Environment Engineering Program, School of Energy, Environmental, Biological, and Medical Engineering, University of Cincinnati, P.O. Box 210012, Cincinnati, OH 45221-0012, USA.
Chemosphere. 2013 Jan;90(2):395-402. doi: 10.1016/j.chemosphere.2012.07.034. Epub 2012 Aug 22.
The adsorptive capacity of multiwall CNTs for copper species in water depends on the type of functional group present on their surface. The alcohol (OH) and acid (COOH) network forces formed by van der Waals bonds within the CNT bundles can define their aggregate state and available sites for copper adsorption. Copper is attracted to different oxygen radicals on the surface and within the bundles of CNTs. The effect of initial concentration shown on isotherm curves was investigated as an impact of different network forces and the presence of impurities leached from as-received CNTs. Deprotonation of CNTs reduced the COOH network forces, improved adsorption capacity and removed the effect of initial concentration. Impurities leached from CNTs under the effect of pH were less than 1 mg g(-1) for each metal, which was insignificant compared to copper in solution. Pristine CNTs were acid washed and purified (Ox-CNTs), improving their adsorption capacity, but the effect of initial concentration was still present. Adsorption of copper is stronger for OH-functionalized CNTs, followed by deprotonated COOH-functionalized CNTs, as-received COOH-functionalized CNT, Ox-CNTs and finally pristine CNTs. FTIR, XPS and zeta potential measurements were used to identify and quantify the different surface functional groups present on CNTs.
多壁 CNT 对水中铜物种的吸附能力取决于其表面存在的官能团类型。 CNT 束内范德华键形成的醇（OH）和酸（COOH）网络力可以定义其聚集状态和可用的铜吸附位点。铜被 CNT 束内表面和表面上的不同含氧自由基吸引。等温曲线上显示的初始浓度的影响被视为不同网络力的影响以及从原始 CNT 中浸出的杂质的存在的影响。CNTs 的去质子化降低了 COOH 网络力，提高了吸附能力，并消除了初始浓度的影响。在 pH 作用下从 CNTs 中浸出的杂质每种金属都小于 1mg g(-1)，与溶液中的铜相比微不足道。原始 CNT 经过酸清洗和纯化（Ox-CNTs），提高了其吸附能力，但初始浓度的影响仍然存在。OH 功能化 CNTs 对铜的吸附更强，其次是去质子化的 COOH 功能化 CNTs、原始 COOH 功能化 CNT、Ox-CNTs 最后是原始 CNTs。FTIR、XPS 和动电电势测量用于鉴定和定量 CNTs 上存在的不同表面官能团。
