Pd/Al bimetallic nanoparticles for complete hydrodechlorination of 3-chlorophenol in aqueous solution

Nanoscale Al particles with average diameter of about 100 nm were employed to prepare Pd/Al nanoparticles (NPs) by chemical displacement deposition. It was proved that Pd2+ acidic deposition solution was superior to its alkaline deposition solution in terms of Pd loading rate on Al NPs. The Pd/Al NPs were characterized by ICP–OES, SEM, TEM, XRD, BET and then used to explore hydrodechlorination (HDC) performance of 3-chlorophenol (3-CP) in aqueous solution. Major factors affecting HDC efficiency were investigated including Al substrate sizes, pH, Pd loadings in Pd/Al NPs, dosage of Pd/Al NPs, and temperature. The optimal results indicated that nanoscale Pd/Al bimetallic particles were highly effective for 3-CP HDC. HDC efficiency was only about 30% in 50 min reaction with micron sizes of Pd/Al particles (100–400 mesh), whereas it increased to 99.7% within 30 min using Pd/Al NPs at 25 °C. Aqueous pH presented remarkable effect on HDC and pH 3–4 was the optimum range for HDC as pH varied from 2 to 11. Pd loadings and Pd/Al dosages were optimized for highly effective HDC as 1.16 wt.% and 2 g/L, respectively. In addition, higher HDC performance was obtained while reaction temperature arrived at 45 °C and 0.389 mM of 3-CP could be completely dechlorinated into phenol only within 10 min reaction.

► 3-Chlorophenol was effectively dechlorinated with the new Pd/Al nanoparticle.
► The reaction mechanism relied on corrosion effect of Al substrate at different pH.
► Major factors affecting the hydrodechlorination efficiency were investigated.
► The hydrodechlorination rate using Pd/Al NPs was dependent on Pd granule size.