Tiếng Việt
Preparation steps of carboxymethyl cellulose sodium
Tạo vào 2024.07.25
1、 Instruments and reagents:
Three necked flask (250m1), electric stirrer, condenser tube, drip funnel, constant temperature water bath, hot water funnel, Brinell funnel, suction bottle, beaker, conical flask, Kjeldahl flask, water pump.
Pure cotton (or paper pulp), 95% ethanol, 75% ethanol, 26% chloroacetic acid alcohol solution, 30% NaOH, acetic acid.
2、 Preparation steps of carboxymethyl cellulose sodium:
- Put 4g of pulp into a three necked bottle, add 100ml of 75% ethanol, and stir. Slowly add 30% NaOH through a dropper funnel while vigorously stirring? 40ml, reflux and warm in a water bath (30-35 ℃) and continue stirring for 30 minutes. Ethanol can promote the penetration and diffusion of alkali into fibers. The temperature during the alkalization process should not exceed 35 ℃ to prevent the alkali fibers from turning yellow.
- After the alkali fiber is cooled to room temperature, 12.5ml of chloroacetic acid alcohol solution is added through a dropping funnel, stirred and refluxed in a 55 ℃ water bath for 45 minutes, and then the temperature is raised to 70 ℃, refluxed and heated, and stirred for 1.5 hours. A reaction temperature that is too high or too low is not good. A low temperature will affect the conversion rate, while a high temperature will affect the water absorption and viscosity of the finished product. Take a small sample that is soluble in water, indicating completion of the reaction.
- Filter while hot and discard the filtrate. Transfer the crude product of carboxymethyl cellulose sodium into a beaker, add 100ml of 95% ethanol in a 50 ℃ water bath to make a slurry, filter, and wash with a small amount of 95% ethanol (15ml × 2) until the product is free of NaCl (tested with AgNO3 solution).
- The product was distilled under reduced pressure in an 80 ℃ water bath to recover the alcohol, and the flask contained pure carboxymethyl cellulose sodium in white powder form.
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