Rosillo-Lopez Martin, Salzmann Christoph G
Department of Chemistry, University College London 20 Gordon Street London WC1H 0AJ UK
RSC Adv. 2018 Mar 20;8(20):11043-11050. doi: 10.1039/c8ra00823j. eCollection 2018 Mar 16.
Heavy metals such a lead or cadmium have a wide range of detrimental and devastating effects on human health. It is therefore of paramount importance to efficiently remove heavy metals from industrial wastewater streams as well as drinking water. Carbon materials, including graphene and graphene oxide (GO), have recently been advocated as efficient sorption materials for heavy metals. We show that highly carboxylated graphene nanoflakes (cx-GNF) outperform nano-graphene oxide (nGO) as well as traditional GO with respect to extracting Fe, Cu, Fe, Cd and Pb cations from water. The sorption capacity for Pb, for example, is more than six times greater for the cx-GNF compared to GO which is attributed to the efficient formation of lead carboxylates as well as strong cation-π interactions. The large numbers of carboxylic acid groups as well as the intact graphenic regions of the cx-GNF are therefore responsible for the strong binding of the heavy metal cations. Remarkably, the performance of the as-made cx-GNF can easily compete with previously reported carbon materials that have undergone additional chemical-functionalisation procedures for the purpose of heavy-metal extraction. Furthermore, the recyclability of the cx-GNF material with respect to Pb loading is demonstrated as well as the outstanding performance for Pb extraction in the presence of excess Ca or Mg cations which are often present under environmental conditions. Out of all the graphene materials, the cx-GNF therefore show the greatest potential for future application in heavy-metal extraction processes.
铅或镉等重金属对人体健康有广泛的有害和破坏性影响。因此，从工业废水流以及饮用水中有效去除重金属至关重要。包括石墨烯和氧化石墨烯（GO）在内的碳材料，最近被倡导作为重金属的高效吸附材料。我们表明，在从水中提取铁、铜、铁、镉和铅阳离子方面，高度羧基化的石墨烯纳米片（cx-GNF）优于纳米氧化石墨烯（nGO）以及传统的GO。例如，cx-GNF对铅的吸附能力比GO高出六倍多，这归因于羧酸铅的有效形成以及强大的阳离子-π相互作用。因此，大量的羧酸基团以及cx-GNF完整的石墨烯区域是重金属阳离子强结合的原因。值得注意的是，所制备的cx-GNF的性能很容易与先前报道的为重金属提取目的而经过额外化学功能化程序的碳材料相媲美。此外，还展示了cx-GNF材料对铅负载的可回收性，以及在通常存在于环境条件下的过量钙或镁阳离子存在下对铅提取的出色性能。在所有石墨烯材料中，cx-GNF因此在重金属提取过程中显示出最大的未来应用潜力。
