| dc.description.abstract | Tannery waste is constituted of organic materials of animal origin mixed with inorganic
salts. Among them, nutrients that are essential to plants and microorganisms, such as
nitrogen, calcium, sulfur, phosphorus, magnesium and potassium, enabling their use as
fertilizers, as well as their reuse. Although, chromium salts are largely applied in leather
tanning, making monitoring its concentrations in fertilizers indispensable. Chrome can
be found in various stages of oxidation, with its to most stable species being Cr(III) and
Cr(VI). They significantly differ by their biological and chemical action, highlighting
that Cr(III) is essential to humans, while Cr(VI) is toxic. For that reason, Ministry of
Agriculture, Livestock and Supply (MAPA) defined its maximum level as 2 mg kg-1.
Many speciation analytical techniques are described in literature, among them are
determination by electroanalytical methods, atomic spectrometry, such as liquid
chromatography associated with inductively coupled plasma mass spectrometry LCICP-MS, and spectrophotometric determination. Spectrometry is the most used because
of its low cost, robustness, and large scale usage. Thus, this research had as its objective
the development of a chrome speciation method by visible (VIS) spectrometry, based
in the NaOH/Na2CO3 alkaline extraction, described in the United States Environmental
Protection Agency (EPA) 3060a method, activated charcoal sample stratum clean up.
The method analytical characteristics were stablished, which comply with MAPA’s
Cr(VI) maximum level. Between the analyzed samples, only one of the fertilizers
complies with the defined limit. Thereby, the method shows itself to be efficient,
robust, and low cost. | |
