Zero-valent Al (ZVAl) is a good electron donor, however its surface passive film impedes the electron release from inside to outside. In this work, a soaking procedure was adopted to activate ZVAl powder, which was used to remove hexavalent chromium (Cr(VI)) in neutral solution. The results indicated that the soaking process can greatly enhance Cr(VI) reduction due to a layer of loose and fine flocculent Al(OH)₃ grains covering on Al particles, which adsorb Cr(VI) ions and speed up the electron release from inner Al. There is an optimal soaking time, which can promote ZVAl to reduce Cr(VI) to Cr(III) in neutral solution up to 90% within 2 min. Mechanism analyses revealed that adsorption of Cr(VI) ions on soaked Al surfaces are beneficial for them to receive more electrons from inner Al, leading to reduction of Cr(VI) ions favorable in competition with Al-water reaction, because these two processes consume electrons simultaneously. It was also found that the soaked Al powder has a good reusability and Cr(VI) removal is >70% when it was recycled for 5 times. This study provides an effective way for activating Al to reduce heavy metal ions in water.

零价铝（ZVAL）是一种良好的电子供体，但其表面钝化膜阻碍了电子从内向外释放。在这项工作中，采用浸泡程序激活 ZVAL 粉末，用于在中性溶液中去除六价铬 (Cr(VI))。结果表明，浸泡过程中由于有一层松散而细小的絮状Al(OH) _{3 ，可以大大促进Cr(VI)的还原。}晶粒覆盖在 Al 颗粒上，吸附 Cr(VI) 离子并加速内部 Al 的电子释放。有一个最佳的浸泡时间，可以促进 ZVALI 在 2 分钟内将中性溶液中的 Cr(VI) 还原为 Cr(III) 高达 90%。机理分析表明，Cr(VI) 离子在浸泡过的 Al 表面上的吸附有利于它们从内部 Al 接收更多电子，导致 Cr(VI) 离子的还原有利于与 Al-水反应竞争，因为这两个过程消耗电子同时。还发现浸泡后的铝粉具有良好的重复使用性，循环使用5次后Cr(VI)去除率>70%。本研究为活化Al降低水中重金属离子提供了有效途径。