Faculty Publications
Permanent URI for this communityhttps://idr.nitk.ac.in/handle/123456789/18736
Publications by NITK Faculty
Browse
10 results
Search Results
Item Straightforward synthesis of calcium levulinate from biomass-derived levulinic acid and calcium carbonate in egg-shells(Elsevier Ltd, 2019) Sharath, B.O.; Tiwari, R.; Mal, S.S.; Dutta, S.Calcium levulinate (CL) is a nutritional supplement for calcium and a chemical intermediate in synthesizing levulinic biofuels. The reported synthesis of CL involve reaction between cellulose-derived levulinic acid (LA) and calcium hydroxide in an aqueous medium. In this work, we report the production of CL using CaCO3 from poultry egg shells. The scalable production uses biomass-derived LA and egg-shell derived CaCO3 under conventional heating and mechanical stirring. The reaction was optimized on temperature, duration of reaction, and equivalent of CaCO3. Using 1.5 equivalent of CaCO3, the reaction completed within 2h at 50°C and afforded up to 97% isolated yield of CL as a crystalline solid. The reaction was also successfully carried out under mechanical grinding and scaled up to 20 g. The purity of the product was confirmed by melting point, FTIR, 1H-NMR and 13C-NMR spectroscopy. © 2019 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the scientific committee of the International Conference on Advanced Materials, Energy & Environmental Sustainability, ICAMEES2018Item Antifouling and performance enhancement of polysulfone ultrafiltration membranes using CaCO3 nanoparticles(2013) Nair, A.K.; Isloor, A.M.; Kumar, R.; A.F., A.F.Calcium carbonate nanoparticles were synthesized from calcium nitrate via chemical precipitation method. The nanoparticles were characterized using scanning electron microscope (SEM), Attenuated total reflectance infra red (ATR-IR) spectrum and by X-ray diffraction (XRD). These nanoparticles were used as additive for polysulfone (PSf) ultrafiltration membrane along with polyethylene glycol (PEG) as pore forming agent. The PSf hybrid membranes were characterized by ATR-IR, XRD, and SEM studies. ATR-IR and XRD results indicated the successful incorporation of the nanoparticles in the membranes. Cross sectional images of the membranes along with the elemental mapping of calcium on the membrane surface were assessed using SEM. Hydrophilicity of the membranes was evaluated in terms of contact angle measurements. The permeability of the membranes was determined by measuring the pure water flux (PWF). Membranes were also subjected to antifouling studies using bovine serum albumin (BSA) as the standard protein for rejection. The membranes showed better permeability and antifouling property with the increased addition of CaCO3 nanoparticles. © 2013 Elsevier B.V.Item Reduced graphene oxide derived from used cell graphite and its green fabrication as an eco-friendly supercapacitor(Royal Society of Chemistry, 2014) Sudhakar, Y.N.; Muthu, M.; Bhat, D.; Senthil Kumar, S.Graphite extracted from a used primary cell was converted into reduced graphene oxide (rGO) using calcium carbonate together with rapid and local Joule heating by microwave irradiation. Electrodes were prepared by ultrasonically dispersing rGO in biodegradable poly(vinylpyrrolidone) (PVP) binder and coating this on recyclable poly(ethyleneterephthalate) (PET) sheet using a low cost screen printing technique. The use of the same polymer (PVP) as a binder, in addition to as the solid polymer electrolyte (SPE), enhances the compatibility and ionic conductivity of the hydrophobic rGO electrode in the supercapacitor system. Further, the phosphoric acid (H3PO4)-doped biodegradable SPE was screen printed for the first time on the rGO electrodes. Ionic conductivity and dielectric studies of the SPE were carried out at different temperatures and different dopant acid concentrations. The morphology, composition and structure of the graphene electrode components were characterized using Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) methods. Transmission electron microscopy (TEM) images showed a single layer or a few layers of rGO sheets and selected area electron diffraction showed the presence of slight defects. The fabricated environmentally friendly, industrially favorable and green supercapacitor showed a specific capacitance of 201 F g-1 and cyclic stability with 97% retention of the initial capacitance over 2000 cycles. Furthermore, the performance of this green supercapacitor is comparable