pH值对废旧棉纤维水热碳化的影响

The Effect of pH on the Hydrothermal Carbonization of Waste Cotton Fiber

以废旧棉纤维为碳源,在亚临界水中制备了形貌结构良好的碳微球,主要探讨了不同初始pH值对棉纤维水热碳化过程的影响规律。亚临界水可破坏棉纤维的晶体结构,使棉纤维碳化形成石墨化程度较低的碳材料,且在碱性、中性和酸性环境下,棉纤维都可脱水碳化,H^+对棉纤维的脱水碳化影响较弱;pH值对碳化产物的结构性能有重要影响,pH值为3.5时可得到粒径均匀的球形碳材料,含碳量达74.99%。液相产物分析表明,pH值越小,棉纤维水热反应过程中葡萄糖的收率越大,产物形貌结构也越好;pH值较高时,葡萄糖的收率较低,产物中难以出现球状结构物质。H^+对碳化产物的含碳量以及热值的提高有益。文章的研究结果可为废旧棉纤维的高值化再利用提供参考。

Carbon microspheres with good morphology and structure were prepared in subcritical water by using waste cotton fiber as carbon source,and then the influence of different initial pH on the hydrothermal carbonization of cotton fiber was discussed.Subcritical water can destroy the crystal structure of cotton fiber,carbonize the fiber and turn it into a carbon material with low degree of graphitization.Whether in alkali,or neutral or acid condition,the cotton fiber can be dehydrated and carbonized.While H+has minor influence on the dehydration and carbonization of the cotton fiber,pH has significant impact on the structural performance of the carbonized product,and when pH=3.5,carbon microspheres with uniform particle size and carbon content up to74.99%can be obtained.The analysis on liquid-phase product shows that the lower the pH,the higher the yield of glucose and the better the morphological structure during the hydrothermal reaction of cotton fiber,and vice versa.The high concentration of H+is beneficial to the yield of carbonized product and the degree of carbonization.The research results in this paper provide a reference for the value-added reutilization of waste cotton fiber.