Desenvolvimento de protocolo de tratamento de resíduos de DNS

Abstract

The 3,5-Dinitrosalicylic acid, also known as DNS (C7H4N2O7) is an aromatic compound used in carbohydrate quantifications and enzymatic assays. DNS is frequently used in the laboratories of the Faculty of Chemical Engineering to perform a kinetic evaluation of the hydrolysis of sucrose catalyzed by invertase and also to determinate total reducing sugars. Considering the toxicity and the residue volume that is formed, there is an urging necessity to treat such volume. Being so, this work proposes a protocol for the treatment of these DNS residues. Even thought there are already plenty of other conventional techniques for this sort of treatment, they may not be applied to the degradation of the DNS because of the recalcitrance of this particular molecule. In virtue of this, the use of Advanced Oxidation Processes (AOPs) of the type UV/H2O2 became necessary. In this context, multiple experiments were carried out in order to evaluate: i) the influence of ultraviolet light on the degradation of the DNS; ii) the influence of combining UV/H2O2 on DNS degradation. In both evaluations there was a diminution on the bandwidth of absorption spectra corresponding the DNS molecule when the range corresponding to the residue (λ = 345 nm). This was analyzed representing, therefore, an indication of degradation. It was found that only the using only ultraviolet light, didn’t result on complete degradation of the residue in the time established experimentally. However, when allying irradiation and oxidant (H2O2), the complete disappearance of the DNS residue was verified. Nonetheless, the formation of active intermediates revealed itself to be presente throughout the spectrophotometric analysis, a fact to be studied in future works.