Treatment of black liquor (BL) by adsorption on AE resins and a subsequent electrochemical degradation of BL to obtain vanillin

Abstract

Abstract The dominating kraft pulping process leads to kraft pulp and to black liquor (BL), which is incinerated for recovery of inorganic chemicals. A certain part of the BL can also be used as a source of organic chemicals without disturbing the recovery and energy balance of the mill. In this research, the removal of low molecular weight (MW) phenolic products from BL without disturbing the recovery process. Strongly basic anion exchange (AE) resin was utilized to deplete BL from different phenolic derivatives on a preparative scale. The adsorbed low MW phenols can be easily liberated by acidic treatment. Completely depleted BL was then electrochemically treated for further highly selective degradation of kraft lignin. This combined approach enabled the concentration of phenolic substances.