Publications by authors named "G Bharath"

35 Publications

Valorization of groundnut shell via pyrolysis: Product distribution, thermodynamic analysis, kinetic estimation, and artificial neural network modeling.

Chemosphere 2021 Jun 15;283:131162. Epub 2021 Jun 15.

Department of Chemical Engineering, Khalifa University, P.O. Box 127788, Abu Dhabi, United Arab Emirates. Electronic address:

Pyrolysis of agricultural biomass is a promising technique for producing renewable energy and effectively managing solid waste. In this study, groundnut shell (GNS) was processed at 500 °C in an inert gas atmosphere with a gas flow rate and a heating rate of 10 mL/min and 10 °C/min, respectively, in a custom-designed fluidized bed pyrolytic-reactor. Under optimal operating conditions, the GNS-derived pyrolytic-oil yield was 62.8 wt.%, with the corresponding biochar (19.5 wt.%) and biogas yields (17.7 wt.%). The GC-MS analysis of the GNS-based bio-oil confirmed the presence of (trifluoromethyl)pyridin-2-amine (18.814%), 2-Fluoroformyl-3,3,4,4-tetrafluoro-1,2-oxazetidine (16.23%), 5,7-dimethyl-1H-Indazole (11.613%), N-methyl-N-nitropropan-2-amine (6.5%) and butyl piperidino sulfone (5.668%) as major components, which are used as building blocks in the biofuel, pharmaceutical, and food industries. Furthermore, a 2 × 5 × 1 artificial neural network (ANN) architecture was developed to predict the decomposition behavior of GNS at heating rates of 5, 10, and 20 °C/min, while the thermodynamic and kinetic parameters were estimated using a non-isothermal model-free method. The Popescu method predicted activation energy (E) of GNS biomass ranging from 111 kJ/mol to 260 kJ/mol, with changes in enthalpy (ΔH), Gibbs-free energy (ΔG), and entropy (ΔS) ranging from 106 to 254 kJ/mol, 162-241 kJ/mol, and -0.0937 to 0.0598 kJ/mol/K, respectively. The extraction of high-quality precursors from GNS pyrolysis was demonstrated in this study, as well as the usefulness of the ANN technique for thermogravimetric analysis of biomass.
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http://dx.doi.org/10.1016/j.chemosphere.2021.131162DOI Listing
June 2021

An efficient and magnetically recoverable g-CN/ZnS/CoFeO nanocomposite for sustainable photodegradation of organic dye under UV-visible light illumination.

Environ Res 2021 Jun 17;201:111429. Epub 2021 Jun 17.

Advanced Materials Research Chair, Chemistry Department, College of Science, King Saud University, Riyadh, 11451, Saudi Arabia.

Effective improvement of an easily recoverable photocatalyst is equally vital to its photocatalytic performance from a practical application view. The magnetically recoverable process is one of the easiest ways, provided the photocatalyst is magnetically strong enough to respond to an external magnetic field. Herein, we prepared graphitic carbon nitride nanosheet (g-CN), and ZnS quantum dots (QDs) supported ferromagnetic CoFeO nanoparticles (NPs) as the gCN/ZnS/CoFeO nanohybrid photocatalyst by a wet-impregnation method. The loading of CoFeO NPs in the g-CN/ZnS nanohybrid resulted in extended visible light absorption. The ferromagnetic g-CN/ZnS/CoFeO nanohybrid exhibited better visible-light-active photocatalytic performance (97.11%) against methylene blue (MB) dye, and it was easily separable from the aqueous solution by an external bar magnet. The g-CN/ZnS/CoFeO nanohybrid displayed excellent photostability and reusability after five consecutive cycles. The favourable band alignment and availability of a large number of active sites affected the better charge separation and enhanced photocatalytic response. The role of active species involved in the degradation of MB dye during photocatalyst by g-CN/ZnS/CoFeO nanohybrid was also investigated. Overall, this study provides a facile method for design eco-friendly and promising g-CN/ZnS/CoFeO nanohybrid photocatalyst as applicable in the eco-friendly dye degradation process.
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http://dx.doi.org/10.1016/j.envres.2021.111429DOI Listing
June 2021

Nano-activated carbon derived from date palm coir waste for efficient sequestration of noxious 2,4-dichlorophenoxyacetic acid herbicide.

Chemosphere 2021 Jun 5;282:131103. Epub 2021 Jun 5.

