Department Of Chemistry
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Item Reduced and oxidized rice straw biochar for hexavalent chromium adsorption: Revisiting the mechanism of adsorption(Elsevier Ltd, 2023-11-01T00:00:00) Dahiya, Amarjeet; Bhardwaj, Akanksha; Rani, Archana; Arora, Meenu; Babu, J. NagendraSurface oxygen functional groups of biochar were tuned by oxidation and reduction of biochar for establishing Cr(VI) adsorption mechanism. Oxygen functional groups (OFGs) on the surface of leached rice straw biochar (LBC4-6) obtained from pyrolysis at 400, 500 and 600 �C, were oxidized to furnish OBC4-6 using modified Hummer's method. Reduced biochar RBC4-6 were obtained by esterification and NaBH4/I2 reduction of oxidized biochar (OBC4-6). The modified biochar were characterized by increase in O/C and H/C ratio, respectively, in case of OBC4-6 and RBC4-6. The Cr(VI) adsorption by modified biochar LBC4-6, OBC4-6, and RBC4-6 showed optimum conditions of pH 3 and dose 0.1 g/L with a good non-linear fit for Langmuir & Freundlich isotherm. The maximum adsorption (Qm) followed the trend: OBC4 (17.47 mg/g) > RBC4 (15.23) > OBC5 (13.23) > LBC4 (10.23) > RBC5 (9.83) > OBC6 (9.60) > RBC6 (7.24) > LBC5 (6.32) > LBC6 (5.98). The adsorption kinetics for adsorption of Cr(VI) on to modified biochar fits pseudo second order (PSO), Elovich and intraparticle diffusion kinetics, showing a chemisorptions in case of biochar L/O/RBC4-6. The lower temperature modified biochar O/RBC4 show better Cr(VI) adsorption. X-ray Photoelectron Spectroscopy (XPS) studies establish optimum OFGs for reduction of Cr(VI) and chelation of the reduced Cr(III). Adsorption and stripping cycles show the oxidized and reduced biochar as better adsorbents with excellent stripping of Cr up to >98 % upon desorption with 1 M NaOH. � 2023Item Tetracycline removal via three-way synergy between pistachio shell powder, zerovalent copper or iron, and peroxymonosulfate activation(Elsevier B.V., 2023-10-20T00:00:00) Kaur, Parminder; Kumar, Atul; Babu, J. Nagendra; Kumar, SandeepPistachio shell powder (PS) immobilized zerovalent iron and zerovalent copper (ZVI@PS and ZVC@PS) were investigated for the tetracycline (TCH) removal via sulfate radical based advanced oxidation process (S-AOP's). Eco-efficient ZVI@PS and ZVC@PS nanocomposite prepared by one-pot redox precipitation method were characterized by using FTIR, XRD, SEM, BET, TGA/DTA, and XPS techniques. The EDX, TGA, and AAS analysis techniques confirmed the loading of 44 % Fe and 40 % Cu (w/w %) onto the pistachio shell biomass in ZVI@PS and ZVC@PS nanocomposites, respectively. This report comprehensively discusses the effect of various contributing factors for the TCH removal via advanced oxidation processes such as catalytic dosage, initial pH, PMS dosage and initial TCH concentrations, etc. Besides that, the role of reactive oxygen species (SO4?,.OH, O2?, and 1O2) in the TCH degradation process was investigated using radical scavenging experiments. A three-way synergistic approach was established between adsorption efficiencies of pistachio shell powder, heterogeneous ZVI or ZVC mediated Fenton-process and enhanced PMS activation process, for the observed enhanced TCH degradations. The observed rate constant (kobs.) values of ZVI@PS-PMS (0.34 min?1) and ZVC@PS-PMS (0.16 min?1) processes for TCH removal suggests that the ZVI@PS was more efficient in TCH removal compared to ZVC@PS. � 2023 The Author(s)Item Fabrication of Monarda citriodora essential oil nanoemulsions: characterization and antifungal activity against Penicillium digitatum of kinnow(Springer, 2023-02-13T00:00:00) Kaur, Kiranjot; Tandon, Ritu; Kalia, Anu; Babu, J. NagendraPostharvest fungal pathogenic invasions are the major root cause of reduced shelf life of kinnow fruit, thereby contributing to the