Effect of solvent type and pH degree on the chemical composition of kraft black liquor via ARAS method

It is barely known that the wastewater, or black liquor, released during the transformation of wood into paper is rich in carbon due to its lignin content. While the chemicals used in paper pulping are recovered by separating them from the black liquor, the value-added chemicals are wasted as they are burned. This study aims to determine how these value-added chemicals dissolved in black liquor and wasted through burning, can be utilized simply and efficiently. To examine the changes in black liquor chemical content, kraft black liquor samples obtained from Pinus brutia (PB) and Populus tremula (PT) woods were adjusted with 1 MH 3 PO 4 to pH 5.5, 7 and 8.5. Chloroform (C), toluene (T) and dichloromethane (DM) were used as solvents for liquid–liquid extraction of the value-added chemicals. High-pressure liquid chromatography (HPLC) was used for both qualitative and quantitative analyses. The Additive Ratio Assessment (ARAS) method determined that the optimal conditions for recovering value-added chemicals were obtained with PT at pH 5.5 with DM as a solvent.