Kirkendall Effect Boosts Phosphorylated nZVI for Efficient Heavy Metal Wastewater Treatment

作者：Li, Meiqi; Shang, Huan; Li, Hao^*; Hong, Yanfeng; Ling, Cancan; Wei, Kai; Zhou, Biao; Mao, Chengliang; Ai, Zhihui^*; Zhang, Lizhi^*

来源：Angewandte Chemie - International Edition, 2021, 60(31): 17115-17122.

DOI：10.1002/anie.202104586

• environmental control
• heavy metal removal
• Kirkendall effect
• nanoscale zerovalent iron
• phosphorylation

Removal of non-biodegradable heavy metals has been the top priority in wastewater treatment and the development of green technologies remains a significant challenge. We demonstrate that phosphorylated nanoscale zero-valent iron (nZVI) is promising for removal of heavy metals (Ni-II, Cu-II, Cr-VI, Hg-II) via a boosted Kirkendall effect. Phosphorylation confines tensile hoop stress on the nZVI particles and "breaks" the structurally dense spherical nZVI to produce numerous radial nanocracks. Exemplified by Ni-II removal, the radial nanocracks favor the facile inward diffusion of Ni-II and the rapid outward transport of electrons and ferrous ions through the oxide shell for surface (Ni-II/electron) and boundary (Ni-II/Fe-0) galvanic exchange. Accompanied by a pronounced hollowing phenomenon, phosphorylated nZVI can instantly reduce and immobilize Ni-II throughout the oxide shell with a high capacity (258 mgNig(-1) Fe). For real electroplating factory wastewater treatment, this novel nZVI performs simultaneous Ni-II and Cu-II removal, producing effluent of stable quality that meets local discharge regulations.