Department of Chemical Engineering
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Item Carbon Dioxide Adsorption over Activated Biocarbons Derived from Lemon Peel(MDPI, 2024-09) Roy, BanasriThe rising concentration of CO2 in the atmosphere is approaching critical levels, posing a significant threat to life on Earth. Porous carbons derived from biobased materials, particularly waste byproducts, offer a viable solution for selective CO2 adsorption from large-scale industrial sources, potentially mitigating atmospheric CO2 emissions. In this study, we developed highly porous carbons from lemon peel waste through a two-step process, consisting of temperature pretreatment (500 °C) followed by chemical activation by KOH at 850 °C. The largest specific surface area (2821 m2/g), total pore volume (1.39 cm3/g), and micropore volume (0.70 cm3/g) were obtained at the highest KOH-to-carbon ratio of 4. In contrast, the sample activated with a KOH-to-carbon ratio of 2 demonstrated the greatest micropore distribution. This activated biocarbon exhibited superior CO2 adsorption capacity, reaching 5.69 mmol/g at 0 °C and 100 kPa. The remarkable adsorption performance can be attributed to the significant volume of micropores with diameters smaller than 0.859 nm. The Radke–Prausnitz equation, traditionally employed to model the adsorption equilibrium of organic compounds from liquid solutions, has been shown to be equally applicable for describing the gas–solid adsorption equilibrium. Furthermore, equations describing the temperature dependence of the Radke–Prausnitz equation’s parameters have been developed.Item Carbonaceous catalysts (biochar and activated carbon) from agricultural residues and their application in production of biodiesel: A review(Elsevier, 2024-03) Chatterjee, Somak; Roy, BanasriCarbonaceous catalysts obtained from agricultural residue could have potential in the production of biofuels such as biodiesel. This review paper discusses the preparation conditions (temperature, heating rate, hold time, inert gas flow rate, etc play key roles in development of textural characteristics of the catalysts) and functionalization methods of biochar and activated carbon derived from agricultural residues and their application to produce biodiesel. Research works reported in achieving maximum yield of biodiesel in terms of variable precursors, alcohol-to-oil ratio, reaction time and temperatures have been profoundly tabulated. Effect of textural properties of the biochar and activated carbon (such as surface area, total pore volume, average pore size, and functional group attached with the catalyst) on the biodiesel yield are examined. Studies on Regeneration and reusing of the spent catalysts are carefully inspected. The economic evaluation studies for the biochar and activated carbon and the applications of these for biodiesel production are scrutinized. Finally, the strategies to increase biomass and catalyst productivity, future prospect and research directions to enhance biofuel/biodiesel production and for the development of biochar and activated carbon from agricultural residues for sustainable biodiesel production is suggested.Item Photovoltaic performance of dye sensitized solar cell based on rutile TiO2 scaffold electrode prepared by a 2 step bi-layer process using molten salt matrices(Elsevier, 2011-08) Roy, BanasriDye sensitized solar cells were made on TiO2 scaffold anodes of rutile particles. These TiO2 scaffold anodes were grown from rutile seeds by using a molten salt synthesis technique. Different thickness coatings of mixed amorphous titanium hydroxide and NaCl–KCl eutectic salt mixture on the rutile seeds were heat treated at different temperatures. The rutile whiskers of different aspect ratios were grown depending on the growth temperature. The best photovoltaic performances were obtained for the device made from the scaffold of 20–50 nm diameter and 0.5–1 μm length nanowhiskers obtained at 700 °C for 5 h of treatment.Item Effect of variable conditions on steam reforming and aqueous phase reforming of n-butanol over Ni/CeO2 and Ni/Al2O3 catalysts(Elsevier, 2014-12) Roy, BanasriA comparison of aqueous phase reforming (APR) and steam reforming (SR) of n-butanol (n-BuOH) over Ni(20 wt%) loaded Al2O3 and CeO2 catalysts has been discussed in this paper. The BuOH conversion increases as the system pressure decreases in APR and SR. For both catalysts, the H2 and CO2 selectivity increased as the pressure increased in SR, reached a maximum at the bubble point pressure, and then decreased in the APR region. The Ni/CeO2 catalyst demonstrated higher selectivity for H2 and CO2than the Ni/Al2O3 catalyst during SR, which are consistent with the results of our previous publication on APR of n-butanol (n-BuOH) over similar catalysts. Unlike in APR, the Ni/CeO2 catalyst produced CO in SR. For both of the catalysts, the activation energies for H2 and CO2 production and BuOH conversion were lower in SR than that in APR. The proposed primary reaction pathway for reforming of BuOH on both catalysts is the same for APR and SR. The n-BuOH dehydrogenated to butaldehyde followed by decarbonylation to propane. Then the propane is steam reformed to hydrogen and carbon monoxide. The CO converts to CO2 mostly through water gas shift.Item Development of Ni–Sn/Al2O3 Nano Catalysts for H2 Production from Biomass by Aqueous Phase Reforming(Igenta, 2014-07) Roy, BanasriPreparation and characterization of nano Ni–Sn/Al2O3 catalysts prepared by Co-precipitation technique has been reported in this paper. Two set of samples have been designed; in first one the metal/support catalyst is directly precipitated from solution mixture of precursors as one pot synthesis, while for the second one, Al2O3 support is prepared by precipitation method and then metal is loaded by standard wet impregnation. Aluminum nitrate, nickel nitrate, tin chloride, and ammonia solution are used as the starting materials. Investigations