Preparation And Research Of Dye Dispersion Based On Lignin From Pulping Black Liquor

Lignin is the second largest natural polymer materials in nature after cellulose.As the main byproduct of the paper industry, it is mainly present in the black liquor, ifnot taken full advantage of, not only has a serious impact on the environment, but alsocauses a great deal of sustainable waste of resources.In this paper, we modified the lignin extracted from pulping black liquor bychemical grafting using Mannich reaction, and synthesized a new kind of lignin dyedispersants. By researching the dispersion properties of the dispersant in the normaland high temperature, we can concluede:1. Acid analysis method to extract lignin using four factors and three levelsorthogonal experiments, study the impact of various factors on lignin extraction rate,the best conditions were as follows: the end of reaction pH2, the optimum reactiontemperature of60°C, flocculation time of40min, flocculation temperature of70°C.The impact of the various factors on the effects of acid precipitation, the pH of thereaction was the largest.2. By infrared spectroscopy, ultraviolet spectroscopy, nuclear magnetic resonance,elemental analysis, and thermal gravimetric analysis of lignin, we can see that thelignin extracted in black liquor was mainly made up by the lilac groups and guaiacylgroups, and the content of the lilac groups was more.3. First, the paper modified the lignin by Mannich reaction, explored the impactof various factors on the dispersion properties of the dispersant using the method oflevel of single factor and orthogonal experiments L16(45), the best combiningconditions were as follows: the amount of imidazole2mol,37%of the formaldehyde10mL, reaction pH of10.6, a reaction temperature of90°C, the formaldehydedropwise added time80min. We also analysed the lignin obtained under the optimumconditions, lignin moisture content of about5.5%, the free formaldehyde content of1.2%.4. By adjusting the kind of reactive monomers amine, we also utilized L16(45)orthogonal research and terrible analysis method, and obtained morpholino-lignin dye dispersant and cationic imidazoline-lignin dye dispersant respectively. We also studiedthe dispersion of the three dispersant in the ambient temperature and high temperatureperformance and concluded: At room temperature, due to the steric effect of the longchain structure of the cationic imidazoline polymer as well as the characteristic thatwas usually used as a softener, the dispersion performance of the cationicimidazoline-lignin dye dispersant was superior to the other two dispersants; However,at high temperatures, the heat stability of the imidazol-lignin dye dispersant was betterand the dispersibility was stronger. Experiments showed that, in the160°C still hadgood dispersing effect, and vice versa, the two remaining dye dispersant can only beused under conditions of120°C or less.