IR@CGCRI - Central Glass and Ceramic Research Institute (CSIR)
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Effect of fluorine substitution on sintering behaviour, mechanical and bioactivity of hydroxyapatite
No full textFluorine substituted hydroxyapatite (FAp) with different degree of fluorine (F) substitution, has been synthesized using hydrothermal synthesis method. In the present work, as synthesized powders were consolidated by sintering at 1200 degrees C in air for 1 h. The sintered specimens were characterized using Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) for phase analysis. Further, fluorine intake in the sintered specimens was evaluated using ion chromatography (IC). XRD peaks clearly showed biphasic nature of the sintered specimen. However, the sintered samples containing more than similar to 60% fluorine substitution showed no P-tricalcium phosphate (beta-TCP) phase formation. The IC results revealed that the degree of fluoridation decreased significantly in the sintered specimen compare to the respective as synthesized powders. The effect of actual fluorine content in the sintered specimens was further evaluated in terms of sinterability, surface energy, mechanical properties and in vitro cytocompatibility study. The surface energy of the sintered specimen decreased from 51.8 mN/m to 42.5 mN/m, in which degree of fluoridation varies from 0% to 110%. The in vitro cytocompatibility of the sintered specimen were carried out against mouse osteoblast cell line (MC3T3-E1). In vitro study showed that all the samples were nontoxic but cell proliferation for the samples containing more than 40% fluorine substitution became significantly low
Utilization of multi-metal laden spent biosorbent for removal of glyphosate herbicide from aqueous solution and its mechanism elucidation
No full textExtensive uses of glyphosate herbicide pose the environmental concerns of surface and ground water contaminations through leaching. The present investigation is based on potential reuse of multi-metal laden spent biosorbent for glyphosate removal. Our previous study showed effective removal of Ni(II), Co(II), Zn(II) and Cd (II) ions in multi-metal system using waste activated sludge from tannery industry as biosorbent. Glyphosate biosorption efficiency of the waste tannery sludge was enhanced from 26.18% to > 92% after increase in the multi-metal loading on the sludge. Feasibility study for actual wastewater treatment showed about 91.7% removal of glyphosate in the simulated agricultural runoff. The glyphosate biosorption exhibited gradual removal process. The rapid 70-75% biosorption was attained in first 2 h of contact time and the final removal of 89-94% was achieved within 24-28 h of contact time. Equilibrium isotherm and kinetics data were obtained by adsorption experiments. Biosorbent characterization and removal mechanism were established. The formation of glyphosate-metal complexation was confirmed by the FTIR, XPS, XRD, XRF, FESEM-EDAX and elemental mapping results. Surface bound multi-metals of the biosorbent could predominantly form mononuclear, bi-, trior tetra-dentate complexes through phosphonate group of glyphosate molecule. Weak binding of glyphosate molecule with the carboxyl and amino groups also occurred. The glyphosate loaded biosorbent were successfully inertized up to 10 wt% in phosphate glass matrix as confirmed by XRD for safe disposal of the toxic sludge in the environment
Synthesis and Characterization of Polyvinylidene-fluoride (PVDF) Nanofiber for Application as Piezoelectric Force Sensor
No full textIn the present study, PVDF nanofibers containing primarily beta-phase have been synthesized by electrospinning process. For electrospinning, a number of PVDF laden precursors were prepared varying the composition of solvents (60%-80% DMF) as well as wt% of PVDF (10wt%, 12wt%, and 15 wt% PVDF). The operating parameters for electrospinning were also varied for achieving optimal size and morphology of the PVDF nanofibers. The synthesized fibers were characterized by Fourier-transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FE-SEM), X-Ray Diffraction (XRD) and differential scanning calorimetry (DSC). PVDF with the solvent ratio of 7:3 