RESUMO
Complexation-ultrafiltration process was investigated to separate selectively Hg(II) and Cd(II) from binary metal solutions by using poly (acrylic acid) sodium salt as a complexing agent. Effects of operating parameters on selective separation factors (beta(Cd/Hg)) of the both metals have been examined in detail. Results indicated that loading rate, pH, concentration of salt added and low-molecular competitive complexing agent affect significantly beta(Cd/Hg) value. Further, a concentration experiment was carried out according to the previous optimum parameters. Rejection coefficient of mercury is close to 1, while that of cadmium is about 0.1. The experiment was characterized by good effectiveness, and enabled the rapid linear increase of mercury concentration and very slow increase of cadmium concentration in the retentate. Then, a diafiltration technique was applied to separate further the both metals. Cadmium concentration in the retentate declines sharply with the diafiltration volume, whereas for mercury it is the contrary.
Assuntos
Cádmio/isolamento & purificação , Mercúrio/isolamento & purificação , Água/química , Resinas Acrílicas/química , Ligação Competitiva , Cádmio/química , Concentração de Íons de Hidrogênio , Mercúrio/química , Sais/química , Soluções , Especificidade por Substrato , UltrafiltraçãoRESUMO
In (CH2)6N4-HCl buffer solution and in the presence of OP emulsifier trace Ni(II) catalyzes strongly the decolorization reaction of Rhodamine B (RhB) by oxidizing with H2O2, and its catalytic extent is linear with the contents of Ni(II) in a certain range. Based on this study, a novel spectrophotometric method for determining Ni(II) was developed. The results show that the maximum absorption of the complex is at 550 nm, the detection limit of the method is 0.4 microg x L(-1) for Ni(II), and Beer's law is obeyed for Ni(II) in the range of 0-0.3 mg x L(-1). The method has been applied to the determination of Ni in FeNiCr alloys with satisfactory results.
Assuntos
Ligas/química , Cinética , Níquel/análise , Espectrofotometria/métodos , Catálise , Resíduos Industriais , Padrões de Referência , Rodaminas/químicaRESUMO
In HNO3 medium the fading reaction of arsenazo III oxidated with Cr2O7(2-) was used as to determine trace Cr in fly ash containing Cr. The results show that the fading reaction has high sensitivity in the medium of 3.2 mol.L-1 nitric acid, the molar absorptivity of 3.9 x 10(6) L.mol-1.cm-1 at 520 nm, and Beer's law is obeyed for Cr (VI) in the range of 0.0-40.0 micrograms.L-1. Contents of Cr in fly ash were determined with satisfactory results.