Unique Microstructure of 3D Self-Assembled Mg(OH)2 Nanoparticles for Methylene Blue Degradation in Presence of Direct Sun Light

Methylene blue (MB) dye present in industrial wastewater is a well-known carcinogenic source. By utilizing phase pure three dimensional self assembly of magnesium hydroxide nanoparticle (3DSAMHNPs) powders with extremely high surface area (∼342 m2.g–1), very high (∼98%) photocatalytic degradation efficacy for MB dye upon only 60 min direct exposure to sunlight is reported here. The designed mesoporous microstructure of the 3DSAMHNPs chracterized with a narrow pore size distribution range of ∼3-9 nm and an average size of ∼6 nm is achieved at room temperature by a facile, cost effective, simple, wet chemical route. The 3DSAMHNPs powders are characterized by XRD, FESEM, TEM, HRTEM, SAED, EDX, BET surface area, pore size distribution, FTIR, XPS DTA and TGA techniques. Based on the experimental results, a mechanism is proposed for the high MB dye degradation efficacy of 3DSAMHNPs powders developed in the current work. Finally, it is suggested that these 3DSAMHNPs materials may find potential applications in future as reusable photocatalysts for the degradation of MB dye in industrial wastewater

Cellulose-ceramic composite flexible paper separator with improved wettability and flame retardant properties for lithium-ion batteries

In quest of developing sustainable separator for lithium-ion batteries (LIBs), this research focuses on functionalization of low cost cellulose based commercial paper using duo-polymer and nano-SiO2 by designing a facile aqueous based industry friendly wet-coating process. Unlike commercial plastic based polyolefin separators (polypropylene/polyethylene), the developed paper separator shows superior thermal stability > 200 degrees C without dimensional shrinkage, excellent electrolyte wettability (147%) with zero contact angle, quicker electrolyte saturation and satisfactory mechanical strength (34.86-38.31 MPa). The electrochemical performance carried out in 2032 coin cells using fabricated paper separators shows comparable performance to that of commercial polypropylene (PP) based separator at different current densities of 0.05-0.4 mA/cm(2) with excellent columbic efficiency (> 96%) and good capacity retention on cycling. The developed separator is found to be compatible with most of the commercial electrodes (MCMB, -LiCoO2, -LiFePO4) used in today's LIBs. The functionalized cellulose-ceramic composite paper separator shows excellent flame retardant properties by offering an added safety features for its successful use in lithiumion batteries

Novel layered GO/Mg(OH)(2) nanocomposites for detection of Cd and Pb ions

Here we report the efficacy of the photoluminescence (PL) spectroscopy for novel detection of as low as 0.0001 to as high as 0.01 ppm of Cd2+ and Pb2+ ions in simulated wastewater solution. The solution comprises of 20 mg of layered graphene oxide (GO)-Mg(OH)(2) nanocomposite (LGOMHNC) powders in 100 ml of DI water. The LGOMHNC powders, synthesized by facile wet chemical route, are characterized by XRD, FESEM, TEM, FTIR, Raman spectroscopy, TGA-DTA, XPS and especially, the PL spectroscopy techniques. After adsorption of Cd2+ and Pb2+ ions, the novel LGOMHNC powders exhibit significant enhancement of the corresponding PL intensities as compared to those of the as-synthesized LGOMHNC powders. These results suggest that PL spectroscopy can indeed emerge as a very important tool for detection of even 0.0001 ppm of Cd2+ and Pb2+ ions in simulated wastewater. In addition, the novel LGOMHNC powders developed in the present work can have huge application potential in futuristic, optical sensor-based detection of the toxic, heavy metal ions like Cd2+ and Pb2+. (C) 2019 Elsevier B.V. All rights reserved

Phase and microstructure evolution during hydrothermal solidification of clay-quartz mixture with marble dust source of reactive lime

Marble dust (200 mu m size), air and water polluting waste, generated by the marble cutting industries has been used as cheap source of lime for hydrothermal solidification of clay-quartz mixtures at different saturated steam pressure (0.525-1.225 MPa). Marble dust was calcined at two different temperatures (900 and 1000 degrees C) and then added to the clay-quartz mixture, with clay/(clay + quartz) ratio 0.9, at two different amounts. The hydrothermally solidified samples were characterized by bulk density, apparent porosity, flexural strength, porosimetric study, phase and microstructural analysis and the results were compared against similarly treated chemical grade CaCO3 containing compositions. Tobermorite [Ca-5(Si6O18H2)center dot 4H(2)O] and hydrogarnet [Ca3Al2(SiO4)(OH)(8)] were the major phases formed in the treated samples, which are responsible for the strength development. Microstructural study supports the generation of these hydrated phases. Porosimetric study reveals that higher exposed area of the chemical grade CaCO3 containing composition results higher extent of hydrothermal reaction and higher strength. Though marble dust containing compositions showed relatively lower strength values, the combined properties of the hydrated products are suitable as new building material where such mesopore containing products With inherent micron range pore size distribution are important parameter

