Bio-assisted synthesized Pd nanoparticles supported on ionic liquid decorated magnetic halloysite: an efficient catalyst for degradation of dyes
Abstract
Abstract Using natural materials, i.e. halloysite nanoclay that is a biocompatible naturally occurring clay and Heracleum persicum extract that can serve as a green reducing agent, a novel magnetic catalyst, Fe 3 O 4 /Hal-Mel-TEA(IL)-Pd, has been designed and fabricated. To prepare the catalyst, halloysite was first magnetized (magnetic particles with mean diameter of 13.06 ± 3.1 nm) and then surface functionalized with melamine, 1,4 dibromobutane and triethanolamine to provide ionic liquid on the halloysite surface (5 wt%). The latter was then used as a support to immobilize Pd nanoparticles that were reduced by Heracleum persicum extract. The characterization of the catalyst established that the loading of Pd in Fe 3 O 4 /Hal-Mel-TEA(IL)-Pd was very low (0.93 wt%) and its specific surface area was 63 m 2 g −1 . Moreover, the catalyst showed magnetic property (Ms = 19.75 emu g −1 ) and could be magnetically separated from the reaction. The catalytic performance of the magnetic catalyst for reductive degradation of methyl orange and rhodamine B in the presence of NaBH 4 in aqueous media was investigated. The activation energy, enthalpy, and entropy for the reduction of methyl orange were estimated as 42.02 kJ mol −1 , 39.40 kJ mol −1 , and −139.06 J mol −1 K −1 , respectively. These values for rhodamine B were calculated as 39.97 kJ mol −1 , 34.33 kJ mol −1 , and −155.18 Jmol −1 K −1 , respectively. Notably, Fe 3 O 4 /Hal-Mel-TEA(IL)-Pd could be reused for eight reaction runs with negligible loss of the catalytic activity (~3%) and Pd leaching (0.01 wt% of the initial loading).