A simple way to prepare palladium nanoparticles decorated with cyclodextrins and ionic liquid. The effects of coating on the catalytic activity and colloidal stability

In this work, palladium nanoparticles (PdNps) were synthesized by reducing palladium chloride with sodium borohydride (NaBH4) aqueous solutions in presence of organic capping ligands such as beta-cyclodextrin (beta CD), an amphiphilic imidazole-based Ionic Liquid (C(12)mimBr) and an amphiphilic beta CD derivative (beta CDMOD14). The results demonstrated that the molecular organization of the capping agents has an important role in the stability of colloidal solution of PdNPs. In particular, the stability of PdNPs coated with beta CDMOD14 (Pd@beta CDMOD14) can be controlled by changing the pH of the colloidal suspension. In addition, we propose that during the synthesis of PdNps and capped with C(12)mimBr (Pd@C(12)mimBr), the source of palladium is a coordination complex formed due to the presence of C(12)mimBr. Additionally, we studied the catalytic activity of Pd@beta CDMOD14 and Pd@ C(12)mimBr using the reduction reaction of aromatic nitro compounds to aromatic amine in the presence of NaBH4, as a model in the remediation of aqueous phase. The kinetic data were modeled to the Langmuir-Hinshelwood equation that allows us to discriminate the affinity of 4-NP and NaBH4 towards modified surface of NPs in terms of their association constants (K4-NP, K-BH4). (C) 2020 Elsevier B.V. All rights reserved.