Browsing by Author "Gupta, R.K."

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Cadmium removal from water by green synthesized nanobioadsorbent [SiO2@DOPP]: Mechanism, isotherms, kinetics and regeneration studies
(Elsevier B.V., 2020-12-09T00:00:00) Saini, Jyoti; Garg, V.K.; Gupta, R.K.
In this study, dried orange peel powder [DOPP] is chemically modified with nanosilica (SiO2) employing sonication technique to produce nanobioadsorbent [SiO2@DOPP]. [SiO2@DOPP] This nanoadsorbent was evaluated for Cd2+ removal from aqueous systems. Successful functionalization of [DOPP] into nanosilica was confirmed by various analytical techniques like XRD, FTIR, SEM, EDX, TEM, DLS, pHzpc and TGA. XRD, FTIR and EDX confirmed the emergence of new peaks after modification of [DOPP] by nanosilica and adsorption of Cd2+ onto [SiO2@DOPP]. Further, TGA spectrum suggested that [SiO2@DOPP] nanoadsorbent is thermally more stable than [DOPP]. pH plays a major role to Cd2+ adsorption onto [SiO2@DOPP]. The optimum conditions for Cd2+ removal include pH = 6.5 and 0.03g adsorbent dose with 100 min contact time. Different adsorption isotherms models [best fitted-(Langmuir adsorption model)], adsorption kinetics [best fitted�(Pseudo second order and Intraparticle diffusion)] were examined for the removal of Cd2+. The maximum monolayer adsorption capacity [qmax] was 142 mg/g. Thermodynamic evaluation indicates the endothermic and spontaneous nature of Cd2+ adsorption onto [SiO2@DOPP]. Furthermore complexation mechanism of Cd2+ onto [SiO2@DOPP] is discussed in detail. The results indicate involvement of functional group interactions, ?�metal interactions, proton exchange, chelate complexes and electrostatic interactions during adsorption of Cd2+ onto [SiO2@DOPP]. Based on the results it has been inferred that [SiO2@DOPP] is a promising nanobioadsorbent to manage environment burden of Cd2+ from aqueous systems. � 2020 Elsevier B.V.
Dispersion analysis and improved F-expansion method for space–time fractional differential equations
(Springer, 2019) Kaur, B; Gupta, R.K.
In this article, an improved F-expansion method with the Riccati equation is suggested for space–time fractional differential equations for exact solutions. The fractional complex transformation is used to convert the space–time fractional differential equations into ordinary differential equations. The application of the method is described by solving space–time fractional potential Yu–Toda–Sasa–Fukuyama equation, and the solutions of the equation are successfully established in terms of the hyperbolic, trigonometric and rational types of functions. The graphical analysis describes the effect of fractional orders α, β, γ, δ of time and space derivatives, respectively, on the wave profile of solutions. The dispersion relation is obtained using the linear analysis, and it shows that waves follow anomalous or normal dispersion depending upon space or time fractional-order values. © 2019, Springer Nature B.V.
Doubly periodic wave structure of the modified Schr�dinger equation with fractional temporal evolution
(Elsevier B.V., 2022-01-01T00:00:00) Kumari, Pinki; Gupta, R.K.; Kumar, Sachin; Nisar, K.S.
Abundant Jacobi elliptic type solutions with distinct physical structures of complex nonlinear conformable time-fractional modified Schr�dinger equation are obtained by using the generalized Jacobi elliptic function (GJEF) method. The Jacobi function expansions may lead to new doubly periodic wave solutions, soliton solutions, and triangular periodic solutions. Nowadays the conformable operator is being used for a better description of the dynamical systems. Motivated by the potential applications of the governed equation in nonlinear optics, biological sciences, and fluid dynamics, these solutions may be significant in the study of wave propagation in the desired field. Symbolic computations are made with the aid of Maple. � 2022 The Authors
Nonclassical symmetries and similarity solutions of variable coefficient coupled KdV system using compatibility method
(Springer Netherlands, 2017) Gupta, R. K.; Singh, Manjit; Gupta, R.K.; Singh, M.
The variable coefficient KdV system is investigated for nonclassical symmetries using compatibility method, and more general symmetries are reported. Several inequivalent reductions are obtained using optimal system of subalgebras, and using well-known methodologies, several traveling wave solutions are also obtained for every reduction. ? 2016, Springer Science+Business Media Dordrecht.
Removal of Methylene Blue from aqueous solution by Fe3O4@Ag/SiO2 nanospheres: Synthesis, characterization and adsorption performance
(Elsevier B.V., 2018) Saini, J.; Garg, V.K.; Gupta, R.K.
In this study, silver silica coated magnetite (Fe3O4@Ag/SiO2) nanospheres were synthesized employing sonication method and their performance was evaluated as nanoadsorbents for the removal of Methylene Blue in batch mode experiments. The physical characteristics of these nanospheres were studied using XRD, SEM, EDX, TEM, and FTIR techniques. The Fe3O4@Ag/SiO2 nanospheres were capable to remove 99.6% Methylene Blue from aqueous solution at pH 7. A possible mechanism for the adsorption of Methylene Blue onto Fe3O4@Ag/SiO2 has been proposed. The adsorption equilibrium and kinetics were studied for experimental data. The removal process followed Langmuir isotherm with maximum monolayer adsorption capacity of 128.5 mg/g. Experimental kinetic data fitted well to Pseudo-second-order and Intraparticle diffusion models. The values of thermodynamic parameters, viz., ?G0, ?S0 and ?H0 confirmed spontaneous, endothermic and feasible adsorption of Methylene Blue under studied experimental conditions. The Fe3O4@Ag/SiO2 nanospheres were regeneratable and reusable for five successive cycles. ? 2017 Elsevier B.V.
Removal of Orange G and Rhodamine B dyes from aqueous system using hydrothermally synthesized zinc oxide loaded activated carbon (ZnO-AC)
(Elsevier Ltd, 2017) Saini, J.; Garg, V.K.; Gupta, R.K.; Kataria, N.
This study reports the synthesis of zinc oxide loaded activated carbon (ZnO-AC) using hydrothermal method and its use to remove organic dyes [Orange G (OG) and Rhodamine B (Rh-B)] from the aqueous system under varying process conditions. ZnO-AC nanoparticles were characterized using XRD, SEM, EDX, DLS, and FTIR. The Langmuir adsorption model was best fitted to the experimental data for both the dyes. Langmuir adsorption capacity (qmax) for OG and Rh-B was 153.8 and 128.2 mg/g, respectively. The rate of adsorption was investigated by various models namely pseudo-first-order, pseudo-second-order and intraparticle diffusion model. Rate mechanism was described by pseudo-second-order model for both the dyes. Thermodynamic studies suggested that removal of Rh-B onto ZnO-AC was endothermic up to a temperature of 40 ?C while OG removal decreased with increase in temperature. Negative values of ? G0 for adsorption of dyes suggested spontaneous adsorption processes. ? 2017 Elsevier Ltd. All rights reserved.