Graphite-modified zero-valent aluminum prepared by mechanical ball milling for selective removal of hydrophobic carbon tetrachloride

[Display omitted] •The first report on improving ZVAl’s hydrophobicity for selective removal of CT.•Gr@ZVAlbm could achieve 100% removal of 0.1 mM CT.•Under the modifying action of Gr, ZVAl reduced hydrogen production by 97.78%.•CT was adsorbed by Gr and then concentrated on the surface of the composite.•The coverage of Gr on ZVAl ensured the output of electrons due to its conductivity. Zero-valent aluminum (ZVAl) is emerging as a new category of water treatment material due to its potent reducing capabilities and superior performance. However, in ZVAl/H2O/pollutant system, H2O will swiftly compete for the electrons released from ZVAl, then producing hydrogen, and accordingly, the degradation efficiency of pollutants will be significantly inhibited. Therefore, it is urgent to develop a ZVAl-based material that can guard H2O in the competition system. To achieve this key breakthrough, graphite (Gr), a natural and inexpensive carbon material, was used as a grinding aid to ball milled with ZVAl to prepare a new composite, Gr@ZVAlbm. At a Gr dosage of 2 wt% and the ball milling speed of 300r, 4 g/L Gr@ZVAlbm achieved 100% degradation of 0.1 mM carbon tetrachloride (CT). More crucially, Gr@ZVAlbm has a high selectivity for CT, and nearly no hydrogen was produced at the same time. In addition, the higher load of Gr reflected the more powerful removal effectiveness of CT with greater inhibition of hydrogen production. Assisting XRD and XPS, Gr was found to play a key role. Firstly, hydrophobic Gr facilitated the mass transfer of CT through adsorption, while preventing H2O from approaching the surface of Gr@ZVAlbm. Secondly, conductive Gr ensured the effective output of electrons. Overall, the excellent properties of Gr synergized with high reducibility of ZVAl, to achieve the targeted removal of organic pollutants. This study firstly provides a method to shield the interference of H2O in the ZVAl/H2O/pollutant system which could selectively and effectively treat hydrophobic organic pollutants in wastewater.