辅助插层剂乙酸对微波法制备膨胀石墨的影响

Effect of Acetic Acid as Auxiliary Intercalation Agent on Preparation of Expanded Graphite by Microwave Method

以天然鳞片石墨为原料,KMnO_4为氧化剂,HNO_3为主插层剂,CH_3COOH为辅助插层剂,采用微波法制备膨胀石墨,利用扫描电镜(SEM)进行微观形貌分析。考察辅助插层剂乙酸对膨胀效果的影响,探究膨胀石墨的最佳制备条件。结果表明,辅助插层剂乙酸对膨胀体积影响显著,EG_3(HNO_3+CH_3COOH混酸作插层剂)的膨胀体积是EG2(HNO_3作插层剂)的2倍;当石墨、KMn O_4、CH_3COOH与HNO_3用量比为1 g∶0.4 g∶6.5 mL∶13 mL时,在40℃下插层反应40 min,膨胀40 s后,膨胀石墨的膨胀体积最大,为121.88 mL/g。由SEM分析可知,天然鳞片石墨为层片结构,插层后结构变化不明显;对比3种插层剂体系可知,EG3蠕虫结构明显,均匀性良好,孔隙结构发达;说明硝酸作为主插层剂,乙酸作为辅助插层剂,能有效改善膨胀效果,使膨胀体积明显提高。

Expanded graphite was prepared by microwave with natural flake graphite as raw material,potassium permanganate as oxidant,nitric acid as intercalating agent and acetic acid as auxiliary intercalation agent.The expanded graphite was characterized by SEM.The effect of acetic acid as auxiliary intercalation agent on the expansion volume and the optimal conditions for preparation of expanded graphite were investigated.The results show that acetic acid as auxiliary intercalation agent has a significant effect on the expansion volume,and the expansion volume of EG3(HNO3+CH3COOH as intercalation agent)is twice as large as EG2(HNO3 as intercalation agent).The Expansion volume is the largest,achieving 121.88 mL/g,when dosage ratio of natural flake graphite,potassium permanganate,acetic acid and nitric acid is 1 g∶0.4 g∶6.5 mL∶13 mL,the intercalation time is 40 min at 40℃,and the expansion time is 40 s.The SEM analysis show that the natural flake graphite is layered,and the graphite structure has no obvious change after intercalation;EG3 has obvious worm structure compared with EG1 and EG2,and the pore structure is uniform and developed.It shows that the expansion effect is obviously improved and the expansion volume is obviously improved,when nitric acid is as the main intercalation agent and acetic acid as the auxiliary intercalation agent.