Cu(II) and Gd(III) doped boehmite nanostructures: a comparative study of electrical property and thermal stability

The present article reports the effect of transition (Cu2+) and rare earth metal (Gd3+) ion doping on structural, microstructural and electrical properties of boehmite nanoparticles. Rietveld refinement is adopted here to refine the x-ray diffractograms for further analyzing the microstructural details and their alteration due to the incorporation of foreign cations. This is probably the first time when dielectric properties of these doped boehmite samples having been reported herein. These samples show remarkably high dielectric constant values which corroborate that doping enhances the microstrain values inside the orthorhombic structure and results in higher crystallographic defects. Enhancement in defect sites causes the augmentation of relative permittivity and ac conductivity. Temperature stability has also been enhanced significantly in our Cu-doped sample. The present study enables us to determine a relationship between crystalline deformation and electrical properties of nanomaterials which may be highly beneficial in fabricating cost-effective energy harvesting devices

In Situ-Grown Cdot-Wrapped Boehmite Nanoparticles for Cr(VI) Sensing in Wastewater and a Theoretical Probe for Chromium-Induced Carcinogen Detection

In modern society, massive industrialization escalates environmental degradation by liberating various contaminants into the environment. Hexavalent chromium is a heavy metal that is being discharged from tannery and other industries, resulting in various carcinogenic diseases. This study reports a carbon dot (cdot)-based fluorometric probe for detecting hexavalent chromium in water. This is the very first time that cdots are tailored over the boehmite nanoparticle's surface using an in situ approach. Validation of formation of the nanocomposite has been discussed in detail employing the Rietveld refinement-based X-ray crystallography method. Vibrational spectroscopy and electron microscopy of the sample authenticate the nucleation process and the growth mechanism. The Stern-Volmer approach and time-resolved fluorescence measurements justify the sensitivity of the sensor (similar to 58 nM), and selectivity is analyzed by exposing the material to different ionic environments. Density functional theory (DFT) is applied herein to analyze the origin of fluorescence and the sensing mechanism of the probe, which shows that photoinduced electron transfer is responsible for the turn-off-based sensing of Cr(VI). The molecular docking simulation is carried out to ensure the binding of cdots to the binding pocket of the glutathione enzyme, which is responsible for treating reactive oxygen species-mediated DNA damage due to elements such as hexavalent chromium. Time-dependent density functional calculations show that the fluorometric probe is capable of detecting Cr(VI) in living cells making it an early stage chromium-mediated carcinogen detector

Development of a Cu(I) doped boehmite based multifunctional sensor for detection and removal of Cr(VI) from wastewater and conversion of Cr(VI) into an energy harvesting source

This article reports a copper doped boehmite (CBH) based nano-material which is capable of detecting and removing hexavalent chromium simultaneously. Basic characterization has been performed to determine its phase purity, particle size (similar to 20 nm), morphology and surface properties (surface area 15.29 m(2) g(-1) and pore diameter 3.9 nm) by using some basic characterization tools. The Rietveld refinement method has been adopted to analyze the microstructural details of the synthesized nanostructure. Photoinduced electron transfer (PET) based quenching of fluorescence is mainly responsible for chromium sensing in this case. This nanosensor is exceptionally sensitive (limit of detection similar to 6.24 mu M) and merely selective towards hexavalent chromium ions. Industrial wastewater samples have also been used here to demonstrate the real life applicability of this material, which shows the same trend. This fluoro-sensor gains its multi-functionality when it comes to the adsorption based removal of Cr(VI) from wastewater. The synthesized material shows a remarkably high adsorption rate (similar to 85% in just 5 minutes) due to its sponge-like porous structure. Adsorption of hexavalent chromium from wastewater enhances the dielectric constant of this material significantly (similar to 7.93 times). Ionic polarization-dependent enhancement of the dielectric constant resulting from industrial wastewater treatment is a quite unmarked approach. Very low tangent loss with augmented dielectric permittivity makes this nano-material desirable for energy harvesting applications. Previously many articles have reported the sensing and removal of various industrial effluents. Keeping this in mind, this work has been designed and, apart from sensing and removal, it provides a new insight into energy harvesting from wastewater

