Abstract Rapid technological developments of electrical and electronic equipment raise a persistence demand for precious elements. The presence of precious metals (PMs) makes e waste recycling economically attractive. In the present study, magnetic multiwalled carbon nanotubes (Fe3O4-o-MWCNTs) were synthesized and utilized as a hydrometallurgical method for extraction of precious elements (Ag, Au, Pd and Pt) from e waste. MWCNTs were synthesized with chemical vapor deposition of acetylene using Ni-Fe-Co/Al2O3 catalyst, decorated with Fe3O4 nanoparticle via co-precipitation and characterized by multiple characterization techniques. Morphology shows that MWCNTs have been efficiently produced (having ~10–20 µm length and ~30 nm internal diameter) and successfully decorated with Fe3O4 nanoparticles. At optimized conditions the adsorbent shows 98% recovery with 3 mol/L nitric acid as eluent for Pd, Ag and Au. However, Pt elution was carried out with 1 mol/L sodium perchlorate. Maximum adsorption capacity calculated from Langmuir isotherm was found as 112, 57, 106 and 104 mg/g for Pd, Pt, Ag and Au, respectively. Results show that Fe3O4-o-MWCNTs composite is a good adsorbent material for extraction of precious metals from e waste due to its high efficiency, sensitivity, reusability and stability in acidic media.

中文翻译：

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磁性多壁碳纳米管复合材料从电子废弃物中分散固相萃取贵金属离子

摘要 电子电气设备技术的飞速发展对贵重元素提出了持久的需求。贵金属 (PM) 的存在使电子废物回收在经济上具有吸引力。在本研究中，磁性多壁碳纳米管 (Fe3O4-o-MWCNTs) 被合成并用作湿法冶金方法从电子废物中提取贵元素（Ag、Au、Pd 和 Pt）。MWCNTs 是使用 Ni-Fe-Co/Al2O3 催化剂通过乙炔的化学气相沉积合成的，通过共沉淀用 Fe3O4 纳米颗粒装饰，并通过多种表征技术进行表征。形态学表明，多壁碳纳米管已被有效地生产（具有~10-20 µm 长度和~30 nm 内径）并成功地用 Fe3O4 纳米粒子装饰。在优化条件下，吸附剂显示出 98% 的回收率，使用 3 mol/L 硝酸作为 Pd、Ag 和 Au 的洗脱液。但是，Pt 洗脱是用 1 mol/L 高氯酸钠进行的。根据 Langmuir 等温线计算的最大吸附容量分别为 112、57、106 和 104 毫克/克，分别为 Pd、Pt、Ag 和 Au。结果表明，Fe3O4-o-MWCNTs复合材料由于其高效、灵敏、可重复使用和在酸性介质中的稳定性，是一种很好的从电子废物中提取贵金属的吸附材料。