Cadmium (Cd), cobalt (Co), nickel (Ni), and zinc (Zn) are important components of batteries and renewable energy technologies but their recovery from pregnant leach solutions or removal from polluted soil systems and water bodies remain challenging. In this study, we report the removal/recovery of heavy metal ions (Cd²⁺, Co²⁺ and Ni²⁺, and Zn²⁺) from sulfate solutions by a novel cementation technique using aluminum (Al) and activated carbon (AC) called “AC/Al-cementation”. The results showed ~0% removal/recovery efficiencies with Al only for the four heavy metals but with “AC/Al-cementation”, these values increased to 96%, 61%, 57%, and 45% for Zn²⁺, Ni²⁺, Co²⁺, and Cd²⁺, respectively. Detailed residue characterizations using SEM-EDX, XPS, and AES showed substantial deposition of heavy metal ions in their elemental forms, indicating that the primary mechanism of removal/recovery was cementation. Moreover, the results identified the critical role of AC as an electron pathway from Al (electron donor) to metal ions (electron acceptors) even though Al was covered with Al₂O₃. Finally, hydrogen overpotential and the subsequent passivation of cemented heavy metals by Al(OH)₃ were important limiting factors and processes affecting the efficiency of “AC/Al-cementation” technique.

镉（Cd），钴（Co），镍（Ni）和锌（Zn）是电池和可再生能源技术的重要组成部分，但是从富集的浸出液中回收或从污染的土壤系统和水体中去除它们仍然具有挑战性。在这项研究中，我们报告了通过使用铝（Al）和活性炭（AC）的新型胶结技术从硫酸盐溶液中去除/回收重金属离子（Cd 2 ⁺，Co ²⁺和Ni ²⁺以及Zn ²⁺） ），称为“ AC /铝水泥”。结果表明，仅Al对四种重金属的去除/回收效率为〜0％，但对于“ AC / Al胶结”，Zn 2 ⁺，Ni的这些值分别提高到96％，61％，57％和45％。²⁺，钴²⁺，和Cd ²⁺。使用SEM-EDX，XPS和AES进行的详细残渣表征显示，重金属离子以其元素形式大量沉积，表明去除/回收的主要机理是固井。而且，结果确认了即使在Al被Al ₂ O ₃覆盖的情况下，AC也是从Al（电子供体）到金属离子（电子受体）的电子路径的关键作用。最后，氢超电势以及随后的Al（OH）₃对胶结重金属的钝化作用是影响“ AC / Al-胶结”技术效率的重要限制因素和过程。