Effects of various morphologies on the optical and electrical properties of boehmite nanostructures

The present article reports three different grain morphologies of boehmite nanoparticles: spherical (EBH), needle-shaped (UBH) and flower-like (HBH). EBH possesses the highest surface area, whereas HBH has the lowest. A novel synthesis route for spherical (EBH) boehmite nanostructures using ethylenediamine has been reported here. Moreover, we have compared the growth mechanisms and morphology-dependent changes in the optical and electrical properties of the three samples. The band gap energies were evaluated to be 5.30 eV, 5.44 and 5.87 eV for EBH, UBH and HBH, respectively. Strong photoluminescence (PL) emission for all the nanostructures, the highest for HBH, was noted. The lowest surface area of HBH provides a surface with fewer defects; this seals the possibility of energy loss via non-radiative recombination of electrons and holes, which enhances the PL intensity. The dielectric constants for EBH, UBH and HBH are 1.49 x 10(6), 1.14 x 10(5), and 7.14 x 10(4), respectively. Variations in the dielectric loss tangents and temperature-dependent electrical properties of the three morphologies were evaluated in support. Also, the ac conductivity and impedance analyses are in good accordance with our dielectric analysis. The present investigation may be highly beneficial in developing biosensors, bio-imaging, and fabricating cost-effective energy storage devices

Particle size mediated investigation of various physicochemical properties of kaolinite clay for fabricating the separator layer of green capacitors

This article reports size fractionation of a natural clay namely kaolinite for fabricating cost-effective green separator material for energy storage devices. kaolinite is reportedly biocompatible and abundantly available in nature, which makes it cost-effective. Such a low-cost clay is found to be in the nano regime when treated in a ball-milling machine for a prolonged duration (12 h). The enhancement in porosity and surface area have also been observed in the treated nano-clay, which subsequently renders it's dielectric constant (similar to 5000 at 40 Hz frequency) remarkably. Henceforth, it can be argued that crystallinity and aspect ratio (S/V) has a prominent impact on the electrical properties of this natural clay. Cyclic voltammetry and galvanostatic charging-discharging measurements depict high specific capacitance (similar to 185 F g(-1)) in the nano-clay sample without the presence of any redox peak making it a good separator material. The slow electrical discharge rate also approves the storage property of this clay sample quite effectively. Abundance, augmented permittivity with a relatively low tangent loss, high specific capacitance and significant resistivity through the material make this nano-clay material a promising `green' dielectric separator for energy storage applications

Natural Clay-Modified Piezocatalytic Membrane for Efficient Removal of Coliform Bacteria from Wastewater

In the modern era, water pollution, especially from industries, agricultural farms, and residential areas, is caused by the release of a large scale of heavy metals, organic pollutants, chemicals, etc., into the environment, posing a serious threat to aquatic ecosystems and nature. Moreover, untreated sewage waste discharged directly into nearby water bodies can cause various diseases to mankind due to the high load of fecal coliform bacteria. This work demonstrates the development of a biocompatible, cost-effective, highly robust, efficient, flexible, freestanding, and reusable membrane using naturally formed biocompatible kaolinite clay-doped poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) for effective piezodynamic destruction of coliform bacteria. In this study, Escherichia coli (E. coli) and Enterococcus faecalis (E. faecalis) have been used to evaluate the mechanical stimulus-responsive antibacterial efficacy of the nanocomposite membrane. The membrane can effectively eradicate nearly 99% viable E. coli and 97% E. faecalis within a span of 40 min under mechanical stimulation (soft ultrasound ∼15 kHz). To further understand the mechanism, an evaluation of reactive oxygen species and bacterial FESEM was performed. These studies revealed that bacterial cells suffered severe visible cell damage after 40 min of piezocatalysis, elucidating the fact that the synthesized membrane is capable of producing a superior piezodynamic antibacterial effect