offers beads free, thin nanofibers in comparison with other compositions. The presence of crystalline beta-phase was successfully confirmed by the XRD analysis. An exothermic peak was also observed by the DSC analysis at the temperature of 70 degrees C. PVDF nanofiber based piezoelectric force sensors were constructed and their performances were tested by applying calibrated load using a universal mechanical testing (UTM) machine and observing the resulting signal in an oscilloscope. A clear correlation was observed between the peak voltage detected by the PVDF force sensor and the applied load. The study revealed the piezoelectric property for force sensing tends to maximize (maximum current -14 mu A, initial sensitivity-160 mV/kPa) around 12 wt% of PVDF due to presence of beta-gamma phase in sample. (C) 2019 Published by Elsevier Ltd
Effect of K doping on Mo6+ stability and ionic conductivity study in La2Mo2O9 as oxide-ion conductor
No full textThe structural stability and ionic conductivity of K doped LAMOX have been extensively studied by many researchers. But the chemical state analysis and relaxation dispersion studies of La1.9K0.1Mo2O9-delta, La1.8K0.2Mo2O9-delta and pristine La2Mo2O9 are very scarcely reported. Here in the present study, the chemical state analysis, relaxation dispersion along with structural stability and ionic conductivity studies are done to investigate the effect of K doping in LAMOX. The room temperature XRD analysis of La1.9K0.1Mo2O9-delta, La1.8K0.2Mo2O9-delta compounds shows formation of beta-LAMOX phase along with K2O as an additional phase. The x-ray photoelectron spectroscopy (XPS) results are analysed for both K doped compositions sintered in air as well as in Ar 90%-H-2 10% atmosphere. Both the compositions show good amount of Mo6+ stabilisation in Ar-H-2 atmosphere. The Raman spectroscopy analysis of La1.9K0.1Mo2O9-delta and La2Mo2O9 shows the signature of oxygen vacancies at 866 cm(-1). The activation energy (E-a) is found to be 0.66 eV for La1.8K0.2Mo2O9-delta. The low value of d.c. conductivity of 12 mu S cm(-1) at 400 degrees C may be due to the hindrance imposed by large ionic radius of K+ ion as compared to La3+ ion in the structure which restricts its applications in IT-SOFCs
Effect of grain boundary and Ar-H-2 atmosphere on electrical conductivity of bulk a-La2Mo2O9 studied by impedance and x-ray photoelectron spectroscopy
No full textThe effect of grain boundary on electrical conductivity of alpha-La2Mo2O9 (LAMOX) over the temperature range of 300 degrees C to 400 degrees C has been investigated in this paper. Grain boundary effect characterisation for the mentioned temperature range has been done by electrochemical impedance spectroscopy (EIS). The calculated values of grain boundary width and specific grain boundary conductivity for alpha-La2Mo2O9 are 14.6 nm and 0.0146 mu S/cm respectively. Total ionic conductivity calculated by EIS for alpha-La2Mo2O9 at 300 degrees C is 1 mu S/cm. Resulting electrical conductivity of grain boundary comes out to be two orders less than the total electrical conductivity suggesting high activation energy requirement for grain boundary conduction. The electrical conductivity of alpha-La2Mo2O9 treated in Ar-H-2 atmosphere (2.5 mS cm(-1) at 200 degrees C) is approximately three orders higher than the electrical conductivity of LAMOX treated in air atmosphere. This may be attributed to reduction of Mo6+ to lower valance states in LAMOX as confirmed by x-ray photoelectron spectroscopy (XPS). Therefore, the low ionic conductivity nature of monoclinic phase of La2Mo2O9 has been explained on the basis of grain boundary conduction mechanism in the present study
Bioactive Nano-Hydroxyapatite Doped Electrospun PVA-Chitosan Composite Nanofibers for Bone Tissue Engineering Applications
