Zero valent iron mediated degradation of the pharmaceutical diazepam |
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Authors: | Bautitz Ivonete Rossi Velosa Adriana C Nogueira Raquel F Pupo |
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Institution: | Department of Analytical Chemistry, Institute of Chemistry of Araraquara, UNESP - Univ Estadual Paulista, CP 355, 14801-970 Araraquara, SP, Brazil |
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Abstract: | Parameters that influence the zero valent iron mediated degradation of the pharmaceutical diazepam (DZP) were evaluated including the iron concentration and its pre-treatment, the effect of complexation with EDTA and oxic versus anoxic condition. It was observed that acid pre-treatment of iron particles is important for degradation efficiency and that H2SO4 is a better choice than HCl, resulting in higher degradation of DZP. Under oxic conditions, the degradation of DZP achieved 96% after 60 min using Fe0 (25 g L−1) pre-treated with H2SO4 in the presence of EDTA (119 mg L−1), while mineralization achieved around 60% after the same time. Under anoxic conditions, degradation occurred, however at lower extent, achieving 67% after 120 min. The addition of EDTA improved the treatment efficiency in 20% leading to 99% DZP degradation after 120 min. The first intermediates formed during DZP degradation were identified using LC/MS analysis and revealed the formation of mono- and di-hydroxylated products from DZP during Fe0/EDTA/O2 degradation, which evidences that OH was the main oxidizing species formed in this process. |
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Keywords: | Emerging contaminants Degradation Zero valent iron Fenton |
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