Interfacial engineering of Al/C composites through shift-speed ball milling for efficient persulfate activation

Zero-valent aluminum (ZVAl) is a newly developed material for water treatment due to its superior reduction capabilities. This study develops a graphite-modified ZVAl composite (Gr@ZVAl^ssbm) with a stress-modulated chemically bonded interface via novel shift-speed ball milling. The synthesis involves a two-stage process: (i) brief high-speed milling to fracture the passive oxide layer on ZVAl, thereby exposing fresh active surfaces for Gr anchoring, followed by (ii) extended low-speed milling to achieve homogeneous Gr dispersion and strengthen the bonding state between ZVAl and Gr. This dual-stage approach not only promotes the enrichment of organic pollutants on the composite surface but also optimizes the electron transfer path. This unique method significantly enhances the composite’s performance in persulfate (PS) activation. Experimental results demonstrate that Gr@ZVAl^ssbm achieves 99.64 % removal of 0.1 mM phenol, representing a substantial improvement compared to conventional ZVAl (32.52 % only). The reaction mechanism is that ZVAl rapidly transfers electrons released from ZVAl through conductive Gr and efficiently activates PS to generate sulfate radicals (SO₄⁻⁾ and hydroxyl radicals (OH), which can be used to remove phenol from water. In conclusion, a new method for the preparation of aluminum-carbon composites for pollutant degradation by shift-speed ball milling is proposed for the first time.