to that of those fabricated using rGO synthesized from commercial graphite and in other literature reports. © 2014 The Royal Society of Chemistry.Item Sea coral-derived cuttlebone reinforced epoxy composites: Characterization and tensile properties evaluation with mathematical models(SAGE Publications Ltd info@sagepub.co.uk, 2016) Periasamy, K.; Mohan Kumar, G.C.Using sea coral as a new bio-mass in processing of particle-filled polymer composites is very promising in the field of structural applications. In this study, waste cuttlebone was used as a filler material in epoxy composites. In general, cuttlebone particles derived from crushing and sieving were in aragonite polymorph form. In the present study, calcite polymorph form was obtained after heat treatment of cuttlebone particles at 400°. Presence of polymorph form, elemental composition and thermal stability were confirmed with different characterization techniques. Composites were prepared with aragonite and calcite polymorph form cuttlebone particles and commercially available calcium carbonate as reinforcement in epoxy matrix. Tensile tests were carried out to determine the composites strength and compared with predefined theoretical models. Heat-treated cuttlebone reinforced epoxy composites showed higher tensile properties and better interaction between filler and matrix than other composites. © SAGE Publications.Item Structural, compositional and spectral investigation of prawn exoskeleton nanocomposite: UV protection from mycosporine-like amino acids(Elsevier Ltd, 2020) Hadagalli, K.; Kumar, R.; Mandal, S.; Basu, B.The present work explores the use of marine resourced prawn exoskeleton/shell as a new class of naturally occurring composite containing UV absorbing proteins. Mycosporine-like amino acids with a central aromatic ring in the exoskeleton/shell of naturally occurring prawns (Fenneropenaeus Indicus) offer excellent UV protection. The architecture of shell composite constitutes a matrix of chitin-proteins with distinct reinforcements such as spherical calcites (CaCO3), microscopic proteins, and traces of hydroxides/oxides of magnesium. The presence of tryptophan, phenylalanine, and tyrosine, forming the basic building blocks of mycosporines, is confirmed by structural, compositional, and microscopic studies on prawn shells. The UV spectroscopic signatures at 290 and 320 nm provides strong evidence for the highest UV absorption. UV absorption attributes to the presence of mycosporine-like amino acids. Hence, the current exploration of naturally occurring prawn shells directs towards an additive-free sunscreen filter without the generation of detrimental free radicals. © 2020 Elsevier B.V.Item Effect of Bioprecipitation and Ferrochrome Ash Stabilization on the Strength of Black Cotton Soil(Springer Science and Business Media Deutschland GmbH, 2023) Kothuri, M.; Devatha, C.P.This study aims to stabilize black cotton soil in an environmentally friendly manner by integrating chemical stabilization and bioprecipitation. To improve the unconfined compressive strength (UCS), the soil was partially replaced by ferrochrome ash (FCA) and blended with urease positive bacteria, urea, and calcium chloride. Characterization studies examined microstructural changes. Leachate analysis determined whether this method is environmentally safe. Consequently, experiments were conducted using a central composite design and the UCS was modeled using response surface methodology (RSM) to evaluate the influence of each additive. Liquid extracts of stabilized soil were analyzed for concentrations of chromium, iron, zinc, lead, nickel, cadmium, copper, titanium, mercury, and arsenic. An improvement in the UCS from 35 kPa to 350 kPa was noticed when 40% of the soil was replaced with FCA and mixed with a bacterial solution of optical density 1.12, containing 0.5 g calcium chloride and 0.5 g urea. FCA content, the optical density of the bacteria, and the urea concentration were the factors affecting the UCS significantly. Lead, cadmium, titanium, mercury, and arsenic were not detected in water-based extracts of stabilized soil due to the immobilization effect of calcite. X-ray diffraction (XRD), Field emission gun scanning electron microscopy (FEGSEM), Fourier transform infrared spectroscopy (FTIR), and Thermogravimetric (TG) analyses supported the formation of calcite due to bioprecipitation. Based on the results, it is concluded that FCA and bioprecipitation complement