Removal of lead (II) and copper (II) from aqueous solution using pomegranate peel as a new adsorbent

Cadmium in soils and groundwater: A review.

Marine pollution from antifouling paint particles.

Adsorption of Cu(II), Ni(II) and Zn(II) on modified jute fibres.

Adsorption of Cu(II), Ni(II) and Zn(II) on dye loaded groundnut shells and sawdust

The adsorption of copper, cadmium, and nickel on goethite was examined in natural groundwater samples from an infiltration site of the river Glatt at Glattfelden (Switzerland). Unfractionated dissolved organic matter was used at its natural concentrations. Metal concentrations were close to environmental conditions. Cu, Cd, and Ni presented the typical pH adsorption edge of cations. The major influence on metal adsorption was due to a strong organic ligand L(I), which inhibited adsorption of Cu, Cd, and Ni in the alkaline pH region. Complexation of Cu, Cd, and Ni by the natural organic ligands was described with a model defining a minimum number of discrete ligands: a strong ligand L(I) at low concentration and additional weaker ligands with higher concentrations. The adsorption of Cu, Cd, and Ni on the goethite surface in the presence of the natural organic ligands was adequately described by considering only surface complexation and complexation in solution by organic ligands. No ternary complexes had to be invoked in the model. The major effect was complexation by the strongest ligand, whereas interactions with other cations and anions had only a minor influence. Competition reactions between Cu and Ni for complexation with the same strong ligand L(I) were observed.

Adsorption of Cu, Cd, and Ni on Goethite in the Presence of Natural Groundwater Ligands

Adsorption of copper, cadmium and nickel at low concentrations on goethite was studied in the presence of the simple organic ligands oxalate, salicylate, and pyromellitate. The experimental metal adsorption behavior was compared to calculations with a surface complexation model to evaluate the most important interactions. Oxalate mostly decreased Cu and Ni adsorption at high pH-values by competition between solution and surface complexation but had no effect on Cd adsorption. Cu adsorption in the presence of oxalate below pH 6 could best be described by defining a ternary complex of type A (surface-metal-ligand). Salicylate had only minor effects on metal adsorption. The adsorption of Cu in the presence of salicylate above pH 5 could be explained by a ternary complex of type A. Pyromellitate increased the adsorption of Cu and Cd in the acidic pH-range, likely by formation of ternary surface complexes of type B (surface-ligand-metal).

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Adsorption of Copper, Nickel, and Cadmium on Goethite in the Presence of Organic Ligands

Cu(II) is a key species with respect to the bioavailability and hence toxicity of copper. Therefore, it is important to elucidate the factors that control Cu(I) steady-state concentrations in natural waters. In this study, a solid-phase-extraction-based method was developed that allows Cu(I) measurements at ambient concentrations. Cu(I) is selectively enriched as a bathocuproine complex on a hydrophobic polymer column, whereas Cu(II), bound to ethylenediamine, is not retained on the column. After elution with acidic methanol, Cu is analyzed with graphite-furnace atomic absorption spectroscopy. The detection limit of the whole analytical procedure is below 1 x 10(-9) M, and the mean recovery of Cu(I) is approximately 70%. We then applied this method to determine Cu(I) in water samples collected from the River Scheldt estuary and the North Sea. Upon irradiation of these filtered water samples in the laboratory (with approximately 5 kW m(-2)), Cu(I) steady-state concentrations ([Cu(I)]ss) were established within a few minutes, and [Cu(I)]ss ranged from 5% to 80% of total dissolved copper, depending on the origin of the water samples. Measured [Cu(I)]ss can be interpreted by considering light-induced reduction of Cu(II) and stabilization of Cu(I) by chloride at high salinity, thermal reduction of Cu(II) by sulfide-containing compounds at low salinity, and fast reoxidation of Cu(I) due to stabilization of Cu(II) by strong organic ligands present at intermediate salinity.

Formation of Cu(I) in estuarine and marine waters: Application of a new solid-phase extraction method to measure Cu(I)

Cuba is a country with considerable potential for economic growth, and special efforts are made to increase the agricultural output. As food production depends on the quality of soils, heavy metal concentrations were measured in 39 soils in the province of Mayabeque, Cuba, and interpreted in light of anthropogenic activities and pedogenic conditions (soil type and properties). With median concentrations of 1.8 Cd, 60.3 Cr, 48.1 Cu, 36.2 Ni, 16.7 Pb, 55.0 Zn, and 0.1 mg/kg Hg, soils of Mayabeque were mostly below Cuban quality reference values (QRV) representing benchmarks of quality standards but no official threshold values. Only Cd concentrations were in many cases above the QRV of 0.6 mg/kg and some Cu concentrations above the one of 83 mg/kg. While Cd, Cr, and Ni concentrations were rather pedogenically driven, Cu, Pb, Zn, and Hg contents were rather anthropogenically influenced. When evaluated statistically, Cd and Cr showed most times a significant influence of both sources. In contrast, Ni and Zn could not be significantly related with the origins investigated in this study. Hence, the allocation of heavy metal concentrations to pedogenic or anthropogenic contamination or pollution sources is tentative and needs further investigations. Nevertheless, the present data adds information on soil heavy metal concentrations in the Caribbean region, serves as reference before further industrial development, and sets the ground for adaptation of the QRV for Cd and possibly future national environmental standards. 

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Diane Buerge-Weirich

Papers

Adsorption of Cu, Cd, and Ni on Goethite in the Presence of Natural Groundwater Ligands

Adsorption of Copper, Nickel, and Cadmium on Goethite in the Presence of Organic Ligands

Formation of Cu(I) in estuarine and marine waters: Application of a new solid-phase extraction method to measure Cu(I)

Heavy metals in soils of Mayabeque, Cuba: multifaceted and hardly discernable contributions from pedogenic and anthropogenic sources