Adsorption of bisphenol A by activated carbon developed from PET waste by KOH activation.

Abstract

This study deals with the preparation of activated carbon (AC) from poly(ethylene terephthalate) (PET) waste and with the physicochemical characterization of AC and its use as adsorbent of bisphenol A (BPA) in aqueous solution. AC was prepared by chemical activation with KOH and by physical activation in steam. The activation with KOH was carried out by impregnation first of PET by wet and dry routes at the PET/KOH weight ratios of 1:1, 1:3, and 1:5 and by carbonization then of the resulting products at 850°C for 2h in N2 atmosphere. The activation in steam was performed by heating at 900°C for 1h. The ACs were characterized by N2 adsorption at - 196°C, mercury porosity, mercury density measurements, FT-IR spectroscopy, and measurement of pH of the point of zero charge (pHpzc). The activation yield is 58.4-49.4% with KOH in aqueous solution, 75.8-23.9% with solid KOH, and 5.9% with steam. Using solid KOH, greater developments of a more heterogeneous porosity with increasing impregnation PET/KOH ratio are achieved. For SK1:5, SBET is 1990m2g-1 and the pore volumes are 0.71cm3g-1, micropores; 0.81cm3g-1, mesopores; and 1.77cm3g-1, macropores. The data of BPA adsorption fit better to the Ho and Mckay second order kinetic model than to the Lagergren first-order kinetic model and to the Langmuir equation than to the Freundlich equation. From the kinetic and thermodynamic standpoints, the adsorption process of BPA is more favorable for SK1:5.