Material and methods
2.1. NZVI synthesis and sulfidation
Ferrous sulfate heptahydrate (99%), sodium borohydride (≥98.5%), palladium acetate and sodium sulfide (99%) were used for preparation of NZVI, Pd-NZVI and sulfidated NZVI were purchased from Sigma–Aldrich. Concentrated HCl (37% w/w) and methanol (HPLC grade) were purchased from Fisher Scientific. Deionised water, methanol and other solutions were deoxygenated prior to reaction by bubbling nitrogen gas.