Fig. 7. Residual cadmium content of the phosphate sample before and after
leaching under different conditions. 1: original sample (as received); 2: sample after
leaching with a 0.1 mol L1 Na2-EDTA solution; 3: sample after partial oxidation of
the organic matter with 40 mg L1 H2O2 solution; 4: sample after partial oxidation
of the organic matter with 40 mg L1 H2O2 followed by leaching with a 0.1 mol L1
Na2-EDTA solution. Solid/liquidratio: 1:4; leaching time: 5 h, temperature: 25 C.