AQUEOUS COMPLEXATION OF CADMIUM, LEAD, AND COPPER BY 2,4,6-TRICHLOROPHENOLATE AND PENTACHLOROPHENOLATE

The subsurface mobility of metals and polychlorinated phenols occurrin g together in contaminated groundwaters may be significantly affected by the extent of aqueous complexation between them. However, no previo us experimental studies have examined these interactions. In light of this, the aqueous complexation of Cd, Pb, and Cu by both 2,4,6-trichlo rophenolate (TCP-) and pentachlorophenolate (PCP-) has been studied at 25 degrees C. Experimental data gathered by ion selective electrode p otentiometry and ultraviolet spectrophotometry indicate that metal-chl orophenol complexation occurs, and we interpret the experimental data in terms of a single 1:1 complex in each system. The log stability con stants for the complexes, with 2 sigma errors, are calculated to be: C d(TCP)(+), 2.5 +/- 0.3; Pb(TCP)(+), 3.0 +/- 0.5; Cu(TCP)(+), 4.9 +/- 0 .4; Cd(PCP)(+), 2.9 +/- 0.3; Pb(PCP)(+), 2.8 +/- 0.5; and Cu(PCP)(+), 4.2 +/- 0.4. Based on these values, a simple correlation technique has been applied to estimate stability constants involving other metals a nd chlorophenols. Calculations using these stability constants suggest that metal-chlorophenolate complexation can drastically alter metal a nd/or chlorophenol mobilities in contaminated groundwaters. Copyright (C) 1997 Elsevier Science Ltd.