水溶性富勒烯对U(Ⅵ)在氧化多壁碳纳米管上吸附的影响

Effect of Hydroxylated and Carboxylated Fullerenes on Oxidized Multi-walled Carbon Nanotubes Adsorbing U(Ⅵ)

采用静态试验法研究了水溶性富勒烯对U(Ⅵ)在氧化多壁碳纳米管上吸附的影响。结果表明,羟基化富勒烯(C60(OH)n)和羧基化富勒烯(C60(C(COOH)2)n)的加入对U(Ⅵ)在氧化多壁碳纳米管上的吸附量影响作用类似。在pH<3范围内,羟基化富勒烯和羧基化富勒烯对吸附几乎没有影响,在pH>3以后,二者开始抑制碳纳米管对U(Ⅵ)的吸附。较低浓度(10 mg/L)的C60(OH)n对U(Ⅵ)的吸附几乎没有影响。而等量的C60(C(COOH)2)n已呈现出明显的抑制作用。但两者的作用机理不同,前者可能是由于羟基化富勒烯和U(Ⅵ)竞争氧化多壁碳纳米管上的吸附位点造成的,后者则可能改变了氧化多壁碳纳米管的表面电荷。用双位点模型对不同固液比和U(Ⅵ)初始浓度下U(Ⅵ)的吸附率随C60(OH)n和C60(C(COOH)2)n初始浓度的变化进行了拟合得到了很好的结果。

The adsorption of U(Ⅵ)on oxidized multi-walled carbon nanotubes(oMWCNTs)as a function of two kinds of soluble fullerene(i.e.hydroxylated fullerene(C60(OH)n)and carboxylated fullerene(C60(C(COOH)2)n) were studied under ambient conditions using batch techniques. The results indicated that the drastic effect of C60(OH)n and C60(C(COOH)2)n on the adsorption of U(Ⅵ) on oMWCNTs have almost not been found at pH<3, whereas the negative effect was observed at pH>3. No obvious inhibition effect on U(Ⅵ) adsorption was induced by C60(OH)n at a lower concentration. C60(C(COOH)2)n showed a significant effect at 10 mg/L. The mechanism of C60(OH)n may be contributed to the competitive adsorption sites on oMWCNTs between C60(OH)n and U(Ⅵ).The surface charge of oMWCNTs may be changed by C60(C(COOH)2)n.The double site sorption model(DSSM) was applied to simulate the adsorption isotherms of U(Ⅵ) in the presence of C60(OH)n and fitted the experimental data well.