Lime Treatment of Prehydrolysis Liquor from the Kraft-Based Dissolving Pulp Production Process

In this study, the concept of using lime for the treatment of industrially produced prehydrolysis liquor (PHL) of kraft-based dissolving pulp production process was tested, and its effect on the concentrations of acetic acid, furfural, UV lignin, and hemicelluloses was explored. Lime treatment resulted in a significant increase in the acetic acid concentration due to alkaline hydrolysis of the acetyl groups bound to the dissolved hemicelluloses in PHL, and the degradation of sugars. At relatively high lime dosages (e.g., above 1.7%), furfural was completely eliminated, while the lignin concentration decreased by 20–25%. The hemicelluloses concentration can be significantly decreased due to the alkaline oxidative degradation. However, when performed in the absence of oxygen/air by bubbling carbon dioxide to the lime/PHL system, the degradation of hemicelluloses was effectively minimized.