Aqueous adsorption of bisphenol A over a porphyrinic porous organic polymer.

A new porphyrinic porous organic polymer (PPOP) with high stability and excellent textural properties (929 m/g surface area with 0.73 cm/g pore volume) was made via the Friedel-Crafts reaction and applied for bisphenol A (BPA) adsorption in water. The material was examined by X-ray diffraction, N adsorption-desorption isotherms, scanning electron microscopy, infrared spectroscopy, X-ray photoelectron spectroscopy, and solid-state C CP-MAS nuclear magnetic resonance spectroscopy. PPOP was proven highly effective for capturing BPA among the many adsorbent materials investigated. The Langmuir model could closely match the adsorption isotherm data with a high adsorption amount of ca. 653 mg/g at 25 °C. Approximately 95% of BPA was adsorbed in 50 min, and the pseudo-second-order kinetic model satisfactorily described the adsorption behavior. This adsorption process was exothermic (ΔH° = -39.10 kJ/mol), and the capacity gradually decreased with increasing pH. Spectroscopic analyses indicated that the BPA adsorption on PPOP was affected by (1) π-π interaction between BPA and the aromatic constituents of PPOP, (2) hydrogen bonding between the N sites of porphyrin units in PPOP and the hydroxyl group of BPA and, and (3) hydrophobic interactions. PPOP was easily regenerated after acetone washing, and >98% efficiency was observed throughout the five repeated adsorption-desorption cycles.