No full textCombination of bioceramics with polymers to fabricate nanofibrous scaffolds holds enormous potential for bone tissue regeneration. In this study, we aim to incorporate HAp nanoparticles in trace doping amount in PVA-chitosan nanofiber matrix to fabricate PVA-chitosan composite nanofibers with improved performance for application as a bone tissue regeneration material. The diameter of the fabricated composite nanofibrous mat is estimated as 300 ± 121 nm. Beads free nanofibers mat with uniform morphology was ascertained for all sample groups by scanning electron microscopy (SEM) and the overall composition was assessed using Fourier transform infrared spectroscopy (FTIR) and energy dispersive X-ray spectroscopy (EDX). SEM images showed a homogeneous distribution of HAp nanoparticles in the composite nanofibers matrix. Further, X-ray diffraction (XRD) was performed to determine the crystallinity of the fabricated scaffolds. Swelling behavior and hydrolytic degradation of nanofibrous mats were subsequently evaluated by immersing in PBS buffer at pH 7.4 at physiological temperature (37 °C). The biocompatibility study of nanofiber scaffolds was performed with MC3T3 cells. Significantly higher cellular viability was observed on HAp nanoparticles incorporated composite nanofibrous scaffold surface after 7 days of culture in comparison to scaffolds without HAp
Synthesis of high surface area mesoporous silica SBA-15 for hydrogen storage application
No full textIn the present report, mesoporous silica SBA-15 was synthesized by different methods such as room temperature aging, hydrothermal, and sonication-mediated hydrothermal methods. The effect of different time and temperature on the synthesis method was investigated by conventional characterization techniques. The powders synthesized by different methods showed different properties, mainly in morphology and pore volume. In comparison to others, the powder synthesized by the hydrothermal method at 100 degrees C for 48 hours showed exceptionally high surface area of 3274 m(2)/g. To date, as per our knowledge, no such value was reported in literature. Finally, the powders were characterized by H-2 storage capacity by the adsorption-desorption method using 99.999% H-2. The hydrogen adsorption capacity of the same powder was observed at 6.02 wt%. Also, this value seems to be the highest H-2 adsorption capacity in comparison to other powders described in literature
Room temperature synthesis of PdxNi100-x nanoalloy: superior catalyst for electro-oxidation of methanol and ethanol
No full textBimetallic Pd-Ni alloy nanoparticles with tunable dimensions, unique composition and excellent electrocatalytic activity towards methanol and ethanol oxidation reaction (MOR and EOR) in alkali, were successfully synthesized by co-reduction of metal precursors in strong alkali medium at room temperature. X-ray diffraction profiles typically signify alloy structure of the particles. Microscopy, diffraction and spectroscopy studies further conform the successful formation of Pd-Ni nanoalloy of determined diameter and morphology. The compositions of this alloy nanoparticles can be easily tuned by typically varying the Pd2+/Ni2+ molar ratio. The mol% of Ni present in the Pd-Ni bimetallic nanoalloy portrays a key role on the catalytic activity for MOR and EOR in alkali. Pd70Ni30/C catalyst exhibits the optimum synergic catalytic activity with improved oxidation of carbonaceous intermediates. Chronoamperometric study satisfactorily proves that Pd70Ni30/C is quite stable at ambient temperature and can be used as anode for MOR and EOR. GRAPHICS]
Prospects of Photonic Crystal Fiber as Physical Sensor: An Overview
No full textPhotonic crystal fiber sensors have potential application in environmental monitoring, industry, biomedicine, food preservation, and many more. These sensors work based on advanced and flexible phototonic crystal fiber (PCF) structures, controlled light propagation for the measurement of amplitude, phase, polarization and wavelength of spectrum, and PCF-incorporated interferometry techniques. In this article various PCF-based physical sensors are summarized with the advancement of time based on reported works. Some physical PCF sensors are discussed based on solid core as well as hollow core structures, dual core fibers, liquid infiltrated structures, metal coated fibers, grating incorporated fibers. With the advancement of sensing technology the possibilities of temperature, pressure, strain, twist, curvature, electromagnetic field, and refractive index sensing are discussed. Also, limitations as well as possible solutions and future hopes are outlined