Here, we report the synthesis, characterization and catalytic evaluation of palladium nanoparticles (PdNPs) using xanthan gum, acting as both reducing and stabilizing agent without using any synthetic reagent. The uniqueness of our method lies in its fast synthesis rates using hydrothermal method in autoclave at a pressure of 15 psi and at 120°C temperature by 10 min time. The formation and size of the PdNPs were characterized by UV-visible spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy and transmission electron microscopy. The catalytic activity of PdNPs was evaluated on the reduction of 4-nitrophenol to 4-aminophenol by sodium borohydride using spectrophotometry.

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A green method for the solvothermal synthesis of copper sulphide nanoparticles (CuS NPs) using xanthan gum as a capping agent was developed. The CuS NPs were characterised by scanning electron microscopy, transmission electron microscopy (TEM), X-ray diffraction, BrunauerÀEmmentÀTeller, zeta analysis, thermal gravimetricÀ differential thermal analysis, Fourier transform infrared and UVÀvisible absorption spectra. These characterisations together determine the composition, structural, thermal and optical properties. The UVÀvisible spectrum had a broad absorption in the visible range. The particle size of the products was observed by TEM in the range of 8À20 nm. The photocatalytic performance of the CuS NPs was evaluated for the degradation of organic dyes (methylene blue, rhodamine B, eosin Y and congo red) under irradiation of solar, visible and UV lights. The CuS NPs showed good photocatalytic activity. Kinetic analyses indicate that the photodegradation rates of dyes usually follow pseudofirst-order kinetics for degradation mechanisms.

CdS nanoparticles (NPs) are synthesized by sonochemical method using tryptophan as a capping agent. The synthesis process is of one step, using biocompatible capping agent, which is nontoxic. The synthesized NPs are characterized by UV-Vis absorption, fluorescence, FTIR, XRD, TGA, DLS, SEM and TEM. The size of NPs is below 10 nm, as observed from XRD and TEM characterizations. Photocatalytic degradation of methyl orange (MO) dye by the CdS NPs as photocatalysts under sunlight irradiation has been studied. The kinetics of catalysis of synthesized CdS NPs with MO dye follows pseudo-firstorder kinetics with reasonable apparent rate constants. A variation of dielectric constant as a function of frequencies of an alternating electric field has been observed with the prepared tryptophan-capped CdS NPs deposited at different concentrations. The electric conductivity of CdS NPs is found to increases with the concentration of tryptophan.

Cadmium sulfide nanoparticles (CdS NPs) were successfully prepared using sonochemical method by employing Schiff-base, (2-[(4-methoxy-phenylimino)-methyl]-4-nitro phenol) as a complexing agent. Here, SB is used as a ligand to control the morphology of NPs. XRD patterns and TEM images show that the synthesized CdS NPs have cubic structures with a diameter of about 2-10 nm. The formation of CdS NPs and their optical, structure, thermal and morphologies were studied by means of UV-vis DRS, fluorescence, FTIR, zeta potential, XRD, SEM and TEM. The interactions between CdS NPs and SB were investigated in an aqueous solution using fluorescence spectroscopy. The fluorescence quenching studies suggest that SB quenches the fluorescence of CdS NPs effectively. The degradation kinetics of methyl red (MR) by the photocatalyst was followed by Langmuir-Hinshelwood model. The results revealed that photocatalytic degradation of MR by SB capped CdS NPs could be considered as a practical and reliable technique for the removal of environmental pollutants. The antibacterial activity of samples was evaluated against E. coli, S. aureus and P. aeruginosa and the results were compared. SB and SB capped CdS NPs could be a potential antibacterial compounds after further investigation.

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