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Competitive Complexation of Cd(II) and Cu(II) by Water‐Soluble Organic Ligands and Na‐Montmorillonite
Author(s) -
Inskeep William P.,
Baham John
Publication year - 1983
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1983.03615995004700060010x
Subject(s) - adsorption , chemistry , metal , montmorillonite , inorganic chemistry , copper , metal ions in aqueous solution , genetic algorithm , nuclear chemistry , organic chemistry , biology , evolutionary biology
Water soluble extracts obtained from a coniferous forest litter layer (FLLE), dried Chicago sludge (CSE), and a peat soil (PE) were used as a source of organic ligands to study the influence of metal complexation on the adsorption of Cd and Cu by Na‐montmorillonite. Adsorption of 50 to 0.1µ M Cd T and Cu T by Na‐montmorillonite (2 g L −1 ) was measured in the presence of the FLLE (1.8 m M total carbon) over a pH range of 4 to 8.5 after a 2‐h equilibrium period under humidified N 2 gas. Equilibrium activity measurements for Cd 2+ and Cu 2+ were made with ion selective electrodes for experiments at 50 and 10 µ M total metal (M T ). After accounting for inorganic complexation, the amount of Cd complexed with organic ligands in the FLLE was much lower than that for Cu. Multiple regression equations where pM ads (metal adsorbed) was tested as a function of pH and pM TS (total soluble metal concentration) showed that Cu adsorption decreased with increased pH values in contrast to adsorption in the absence of FLLE. Conversely, the adsorption of Cd was only slightly affected. Adsorption of 10 µ M Cu T in the presence of CSE and PE showed similar effects on adsorption, revealing the importance of water soluble complexing ligands in controlling Cu speciation.