Activated carbons for the adsorption of ibuprofen

Powdered activated carbons prepared from cork waste were studied for the ibuprofen removal from liquid phase. Two carbons were used: CAC obtained by chemical activation with K2CO3, and CPAC prepared by a two-step method, chemical activation with K2CO3 followed by steam activation. The ash content analysis showed that, for this raw material, the previous acid treatment can be omitted. The textural properties of the samples, evaluated by low temperature NZ adsorption, show that the main difference is related with the volume of the larger micropores (supermicropores), which is more developed for CPAC. The surface chemistry characterization, made by the determination of the point of zero charge (PZC) and Boehm's titration, show that the second activation step led to an activated carbon with less acidic groups, associated with the absence of the strongest acidic groups. Kinetic and equilibrium adsorption data show that the process obeys to the pseudo-second order kinetic equation and Langmuir adsorption model. Between 25 and 40 C no significant influence of the temperature on ibuprofen adsorption was observed. Results indicate that the removal efficiency is higher than 90% between pH 2 and 4 and decreases as pH values increase to a value of 11. The results show that both samples are suitable for ibuprofen removal, although CPAC has advantages, namely, high initial adsorption rate, high adsorption capacity and high removal efficiency, in some cases 100%, for a large range of pH. (c) 2007 Elsevier Ltd. All rights reserved.