The adsorption of pentachlorophenol from aqueous solutions onto exchanged Al-MCM-41 materials

Abstract

The ability of a mesoporous molecular sieve to adsorbchlorinated phenols was studied experimentally. Thus, the adsorption isothermsof pentachlorophenol (PCP) from aqueous solutions were measured on (M)Al-MCM-41 (M = Na+, K+, Cu2+, Cr3+) at intervals of 10 K between 303 Kand 323 K. The experimental isotherms obtained were of the S-type in terms ofthe classification of Giles and co-workers. The best fit of the adsorption isothermdata was obtained using the Freundlich model. The adsorption affinity of PCPincreased in the order (K)Al-MCM-41 <(Cr)Al-MCM-41 <(Na)Al-MCM-41 <(Cu)Al-MCM-41. At the same temperature, the adsorption of PCP on (Cu)Al-MCM-41 was more pronounced compared to its adsorption on alumina-pillaredmontmorillonite and mesoporous alumina aluminium phosphates. Analysis ofthe isosteric curves showed that (Cu)Al-MCM-41 and (Na)Al-MCM-41 presenteda heterogeneous profile. In contrast, (K)Al-MCM-41 and (Cr)Al-MCM-41 didnot exhibit energetic heterogeneity throughout the entire range of coverage.