Evaluating the detection efficacy of advanced bimetallic plasmonic nanoparticles for heavy metals, hazardous materials and pesticides of leachate in contaminated groundwater.

During the decomposition of trashes, leachate is created and leaching is gradually pollutes the surface and groundwater. Thus, the most severe ecological impact is the risk of ground water pollution because of collection of leachate from unlined insecure landfills. Due to the low biodegradable organic strength, irregular productivity and composition, the environmentally neglected landfill leachate treatment is challenging. This work was conducted on a synthetically effective bimetallic surface enhanced Raman spectroscopic (SERS) nanosensor by gold/silver-bimetallic nanoparticles (Au/Ag-NPs), and used for the specific detection of municipal solid waste (MSW) landfill leachate in groundwater. The optical study of Au/Ag-NPs led to reflections from Ag cores and small Au shells. The structural studies represent the FCC structure of Au/Ag-NPs. The core-shell nanocrevice NPs with particle size of 23 nm played an important role with plasmonic behaviour enhances the electromagnetic excitation to achieve SERS detection and plasmonic photocatalysis. Thus, obtained results clearly show that Au was successfully added to Ag-NPs, and its existence can also be confirmed by energy dispersive spectroscopy (EDAX). The prepared SERS based sensors have the potential to detect aromatic hydrocarbon, pesticides and heavy metals from environmentally ignored MSW landfill leachate. In general, the application of this new synergetic strategy of the photocatalytic degradation of leachate was irradiated by visible wavelength with the rate constant of 0.0036/min, 0.0047/min and 0.005/min by Ag-NPs, Au-NPs and Au/Ag-NPs respectively. Overall, this is the only study achieved efficiently with photocatalytic degradation and SERS detection of environmentally ignored real sample (leachate) to make pollutant free homeland aquifers.

Surface enhanced Raman spectral studies of 2-bromo-1,4-naphthoquinone.

Silver nanoparticles have been synthesized by a simple and inexpensive solution combustion method with urea as fuel. The structural and morphology of the silver nanoparticles were investigated through X-ray powder diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM) and Energy Dispersion Spectra (EDS) techniques. Structural and morphological results confirmed the nanocrystalline nature of the silver nanoparticles. Density Functional Theory (DFT) calculations were also performed to study the ground and excited state behavior of 2-bromo-1,4-naphthoquinone (2-BrNQ) and 2-BrNQ on silver nanoparticles. Surface-Enhanced Raman Scattering (SERS) spectra of 2-BrNQ adsorbed on silver nanoparticles were investigated. The CO, CH in-plane bending and CBr stretching modes were enhanced in SERS spectrum with respect to normal Raman spectrum. The spectral analysis reveals that the 2-BrNQ adsorbed 'stand-on' orientation on the silver surface. Density Functional Theory (DFT) calculations are also performed to study the vibrational features of 2-BrNQ molecule and 2-BrNQ molecule on silver surface.

Surface Enhanced Raman Spectroscopic investigations of 2-bromo-3-methylamino-1,4-naphthoquinone on silver nanoparticles.

Surface Enhanced Raman Spectroscopic technique has been employed to investigate the orientation of 2-bromo-3-methylamino-1,4-naphthoquinone (BMANQ) on silver nanoparticles. Silver nanoparticles have been prepared by solution combustion method with citric acid as fuel. Silver nanoparticles were characterized by X-ray Diffraction (XRD), High Resolution Transmission Electron Microscopy (HRTEM) and Scanning Electron Microscopy (SEM). XRD and morphological results confirmed the nanocrystalline nature of the prepared silver nanoparticles. The observed intense CO stretching, CBr stretching and NH2 vibration suggests that the BMANQ molecule may be adsorbed in a 'stand-on' orientation to the silver surface. The calculated highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy show that charge transfer occurs within the molecule.

Spectroscopic investigations on the orientation of 1,4-dibromonaphthalene on silver nanoparticles.

Silver nanoparticles (Ag NPs) have been prepared by solution combustion method with glycine as fuel. Silver nanoparticles were characterized by X-Ray Diffraction (XRD), High Resolution Transmission Electron Microscopy (HRTEM) and UV-visible spectroscopy. The prepared silver nanoparticles exhibit cubic crystalline structure with grain size of 59 nm. HRTEM image shows that the silver nanoparticles have strain and four-fold symmetry formed by twinning in the crystal structure. The optical adsorption spectrum shows that the surface plasmon resonance peak of silver is observed at 380 nm. The orientation of 1,4-dibromonaphthlaene (1,4-DBrN) on silver nanoparticles has been inferred from nRs and SERS spectral features. The absence of a C-H stretching vibrations, the observed high intense C-H out-of-plane bending modes and high intense C-Br stretching vibration suggest that the 1,4-DBrN molecule may be adsorbed in a 'stand-on' orientation to the surface.