Removal of Heavy Metals from Wastewater Using Novel Polydopamine-Modified CNTs-Based Composite Membranes

The presence of major heavy metals including Pb2+, Cu2+, Co2+, Ni2+, Hg2+, Cr6+, Cd2+, and Zn2+ in water is of great concern because they cannot degrade or be destroyed. They are toxic even at very low concentrations. Therefore, it is necessary to remove such toxicants from water. In the current study, polydopamine carbon nanotubes (PD-CNTs) and polysulfone (PS) composite membranes were prepared. The structural and morphological features of the prepared PDCN composite membranes were studied using FTIR, XRD, SEM, and EDS. The potential application of PDCNs for heavy metal removal was studied for the removal of Pb2+, Cr6+, and Cd2+ from wastewater. The maximum removal efficiency of 96.1% was obtained for Cr6+ at 2.6 pH using a composite membrane containing 1.0% PD-CNTs. The removal efficiencies decreased by 64.1 and 73.4, respectively, by enhancing the pressure from 0.50 up to 0.85 MPa. Under the same circumstances, the percentages of Pb+2 removal at 0.49 bar by the PDCNS membranes containing 0.5% and 1.0% PD-CNT were 70 and 90.3, respectively, and decreased to 54.3 and 57.0, respectively, upon increasing the pressure to 0.85 MPa. The results showed that PDCNS membranes have immense potential for the removal of heavy metals from water

Facile Preparation of Fe3O4 Nanoparticles/Reduced Graphene Oxide Composite as an Efficient Anode Material for Lithium-Ion Batteries

Iron oxides are considered promising electrode materials owing to their capability of lithium storage, but their poor conductivity and large volume expansion lead to unsatisfactory cycling stability. In this paper, an inexpensive, highly effective, and facile approach to the synthesis of Fe3O4 nanoparticles/reduced graphene oxide composite (Fe3O4/RGO) is designed. The synthesized Fe3O4/RGO composite exhibits high reversible capability and excellent cyclic capacity as an anode material in lithium-ion batteries (LIBs). A reversible capability of 701.8 mAh/g after 50 cycles at a current density of 200 mA·g−1 can be maintained. The synergetic effect of unique structure and high conductivity RGO promises a well soakage of electrolyte, high structure stability, leading to an excellent electrochemical performance. It is believed that the study will provide a feasible strategy to produce transition metal oxide/carbon composite electrodes with excellent electrochemical performance for LIBs

Plasmonic Nano Silver: An Efficient Colorimetric Sensor for the Selective Detection of Hg2+ Ions in Real Samples

Environmental pollution caused by heavy metal ions has become a major health problem across the world. In this study, a selective colorimetric sensor based on starch functionalized silver nanoparticles (St-Ag NPs) for rapid detection of Hg2+ in real samples was developed. The environmentally friendly green approach was utilized to synthesize starch functionalized silver nanoparticles (St-AgNPs). A multi-technique approach involving UV-Vis absorption spectroscopy, Fourier transform infrared (FT-IR), X-ray diffraction (XRD), and scanning electron microscope (SEM) was used for the characterization of St-Ag NPs. These starch functionalized AgNPs were tested for the detection of heavy metals at 25 degrees C. The screening process revealed clear changes in the AgNPs color and absorption intensity only in the presence of Hg2+ due to the redox reaction between Ag-0 and Hg2+. The color and absorption intensity of nanoparticles remain unchanged in the presence of all the other tested metals ion. The proposed method has strong selectivity and sensitivity to Hg2+ ions, with a detection limit of 1 ppm revealed by UV-visible spectrophotometry. The proposed procedure was found to be successful for the detection of Hg2+ in real samples of tap water

Electrosynthesis and Characterization of Novel CNx-HMMT Supported Pd Nanocomposite Material for Methanol Electro-Oxidation

