Abstract

BARBOSA LOPEZ, Aida Liliana  and  CASTRO SIERRA, Isel María. Comparative Study of Catalytic Systems TiO₂ and Nb₂O₅ · 3H₂O in Cyanide Degradation According to Oxidant Type. ing.cienc. [online]. 2012, vol.8, n.16, pp.257-280. ISSN 1794-9165.

This article discusses the viability of using agents such as niobium photocatalyst in decreasing higher energy of the band gap. To do so competitively with TiO₂, the presence of oxidation helpers such as H₂O₂ and O₃ could present surprising results in the catalytic performance due to higher generation of OH o radicals. Oxidation helpers are shown to assist in obtaining larger area oxides and textural properties different from commercial niobium oxide, and enhancing its catalytic activity in free cyanide removing. The article presents experimental results of cyanide photodegradation of 100mg/l with Degussa P- 25 TiO₂ and Nb₂O₅·3H₂O, using a type CPC photoreactor and sunlight as the radiation source. Taking an inclination equal to Cartagena latitude of 10,450, the results show a clear effect of pH, catalyst type and oxidation auxiliar agent on photodegradation reaction. The ion cyanide reduction of polluted effluent was enhanced by oxidizing agent (O₃ and H₂O₂) addition. This may suggest a greater susceptibility to free cyanide oxidation and cianate indirect oxidation due to higher hydroxyl radical generation, which was induced by H₂O₂ or O₃ presence under solar radiation. The results showed free cyanide photocatalytic oxidation percentages between 64% and 72% using Nb₂O₅ · 3H₂O and 67% and 71% using TiO₂ Degussa P-25. The catalysts were characterized structurally by XRD, BET, Raman and FTIR, with the purpose of correlating morphological changes in catalytic performing.

Keywords : photocatalysis; ozone; niobium oxide; titanium oxide; hydrogen peroxide.

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