Adsorption of sulfamethazine by multi-walled carbon nanotubes: effects of aqueous solution chemistry
Adsorption of sulfamethazine by multi-walled carbon nanotubes: effects of aqueous solution chemistry
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DOI：
10.1039/c4ra15056b
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发表时间：
2015-03
期刊：
影响因子：
3.9
通讯作者：
Quanquan Yang;Guangcai Chen;Jian-feng Zhang;Helian Li
中科院分区：
文献类型：
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作者：
Quanquan Yang;Guangcai Chen;Jian-feng Zhang;Helian Li
研究了不同pH、离子强度、阳离子和阴离子条件下，原始和羟基化多壁碳纳米管（P-MWCNTs、H-MWCNTs）对磺胺乙嗪（SMZ）的吸附性能。结果表明，拟二阶模型和Langmuir模型可以很好地描述SMZ在MWCNTs上的吸附。SMZ在MWCNTs上的吸附是离子强度和pH依赖性的，这表明疏水和静电相互作用可能是主要的吸附机制。0.5 mM处阳离子的存在对SMZ吸附有不同的影响。在溶液pH为2.3和4.9时，由于Cu2+与SMZ+和SMZ±的竞争作用，Cu2+对SMZ的吸附量略微下降了10% ~ 20%。而在pH为7.4和10.0时，Cu2+对SMZ−的吸附增加了20% ~ 60%，这是由于Cu2+ -SMZ络合物的促进作用。Al3+促进了SMZ在P-MWCNTs上的吸附，这可能是由于Al3+通过金属桥的促进作用，而抑制了H-MWCNTs对SMZ的吸附，这可能是由于Al3+与SMZ对带负电官能团的竞争作用，以及在pH为2.3、4.9和7.4时吸附的Al3+具有较大水化半径的屏蔽作用。随着0.5 mM阴离子（Cl−、CO32−、SO42−、PO43−）的加入，由于MWCNTs表面负电荷密度的增加，SMZ吸附量略有下降。μ-FTIR结果表明，π -π相互作用也可能在吸附过程中起重要作用。
The adsorption of sulfamethazine (SMZ) by pristine and hydroxylated multi-walled carbon nanotubes (P-MWCNTs, H-MWCNTs) was studied under varied pH, ionic strength, cations and anions in solution. The results suggest that the SMZ adsorption onto MWCNTs can be depicted well by the pseudo-second-order and Langmuir models. The adsorption of SMZ onto MWCNTs was ionic strength and pH dependent, which indicated hydrophobic and electrostatic interactions, may be the main adsorption mechanisms. The presence of cations at 0.5 mM showed different effects on SMZ adsorption. Cu2+ slightly decreased SMZ adsorption by 10% to 20% at solution pH of 2.3 and 4.9, due to the competing effect of Cu2+ with SMZ+ and SMZ±. But Cu2+ increased SMZ− adsorption by 20% to 60% at solution pH of 7.4 and 10.0, due to the facilitating effect of the complex formation of Cu2+–SMZ. Al3+ promoted the SMZ adsorption onto P-MWCNTs, which can be attributed to the facilitating effect of Al3+ through a metal bridge, while inhibiting the SMZ adsorption by H-MWCNTs, which can be ascribed to the competing effect between Al3+ and SMZ for the negatively charged functional groups and the shielding effect of adsorbed Al3+ with a larger hydration radius at pH of 2.3, 4.9 and 7.4. SMZ adsorption was slightly decreased with the addition of 0.5 mM anions (Cl−, CO32−, SO42−, PO43−) due to the increase in density of negative charge on the MWCNTs' surface. The μ-FTIR results showed that π–π interaction may also play an important role in the adsorption process.