Department of Chemical Engineering, Khalifa University, P.O. Box 127788, Abu Dhabi, United Arab Emirates. Electronic address:

Alarming water contamination rates by toxic herbicides have drawn attention to treat these pollutants using efficient, easy, and economic techniques. In this work, date-palm coir (DPC) waste-based nano-activated carbon (DPC-AC) was successfully prepared and examined for adsorptive removal of toxic 2,4-dichlorophenoxyacetic acid (2,4-DPA) herbicide from synthetic wastewater. The DPC-AC was synthesized via a single-step carbonization-KOH activation approach. The nanosorbent displayed a flaky morphology with graphitic structure and oxygen-rich surface functionalities. The nanocarbon with a mean particle size of 163 nm possessed a high specific surface area of 947 m/g with an average pore size of 2.28 nm. High 2,4-DPA removal efficiency of 98.6% was obtained for the optimal adsorption conditions of pH 2, dosage 0.15 g, rotational speed 100 rpm, time 90 min, and initial 2,4-DPA concentration of 100 mg/L. Langmuir isotherm best described the equilibrium behavior with a theoretical maximum of 50.25 mg/g adsorption capacity for the system. Pseudo-second order model was more appropriate in quantifying the kinetics for all initial feed concentrations. Thermodynamically, the adsorption process was spontaneous, endothermic, and involved low activation energy. A plausible mechanism for the adsorption-desorption of 2,4-DPA onto DPC-AC is also discussed. Cost analysis and regenerability studies proved the economic value ($3/kg) and reusable nature of DPC-AC without any significant loss in its performance. Overall, this study highlights the advantages of DPC waste valorization into efficient nanoadsorbent and the sequestration of noxious 2,4-DPA herbicide from its aqueous streams using this nanosorbent.
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http://dx.doi.org/10.1016/j.chemosphere.2021.131103DOI Listing
June 2021

Adsorptive removal of noxious atrazine using graphene oxide nanosheets: Insights to process optimization, equilibrium, kinetics, and density functional theory calculations.

Environ Res 2021 Jun 6;200:111428. Epub 2021 Jun 6.

Department of Chemical Engineering, Khalifa University, P.O. Box 127788, Abu Dhabi, United Arab Emirates.

Atrazine is a toxic herbicide whose alarming rate of contamination in the drinking water and wastewater poses a severe threat to the environment and human health. Here in this study, the graphene oxide (GO) nanosheets were prepared using Hummers' method with minor modification and studied as a potential adsorbent for atrazine removal from simulated wastewater. The spectroscopy and microscopic analysis confirmed the successful formation of GO with a multilayer structure resembling the crumpled sheets with random stacking. The Response Surface Methodology (RSM) employing Box Behnken design (BBD) was successfully developed to predict the optimal conditions for maximal atrazine removal as adsorbent dosage 121.45 mg/L; initial feed concentration 27.03 mg/L; temperature 27.69 °C, pH 5.37, and time 180 min. The atrazine adsorption onto GO was found to be higher in acidic pH and lower temperature. Density functional theory (DFT) calculation of adsorbent-adsorbate complex in the implicit solvent medium suggests adsorption affinity energy of -24.4 kcal/mol for atrazine. A careful observation of the molecules configuration and binding energy showed that the π-π interactions and hydrogen bonds played a significant role in the adsorption phenomena. Langmuir isotherm suited well to the adsorption process with a maximum adsorption capacity of 138.19 mg/g, at 318 K. The fitness of kinetic models for atrazine adsorption onto GO nanosheets were in following order Ho < Sobkowsk-Czerwi < Avrami model based on their correlation coefficient (R) values. Reusability analysis showed that GO nanosheets could be effectively recycled using 0.01 N NaOH up to six cycles of atrazine removal. Thus, this study provided a theoretical and experimental basis for the potential application of GO nanosheets as a novel adsorbent for the removal of hazardous atrazine.
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http://dx.doi.org/10.1016/j.envres.2021.111428DOI Listing
June 2021

High-Grade Biofuel Synthesis from Paired Electrohydrogenation and Electrooxidation of Furfural Using Symmetric Ru/Reduced Graphene Oxide Electrodes.

ACS Appl Mater Interfaces 2021 Jun 19;13(21):24643-24653. Epub 2021 May 19.

Department of Chemical Engineering, Khalifa University, P.O. Box 127788, Abu Dhabi 127788, United Arab Emirates.

Electrochemical hydrogenation is a challenging technoeconomic process for sustainable liquid fuel production from biomass-derived compounds. In general, half-cell hydrogenation is paired with water oxidation to generate the low economic value of O at the anode. Herein, a new strategy for the rational design of Ru/reduced graphene oxide (Ru/RGO) nanocomposites through a cost-effective and straightforward microwave irradiation technique is reported for the first time. The Ru nanoparticles with an average size of 3.5 nm are well anchored into the RGO frameworks with attractive nanostructures to enhance the furfural's paired electrohydrogenation (ECH) and electrooxidation (ECO) process to achieve high-grade biofuel. Furfural is used as a reactant with the paired electrolyzer to produce furfuryl alcohol and 2-methylfuran at the cathode side. Simultaneously, 2-furic acid and 5-hydroxyfuroic acid along with plenty of H and e are generated at the anode side. Most impressively, the paired electrolyzer induces an extraordinary ECH and ECO of furfural, with the desired production of 2-methylfuran (yield = 91% and faradic efficiency (FE) of 95%) at = 97%, outperforming the ECH half-cell reaction. The mechanisms of the half-cell reaction and paired cell reaction are discussed. Exquisite control of the reaction parameters, optimized strategies, and the yield of individual products are demonstrated. These results show that the Ru/RuO nanocomposite is a potential candidate for biofuel production in industrial sectors.
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http://dx.doi.org/10.1021/acsami.1c02231DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8289174PMC
June 2021
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