Complexations in illite-fulvic acid-Cu2+ systems

As part of an extended project to illustrate how :heavy metals are complexe d by natural aquatic particles, we conducted various experiments to study t he adsorption of fulvic acid (FA) at aqueous illite surfaces and the comple xation of heavy metal copper(II) in illite-FA bi-complexant systems. By ana lyzing batch adsorption and potentiometric titration data, we found that (i ) the adsorption of FA by illite decreases with increases in pH values and its pH adsorption edge resembles those of SiO2-FA and montmorillonite-FA sy stems described by other researchers, (ii) it is possible to effectively si mulate the complexation of Cu2+ ions in illite-FA bi-complexant systems by taking it to be an additive complexation of two mono-complexant systems (FA -Cu2+ and illite-Cu2+) and (iii) FA can inhibit the retention of heavy meta ls at solid surfaces by forming soluble complexes with metal ions. The abov e results and conclusions are supported by FT-IR analysis of various illite -FA-Cu2+ systems. (C) 1998 Elsevier Science Ltd. All rights reserved.