Novel nano lignin and preparation method thereof
A technology for nano-lignin and industrial lignin, which is applied in the field of novel nano-lignin and its preparation, can solve the problems of easy dispersion, low reactivity, poor compatibility of liquid polyols, etc., so as to improve the hydroxyl content and reduce the molecular weight of lignin. Effect
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Embodiment 1
[0046] In order to investigate the effects of chemical hydrolysis, ultrasound and medium on the preparation of nano-lignin, the lignin particle dispersion system was prepared by chemical hydrolysis or ultrasound respectively. The results are as follows: Figure 1~4 shown.
[0047] (1) Disperse the alkali lignin directly in each medium, the results are as follows figure 1As shown, alkali lignin cannot be well dispersed in water, methanol, ethanol, n-propanol, isopropanol, 1,3-propanediol, tetrahydrofuran and butyl acetate, and alkali lignin particles precipitate at the bottom, indicating that the above None of the media can prepare nano lignin.
[0048] (2) Disperse alkali lignin directly in each medium, after ultrasonic treatment, the result figure 2 As shown, alkali lignin is difficult to disperse in water, isopropanol, 1,3-propanediol, tetrahydrofuran and butyl acetate, and partially disperses in methanol, ethanol and n-propanol. Therefore, it is difficult to obtain nano...
Embodiment 2
[0052] In order to determine the appropriate chemical hydrolysis conditions: hydrolysis temperature, hydrolysis time, lignin concentration, sodium hydroxide concentration, etc., the experimental results of preparing nano-lignin are given here by taking the hydrolysis time as an example.
[0053] Take alkali lignin and NaOH aqueous solution (the concentration of alkali lignin is 5wt%, the concentration of sodium hydroxide is 15wt%, and the rest is water) to react in a hydrothermal kettle (the hydrolysis temperature is 190°C, and the hydrolysis time is 0-8h), and the reaction After the end, the hydrothermal kettle is placed in room temperature water and rapidly cooled to room temperature. The pH of the above reaction solution was adjusted to 2 with 2 mol / L sulfuric acid aqueous solution, centrifugally filtered and washed with water until the reaction solution was neutral to obtain depolymerized lignin particles. The depolymerized lignin particles were put into methanol, and subj...
Embodiment 3
[0059] Take 6g of alkali lignin and 74g of NaOH aqueous solution (15wt% NaOH, 60wt% methanol), react in a hydrothermal kettle for 7 hours, and the reaction temperature is 190°C; The pH of the above reaction solution was adjusted to 2 with 2 mol / L sulfuric acid aqueous solution, centrifugally filtered and washed with water until the reaction solution was neutral to obtain depolymerized lignin particles. The depolymerized lignin particles were put into methanol, ultrasonically treated and freeze-dried to obtain a new type of nano-lignin with an average particle size of 306nm, a hydroxyl content of 20mmol / g, and an average weight-average molecular weight of 2216g / mol.
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