each other to overcome their limitations and successfully enhanced the strength of black cotton soil in an environmentally conscious manner. © 2023, The Author(s), under exclusive licence to Springer Nature Switzerland AG.Item Synergistic effect of nano silica on carbonation resistance of multi-blended cementitious mortar(Elsevier Ltd, 2023) Snehal, K.; Das, B.B.; Barbhuiya, S.Confiscation of alkaline buffer in a blended cementitious system surges the risk of carbonation. Understanding the carbonation mechanism and kinetics of multi-blended cementitious systems in correspondence to microstructural properties is the need of the hour. In this context, the change in the microstructure of binary, ternary, and quaternary blended cementitious mortar mix comprising of fly ash or/and ultra-fine fly ash or/and nano-silica upon accelerated carbonation (3.5% CO2; 70% RH) was studied. All multi-blended mixes were proportioned using modified Andreasen and Andersen particle packing theory. Permeable porosity and carbonation parameters such as carbonation depth, rate of change in compressive strength, and carbonation shrinkage were measured. Further, qualitative/quantitative estimation of carbonation phases was done using characterization techniques such as TGA and FTIR. In control mix with solely OPC, the reaction of CO2 with calcium-bearing phases showed chemo-mechanical changes leading to 18% improvement in strength at 30 days of exposure. The optimized multi-blended cementitious systems with nano-silica exhibited higher resistance to carbonation kinetics. Phase assemblages quantified through TGA within depth of carbonation imply a negligible concentration of portlandite (CH). However, mixes without nano-silica exhibited a significant reduction in bound water content associated with C–S–H/AFt/AFm phases and intensified the precipitation of calcium carbonate (CaCO3) phase. Asymmetric stretching band of C–O–C at 1424 cm−1 corresponding to calcite phase measured using FTIR validates the outcomes of TGA. © 2023 Elsevier LtdItem Effect of Temperature on Solid-State Reaction of Prawn Shell-Derived Phase-Pure β-Tricalcium Phosphate(Springer, 2024) Satish, P.; Praveen, L.L.; Gautam, V.; Hadagalli, K.; Mandal, S.Over the past three decades, bioresorbable ceramics such as beta-tricalcium phosphate (β-TCP)-based porous scaffolds have been extensively studied. β-TCP-based scaffolds or cements for bone tissue applications have proved to be an outstanding alternative to repair and regenerate bone tissue defects caused by trauma or injury. In this study, an investigation on submicron β-TCP powders derived from prawn shell (Fenneropenaeus indicus, a source of marine biowaste) via solid-state reaction approach was carried out, which has calcite (CaCO3) in its exoskeleton (nonedible). The prawn shell-derived β-TCP can be prepared conventionally with dicalcium phosphate (CaHPO4) at different temperatures 900, 1000, 1100, and 1200 °C. The EDX spectra detect the Ca:P ratio of 1.5 confirming the formation of pure β-TCP at 1100 °C, which is in complete agreement with theoretical ratio. X-ray diffraction pattern revealed the phase-pure crystalline rhombohedral crystal structure of β-TCP with an average crystallite size of ~ 25.8 nm, prepared at 1100 °C. The field emission scanning electron microscopy images showed a homogeneous distribution of β-TCP powders with an average grain size of 3.07 µm at 1100 °C. Furthermore, Raman spectroscopy and Fourier transform infrared spectroscopy confirm the characteristics peaks of β-TCP. Differential scanning calorimetry and thermogravimetric analysis are performed to study the thermal behavior of the initial precursors mixture to synthesize β-TCP. β-TCP scaffolds sintered at 1100 °C exhibited compressive strength of ~ 6.2 MPa, for which Ca/P ratio is 1.51. Biodegradation study conducted on β-TCP scaffolds sintered at 1100 °C has shown slow degradation rate up to 5 days. Therefore, the prawn shell-derived β-TCP has physical and morphological properties which projects it as a promising implantable biomaterial for synthetic bone graft substitutes. © ASM International 2024.Item Microstructure, Mechanical Properties, and Tribological Properties of Fe-Based Composite Coatings Reinforced with WC-Co and Cr3C2(Springer, 2025) Chandramouli, T.V.; Joladarashi, S.; Ramesh, M.R.; Rahman, M.R.Fe-based (stainless steel 316L) coatings are widely employed in the aerospace, chemical processing, petrochemical, and marine industries