Deepti Mishra

Characterisation Studies and Impact of Chemical Treatment on Mechanical Properties of Sisal Fiber

The availability of natural fibers with their high performance and low cost contributes to a healthy ecosystem and fulfills the economic interests of the society. Sisal fiber, which is easily cultivated, is one of the most widely used natural fibers. For the present studies, characterisation of locally available sisal fiber of M.P. state in India was carried out with the investigation on the effect of alkali treatment with a wide range of different concentrations on the mechanical properties of sisal fiber. The physical and chemical properties of sisal fiber were analyzed with known methods and results were found to be similar to earlier reported values. Alkali treatment was carried out with different concentrations and mechanical properties were evaluated with Lloyd Fiber Testing Instrument. The results show that the chemical treatment enhances the mechanical properties of fiber up to a limit and is found to decrease with further increase in concentration. Scanning Electron Microscopy was used to investigate the morphology of untreated and alkali treated sisal fibers which indicated that the different concentrations of alkali alter the fiber surfaces with variations. Sisal fibers before and after alkali treatment were characterised further by thermogravimetry to establish their thermal stability, and measurements showed that alkali treated fiber became more thermal resistant than the untreated fiber and it was also noticed that thermal resistance decreases at higher concentration.

Synthesis and characterization of iron oxide nanoparticles by solvothermal method

In the present work iron oxide nanoparticles have been synthesized by alkaline solvo thermal method using anhydrous ferric chloride, sodium hydroxide, polyethylene glycol and cetyl trimethyl ammonium bromide and characterized by X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Field Emission Scanning Electron Microscopy (FESEM), Energy-dispersive X-ray Spectroscopy (EDX) and Thermal Gravimetric Analysis (TGA). XRD indicated that the product is a mixture of different phases of iron oxide viz. gamma-Fe2O3 (maghemite, tetragonal), Fe2O3 (maghemite, cubic), Fe3O4 (magnetite, cubic) and ɛ-Fe2O3(epsilon iron oxide). FESEM studies indicated that size of the particles is observed in the range of about 19.8 nm to 48 nm. EDX spectral analysis reveals the presence of carbon, oxygen, iron in the synthesized nanoparticles. The FTIR spectra indicated absorption bands due to O-H stretching, C-O bending, N-H stretching and bending, C-H stretching and Fe-O stretching vibrations. TGA curve represented weight loss of around 3.0446 % in the sample at temperature of about 180°C due to the elimination of the water molecules absorbed by the nanoparticles from the atmosphere.

Formulation of Mechanochemically Evolved Fly Ash Based Hybrid Inorganic–Organic Geopolymers with Multilevel Characterization

In this research, advanced hybrid inorganic–organic geopolymeric material is developed by environmentally and user friendlier approach. The presented novel approach for geopolymer formation certainly overcomes the existing drawbacks of geopolymerization technology. The effect of rice husk ash and Na2O/SiO2 ratios on geopolymer gel formation and mechanical strength has been previously identified via solution chemistry route; however, development of geopolymeric material having hybrid inorganic–organic characters via together mechanochemical grinding of raw materials and effect of mechanochemically activated Na2SiO3 on geopolymeric properties via solid state route has never before been explored. Together mechanochemical grinding of raw materials of varying compositions in solid state resulted in the formation of ready to use geopolymeric precursors; which on just addition of water led to development of advanced hybrid inorganic–organic geopolymeric material with considerably enhanced properties. XRD, FTIR and SEM characterization data of developed geopolymeric precursor powder and hybrid inorganic–organic geopolymeric material are reported and discussed in detail. As the results of the investigations, the relationship between geopolymer composition, grinding mechanism and material properties established. The composition which exhibited synergistic effect of both rice husk and SMS is found to be excellent in performance. The study showed that it is practical and better to adopt this greener solid state approach for preparation of geopolymer instead of user-unfriendlier hazardous alkaline solution based approach, to achieve sustainable growth in geopolymers as like Portland cement.

