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melodybusy

木虫 (著名写手)

[求助] 氧化石墨烯水溶液算是胶体体系么?给个高亮吧!大家交流下

如题,氧化石墨烯用hurmurs方法制备后,超声在水溶液里。分散性还挺好的。放置那里几天后就分层了,明显的上面是水系,下面就是氧化石墨烯? 所以想问下这个氧化石墨烯水溶液是胶体体系吗??
另外,如果这个是胶体体系,那么氧化石墨烯胶体带各种电荷??在电场作用下怎么运动?
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zzlcsu

铁虫 (正式写手)

引用回帖:
8楼: Originally posted by melodybusy at 2012-12-20 20:33:21
我超声后就是黑色的胶体状溶液啊! 是0.1g/ml的浓度...

是偏棕色的,越稀的话应该会偏红一点吧,0.1mg/ml还沉的话应该就是氧化剥离没做好
The graphene oxide used in this work was prepared from natural graphite  (Alfa Aesar) by using a modified Hummers method.
5 g of graphite and 2.5 g  of sodium nitrate (NaNO3) were mixed with 160 mL of concentrated sulfuric acid (H2SO4, 95%, Sigma–Aldrich) in a 500 mL flask. After the mixture was stirred for 30 min in an ice bath, 18 g of potassium permanganate (KMnO4) was
added under vigorous stirring. The rate of addition was carefully controlled to keep the reaction temperature lower than 20 °C. After th e mixture was continuously stirred at room temperature(我这里用的是40度水浴,温度不能过高,这里面全是七氧化二锰,50度剧烈分解,很危险的。后面里面会变得非常粘稠,和泥浆差不多,所以磁力搅拌一定要给力) overnight, 150 mL of deionized  (DI) water was slowly added under vigorous agitation. After the diluted suspension was stirred for one day, 50 mL of 30 wt.% H2O2 was added to the mixture. Finally, the mixture wa s washed by rinsing and centrifugation with 5 wt.% HCl and then DI water for several times. (水洗会比较难离心,酸洗基本3000转就可以,水洗到后面我是20000转5分钟都不能离心的彻底) Chemical exfoliation of thus-obtained graphite oxide was carried out in an ultrasonic bath. After ultrasonication, a GO colloid was obtained.
后者用improve hummer method,效果也不错
11楼2012-12-20 21:38:43
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xiejf

专家顾问 (文学泰斗)

麦麦爸爸爱小牛

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melodybusy: 金币+2, ★★★很有帮助 2012-12-20 20:34:24
一般认为是胶体,尺寸差不多
麦麦爸爸爱小牛
2楼2012-12-20 15:17:49
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zzlcsu

铁虫 (正式写手)

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melodybusy: 金币+3, ★★★很有帮助 2012-12-20 20:34:43
是胶体的,带负电荷,上面有很多的羧基,羟基等,在酸里面会聚沉的,碱性易还原而变黑沉淀,中性条件可以保存一段时间,至于你说的分层可能是氧化的时候没做好或者超声没有剥开
3楼2012-12-20 15:41:35
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zzlcsu

铁虫 (正式写手)

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melodybusy: 金币+3, ★★★很有帮助 2012-12-20 20:30:50
引用回帖:
3楼: Originally posted by zzlcsu at 2012-12-20 15:41:35
是胶体的,带负电荷,上面有很多的羧基,羟基等,在酸里面会聚沉的,碱性易还原而变黑沉淀,中性条件可以保存一段时间,至于你说的分层可能是氧化的时候没做好或者超声没有剥开

这是7mg/ml的,放置2天下面不会沉淀的

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4楼2012-12-20 15:45:16
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