postharvest losses. Development of eco-friendly alternates are the need of the hour owing to health safety concerns for replacing the ongoing synthetic fungicide use. Essential oils with promising antimicrobial activities offer a promising solution but their hydrophobicity poses a big hindrance for exploiting the same. Present work was planned to explore their antimicrobial potential by developing their hydrophilic formulation with the use of nanotechnology. An in vitro study was conducted to assess the efficacy Monarda citriodora essential oil (MCEO) and its emulsions against major postharvest fungal pathogen of Kinnow; Penicillium digitatum. Both micro and nano formulations were prepared for different ratios of MCEO (0.5 to 3%) with different surfactant combinations and oil-surfactant-ratios (OSR) of 1:1 to 1:3. The influence of several process factors such as surfactant and oil phase concentrations, as well as sonication time intervals on emulsion stability was investigated by assessing attributes such as droplet diameter, Polydispersity index (PDI), zeta (?) potential and rheology. An emulsion formulated with 1% oil and 1:1 OSR treated with ultrasonic waves for 15�min was optimized with droplet diameter of 52.2�nm, 0.245 PDI and ?�21�mV of ? potential with consistent stability till 1�month. Further, in vitro antifungal activity of the optimized MCEO nanoemulsion exhibited the best efficacy with 100% inhibition at 200�mg L?1. Graphical Abstract: [Figure not available: see fulltext.] � 2023, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.Item Direct Michael addition/decarboxylation reaction catalyzed by a composite of copper ferrite nanoparticles immobilized on microcrystalline cellulose: an eco-friendly approach for constructing 3,4-dihydrocoumarin frameworks(Royal Society of Chemistry, 2022-10-27T00:00:00) Kumar, Bhupender; Borah, Biplob; Babu, J. Nagendra; Chowhan, L. RajuA composite of copper ferrite oxide nanoparticles immobilized on microcrystalline cellulose (CuFe2O4@MCC) was synthesized. The synthesized composite was characterized by FESEM with EDS-Mapping, TEM, P-XRD, TEM, and BET analysis and investigated for its catalytic activity toward Tandem Michael addition and decarboxylation of coumarin-3-carboxylic acid with cyclic 1,3-diketones to obtain novel 3,4-dihydrocoumarin derivatives. This protocol was established with wide substrate scope and significant yield. The significant characteristics of this methodology are mild reaction conditions, easy setup procedure, non-toxic, and cost-effectiveness. A gram-scale synthesis with low catalyst loading was also demonstrated. � 2022 The Royal Society of Chemistry.Item Synergistic effect of eco-friendly pistachio shell biomass on nano-MnO2 for crystal violet removal: kinetic and equilibrium studies(Institute for Ionics, 2022-05-07T00:00:00) Kumar, S.; Brar, R. Singh; Saha, S.; Dahiya, A.; Kalpana; Babu, J. NagendraPistachio shell powder-supported MnO2 nanostructure-based eco-friendly nanocomposite (nMPP) was prepared via one-pot redox precipitation method and was characterized by FTIR, XRD, SEM, TEM, BET, TGA/DTA, and XPS techniques. SEM and TEM analysis revealed the pseudo-spherical and nanorod morphologies of the synthesized nano-MnO2 and found agglomerated on the pistachio biomass. The nMPP contains nearly 41% Mn as MnO2 (w/w %) dispersed onto the pistachio shell biomass as confirmed from EDX, TGA, and AAS analysis. The nMPP exhibits multi-process crystal violet (CV) removal phenomenon under different pH of aqueous dye solution. Under acidic pH, nMPP caused oxidative degradation of CV by in situ formed.OH radicals; while under the neutral pH, CV undergoes monolayer adsorption onto the surface of nMPP as confirmed from Langmuir adsorption isotherm fit with maximum equilibrium adsorption value of 148.7�mg.g?1. The nMPP