Upgrading spent liquors from the NSSC process. I. Identification and quantification of organic components

Modern trends require for pulping processes friendlier to the environment. In the NSSC (Neutral Sulfite Semi-Chemical) process there is a need for dis posing spent liquors economically and ecologically. A better knowledge on t he solubilized substances, and suitable separation techniques are desired. The present work is concerned with the identification and quantification of organic components in spent liquors. Hybrid poplar (Populus deltoides) was used as raw material. Twenty-nine spent liquor samples were analyzed. Two procedures and several methods for organic materials determinations were us ed. Solvent extraction, and HPLC using common detection arrangements (UV an d refraction index) were applied. They have shown to be useful and simple t o perform for the determination of organic material balances; The content o f different organic materials present in all spent liquors was: lignosulfon ates: 59-69%, hemicelluloses: 2-24%, simple sugars: not detected, acetic ac id: 12-29% and formic acid: 1.6-2.4%.