Simultaneous sorption of organic compounds and phosphate to inorganic-organic bentonites from water

Simultaneous sorption of organic compounds and phosphate from water by inorganic-organic bentonites (IOBs) was investigated, which would contribute to the treatment of contaminated water containing both of these contaminants. A series of IOBs were synthesized by intercalating bentonite with both cetyltrimethyl ammonium bromide (CTMAB) and hydroxy-aluminum at their various ratios, and the obtained materials had large basal spacing, low surface area and high organic carbon contents. Sorption experiments with phenol, p-chlorophenot, 2,4-dichlorophenol, 2-naphthol, nitrobenzene, p-nitrotoluene or naphthalene together with phosphate demonstrated that IOBs could simultaneously remove organic compounds and phosphate from water, due mainly to the partition and ligand exchange mechanism, respectively. The sorption capacity of IOBs with organic compounds was retained as those of organobentonites, and the removed amount were in the range of 42-98% for the tested organic compounds. In addition, the removal efficiency of phosphate by IOBs is higher than that by the corresponding hydroxy-aluminum pillared bentonites, and more than 98% phosphate were removed at the initial concentration of 20 mg/L (calculated as P). The coexisting organic compounds had little influence on the sorption of phosphate to IOBs under the experimental conditions. Thus, IOBs could be promising sorbents for simultaneous removal of organic compounds and phosphate from water. (C) 2006 Elsevier B.V. All rights reserved.