Pakulski Dawid, Gorczyński Adam, Marcinkowski Dawid, Czepa Włodzimierz, Chudziak Tomasz, Witomska Samanta, Nishina Yuta, Patroniak Violetta, Ciesielski Artur, Samorì Paolo
Faculty of Chemistry, Adam Mickiewicz University, Uniwersytetu Poznańskiego 8, 61-614 Poznań, Poland.
Research Core for Interdisciplinary Sciences, Okayama University, 3-1-1 Tsushimanaka, Kita-ku, Okayama, 700-8530, Japan.
Nanoscale. 2021 Jun 17;13(23):10490-10499. doi: 10.1039/d1nr02255e.
Pollution of wastewater with heavy metal-ions represents one of the most severe environmental problems associated with societal development. To overcome this issue, the design of new, highly efficient systems capable of removing such toxic species, hence to purify water, is of paramount importance for public health and environmental protection. In this work, novel sorption hybrid materials were developed to enable high-performance adsorption of heavy metal ions. Towards this end, graphene oxide (GO) exhibiting various C/O ratios has been functionalized with ad hoc receptors, i.e. terpyridine ligands. The maximum adsorption capacity of highly oxidized/terpyridine hybrids towards Ni(ii), Zn(ii) and Co(ii) was achieved at pH = 6 and 25 °C reaching values of 462, 421 and 336 mg g-1, respectively, being the highest reported in the literature for pristine GO and GO-based sorbents. Moreover, the uptake experiments showed that heavy metal ion adsorption on GO-Tpy and GOh-Tpy is strongly dependent on pH in the range from 2 to 10, as a result of the modulation of interactions at the supramolecular level. Moreover, the ionic strength was found to be independent of heavy metal ion adsorption on GO-Tpy and GOh-Tpy. Under ambient conditions, adsorption capacity values increase with the degree of oxidation of GO because dipolar oxygen units can both interact with heavy-metal ions via dipole-dipole and/or ionic interactions and enable bonding of more covalently anchored terpyridine units. Both adsorption isotherms and kinetics studies revealed that the uptake of the heavy metal ions occurs at a monolayer coverage, mostly controlled by the strong surface complexation with the oxygen of GO and nitrogen-containing groups of terpyridine. Furthermore, selectivity of the hybrid was confirmed by selective sorption of the above heavy metal ions from mixtures involving alkali (Na(i), K(i)) and alkaline Earth (Mg(ii), Ca(ii)) metal ions due to the chelating properties of the terpyridine subunits, as demonstrated with municipal drinking (tap) water samples. Our findings provide unambiguous evidence for the potential of chemical tailoring of GO-based materials with N-heterocyclic ligands as sorbent materials for highly efficient wastewater purification.
重金属离子对废水的污染是与社会发展相关的最严重环境问题之一。为克服这一问题，设计能够去除此类有毒物质从而净化水的新型高效系统，对公众健康和环境保护至关重要。在这项工作中，开发了新型吸附杂化材料以实现对重金属离子的高性能吸附。为此，具有不同C/O比的氧化石墨烯（GO）已用特定受体即三联吡啶配体进行了功能化。高度氧化的/三联吡啶杂化物对Ni(ii)、Zn(ii)和Co(ii)的最大吸附容量在pH = 6和25 °C时分别达到462、421和336 mg g-1，是文献中报道的原始GO和基于GO的吸附剂的最高值。此外，吸附实验表明，由于超分子水平上相互作用的调节，GO-Tpy和GOh-Tpy对重金属离子的吸附在2至10的pH范围内强烈依赖于pH值。此外，发现离子强度与GO-Tpy和GOh-Tpy对重金属离子的吸附无关。在环境条件下，吸附容量值随GO的氧化程度增加，因为偶极氧单元既能通过偶极-偶极和/或离子相互作用与重金属离子相互作用，又能使更多共价锚定的三联吡啶单元键合。吸附等温线和动力学研究均表明，重金属离子的吸附发生在单层覆盖，主要受与GO的氧和三联吡啶含氮基团的强表面络合控制。此外，由于三联吡啶亚基的螯合特性，通过从包含碱金属（Na(i)、K(i)）和碱土金属（Mg(ii)）、Ca(ii)）金属离子的混合物中选择性吸附上述重金属离子，证实了该杂化物的选择性，市政饮用水（自来水）样品也证明了这一点。我们的研究结果为用N-杂环配体对基于GO的材料进行化学剪裁作为高效废水净化吸附剂材料的潜力提供了明确证据。