In the current research work, palladium (Pd) nanoparticles were electrochemically deposited on a nitrogen doped montmorillonite (CNx-MMT) support using the underpotential deposition (UPD) method. The prepared Pd based composite electrode was studied as an electrocatalyst for methanol fuel oxidation. The catalysts and the supporting materials montmorillonite, acid activated montmorillonite, and nitrogen doped montmorillonite (MMT, HMMT and CNx-HMMT) were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS) and electrochemical characterization by cyclic voltammetry (CV). The results indicated that Pd supported on CNx-HMMT possesses enhanced electrocatalytic activity and stability compared to commercial Pd/C, which was attributed to its higher electrochemical surface area (ECSA) (23.00 m2 g−1). The results demonstrated the potential application of novel Pd/CNx-HMMT composite nanomaterial as electrocatalysts for methanol electrooxidation in direct methanol fuel cells (DMFCs)

Ultrafast Studies of ZrTe3 by Transient Absorption Spectrometer

Two-dimensional (2D) tri-TMDCs carrier dynamics provide a platform for studying excitons through Ultrafast Pump-Probe Transient Absorption Spectroscopy. Here we studied the ZrTe3 nanosheets (NTs) exciton dynamics by transient absorption (TA) spectrometer. We observed different carrier dynamics in the ZrTe3 NTs sample at different pump powers and with many wavelengths in the transient absorption spectrometer. The shorter life decay constant is associated with electron-phonon relaxation. Similarly, the longer-life decay constant represents the long live process that is associated with charge separation. The interactions between carrier-phonons at nanoscale materials can be changed by phonons quantum confinements. The hot carrier lifetime determined the strength of carrier phonon interactions. The value of fast decay in the conduction band is due to carrier relaxation or the carrier gets trapped due to surface states or localized defects. The value of slow decay is due to the recombination of surface state and localized defects processes. The lifetime declines for long wavelengths as size decreases. Whereas, during short wavelength-independent decay, carrier characteristics have been observed. TA spectroscopy is employed to investigate insight information of the carrier's dynamical processes such as carrier lifetime, cooling dynamics, carrier diffusion, and carrier excitations. The absorption enhanced along excitons density with the increase of pump power, which caused a greater number of carriers in the excited state than in the ground state. The TA signals consist of trap carriers and (electron-hole) constituents, which can be increased by TA changes that rely on photoexcitation and carrier properties

Superior Electrochemical Performance of Two-Dimensional {RGO}/Cu/Cu2O Composite as Anode Material for Lithium-Ion Batteries

In recent years, graphene has attracted the interest of many researchers working on LIB anode materials owing to its unique 2D structure, thermal stability, and fast electron transfer. In this work, RGO/Cu/Cu2O nanocomposites were synthesized through a hydrothermal procedure. The as-prepared nanocomposites exhibited a high lithium storage capacity with improved cycling stability and great rate performance, i.e., the discharge capacity was 371.8 mAh/g after 100 cycles at a current density of 500 mA/g. These excellent properties were associated with the sheet structure symmetry of graphene enriched with the multifunctional Cu-Cu2O component, which prevented aggregation and accommodated the volume changes of the anode material during the charge–discharge tests. The RGO/Cu/Cu2O composite conferred to the LIB anode the ability to resist electrode cracking. The approach proposed in this paper can be also generalized for the synthesis of other carbon-based anode materials for LIBs

Electrosynthesis and Characterization of Novel {CNx}-{HMMT} Supported Pd Nanocomposite Material for Methanol Electro-Oxidation

In the current research work, palladium (Pd) nanoparticles were electrochemically deposited on a nitrogen doped montmorillonite (CNx-MMT) support using the underpotential deposition (UPD) method. The prepared Pd based composite electrode was studied as an electrocatalyst for methanol fuel oxidation. The catalysts and the supporting materials montmorillonite, acid activated montmorillonite, and nitrogen doped montmorillonite (MMT, HMMT and CNx-HMMT) were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS) and electrochemical characterization by cyclic voltammetry (CV). The results indicated that Pd supported on CNx-HMMT possesses enhanced electrocatalytic activity and stability compared to commercial Pd/C, which was attributed to its higher electrochemical surface area (ECSA) (23.00 m(2) g(-1)). The results demonstrated the potential application of novel Pd/CNx-HMMT composite nanomaterial as electrocatalysts for methanol electrooxidation in direct methanol fuel cells (DMFCs)