regarding the structure - property relations are being carried out through TGA, FTIR, and XRD which will be discussed in detail.Item Synthesis of nanoscale oxide scaffold on Nitinol surface using hydrothermal treatment(Taylor & Francis, 2015-04) Roy, BanasriNanostructured scaffolds were synthesized on the surface of equiatomic NiTi alloy (Nitinol) via hydrothermal treatment at 120 ± 1°C and 250 kPa using alkali (NaOH) solution of different strength. The scaffolds were found to be composed of intermingled nanopetals with varying morphology and phase content depending on the treatment time and alkali concentration. Single or mixed Ni3Ti3O, NiTiO3, H2Ti3O7 and TiO2 (anatase and rutile) phases were observed in the scaffold by X-ray diffraction study. Standard hemolysis testing showed significant biocompatibility improvement of the scaffolds grown in low strength alkali. Measurement of Ni release in the simulated body fluid (SBF) revealed that Ni release can be decreased from ∼60 μg L− 1 for the mechanically polished bare NiTi surface to ∼2·7 μg L− 1 for the scaffolded surface (scaffolds grown in low strength alkali).Item Study of preparation method and oxidization/reduction effect on the performance of nickel-cerium oxide catalysts for aqueous-phase reforming of ethanol(Elsevier, 2015-12) Roy, BanasriThe effect of preparation method and oxidation state of the active metal on the catalytic activity of Ni–Ce–O catalysts was studied for aqueous phase reforming of ethanol. A sol-gel (SG) route and a solution combustion synthesis (SCS) method were used for the preparation of 10 wt% Ni loaded catalysts. The catalytic activity of three groups of catalysts; reduced at 425 °C (HR, metallic Ni), reduced at 1000 °C (FR, metallic Ni), and not reduced (NR, as NiO) were tested at different operating conditions. The difference in the metal particle sizes, governed by the preparation method, affects the catalytic efficiency most, not the reduced or oxidized state of Ni. The SG samples were superior for ethanol conversion and selectivity for H2 and CO2 compared to the SCS samples. The X-ray photoelectron spectroscopy (XPS) analysis of the samples demonstrated that the relative ratio of Ce2O3 to CeO2 increased inside the reactor. While Ni doping increases oxygen mobility in the Ce–O lattice, Ce3+ converts Ni2+ to metallic Ni inside the reactor. This can explain why the reduction stage for Ni–Ce–O system in APR is irrelevant. Higher oxygen mobility through the support helps oxidation of CO to CO2 leading to improved catalytic performance.Item Synthesis of Mixed-Phase TiO2 Powders in Salt Matrix and Their Photocatalytic Activity(Taylor & Francis, 2016-05) Roy, BanasriThree mixed-phase TiO2 powders, containing ∼80 volume % anatase and ∼20 volume % rutile, were prepared from amorphous titanium hydroxide and three different salt matrices—pure sodium chloride, pure Na2CO3, and pure disodium hydrogen phosphate (DSP). Amorphous titanium hydroxide and salt mixtures were heat treated at 875°C in a rapid thermal annealing system for different times, according to the time–temperature phase transformation graphs. Time-dependent UV degradation of aqueous solutions of methylene blue dye (15 ppm) in the presence of mixed-phase powders was used to monitor the activity of the catalysts. Microstructural study of the powders by scanning electron microscope and transmission electron microscope combined with phase analysis by XRD and optical absorbance by UV-absorption spectroscopy indicated that the higher photocatalytic activity of the powder obtained from pure DSP salt could be explained by its smaller rutile particle size and anatase–rutile interparticle bonding.Item Synthesis of Al-doped Nano Ti-O scaffolds using a hydrothermal route on Titanium foil for biomedical applications(Elsevier, 2016-09) Roy, BanasriAl-doped and undoped Ti-O nanowire scaffolds were fabricated on the surface of titanium foil via a one-step hydrothermal reaction in the presence of an alkali solution at 120±1 °C temperature and at 15 psi pressure. Grazing Incidence X-Ray and electron microscopy analyses confirmed that the phase composition, length and diameter of the nanowires depend on alkali concentration and reaction time, and the Al doping. Whereas, Al doping retarded the oxide phase formation and transformation rate and changed the morphology of the nanowires. Preliminary hemolysis test showed better biocompatibility of the Al-doped scaffolds compared to the undoped ones.Item Low temperature solid oxide electrolytes (LT-SOE): A review(Elsevier, 2017-01) Roy, BanasriLow temperature solid oxide fuel cell (LT-SOFC) can be a source of power for vehicles, online grid, and at the same time reduce system cost, offer high reliability, and fast start-up. A huge amount of research work, as evident from the literature has been conducted for the enhancement of the ionic conductivity of LT electrolytes in the last few years. The basic conduction mechanisms, advantages and disadvantages of different LT oxide ion conducting electrolytes {BIMEVOX systems, bilayer systems including doped cerium oxide/stabilised bismuth oxide and YSZ/DCO}, mixed ion conducting electrolytes {doped cerium oxides/alkali metal carbonate composites}, and proton conducting electrolytes {doped and undoped BaCeO3, BaZrO3, etc.} are discussed here based on the recent research articles. Effect of various material aspects (composition, doping, layer thickness, etc.), fabrication methods (to achieve different microstructures and particle size), design related strategies (interlayer, sintering aid etc.), characterization temperature & environment on the conductivity of the electrolytes and performance of the fuel cells made from these electrolytes are shown in tabular form and discussed. The conductivity of the electrolytes and performance of the corresponding fuel cells are compared. Other applications of the electrolytes are mentioned. A few considerations regarding the future prospects are pointed.