SORPTION OF ORGANIC COMPOUNDS BY A1 AND Zr-HYDROXY- INTERCALATED AND PILLARED BENTONITE

Abst raet~wing to their large and chemically active surface, hydroxy-intercalated and pillared clays can be potent sorbents for organic compounds. The sorption behavior of A1 and Zr-hydroxy-intercalated bentonite (HA1-, HZr-MX80), A1 and Zr-pillared bentonite (A1-MX80, Zr-MX80), and a commercial A1-pillared bentonite (EXM 534) for 3-chloroaniline (3-CA), atrazine (AT), and 3-chlorophenol (3-CP) was investigated. The results were compared with the sorption behavior of the untreated Na-rich bentonite (MX80) and granulated activated carbon (GAC). Also the influence of the salinity of the sorbate and the age of the sorbents was studied. A1 and Zr-hydroxy-intercalated an pillared bentonites sorbed higher amounts of 3-CA, AT, and 3-CP than the untreated bentonite. The quantities orbed related to the electron-donating properties of the sorbate and the acidity of the sorbents. Sorbed quantities increased from the hydroxy-intercalated o the pillared species, and from the AI to the Zr forms. The organic bases, 3-CA and AT, were sorbed in higher quantities than the organic acid 3-CP. For AT, the sorbents exhibited a high affinity. Aging of the samples and a high ionic strength of the sorbate reduced the sorption of 3-CA, whereas the sorptioa of AT was not affected greatly. The sorption capacity of GAC for organic bases was generally higher than that of the hydroxy-intercalated and pillared bentonites. The data suggest hat at initial concentrations at a ppm level, 3-CA and AT can be entirely removed from aqueous olutions by A1 and Zr-hydroxy-intercalated an pillared bentonites. These materials, es-pecially Zr-pillared bentonites, represent potent alternative sorbents for atrazine, chloroanilines, and prob-ably a wide range of other organic bases