Enhanced adsorption of p-nitroaniline from water by a carboxylated polymeric adsorbent

In the present study a carboxylated polymeric adsorbent ZK-1 was synthesized for enhanced removal of p-nitroaniline (PNA) from aqueous solution. A commercial polymeric adsorbent XAD-4 was selected for comparison purpose. Characterization of ZK- I was characterized by infrared spectroscopy and pore size distribution analysis. Experimental results showed that PNA adsorption onto ZK- I was greatly enhanced due to its micropore structure and the carboxylic group introduced onto polymeric matrix. Different pH-dependent adsorption tendency of PNA onto XAD-4 and ZK- I was observed mainly due to the role of carboxyl group on the ZK- I surface. Isotherms of PNA adsorption onto ZK- I and XAD-4 could be represented by Langmuir model reasonably. More favorable PNA adsorption onto ZK- I than X AD-4 was further demonstrated by thermodynamic ananlysis. Kinetic studies demonstrated that PNA uptake onto ZK-1 followed the pseudo-second order model, while that onto XAD-4 would be more suitably represented by the pseudo-first order model. Column adsorption runs indicated that PNA could be completely removed from aqueous system by ZK-1. Moreover, efficient regeneration of the spent adsorbent ZK- I was readily achieved by ethanol and water for its repeated use. (C) 2007 Elsevier B.V. All rights reserved.