Paperator: The Paper-Based Ceramic Separator for Lithium-Ion Batteries and the Process Scale-Up Strategy

Due to its flexibility, cost-effectiveness, and natural abundance, paper has become a material of choice for its targeted applications in electronic and optoelectronic devices. With an aim to develop a paper-based ceramic separator (henceforth will be referred to as paperator), a low-cost paper substrate sourced from the local market has been functionalized by the wet-coating method using duo-polymer (chitosan and polyvinyl alcohol) and ceramic (BaTiO3) nanopowder. The developed paperator shows excellent air permeability, improved thermal stability of up to 200 degrees C without dimensional shrinkage, quicker wettability to an electrolyte, and comparable electrochemical performance to that of polypropylene-based commercial separator. The modification of the paper substrate using polymer and ceramic particles has also improved the tensile strength of the paperator to a maximum value of 45.23 MPa w.r.t. 28.20 MPa for pristine paper. The electrochemical performance of the developed paperators shows satisfactory cell performance at different current densities with excellent coulombic efficiency and comparable discharge capacities with that of a commercial separator. Compared to the commercial PP-based membrane, slightly lowered discharge capacities are obtained from the cells fabricated with developed paperators, which may primarily be due to the higher thickness (60/70 mu m) and cellulosic tortuosity. Electrochemical performances of the developed ``paperators'' were also evaluated for use in supercapacitors (SCs) by fabricating SC cells and their testing as per IEC 62391-1, which showed the cell capacitance and ESR values of 17.2 +/- 0.8 F and 76 +/- 3 m Omega, respectively, and the results were also compared with those of commercial cellulose-based paper separators. Based on the R&D achievements, the present study has also been extended for a scale-up strategy to produce a paper-based separator in roll form, where a ``paperator'' of 60 mm in width in a continuous manner has been fabricated by using in-house-designed semi-automated double-decker separator fabricator machine

Advanced Sustainable Trilayer Cellulosic ``Paper Separator'' Functionalized with Nano-BaTiO3 for Applications in Li-Ion Batteries and Supercapacitors

In the quest of developing a sustainable, low-cost andimprovedseparator membrane for application in energy storage devices likelithium-ion batteries (LIBs) and supercapacitors (SCs), here we fabricateda trilayer cellulose-based paper separator engineered with nano-BaTiO3 powder. A scalable fabrication process of the paper separatorwas designed step-by-step by sizing with poly-(vinylidene fluoride)(PVDF), thereafter impregnating nano-BaTiO3 in the interlayerusing water-soluble styrene butadiene rubber (SBR) as the binder andfinally laminating the ceramic layer with a low-concentration SBRsolution. The fabricated separators showed excellent electrolyte wettability(216-270%), quicker electrolyte saturation, increased mechanicalstrength (43.96-50.15 MPa), and zero-dimensional shrinkageup to 200 degrees C. The electrochemical cell comprising graphite|paperseparator|LiFePO4 showed comparable electrochemical performancesin terms of capacity retention at different current densities (0.05-0.8mA/cm(2)) and long-term cycleability (300 cycles) with coulombicefficiency >96%. The in-cell chemical stability as tested for 8weeksrevealed a nominal change in bulk resistivity with no significantmorphological changes. The vertical burning test as performed on apaper separator showed excellent flame-retardant property, a requiredsafety feature for separator materials. To examine the multidevicecompatibility, the paper separator was tested in supercapacitors,delivering a comparable performance to that of a commercial separator.The developed paper separator was also found to be compatible withmost of the commercial cathode materials such as LiFePO4, LiMn2O4, and NCM111

