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Lead II chloride solutions containing 10, 100 and 1 000 ppm Pb were decontaminated with chemically treated bark. The percentage of Pb cations removed from solution was found to depend on pH and initial concentration: about 99% of the initial Pb content can be removed at pH of about 3.5, 5.5 and 6.5 for initial concentrations of 10, 100 and 1 000 ppm respectively. The maximum retention capacity of the treated bark was about 83 mg Pb/g modified bark. Infra-red spectroscopy of loaded bark suggested that the Pb reacts with hydroxyl groups of the phenolic constituents of the bark. On the other hand, the release of two H+ ions when a Pb cation is removed by the bark seems to indicate ion exchange with hydrogen from the hydroxyl groups., Lead II chloride solutions containing 10, 100 and 1 000 ppm Pb were decontaminated with chemically treated bark. The percentage of Pb cations removed from solution was found to depend on pH and initial concentration: about 99% of the initial Pb content can be removed at pH of about 3.5, 5.5 and 6.5 for initial concentrations of 10, 100 and 1 000 ppm respectively. The maximum retention capacity of the treated bark was about 83 mg Pb/g modified bark. Infra-red spectroscopy of loaded bark suggested that the Pb reacts with hydroxyl groups of the phenolic constituents of the bark. On the other hand, the release of two H+ ions when a Pb cation is removed by the bark seems to indicate ion exchange with hydrogen from the hydroxyl groups.

The efficiency of modified bark in removing Cd cations from effluents after conventional neutralisation and precipitation was tested. About 99.9% of Cd was removed from synthetic solutions containing 10 ppm, 99% from solutions with 100 ppm and 96% from solutions with 1 000 ppm. Pilot plant trials using an industrial effluent containing about 0.5 ppm led to almost complete elimination., The efficiency of modified bark in removing Cd cations from effluents after conventional neutralisation and precipitation was tested. About 99.9% of Cd was removed from synthetic solutions containing 10 ppm, 99% from solutions with 100 ppm and 96% from solutions with 1 000 ppm. Pilot plant trials using an industrial effluent containing about 0.5 ppm led to almost complete elimination.

Chemically treated bark of pedunculate oak, Scots pine, European beech and European spruce was used to decontaminate copper acetate, chloride, nitrate and sulphate containing 10, 100 and 1 000 ppm Cu. The percentage of metal removed varied from 40% to 99%, depending on pH and initial concentration, and to some extent on the salt used. The maximum retention capacity of the treated bark varied from 31 to 43 mg Cu/g dry bark. Loaded bark was analysed by SEM and IR spectroscopy: Cu was uniformly distributed with no observed segregation, and appeared to be bound to the acidic sites of the bark. No anions were detected by either technique., Chemically treated bark of pedunculate oak, Scots pine, European beech and European spruce was used to decontaminate copper acetate, chloride, nitrate and sulphate containing 10, 100 and 1 000 ppm Cu. The percentage of metal removed varied from 40% to 99%, depending on pH and initial concentration, and to some extent on the salt used. The maximum retention capacity of the treated bark varied from 31 to 43 mg Cu/g dry bark. Loaded bark was analysed by SEM and IR spectroscopy: Cu was uniformly distributed with no observed segregation, and appeared to be bound to the acidic sites of the bark. No anions were detected by either technique.