Study On Rapid-determining Cadmium,Mercury And Lead By Test Paper

After studying the regularity of the visual colorimetry and the chromogenesis between the basic tritane dyes and heavy metals, a new method was proposed for the rapid-determining trace heavy metals in aquatic environment. The result showed as follows: Using marination method, 0.002% victoria blue B could be impregnated in the quantitative filter paper to make test paper. Cadmium was detected in the aquatic environment by this test paper. The optimum reaction conditions were studied in detail. The ascorbic acid and potassium iodide were added, their concentrations were 0.005mol/L and 0.15mol/L in the solution. And the solution was adjusted [H+] to 0.34mol/L with the nitric acid. 2% o-phenanthroline was used for the masking agent. The blue-green complex was obtained with the reaction of Cd (â…¡) and test paper. The reaction was linear with the concentration of Cd (â…¡) in the range of 0.10- 20.00 mg/L, and the detection limit was 0.10 mg/L. Similarly, 0.001% crystal violet can be impregnated in the quantitative filter paper for the rapid-determining mercury in the aquatic environment. The optimum reaction conditions were as follows: 0.005mol/L ascorbic acid, 0.15mol/L potassium iodide, 0.30mol/L hydrogen, 2% pyrolidine dithiocarboxylate (APDC) as the masking agent. The violet complex was obtained with the reaction of Hg (â…¡) and test paper. The reaction was linear with the concentration of Hg (â…¡) in the range of 0.25- 20.00 mg/L, and the detection limit was 0.05 mg/L. 0.1% malachite green can be impregnated in the quantitative filter paper for the rapid-determining lead in the aquatic environment. The optimum reaction conditions were as follows: 0.005mol/L ascorbic acid, 0.15mol/L potassium iodide, 0.34mol/L hydrogen. The blue-and-green complex was obtained with the reaction of Pb (â…¡) and test paper. The reaction was linear with the concentration of Pb (â…¡) in the range of 1.0- 20.00 mg/L, and the detection limit was 0.5 mg/L. The method has been used to determine trace Cd(â…¡),Hg(â…¡),Pb(â…¡) in different water samples, and the results were in well conformity with the AAS or AFS method, we have applied for three national patents about these conclusions.Based on the above research and the correlative references, the experimental mechanics was studied and discussed in this thesis. Victoria blue B,crystal violet and malachite green were acid-base indicators or biological dyes, which could combine the proton to exist in different acidic solution. Its color changed with the acidity modified. Heavy metals reacted with iodine, then generated the ternary complex with the tritane cation, which created the more conjugate complex and made the chromogenesis buildup. The color of this complex did not change with the variable acidity because it did not go on protonizing . If the color of this complex was different from above three dyes, it was impossible for visual colorimetry.