A voltametria de redissolução catódica aplicada na determinação de manganês em águas de abastecimento

Abstract

The discharge of industrial effluents, atmospheric depositions, the sewers of the urban centers and the contamination originated from the farm exploration have been contributing to the load’s increase of the heavy 32 metals in freshwater. In relation to these metals, the manganese particularly a element of great importance in aquatic systems, since the particles or colloids of its oxide have high adsorptive properties, and the behavior of this element depends of its oxidation/reduction’s processes. A simple method used in order to determinate the Mn using the CSV - Cathodic Stripping Voltammetry, was developed with the objective of quantify it in three Water Treatment Plant (WTP): Santa Barbara, Sinnott and Moreira (Pelotas/Rio Grande do Sul State). The analysis presented that the total fraction of this metal is between 54.54 and 63.30 μg L -1 for raw water and between 61.10 and 147.09 μg L -1 for the treated water. The study was developed with the usage of a glassy carbon electrode in order to determinate the Mn in buffer solution of 0.05 mol-1 L of ammonium acetate, wherein, under these conditions, the pH of 10.1 was maintained. The accuracy of the proposed method was verified through a reference certify material, and meantime the application of the statistic tests, wherein was concluded that there were no significant differences among the results found in a confidence average of 95%. This method can be characterized as simple, reproducible, demanding only small quantities of reagents and samples