nanomaterial exhibits a synergistic effect between adsorption efficiencies of pistachio shell biomass and nano-MnO2 for the effective removal of toxic CV dye. The maximum saturation adsorption and rate constant (k 2) value obtained from the pseudo-second-order kinetic fit model were 119.13�mg.g?1 and 5.0 � 10�4�g.mg?1�min?1, respectively. Graphical abstract: [Figure not available: see fulltext.] � 2022, The Author(s) under exclusive licence to Iranian Society of Environmentalists (IRSEN) and Science and Research Branch, Islamic Azad University.Item Synthesis of in situ immobilized iron oxide nanoparticles (Fe3O4) on microcrystalline cellulose: Ecofriendly and recyclable catalyst for Michael addition(John Wiley and Sons Ltd, 2021-09-21T00:00:00) Kumar, Bhupender; Reddy, Marri Sameer; Dwivedi, Kartikey Dhar; Dahiya, Amarjeet; Babu, J. Nagendra; Chowhan, L. RajuMicrocrystalline cellulose-immobilized Fe3O4 magnetic nanoparticles (Fe3O4@MCC) with iron loading 5%�20% are synthesized and characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The synthesized nanocomposites were studied for their catalytic activity towards Michael addition reaction by employing 1,3-cyclohexadione/dimedone and styrylisoxazole in an aqueous ethanolic medium. The catalyst with 15% iron loading showed the highest efficiency with an excellent yield. Michael addition reaction is one of the most important reaction for the creation of a carbon�carbon bond and widely used in organic synthesis under mild condition. The prepared catalyst performed well in Michael addition reaction and afforded the product in excellent yield. The products were isolated by simple filtration without use of any chromatographic techniques. The scale-up experiment on 10-mmol scale proved the sustainability of the methodology. The catalyst was recycled, and the recovered catalyst data showed no considerable depreciation in catalytic activity even after 5 consecutive cycles. The advantages of this green and safe procedure include a simple reaction set-up, very mild reaction conditions, high yields, moderate reaction time, recyclable catalyst, and easy separation of the products without use of any tedious separation techniques. � 2021 John Wiley & Sons, Ltd.Item Synergistic effect of pistachio shell powder and nano-zerovalent copper for chromium remediation from aqueous solution(Springer Science and Business Media Deutschland GmbH, 2021-07-06T00:00:00) Kumar, Sandeep; Brar, Ravinderdeep Singh; Babu, J. Nagendra; Dahiya, Amarjeet; Saha, Sandip; Kumar, AvneeshPistachio shell powder supported nano-zerovalent copper (ZVC@PS) material prepared by borohydride reduction was characterized using SEM, FTIR, XRD, TGA/DTA, BET, and XPS. SEM, XRD, and XPS revealed the nano-zerovalent copper to consist of a core-shell structure with CuO shell and Cu(0) core with a particle size of 40�100 nm and spherical morphology aggregated on PS biomass. ZVC@PS was found to contain 39% (w/w %) Cu onto the pistachio shell biomass. Batch sorption of Cr(VI) from the aqueous using ZVC@PS was studied and was optimized for dose (0.1�0.5 g/L), initial Cr(VI) concentration(1�20 mg/L), and pH (2�12). Optimized conditions were 0.1 g/L doses of sorbent and pH=3 for Cr(VI) adsorption. Langmuir and Freundlich adsorption isotherm models fitted well to the adsorption behavior of ZVC@PS for Cr(VI) with a pseudo-second-order kinetic behavior. ZVC@PS (0.1g/L) exhibits qmax for Cr(VI) removal up to 110.9 mg/g. XPS and other spectroscopic evidence suggest the adsorption of Cr(VI) by pistachio shell powder, coupled with reductive conversion of Cr(VI) to Cr(III) by ZVC particles to produce a synergistic effect for the efficient remediation of Cr(VI) from aqueous medium. Graphical abstract: [Figure not available: see fulltext.] � 2021, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.