COPPER ADSORPTION BY ESTERIFIED AND UNESTERIFIED FRACTIONS OF SPHAGNUM PEAT MOSS AND ITS DIFFERENT HUMIC SUBSTANCES

The Cu(II) binding properties of Canadian Sphagnum peal moss, humic ac id and humin extracted from the peat moss were investigated. Batch pH profile experiments indicated that the adsorption of Cu(II) is pH depe ndent. At pH 4.0 and 5.0 about 99% of Cu(II) was bound by all three bi omasses. Time-dependent experiments showed that the binding of Cu(II) is very rapid. The Cu(II) binding capacities at pH 4.0 were 16.1 mg pe r gram peal moss, 28.2 mg per gram humic acid, and 17.9 mg per gram hu min. More than 90%, of Cu(II) bound to the biomasses was recovered by treatment with 0.1 M HCl. We showed that carboxyl groups on these humi c substances are responsible for some of the Cu(II) binding by esterif ying them with methanol in the presence of trimethoxymethane (trimethy l orthoformate) and observing a decrease in Cu(II) binding. Infrared a nalysis confirmed the esterification and base hydrolysis of the esteri fied biomasses corroborated that esterification (and not degradation) had occurred since the metal-binding ability was regained. Our results provide important information on the interaction of Cu(lI) ions with Sphagnum peal moss and its humic fractions. This may have practical ap plications for the removal of hazardous copper ions from contaminated water supplies.