Regeneration of an activated carbon bed exhausted by industrial phenolic wastewater

Abstract

The main objective of this study is the regeneration of an activated carbon bed exhausted by industrial phenolic wastewater. The regeneration of activated carbon beds is carried out before proceeding with the next exhaustion stage. The liquid retained in the column is rinsed out with water and solutions of sodium bicarbonate IN and, subsequently, sodium hydroxide 1.5N are used to regenerate the beds. The column is cleansed with water. A solution of sulfuric acid 0.5N is added, and then water, until a pH of less than 3 is reached. After this treatment process, the columns are ready for the adsorption stage of the next cycle of adsorption-regeneration. pH variations of the solution of each column and the concentration of the analyzed components, phenol, Salicylic acid, 4-hydroxybenzoic acid and 4-hydroxyisophthalic acid are taken as time passes. A maximum concentration of salicylic acid and 4-hydroxyisophthalic acid with approximately pH 6.5 is observed. 4-Hydroxybenzoic acid is desorbed mostly between pH 9 and 10. The maximum phenol concentration appears at a pH of around 12. It is shown that the largest quantity of 4-hydroxybenzoic acid and the second highest concentration of salycilic acid are produced by the effect of the carbonates.