Magnetite is known to exhibit high catalytic reactivity in Fenton-like reactions merely at low pH conditions. Here we report the association of Cu²⁺ ion can significantly enhance peroxydisulfate (PDS) activation with magnetite under environmental aquatic conditions (near neutral pH). Cu²⁺ is able to synergistically activate PDS with magnetite to generate radicals, e.g., SO₄^·−, at neutral or slightly alkaline pH, and such synergistic activation of PDS is promising to degrade various contaminants in groundwater. In-depth study reveals Cu²⁺ ion adsorbed on magnetite plays a crucial role in PDS activation. The adsorbed Cu²⁺ is labile to be reduced by the structural Fe(II) on magnetite to generate Cu⁺, which is relatively stable in the presence of magnetite at neutral or alkaline pH, but extremely unstable at acidic pH. The generated Cu⁺ on magnetite surface, rather than Cu²⁺, contributes to PDS activation in the reaction system, and the recycling of Cu⁺/Cu²⁺ sustains continuous activation of PDS. This study is among the first to report the synergistic activation of PDS by magnetite and Cu²⁺ ion at neutral pH, and unambiguously discern the role of Cu⁺ in PDS activation. The new mechanistic knowledge provides a more accurate understanding of PDS activation by natural minerals in environmental remediation.

已知磁铁矿仅在低pH条件下在Fenton样反应中显示出高催化反应性。在这里，我们报告了在环境水生条件（接近中性pH）下，Cu ²⁺离子的缔合可以显着增强过氧化二硫酸盐（PDS）与磁铁矿的活化。Cu ²⁺能够在中性或弱碱性pH下与磁铁矿协同活化PDS产生自由基，例如SO ₄ ^{· -}，而PDS的这种协同活化有望降解地下水中的各种污染物。深入研究表明，吸附在磁铁矿上的Cu ²⁺离子在PDS活化中起关键作用。吸附的Cu ²⁺易被磁铁矿上的结构Fe（II）还原而生成Cu ⁺，而Cu ⁺在磁铁矿存在下在中性或碱性pH值下相对稳定，而在酸性pH值下极不稳定。在磁铁矿表面而不是Cu ²⁺上生成的Cu ⁺有助于反应系统中的PDS活化，并且Cu ⁺ / Cu ²⁺的循环维持了PDS的连续活化。这项研究是第一个报告磁铁矿和Cu ²⁺离子在中性pH下协同激活PDS的研究，并且明确地认识到Cu ⁺的作用在PDS激活中。新的机械知识提供了对环境修复中天然矿物激活PDS的更准确了解。