Catalysis of CuO on degradation of organic substance in Bayer liquid

Abstract

In this study, catalytic wet oxidation technology was used to remove organic substances from Bayer liquid. First, under the optimal conditions without a catalyst (13.98 g/L of O₂ addition, oxidation temperature of 220 °C, and oxidation time of 100 min), the removal efficiencies of total organic carbon, sodium humate, and sodium oxalate were 86.59%, 92.96%, and 71.36%, respectively. The mechanism of a free radical chain reaction of wet oxidation removal of organic substances was studied. Then, under the optimal conditions using CuO as a catalyst (13.98 g/L of O₂ addition, the catalytic temperature of 250 °, the catalytic time of 100 min, and the catalyst dose of 6% of the ore added mass), the total organic carbon removal efficiency was 98.36%, and sodium humate and sodium oxalate can basically be removed completely. The catalysis of CuO was mainly reflected in two aspects: the copper hydroxyl complex ([Cu(II)(OH) _x]^2−x) formed by the dissolution of CuO was catalyzed based on the complex reaction mechanism, and the dissolved CuO catalyzed the free radical chain reaction. The catalytic wet oxidation technology exhibited high organic substance removal efficiency, especially for removing sodium oxalate, which could negatively affect the alumina products.

Keywords

organic substance / catalysis / wet oxidation / CuO / removal of organic substance

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