A NOVEL PROCESS FOR MAKING ALKALINE IRON OXIDE NANOPARTICLES BY A SOLVO THERMAL APPROACH

In the present work alkaline iron oxide nanoparticles are synthesized by a novel solvo thermal approach and characterized exhaustively by various complementary techniques. Field emission scanning electron microscopy (FESEM) studies reveal that the size of nanoparticles is in the range of 31.5 nm to 96.9 nm. Energy-dispersive X-ray spectroscopy spectral analysis reveals the presence of oxygen, carbon, iron, and sodium. The X-ray diffraction studies confirm the formation of tetragonal NaFeO2 as the major phase along with orthorhombic NaFeO2·H2O and rhombohedral FeCO3 (siderite) as the minor phases. Fourier transform infrared spectroscopy exhibits peaks due to the stretching and bending vibrations of O-H, C=O, CH3-N, CH3, C-H, C-N, and Fe-O groups. Differential scanning calorimetry (DSC) results display an endothermic peak at 100.85°C and a very small endothermic peak at 791.56°C with 819.73 mJ and 349.28 mJ energies respectively. These DSC peaks can be correlated with thermal gravimetric analysis (TGA) peaks representing 31.04% weight loss and 7.70% weight loss respectively in the sample at around 160°C and 980°C respectively.

Facile and controlled synthesis of copper sulfide nanostructures of varying morphology

Copper sulfide nanostructures with different morphology have been developed using wet chemical route. The product so obtained have been characterized using X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), Ultraviolet visible spectroscopy (UV–Vis) and photoluminescence (PL) technique. Effect of reaction medium on the morphology of the obtained samples has been studied in detail. We hereby demonstrate that while the reaction medium used has no impact on the phase of the prepared sample, however it plays an important role in deciding the morphology. CuS nanoparticles, nanoflower and nanoflakes like structure have been prepared under optimized condition using facile method in small period of time.

Effect of SO42-, Cl– and NO3- anions on the formation of iron oxide nanoparticles via microwave synthesis

In the present work iron oxide nanoparticles have been prepared by microwave assisted synthesis with the influence of different precursor salts and synthesis of magnetite, hematite, Iron oxide hydroxide and maghemite nanoparticles. Synthesized iron oxide nanoparticles were characterized with Infrared Spectroscopy (FTIR), Field Emission Scanning Electron Microscopy (FESEM), and Energy-dispersive X-ray Spectroscopy (EDX). XRD measurements show that the peaks of diffractogram are in agreement with the theoretical data of magnetite, hematite, FeO(OH) (Iron oxide hydroxide) and maghemite. Crystallite size of the particles was found to be 33, 45, 36 and 43.5 nm for Fe3O4, α-Fe2O3, FeO(OH) and γ-Fe2O3. FESEM studies indicated that size of the particles is observed in the range of about 19.4 to 46.7 nm (Fig. 2a, average 32 nm), 29.1 to 67.6 nm (Fig. 2b average 45 nm), 29.1 to 40.8 (Fig. 2c average 36.6 nm), 29.1 to 80 nm (Fig. 2d average 43.5) for Fe3O4, α-Fe2O3, FeO(OH) and γ-Fe2O3 respectively. EDX spectral analysis reveals the presence of carbon, oxygen, iron in the synthesized nanoparticles. The FTIR graphs indicated absorption bands due to O–H stretching, C–O bending, C–H stretching and Fe–O stretching vibrations.

Development and Characterization of Inorganic-Organic (Si-O-Al) Hybrid Geopolymeric Precursors via Solid State Method

AbstractIn this study, an innovative one part, solution free concept applied for the development of hybrid inorganic–organic geopolymeric precursors having Si-O-Al networks at the precursor stage only. For the process development, fly ash, sodium hydroxide along with rice husk were together mechano-chemically dry grinded for a period of 8, 16 and 24 hours and ‘organic in-organic hybrid geopolymeric precursors’ in solid powder form is obtained. Mechanico-chemically derived tailored organic in-organic hybrid geopolymeric precursors were characterized by different techniques like XRD, 29Si MAS NMR, 27Al MAS NMR, SEM and FESEM. XRD results revealed presence of inorganic phases and organic phase in organic in-organic hybrid geopolymeric precursors. 29Si MAS NMR spectra revealed partial transformation of tertracoordinated Si into pentacoordinated silica due to presence of organic moiety.27Al MAS NMR spectra indicated presence of peaks centered at δ 52 to δ 66 ppm confirmed the formation of geopolymeric precursors. Developed geopolymeric precursor overcome the process drawbacks of conventional geopolymerization process via solution chemistry by making it user friendly as geopolymer from these geopolymeric precursor is obtained by addition of water only unlike conventional geopolymerization process which involves addition of hazardous alkaline solution to aluminosilicate raw material like fly ash. Further, the development of geopolymeric precursor utilize two environmentally unsafe waste materials and resulted in development of material with improved mechanical properties. Graphical AbstractSolid state preparation of hybrid geopolymeric precursors with characterization studies