【公開日：2023.07.31】【最終更新日：2023.05.12】
課題データ / Project Data
課題番号 / Project Issue Number
22UT0164
利用課題名 / Title
PCB廃棄物の溶媒浸出
利用した実施機関 / Support Institute
東京大学 / Tokyo Univ.
機関外・機関内の利用 / External or Internal Use
内部利用（ARIM事業参画者以外）/Internal Use (by non ARIM members)
技術領域 / Technology Area
【横断技術領域 / Cross-Technology Area】（主 / Main）計測・分析/Advanced Characterization（副 / Sub）-
【重要技術領域 / Important Technology Area】（主 / Main）マテリアルの高度循環のための技術/Advanced materials recycling technologies（副 / Sub）-
キーワード / Keywords
Solvent extraction, acid leaching, critical materials, waste PCB,X線回折/X-ray diffraction,分離・精製技術/ Separation/purification technology,資源循環技術/ Resource circulation technology
利用者と利用形態 / User and Support Type
利用者名（課題申請者）/ User Name (Project Applicant)
金 容九
所属名 / Affiliation
東京大学
共同利用者氏名 / Names of Collaborators in Other Institutes Than Hub and Spoke Institutes
Diana Gomez
ARIM実施機関支援担当者 / Names of Collaborators in The Hub and Spoke Institutes
利用形態 / Support Type
（主 / Main）機器利用/Equipment Utilization（副 / Sub）-
利用した主な設備 / Equipment Used in This Project
報告書データ / Report
概要（目的・用途・実施内容）/ Abstract (Aim, Use Applications and Contents)
The extraction of valuable metals from secondary resources is a priority in the context of the circular economy. Solvent extraction is one of the conventional processes employed for the extraction of metals. This work investigates the extraction of Er, Ir, and Ag from printed circuit boards (PCBs) by synergistic solvent extraction. XRD analyses were carried on to determine the heterogenicity of the sample after some purification with the proposed method.
実験 / Experimental
Waste Printed Circuit Boards (WPCBs) were sorted manually from shredded waste electric appliances provided by a waste recovery company in Japan. The sample was shredded and divided into two size fractions, above and below 250 μm. Then, the samples were digested (0.5% weight/volume) in aqua regia 1 M at 75°C for 120 min. The dissolutions were analyzed by an inductively coupled plasma optical emission spectrometer (ICP-OES, Perkin Elmer precisely, Optima 5300 DV dual detector), and then alkali precipitated with NaOH. The precipitates were collected and left to dry to analyze them with X-ray diffraction (XRD).
結果と考察 / Results and Discussion
The ICP-OES analysis showed a high concentration of Erbium (Er) and Iridium (Ir), two critical metals with high value for technological applications. Eh-pH diagrams obtained from the Er-Ir-Ag-Cl-N-Na-H2O system at 25 °C showed no precipitation in the range in which precipitation was obtained experimentally. Results with the X-ray diffraction (Figure 1) showed some coincidences with the Erbium selenide structure, but Selenium (Se) was not detected by subsequent ICP-OES analysis; it is concluded that the general structure of the WPCB is heterogeneous. Nonetheless, in Figure 1 it is possible to observe the change of structure from the WPBS without further treatment (red line) to that of the samples after leaching and alkali precipitation (Figure 2). After analyzing these results, the reason for precipitation is attributed to the formation of metal hydroxides not soluble in the solution, as suggested by the literature (Yu et al., 2022).
Although the simple process given to
the sample (i.e. shredding, aqua regia dissolution, and alkali precipitation)
to concentrate the target elements of this study, Er and Ir, didn’t show a
clear crystalline structure, there is evidence of changes in the structure of
the analyzed samples. This method will be taken as a pretreatment for further
purification that is clearly required to concentrate and identify the desired
elements by X-ray diffraction.
図・表・数式 / Figures, Tables and Equations
Figure 1. XRD analysis comparison of initial sample of WPCB and precipitates from enriched Er and Ir samples (below and above 250 μm, respectively).
Figure 2. Precipitated samples after alkali precipitation. Wet samples from (a) > 250 μm fraction size or Ir enriched sample, (b) < 250 μm fraction size or Er enriched sample, and dry samples from (c) > 250 μm fraction size and (d) < 250 μm fraction size.
その他・特記事項（参考文献・謝辞等） / Remarks(References and Acknowledgements)
Yu, S., Liu, Y., Pang, H., Tang, H., Wang, J., Zhang, S., & Wang, X. (2022). Novel nanomaterials for environmental remediation of toxic metal ions and radionuclides. Emerging Nanomaterials for Recovery of Toxic and Radioactive Metal Ions from Environmental Media, 1–47. https://doi.org/10.1016/B978-0-323-85484-9.00002-9
成果発表・成果利用 / Publication and Patents
論文・プロシーディング（DOIのあるもの） / DOI (Publication and Proceedings)
口頭発表、ポスター発表および、その他の論文 / Oral Presentations etc.
特許 / Patents
特許出願件数 / Number of Patent Applications：0件
特許登録件数 / Number of Registered Patents：0件