Yang Kou, Nikolaev Konstantin G, Li Xiaolai, Ivanov Artemii, Bong Jia Hui, Erofeev Ivan, Mirsaidov Utkur M, Kravets Vasyl G, Grigorenko Alexander N, Zhang Shanqing, Qiu Xueqing, Novoselov Kostya S, Andreeva Daria V
Institute for Functional Intelligent Materials, National University of Singapore, Singapore 117544, Singapore.
School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou 510006, China.
Proc Natl Acad Sci U S A. 2024 Oct 15;121(42):e2414449121. doi: 10.1073/pnas.2414449121. Epub 2024 Oct 7.
The extraction of gold (Au) from electronic waste (e-waste) has both environmental impact and inherent value. Improper e-waste disposal poses environmental and health risks, entailing substantial remediation and healthcare costs. Large efforts are applied for the recovery of Au from e-waste using complex processes which include the dissolution of Au, its adsorption in an ionic state and succeeding reduction to metallic Au. These processes themselves being complex and utilizing harsh chemicals contribute to the environmental impact of e-waste. Here, we present an approach for the simultaneous recovery and reduction of Au and Au ions from e-waste to produce solid Au forms, thus skipping several technological steps. We develop a nanoscale cross-dimensional composite material via self-assembly of two-dimensional graphene oxide and one-dimensional chitosan macromolecules, capable of acting simultaneously as a scavenger of gold ions and as a reducing agent. Such multidimensional architecture doesn't require to apply any voltage for Au adsorption and reduction and solely relies on the chemisorption kinetics of Au ions in the heterogeneous GO/CS nanoconfinements and their chemical reduction on multiple binding sites. The cooperative phenomena in ionic absorption are responsible for the extremely high efficiency of gold extraction. The extraction capacity reaches 16.8 g/g for Au and 6.2 g/g for Au, which is ten times larger than any existing gold adsorbents can propose. The efficiency is above 99.5 wt.% (current limit is 75 wt.%) and extraction ability is down to very low concentrations of 3 ppm.
从电子废物（电子垃圾）中提取金（Au）既具有环境影响又具有内在价值。电子废物的不当处置会带来环境和健康风险，需要大量的修复和医疗成本。人们付出了巨大努力，采用复杂的工艺从电子废物中回收金，这些工艺包括金的溶解、其离子态的吸附以及随后还原为金属金。这些工艺本身复杂且使用苛刻的化学物质，加剧了电子废物对环境的影响。在此，我们提出一种从电子废物中同时回收和还原金及金离子以生产固态金形式的方法，从而跳过几个技术步骤。我们通过二维氧化石墨烯和一维壳聚糖大分子的自组装开发出一种纳米级跨维度复合材料，它能够同时作为金离子的 scavenger 和还原剂。这种多维结构在金的吸附和还原过程中不需要施加任何电压，仅依赖于金离子在异质 GO/CS 纳米限制环境中的化学吸附动力学及其在多个结合位点上的化学还原。离子吸收中的协同现象导致了极高的金提取效率。金的提取容量达到 16.8 g/g，金的提取容量达到 6.2 g/g，这比任何现有的金吸附剂所能达到的容量大十倍。效率高于 99.5 wt.%（当前限制为 75 wt.%），提取能力低至 3 ppm 的极低浓度。 （注：scavenger 此处结合语境可译为“捕获剂”之类更合适的词，但原文未给出准确对应中文，暂保留英文）
