Department Of Environmental Science And Technology
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Item Multifunctional nanohybrid for simultaneous detection and removal of Arsenic(III) from aqueous solutions(Elsevier Ltd, 2021-12-01T00:00:00) Singh, Simranjeet; Khasnabis, Sutripto; Anil, Amith G.; Kumar, Vijay; Kumar Naik, TS Sunil; Nath, Bidisha; Garg, Vinod Kumar; Singh, Joginder; Ramamurthy, Praveen C.Herein, for the adsorption and detection of As (III), multifunctional nanohybrid have been synthesized using a solvothermal approach. Structural and functional characterizations confirmed the impregnation of the ZnO over graphene oxide. Nanohybrid exhibits a remarkable qmax (maximum adsorption capacity) of 8.17 mg/g, at an adsorbent dose of 3 g/L and pH of 8.23. Higher adsorption with nanohybrid was attributed to a large BET surface area of 32.950 m2/g. The chemical nature and adsorption behaviour of As(III) on ZnO-GO were studied by fitting the data with various adsorption isotherms (Langmuir & Freundlich) and kinetics models (six models). It is observed from the findings that removal of As(III) with ZnO-GO nanocomposite appears to be technically feasible with high removal efficiency. The feasibility of the nanocomposite to function as a sensor for the detection of As(III) was also evaluated. The fabricated sensor could detect As(III) with a lower limit of detection of 0.24 ?M and linear range up to 80 ?M. Overall, this study is significant in nanohybrid as a multifunctional composite for the adsorption and detection of As (III) from wastewater. � 2021 Elsevier LtdItem 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.Item Green synthesized SiO2@OPW nanocomposites for enhanced Lead (II) removal from water(Elsevier B.V., 2020) Saini J.; Garg V.K.; Gupta R.K.The orange peel waste (OPW) was chemically spiked with silica nanospheres, to develop a novel, nanocomposite (SiO2@OPW) with enhanced adsorption capacity for heavy metals. The dispersion of silica nanospheres into orange peel waste was confirmed by XRD, FTIR, TEM, SEM and EDX. Adsorption of Pb2+ ions onto SiO2@OPW was studied in batch mode under varying process conditions such as pH, metal concentration, contact time and adsorbent dosage. The maximum adsorption capacity for OPW and SiO2@OPW was 166.7 mg/g and 200.0 mg/g, respectively calculated employing the Langmuir isotherm model. The kinetic data followed pseudo second order and intraparticle diffusion models. The maximum removal of Pb2+ ions was at pH = 6.0, adsorbent dosage = 0.02 g/L and contact time 60 min. Regeneration and reusability of SiO2@OPW was studied for five cycles. Owing to reusability and high adsorption capacity, SiO2@OPW nanocomposites may be considered as a promising adsorbent for the removal of heavy metals from water and wastewater.Item 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.Item Removal of Congo red and Brilliant green dyes from aqueous solution using flower shaped ZnO nanoparticles(Elsevier Ltd, 2017) Kataria, N.; Garg, V.K.This work reports preparation and characterization of ZnO nanoparticles prepared by low temperature hydrothermal methods and their application for anionic dye (Congo red) and cationic dye (Brilliant green) removal from aqueous medium. The adsorption capacity of ZnO nanoparticles for Congo red dye and Brilliant green dye was up to 71.4 and 238 mg/g, respectively under selected process conditions. Dye adsorption behaviour has been explained applying different isotherms. Freundlich isotherm model best fitted to the dye removal data. Adsorption kinetics of both dyes is well explained by pseudo-second order model. Physical adsorption has been investigated using thermodynamic parameters viz., Gibb's free energy (?G?), enthalpy (?H?) and entropy (?S?). The reusability of ZnO nanoparticles was examined upto three cycles. ? 2017 Elsevier Ltd. All rights reserved.