Enhanced extraction of copper from electronic waste via induced morphological changes using supercritical CO2
Enhanced extraction of copper from electronic waste via induced morphological changes using supercritical CO2
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DOI：
10.1016/j.resconrec.2020.105296
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发表时间：
2021-03-06
影响因子：
13.2
通讯作者：
Park, Ah-Hyung Alissa
中科院分区：
文献类型：
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作者：
Hsu, Emily;Durning, Christopher J.;Park, Ah-Hyung Alissa
电子垃圾(电子垃圾)是世界上增长最快的垃圾类别之一。本研究探讨了超临界二氧化碳(SCCO(2))和水溶液作为共溶剂来处理电子垃圾，特别是用于提取铜。选择印刷电路板(PCB)作为研究的电子废弃物。为了进行控制实验，制备了熔压铜箔和聚碳酸酯薄片作为多氯联苯的替代品。结果发现，SCCO(2)和酸预处理会导致聚合物的形态发生剧烈变化，产生气孔、裂缝和分层。这一发现被转化为实际的废旧印刷电路板系统。这一独特的工艺包括用SCCO(2)和120℃的硫酸对印刷电路板进行前处理。C和148大气压下浸泡30分钟，然后在环境条件下，在含有2M硫酸和0.2M过氧化氢的溶剂中浸泡处理过的多氯联苯。实验结果表明，经SCCO(2)和酸处理后，印制板中82%的铜在4h内被提取出来，导致塑料(聚合物组分)的结晶，形成气孔，削弱了印制板的结构，从而促进了溶剂向埋藏金属界面的迁移。这种使用SCCO(2)的新工艺可以减少从电子垃圾中提取铜的物理处理(例如，印刷电路板的研磨)和酸的使用，为目前的金属回收方法提供了一种更绿色的替代方案，这些方法是能源密集型的，而且对环境的影响很大。
Electronic waste (e-waste) is one of the fastest growing waste segments in the world. This study investigates the use of supercritical CO2 (scCO(2)) and aqueous acid as co-solvent for the treatment of e-waste, specifically for the extraction of copper. Printed circuit board (PCB) was selected as the e-waste of study. In order to perform controlled experiments, melt-pressed Cu foil and polycarbonate sheets were prepared as surrogates for PCBs. It was found that a scCO(2) and acid pre-treatment induced drastic morphological changes in the polymer, creating pores, cracks, and delamination. This finding was translated to the actual waste PCB system. This unique process involved the pre-treatment of the PCB with scCO(2) and aqueous sulfuric acid at 120. C and 148 atm for 30 min followed by leaching of the treated PCB in a solvent containing 2 M sulfuric acid and 0.2 M hydrogen peroxide at ambient conditions. Experimental results showed that 82% of the copper contained in the PCB was extracted in under 4 h. The characterization of the PCB demonstrated that the pre-treatment with scCO(2) and acid induced the crystallization of the plastics (polymer component), creating pores and weakening the structure of the PCB, thereby enhancing the transport of the solvent to the buried metal interfaces. This novel process using scCO(2) could reduce physical processing (e.g. grinding of the PCB) and acid usage during the extraction of Cu from e-waste, providing a greener alternative for current methods of recycling of metals, which are energy intensive with large environmental footprints.