Green Synthesis of Silver Nanoparticles (Ag-NPs) Using <i>Debregeasia Salicifolia</i> for Biological Applications

The synthesis of nanoparticles (NPs) using the green route is environmentally harmonious and cost-effective compared to conventional chemical and physical methods. In this study, the green synthesis of silver NPs was carried out using an extract of Debregeasia salicifolia. The synthesized Ag NPs were characterized by means of different techniques i.e., UV-Vis spectroscopy, FTIR spectroscopy, SEM, and XRD. The XRD pattern exhibited distinctive Bragg’s peaks at (200), (111), (311), and (220). The XRD analysis confirmed the face-centered cubic geometry of the synthesized NPs and revealed that the nature of these NPs is crystalline. The synthesized NPs were verified for their antibacterial activities against Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus) bacteria. It showed that antibacterial activity of synthesized silver (NPs) was increased with increasing concentrations of both calcined and non-calcined NPs. The antioxidant activities of Ag NPs were also determined against ABTS at different concentrations for both calcined and non-calcined Ag NPs. Non-calcined Ag NPs have greater antioxidant activity than calcined Ag NPs. This report has a significant medicinal application, and it might open up new horizons in this field

Novel Sepiolite Reinforced Emerging Composite Polymer Electrolyte Membranes for high Performance Direct Methanol Fuel Cells

Methanol permeation is the main issue of Nafion membranes when they are used as a polymer electrolyte membrane (PEM) in direct methanol fuel cells (DMFCs). In the current study, novel nanocomposite polymer membranes are prepared by the integration of surface-modified sepiolite (MS) in polyvinylidene fluoride grafted polystyrene (PVDF-g-PS) copolymer as PEM in DMFCs. Sepiolite surface is chemically modified using vinyltriethoxysilane and analyzed by fouriertransform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM). Nanocomposite PVDF-g-PS/MS membranes are prepared by phase inversion technique and subsequently treated with chlorosulfonic acid to induce sulfonic acid (SO3H) active sites at the membrane surface. The prepared nanocomposite membranes (S-PPMS) are analyzed for their physicochemical characteristics in terms of water uptake percentage, cation exchange capacity (CEC), proton conductivity (σ), and methanol permeability. MS dispersion in the copolymer matrix is proved through morphological SEM examination. The S-PPMS membranes exhibit increased proton conductivity due to the presence of well-dispersed MS and surface functional –SO3H groups. A peak power density of 210 mWcm−2 is recorded for S-PPMS10 at 110 °C which is higher than the output obtained from Nafion-117. These promising results indicate the potential utilization of prepared nanocomposite PEMs for DMFC application

Plasmonic Nano Silver: An Efficient Colorimetric Sensor for the Selective Detection of Hg2+ Ions in Real Samples

Environmental pollution caused by heavy metal ions has become a major health problem across the world. In this study, a selective colorimetric sensor based on starch functionalized silver nanoparticles (St-Ag NPs) for rapid detection of Hg2+ in real samples was developed. The environmentally friendly green approach was utilized to synthesize starch functionalized silver nanoparticles (St-AgNPs). A multi-technique approach involving UV-Vis absorption spectroscopy, Fourier transform infrared (FT-IR), X-ray diffraction (XRD), and scanning electron microscope (SEM) was used for the characterization of St-Ag NPs. These starch functionalized AgNPs were tested for the detection of heavy metals at 25 &deg;C. The screening process revealed clear changes in the AgNPs color and absorption intensity only in the presence of Hg2+ due to the redox reaction between Ag0 and Hg2+. The color and absorption intensity of nanoparticles remain unchanged in the presence of all the other tested metals ion. The proposed method has strong selectivity and sensitivity to Hg2+ ions, with a detection limit of 1 ppm revealed by UV-visible spectrophotometry. The proposed procedure was found to be successful for the detection of Hg2+ in real samples of tap water