centrifugation (4000 rpm × 20 min × 4 times), washed with methanol, hexane, and acetone (three times with each solvent) and dried in open air to obtain the hybrid composite material (Poly-SMP-PyβCD, 4, 3.94 g). ΒCD and PyβCD (2) was polymerized without SMP following the same procedure as described above and precipitated in acetone (Scheme 1)
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