owing to their low and stable price, excellent corrosion resistance, and durability. However, at elevated temperatures, their performance is limited due to wear. Thus, the current investigation incorporates tungsten carbide (WC-Co) and chromium carbide (Cr3C2) into the Fe-based coating to enhance its wear resistance at high temperatures. SS316L reinforced by 30% of WC-Co and Cr3C2 by mechanical mixture, then sprayed using high-velocity oxy fuel spraying method. Coating characteristics, such as microstructures and phase analysis, were measured using FESEM/EDS and XRD. Coating density, microhardness, and bond strength were examined by water immersion, Vickers indentation, and ASTM C-633 methods, respectively. A ball-on-disk tribometer was employed to conduct wear examination at various temperatures (25, 300, and 600 °C) and loads (10 and 30 N) against the alumina counter body. The wear rate and friction coefficient of SS316L-30%WC-Co decrease from 25 to 600 °C, while the wear rate of SS316L-30%Cr3C2 increases with temperature up to 300 °C and then decreases at 600 °C. The oxide phase adheres strongly to underlying surfaces forming a protective layer (Cr2O3, NiWO4, Fe2O3, and NiMO4), changing the mode of wear mechanism. At higher temperatures and loads, the coating exhibited oxidation modified adhesive wear, and coatings provide excellent wear resistance along with reduction in friction. This research provides a novel approach for future standardization and evaluation of coatings on metal alloys for industrial applications. © ASM International 2024.Item Effect of CO2 curing on phase compositions of nano silica blended cementitious mortar partially replaced with carbonated recycled fine aggregates(Elsevier Ltd, 2025) Trivedi, S.S.; Ansari, F.; Das, B.B.; Barbhuiya, S.This manuscript examines the quantification of CO2 uptake, hydration and carbonation phases such as calcium hydroxide (Ca(OH)2, CH), calcium carbonate (CaCO3, CC), magnesite (MgCO3), hydromagnesite (MgCO3.Mg(OH)2.4H2O, Hmgs), siderite (FeCO3) and subsequent carbonation and hydration degrees (CD, HD) in cementitious mortar (CM) incorporating colloidal nano silica (CNS) and carbonated and uncarbonated recycled concrete fine aggregates (RCF) subjected to accelerated carbonation curing (carbonated RCF- CRCF, Non-carbonated RCF- NCRCF). The RCF was prepared through multi cycle jaw crushing technology followed by repeated abrasion cycles and subsequently treated using accelerated carbonation. The mass loss resulting from the breakdown of these compounds at specific temperature ranges (220–350 °C for Hmgs, 250–400 °C for FeCO3, 400–500 °C for CH, 460–900 °C for MgCO3, and 600–800 °C for CC and CO2) was calculated using a thermogravimetric (TG) analyzer. The main findings of this research work confirms the presence of vaterite, calcite, tobermorite (Ca2.25[Si3O7.5(OH)1.5].8H2O or CSH gel), and magnesite polymorphs for CM incorporating 6–9 % CRCF and 1 % CNS as validated by the increased areas of peaks from fourier transform infrared spectroscopy (FTIR) analysis at 714 cm?1, 875 cm?1, 1007 cm?1, and 1405 cm?1, respectively which is further recognized by the increased peak intensities in X-ray diffraction (XRD) analysis. The important findings from the scanning electron microscopy (SEM) analysis revealed the development of additional C-S-H and calcite phases filling the pores and densifying the matrix in CRN mixes while the Ca/Si atomic ratio significantly decreased up to 67 % for CRN-19 mix as found by the energy dispersive X-ray spectroscopy (EDAX). The fresh and hardened state properties of blended mixes highlight the increase in dry density and compressive strength that are found maximum for CRN-19 mix of 57.9 MPa at 28 days owing to the highest rate of strength contribution of 27.95 % from the mix components such as 9 % CRCF and 1 % CNS. However, the flowability is observed to get reduced for all the mixes with CRN-13 mix illustrating approximately 83 % flow values with reference to the control mix. Furthermore, the durability performance of CRCF based primary mixes and all the secondary blends are found to show lowest ingress of chloride ions and permeable porosity values, illustrating up to 73 % and 39 % fall respectively to that of control mix at 28 and 56 days cured samples. Based on the comprehensive investigation and analysis, it is recommended to use pre-carbonated RCF and CNS for developing sustainable CM and achieving CO2 sequestration. © 2025 Elsevier Ltd