Removal of chlorinated phenols from aqueous solutions by adsorption on alumina pillared clays and mesoporous alumina aluminum phosphates

Alumina pillared montmorillonite (AIPMt) and mesoporous alumina aluminum phosphates (AAPs) were contacted with aqueous, 2,4-dichlorophenol, 2,4,6-trichlorophenol and pentachlorophenol solutions, at a concentration range between 25 and 250 μg/litre, in batch equilibrium experiments, in order to determine their adsorption properties. The removal of chlorophenols by the adsorbents increase with increasing chlorine substitution in their molecules. In the case of pentachlorophenol, the increased affinity allows adsorption to occur much more efficiently than in the case of other compounds. AIPMt material adsorbs 26.3% of 2,4-dichlorophenol, 75.6% of 2,4,6-trichlorophenol and 95.2% of pentachlorophenol at equilibrium. The adsorption of chlorophenols on mesoporous AAPs is much less pronounced as compared to clays but increases with the ratio of P/Al, as the surface acidity of those solids also increases. The AAP mixture with a ratio P/Al = 0.6 adsorbs 14.8% of 2,4-dichlorophenol, 27.1% of 2,4,6-trichlorophenol and 58.3% of pentachlorophenol. The amounts of chlorophenols decomposed during the treatment increase in AAPs and especially in those with a higher P/Al ratio (=0.6).