The Pd/Al nanoparticles (NPs) prepared by aqueous cementation were employed to probe hydrodechlorination (HOC) efficiencies of 4-chlorophenol (4-CP) in aqueous solution and 2-chlorobiphenyl (2-PCB) in surfactant solution. Major factors affecting HDC performance were investigated including acidic types, pH conditions, and surfactant types and their concentrations. Among HCl, H2SO4, H3PO4, formic acid, and acetic acid, only HCl was the proper pH adjustor to initiate HDC reaction of 4-CP with Pd/Al NPs at pH 3.0 due to the particular penetration function of active Cl- on the compact oxide film of Al. Aqueous pH states obviously influenced HDC efficiency and its values stable at pH 3-4 were the optimum range for HDC with HCl adjustor. 0.389 mM of 4-CP could be almost completely dechlorinated into phenol after 30-min reaction using 2 g/L of Pd/Al NPs with 1.2 wt.% of Pd loading. In addition, the effect of surfactants on HDC process of highly hydrophobic 2-PCB was explored, which were employed for its better solubilization. The addition of surfactants including SDS, CTAB, Tween 80, or Brij 30 had adverse effect on HOC activity of Pd/Al NPs due to their inhibiting effect on Al corrosion. The adverse effect was closely related with the concentrations of surfactants especially for each CMC level and molecular structures. (C) 2013 Published by Elsevier B.V.