Purpose

Metal contamination in water is a worldwide persistent problem. We developed a nano-adsorbent, TEPA-MIL-101(Cr) that exhibits effective removal of heavy metals from real water samples.

Methods

MIL-101(Cr) was synthesized under solvo-thermal condition. Then MIL-101(Cr) was dehydrated and degassed at high temperature under vacuum to generate the coordinately unsaturated sites which are used for tetraethylene pentamine (TEPA) grafting. The structures, morphologies, and compositions of the sorbents have been characterized. Langmuir and Freundlich isotherm models were applied for describing the adsorption process onto TEPA-MIL-101(Cr).

Results

The successful grafting of TEPA on MIL-101(Cr) was verified by Fourier transform infrared. The results of X-ray diffraction, scanning electron microscopy, and CHN analysis show that the structure of TEPA-MIL-101(Cr) retains the original structure of MIL-101(Cr). Thermogravimetric analysis indicates thermo-stability of the adsorbent up to 300 °C. Optimal conditions for adsorption were determined as pH = 6.5 and contact time = 1 h. The adsorption capacities of TEPA-MIL-101(Cr) for Pb(II), Cu(II), Cd(II), and Co(II) from aqueous samples were 227.5, 217.7, 221.4, and 215.6 mg/g respectively, which is on average more than 8 times that of MIL-101(Cr). Analysis of Langmuir and Freundlich models for describing the adsorption isotherms of TEPA-MIL-101(Cr) reveals that the metal ions were absorbed onto TEPA-MIL-101(Cr) by a favorable physical absorption process.

Conclusions

TEPA-MIL-101(Cr) was synthesized successfully by a simple, and cost-effective method. The removal efficiency of TEPA-MIL-101(Cr) for the metal ions achieved more than 95 % in real water samples, which in addition to its thermal stability character make it a promising candidate for water treatment purposes.

中文翻译：

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用于去除水中金属的四乙烯五胺官能化 MIL-101(Cr) 的合成和表征

目的

水中的金属污染是一个世界性的长期问题。我们开发了一种纳米吸附剂 TEPA-MIL-101(Cr)，可有效去除真实水样中的重金属。

方法

MIL-101(Cr) 是在溶剂热条件下合成的。然后将MIL-101(Cr)在真空下高温脱水和脱气，生成用于四乙烯五胺(TEPA)接枝的配位不饱和位点。已经对吸附剂的结构、形态和组成进行了表征。Langmuir 和 Freundlich 等温线模型用于描述 TEPA-MIL-101(Cr) 上的吸附过程。

结果

傅里叶变换红外验证了TEPA在MIL-101(Cr)上的成功接枝。X射线衍射、扫描电镜和CHN分析结果表明，TEPA-MIL-101(Cr)的结构保留了MIL-101(Cr)的原始结构。热重分析表明吸附剂的热稳定性高达 300 °C。吸附的最佳条件确定为 pH = 6.5 和接触时间 = 1 小时。TEPA-MIL-101(Cr) 对水样中 Pb(II)、Cu(II)、Cd(II) 和 Co(II) 的吸附能力分别为 227.5、217.7、221.4 和 215.6 mg/g，平均是 MIL-101(Cr) 的 8 倍以上。

结论

TEPA-MIL-101(Cr) 是通过一种简单且具有成本效益的方法成功合成的。TEPA-MIL-101(Cr) 对金属离子的去除效率在实际水样中达到了 95% 以上，除了其热稳定性之外，这使其成为水处理用途的有希望的候选者。