Method for preparing lignin-based heavy metal ion adsorption material through sulfhydryl-alkenyl click reaction
A heavy metal ion and lignin-based technology, applied in the field of preparation of lignin-based heavy metal ion adsorption materials, can solve the problems of complex modification process, serious secondary pollution, high energy consumption, etc., to overcome the complex modification process and improve the adsorption High selectivity and high reaction efficiency
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[0026] The preparation method of the lignin-based heavy metal ion adsorption material comprises the following steps:
[0027] The first step, preparing alkenyl lignin: dissolving lignin and alkenyl compound in solvent A according to the hydroxyl group in lignin: alkenyl compound monomer molar ratio is 1:1~1:20, adding catalyst I, at 10 Stir the reaction at ~100°C for 1-8 hours. After the reaction is completed, the precipitate is precipitated with solvent B, filtered, the precipitate is washed with solvent B to remove catalyst I and excess alkenyl compound, and freeze-dried at -20~0°C to obtain alkenyl lignin, whose structure is shown as
[0028]The second step is to prepare the lignin-based heavy metal ion adsorption material: the alkenyl lignin and the mercapto compound rich in nitrogen and oxygen atoms are mixed in the solvent according to the alkenyl in the alkenyl lignin: the mercapto compound molar ratio is 1:1~1:40 Mix uniformly in C, add catalyst II, and react at 10-...
Embodiment 1
[0032] Dissolve 2.0 g of lignin acetate (hydroxyl content 10.2 mmol) in 80 mL of 0.5 mol / L sodium hydroxide solution, add 2.5 g of bromopropylene (21 mmol), and react at 80° C. for 4 h. Cool to room temperature after the reaction, adjust the pH of the solution to about 2 with 2mol / L hydrochloric acid, and precipitate a pale yellow solid. The solid was filtered, washed with deionized water and ethanol to remove excess inorganic salts and propylene bromide compounds, and freeze-dried at -20°C to obtain brown-yellow alkenyl lignin. The resulting 1.5 g alkenyl lignin (alkenyl content 4.5 mmol) was dissolved in 20 mL 1,4-dioxane solution, 5.9 g acetylcysteine (36 mmol) and 0.12 g 2,2-dimethoxy Base-2-phenylacetophenone, at a wavelength of 365nm, a light intensity of 20mW / cm 2 The reaction was carried out under the irradiation of ultraviolet light for 1.5 hours. After the reaction, 1,4-dioxane was distilled off under reduced pressure, and the crude product was filtered and washe...
Embodiment 2
[0046] Dissolve 5.0 g of kraft lignin (hydroxyl content 37 mmol) in 100 mL of acetone solution, add 5.7 g of chloropropene (74 mmol), 1.2 g of potassium carbonate, and react under reflux at 70° C. for 6 h. After the reaction, cool to room temperature, adjust the solution to acidity with 1mol / L dilute nitric acid, and precipitate a brown crude product, filter the solid, wash with deionized water and ethanol to remove excess chloropropene, and freeze-dry at -20°C to obtain a brown alkenyl lignin solid . The obtained 1.5g alkenyl lignin (alkenyl content 5.8mmol) was dissolved in 20mL tetrahydrofuran solution, and 5.2g thiocyanuric acid (29mmol) and 0.15g 2,2-dimethoxy-2-phenylbenzene were added Ethyl ketone at a wavelength of 365nm and a light intensity of 10mW / cm 2 react under UV light for 2 hours. After the reaction, the residual tetrahydrofuran was distilled off under reduced pressure, and the crude product was filtered and washed with methanol and deionized water to remove ...
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