Deepak Mohapatra

Bio: Deepak Mohapatra is an academic researcher from National Institute of Technology, Rourkela. The author has contributed to research in topics: Spinel & Pseudoboehmite. The author has an hindex of 4, co-authored 4 publications receiving 270 citations.

Nanostructured Al2O3-ZrO2 composite synthesized by sol-gel technique: powder processing and microstructure

Abstract: Al2O3–ZrO2 composite gel powder was prepared by sol–gel route. The gel precursor compositions were preferred to achieve yield of 5–15 mol% zirconia after calcination of respective powders. The precursor gel was characterized by Differential Thermal Analysis (DTA)/Thermo Gravimetric (TG), IR and X-ray Diffraction study (XRD). The analysis reveal the gel contained pseudoboehmite and amorphous Zr(OH)4, which was decomposed in three and two stages respectively. The phase transformation of alumina during calcination followed the sequence of pseudoboehmite → bayerite → boehmite → γ-Al2O3 → θ-Al2O3 → α-Al2O3, while that of ZrO2 follows amorphous ZrO2 → t-ZrO2 → (t + m) ZrO2. Fourier Transform Infrared Spectroscopy (FTIR) studies showed that the number of M–OH and M–O bond increases with zirconia due to a change in the cationic charge of the composite powder. Transmission Electron Microscopy (TEM) photograph of calcined powder exhibited the presence of dispersed as well as agglomerated nano sized spherical particles. SEM and Electron Probe Microscope Analysis (EPMA) confirmed the near uniform distribution of zirconia particles in the alumina matrix.

Effect of in situ spinel seeding on synthesis of MgO-rich MgAl2O4 composite

Abstract: MgO-rich MgAl2O4 spinel was prepared by adopting solid-state reaction of commercially available sintered seawater magnesia and α-alumina. Starting materials were mixed in weight ratio (Al2O3: MgO) of 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, where the developed MgAl2O4 spinel crystal seed in calcined powder varied (5–50%) with respect to addition of MgO content and temperature. Around 70% spinellisation could be noticed in Al2O3: MgO (1:1) batch through double stage sintering. Densification and grain size of the sintered specimen was found to be greatly dependent on initial calcination temperature and content of primary spinel seed. The diametrical compressive strength of sintered specimen was ∼115 MPa for highest amount of spinel content. The hardness of MgO-rich spinel composite was varied with spinel addition.

Mechanical characterization of kenaf/glass fibre hybrid composite laminates: An experimental and numerical approach

Abstract: The potentials of natural fibre encourage researchers to shift their interest from synthetic fibre. Numerous works have been done on the effective use of several natural fibres in manufacturing composites for automotive and structural applications. In the current investigation, effort has been made to evaluate the effect of the addition of glass fibre and influence of stacking sequence on mechanical properties of kenaf-/glass-reinforced hybrid composite laminates. Hybrid laminates with five different stacking sequences were fabricated by using hand layup technique. After curing, the fabricated composite laminates were cut to the dimension as per ASTM standard. Different tests have been carried out to determine tensile strength, flexural strength, and micro-hardness of fabricated laminates. Based on the findings, a sharp increase in mechanical properties is observed due to addition of glass fibre. Laminate with four layers of kenaf fibre shows minimum values of tensile strength, flexural strength and micro-hardness values. On subsequent addition of glass layer to the laminates, an increase in tensile strength from 35.78 to 166.38 MPa, flexural strength from 42.91 MPa to 155.83 MPa and micro-hardness value from 11.51 to 20.84 HV are reflected. To validate the experimental findings, numerical analysis has been made by using ANSYS R19.0 software. On comparison of experimental and numerical values, the deviation of the result is limited to 3%–12%. The morphology of fracture surfaces is also studied by using scanning electron microscope.

Nano‐adsorbents for the removal of metallic pollutants from water and wastewater

Abstract: Of the variety of adsorbents available for the removal of heavy and toxic metals, activated carbon has been the most popular. A number of minerals, clays and waste materials have been regularly used for the removal of metallic pollutants from water and industrial effluents. Recently there has been emphasis on the application of nanoparticles and nanostructured materials as efficient and viable alternatives to activated carbon. Carbon nanotubes also have been proved effective alternatives for the removal of metallic pollutants from aqueous solutions. Because of their importance from an environmental viewpoint, special emphasis has been given to the removal of the metals Cr, Cd, Hg, Zn, As, and Cu. Separation of the used nanoparticles from aqueous solutions and the health aspects of the separated nanoparticles have also been discussed. A significant number of the latest articles have been critically scanned for the present review to give a vivid picture of these exotic materials for water remediation.