Brown algae-based preparation, characterization and application of Pd nanocatalyst for enhanced reductive azo dye degradation

This study describes a simple green one-pot synthesis of the Palladium Nanocatalyst (PdNC) using the crude extract of a seaweed Saragassum cervicorne (S. cervicorne). The formation of PdNC was monitored by Ultraviolet-visible (UV-Vis) spectroscopy. The characteristic functional groups of phytochemicals in extract and capped PdNC surfaces were identified by FTIR analysis. The Scanning electron microscopy (SEM) analysis of the extract revealed the smooth surface area while that of the catalyst was found to be rough and irregular whereas Energy-dispersive X-ray spectroscopy (EDS) confirms the existence of Pd in the catalyst. The powder X-ray diffraction (XRD) analysis confirmed the crystalline nature of PdNC with a cubic face-centred structure. The transmission electron microscopy (TEM) was used to record the images of PdNC with a particle size of 3.131 to 16.45 nm. TGA reports reveal the degradation of the PdNC occurred at 197.8 °C. The catalytic activity PdNC was tested against the reduction of hazardous azo-dyes such as Congo red (CR), Methyl orange (MO) and Methyl red (MR) with NaBH4 as electron donor. The PdNC catalysed azo-dyes in presence of aqueous NaBH4 and was examined by UV–visible spectroscopy where PdNC mediated the electron transfer from NaBH4 to azo-dyes as a carrier. The maximum degradation was observed for Methyl Orange (0.08 mM) of about 99.66% with 60 μg/μL PdNC. Congo red (0.1 mM) showed the highest degradation of 99.25% with a catalyst loading of 40 μg/μl while that of Methyl red (0.1 mM) with 80 μg/ μL catalyst was 95.45%. The preparation of catalyst using water and exploiting water-soluble components of S. cervicorne as reducing agents makes this one-pot preparation of catalyst a novel approach for the preparation of Pd nanocatalyst. The replacement of non-toxic solvents, as well as the use of unexplored brown seaweed, is of primary importance from an economic as well as environmental perspective. Therefore, the newly prepared PdNC is a promising catalytic material obtained by the green facile synthetic method and exhibit enhanced catalytic activity in stimulation on the reduction of harmful azo dyes