A critical note on nanoscale plasticity in 20 ZTA ceramics

The present work reports the very first observations on initiation of nanoscale plastic events in 20 ZTA (Zirconia Toughened Alumina) ceramics. The nanomechanical properties as well as the intrinsic contact deformation resistance of the present ZTA ceramic are studied here as a function of low loads (i.e., 10-1000 mN). Here we report for the very first time, the detailed mechanisms on the genesis of `micro pop-in' events that characterize the nanoscale plasticity initiation in the 20 ZTA ceramics. These new results along with field emission scanning electron microscopy (FESEM) based evidences confirm that the combined contributions from the maximum shear stress generated underneath the nanoindenter, the formations of shear bands and localized microcracking play significant roles in the initiation of nanoscale plastic events in the 20 ZTA ceramics

Nanoflower, nanoplatelet and nanocapsule Mg(OH)(2) powders for adsorption of CO2 gas

The soft chemical synthesis of self-assembled magnesium hydroxide (Mg(OH)(2)) nanoplatelets with surface area as high as about 300 m(2) g(-1) was achieved in the present work. The nanopowders such as MHN, MHCl, MHBr were synthesized at similar to 30 A degrees C without using any catalyst or surfactant using, respectively, precursor solutions of Mg(NO3)(2), MgCl2, MgBr2 and characterized by XRD, BET surface area, BJH pore size analysis, FTIR, FE-SEM, TEM and EDX techniques. It was found that the MHN and MHCl nanopowders comprised of nanoflowers formed by self-assembly of nanoplatelets and porous nanoplatelets, while the MHBr nanopowders comprised of a random assembly of nanocapsules. The powders possessed the technologically important quality of reproducible CO2 adsorption at room temperature and its desorption at a relatively lower temperature of 75 A degrees C. Based on the experimental evidences, the mechanisms of various microstructure formations and CO2 adsorption mechanism were also proposed

Indentation size effect and energy balance issues in nanomechanical behavior of ZTA ceramics

It is well known that physical, structural, mechanical as well as other functional properties change drastically at the nanoscale, thereby giving rise to size effects in all materials, especially ceramics. Therefore, it is extremely relevant today to understand the basic scientific issues involved in the development of size effects in materials, particularly ceramics which are characteristically brittle in nature. Hence, to be able to design better contact resistant ceramics; it is of significant importance to understand the genesis of indentation size effect (ISE) in the nanomechanical response of structural ceramics like zirconia toughened alumina (ZTA). Here we report the first ever systematic study on ISE in nanoindentation behavior of 10, 20 and 40 volume% (vol%) ZTA. The nanoindentation experiments were conducted at an ultra low load range of 1-1000 mN. As the experimental data showed the presence of strong ISE, the efficacies of existing models in explaining the same; were critically examined. Among existing models, the strain gradient plasticity model provided the real physical reason for the genesis of ISE in ZTA and hence, explained the data the best. Similarly, existing models were used to predict the variations in experimentally measured ratios of plastic to total energy spent in the nanoindentation process. The results showed that the Malzbender model predicted experimental data the best. This observation implied the best efficacy of the internally expanded cavity concept in explaining the nanoindentation response of the present ZTA ceramics. In addition, the other possible mechanisms of ISE in ZTA were discussed. Finally, the linkage of microstructural parameters to ISE in ZTA was explored

Synthesis of mixed calcite-calcium oxide nanojasmine flowers

Here we report for the very first time a simple, inexpensive, room temperature synthesis method of formation of mixed calcite calcium oxide nanojasmines (CTCaONJs). The method involves chemical precipitation in aqueous medium at room temperature in open atmosphere in order to allow natural carbonation to occur. Aqueous solutions of calcium nitrate dihydrate (Ca(NO3)(2)center dot 2H(2)O) and sodium hydroxide are used as precursors. The nanopowder is characterized by the Fourier transform infrared (FTIR) spectrometry, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDAX), BET (Brunauer-Emmett-Teller), BJH (Barrett-Joyner-Halenda) techniques. Optical properties of nanojasmines (NJs) were investigated by UV-vis spectroscopy. The powder has calcite as the major phase and calcium oxide as the minor phase. The crystallite size of calcite along (104) crystallographic direction is about 18 nm with a size strain of about 1.03%. The high (e.g., 8.8 m(2)g(-1)) surface area powder exhibits a mesoporous microstructure with 5-15 nm pore size. Further, it possesses a relatively higher optical band gap of 5.87 eV. The FESEM and TEM based evidences show that the CTCaONJ flowers mainly comprise of nanoplatelets made up of irregular nanorods and nanowires consisting of amorphous spherical nanoparticles. Based on these experimental evidences a qualitative model is proposed to explain the growth mechanism of the CTCaONJ flowers. (C) 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved