Adsorption properties of graphene oxide/SiO2 composites for Cd(Ⅱ)
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摘要: 以氧化石墨烯(GO)、正硅酸乙酯(TEOS)为原料,聚氧乙烯-聚氧丙烯-聚氧乙烯(P123)为表面活性剂,合成了GO/SiO2复合材料。通过静态吸附试验,探讨了pH、GO/SiO2投加量、吸附时间和Cd(Ⅱ)初始浓度对GO/SiO2吸附Cd(Ⅱ)的影响,采用了FTIR、XRD、SEM和EDS对GO/SiO2吸附Cd(Ⅱ)进行表征分析,并探讨了其对Cd(Ⅱ)的吸附机制。结果表明,当溶液pH为8.5,投加量为0.25 g/L,吸附时间为100 min时,GO/SiO2吸附Cd(Ⅱ)效果最佳。吸附过程较好的拟合了准二级动力学模型(R2 ≈1)和Freundlich等温吸附模型(R2 ≈1)。XRD表明SiO2与GO成功复合;FTIR、SEM等结果表明,GO/SiO2吸附Cd(Ⅱ)前后自身结构并未发生变化,其对Cd(Ⅱ)具有很好的吸附效果,对Cd(Ⅱ)的吸附机制以—OH、—COOH的离子交换作用为主,Si—OH的络合反应并存。Abstract: The graphene oxide/SiO2 composite (GO/SiO2) was fabricated using graphene oxide (GO), ethylsilicate (TEOS) as the raw material, oxygen polyoxyethylene-polypropylene-polyoxyethylene (P123) as the surfactant. Through a static test, different experimental parameters such as solution pH, dosing, adsorption time and initial concentration were examined to investigate their effects on adsorption of cadmium by GO/SiO2. The GO/SiO2 composite was investigated by FTIR, XRD, SEM and EDS. The experimental results show that the optimal pH, dosing, adsorption time is 8.5, 0.25 g/L, and 100 min, respectively. The equilibrium data fit well with the pseudo-second-order model(R2 ≈1) and Freundlich model(R2 ≈1). XRD indicate that SiO2 has been successfully combined with GO. FTIR and SEM indicate that GO/SiO2 structure itself keeps unchanged, and the GO/SiO2 has good adsorption effect on Cd(Ⅱ), in which ionexchange of —OH and —COOH play a major role, with the assistant of complexation reaction of Si—OH in the adsorption.
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Key words:
- graphene oxide(GO) /
- SiO2 /
- composites /
- Cd(Ⅱ) /
- adsorption
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