1. Adsorption of alkali solution. After the residual lye is neutralized by the alkali tower (containing potassium carbonate solution), a small amount of potassium carbonate droplets are entrapped and separated by precipitation into the white clay bed. Due to the strong adsorption effect of activated alumina, the residual lye is adsorbed, so that the alkalinity of working solution is reduced from 0.1g/L to below 0.005g/L, which is suitable for hydrogenation reaction.
2. Absorption of water. The water entrained in the extract solution and 80% of the water produced by the decomposition of hydrogen peroxide is absorbed by the concentrated potassium carbonate solution, and a small amount of water is absorbed by the activated alumina together with the alkali solution. After the white soil bed, the water in the working solution drops to below 3 ml/L, but with the extension of the use period, the water absorption of activated alumina reaches saturation, that is, the absorption and release to maintain equilibrium, and its role in absorbing water will not be obvious.
3. Decomposition of hydrogen peroxide. Alkali concentration is appropriate, alkali tower decomposition of extractive fluid hydrogen peroxide capacity of 60% to 70%, activated alumina due to the adsorption of potassium carbonate solution, its ability to decompose hydrogen peroxide 20% to 30%. If the extracted residue hydrogen peroxide content of 0.2 g / L, after the alkali tower down to 0.06 ~ 0.08 g / L, and then after the white clay bed down to 0.042 ~ 0.056 g / L.
4. Regeneration of degraded materials. The hydrogenated white clay bed can regenerate the epoxide of tetrahydro-2-ethylanthraquinone generated in the oxidation reaction, and the post-treatment white clay bed can regenerate the degradation products such as 2-ethylanthrone and 2-ethyl-10-hydroxyanthrone generated in the hydrogenation reaction. The role of activated alumina varies in different production units due to the different composition of degradates, so equal attention should be paid to the use of hydrogenation and post-treatment white clay beds. At the same time, due to the increase of total solids in the working solution, the density and viscosity of the working solution increases, so that the oxidation and extraction yield is reduced, and the system is difficult to operate; some water-soluble degradation substances can cause the yellowing of the product appearance, organic carbon content increases, which not only reduces the product quality, but also increases the difficulties of product refining, concentration and dangerous.