Flocculation Performance of Graphene Oxide for Removal of Methylene Blue from Water
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摘要: 以氧化石墨烯（GO）为絮凝剂，以水溶性阳离子型染料亚甲基蓝(MB)为处理对象，研究了GO对MB的絮凝效果，拟突破传统絮凝剂不能有效去除可溶性染料的瓶颈. 通过改进的Hummers法制备了GO，利用SEM、XRD、FT-IR对其进行了表征. 探讨了染料初始质量浓度、絮凝剂投加量、溶液pH以及搅拌时间对絮凝效果的影响，并通过测定GO、MB、反应前后溶液的电位和反应前后物质的红外光谱，分析了可能存在的絮凝机理. 同时，比较了几种常用的无机、有机絮凝剂对MB的絮凝效果. 结果表明：当pH=4，染料初始质量浓度为70 mg/L，絮凝剂投加量为180 mg/L，絮凝时间为9 min时，絮凝效率达到95%. 电性中和对絮凝过程起着主要作用，同时还存在吸附架桥作用. 与其他常用絮凝剂相比，GO具有投加量少、去除率高、pH适用范围广等优点，是一种具有广阔应用前景的絮凝剂.Abstract: Traditional flocculants cannot be used to effectively remove the soluble dyes. In this study, graphene oxide (GO) was synthesized by means of modified Hummers and evaluated for its material characteristics and efficiency for flocculating water-soluble cationic dye methylene blue (MB) from wastewater. The effects of pH, coagulant dosage, initial MB concentration and stirring time on MB removal were investigated. Flocculation mechanism was also explored in combination with zeta potential measurements and FT-IR. Moreover, several common inorganic and organic flocculants were compared with GO in their efficiency for MB removal. The results indicate that GO exhibits much higher efficiency in flocculating MB than the usually used flocculants. High removal efficiency (95%) is achieved by GO at the optimum conditions of the MB initial concentration of 70 mg/L and 180 mg/L GO with 9 min stirring time at pH 4. The predominant flocculation mechanism of coagulant GO is the coexistence of the neutralization mechanism and the adsorption bridge mechanism. The results of this research suggest that GO may be used extensively in the future in flocculating soluble cationic dyes for its high efficiency and extensive pH application.
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Keywords:
- graphene oxide /
- methylene blue /
- flocculation /
- flocculation mechanism /
- neutralization
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