Metal ion [Tartric acid] (M) Kd values at different pH 3 3.5 4 5 6 Cu(II) 0.1 1101 671 527 202 155 0.2 698.3 320 130 110 79.7 0.3 250.1 106 80.5 50.8 38.9 0.5 55.6 55.6 39.7 52.3 55 1 14 19.3 11.8 8.4 6.5 0.1 1800 1320 432 402 200 0.2 640.7 618 220 111 131 Zn(II) 0.3 588.2 300 95 71.8 59 0.5 134 115 74 28.1 36.8 1 81 35.5 25.2 11.8 5.3 0.1 2221 980 610 421 261 0.2 668.4 640 231 116 142 Pb(II) 0.3 435.9 341 95.3 82.2 30.4 0.5 130.2 82.5 80 40.3 4.7 1 10.8 45.4 34.9 17 2.8

Table 3: Kd Values of Metal Ions at Various Tartaric Acid Concentrations and pH Values.