The ability of corncobs to retain copper ions was studied with respect to the origin of the materials (inner or outer parts of the cobs), the granulometry, the pH, and chemical modifications with maleic anhydride (MA) and succinic anhydride (SA). Esterification, characterized by Fourier transform infrared and X-ray photoelectron spectroscopy, led to a large increase in copper retention in comparison with unmodified corncobs. The retention capacity was improved up to 6 times with SA-modified corncobs at pH 5. The adsorption behavior of MA- and SA-grafted samples, with respect to copper, appeared to be different at pH 4 and pH 5, and this was attributed to a difference in the pK(a) values of the grafted carboxylic functions. (C) 2003 Wiley Periodicals, Inc.