Estudo da degradação de amônia com ácido de caro em efluentes industriais aquosos

Abstract

Ammonia is considered a pollutant substance in water. The legislation allows a maximum concentration of ammonia of 5.0 mgL in industrial effluents. As various industrial processes generate waste with high ammonia concentrations and more than this limit, the present work aims to study the use of caro acid on degradation of ammonia in effluents. The sulfuric acid in the presence of hydrogen peroxide has high oxidative power, which is able to oxidize the ammonia to nitrate under determined conditions. The main objective of this work was to study of these reaction variables such as time, concentration of reactants, catalysts, in order to optimize the process of degradation. It was used sample of synthetic wastewater containing ammonia in the range of 20-40 mg/L and the degradation process parameters were varied such as the metal used as catalyst (Cu2+, Fe2+, Co2+ and Mo6+), the concentration of these catalysts, the degradation process temperature and H2SO5:NH3 molar ratio. At this work, it was observed that the degradation of Caro's acid with ammonia catalyzed with cobalt (II) showed the best results. Caro's acid has proved to be more efficient under the following conditions: [Co2+] = 2 mg/L, pH = 9, H2SO5:NH3 = 6,25:1, temperature = 40 ºC, leading to values below 0,1 mg/L of ammonia in just 60 minutes in a synthetic wastewater with ammonia nearly 25 mg/L. The use of cobalt as catalyst reduces the amount of acid required expensive addition to the oxidation process no limit for disposal of cobalt in industrial effluents