Browsing by Author "Anuj Kumar Prajapati"

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Adsorption-Desorption Surface Bindings, Kinetics, and Mass Transfer Behavior of Thermally and Chemically Treated Great Millet Husk towards Cr(VI) Removal from Synthetic Wastewater
(Hindawi Limited, 2022) Anuj Kumar Prajapati; Pushkar Verma; Satyansh Singh; Monoj Kumar Mondal; Muhammad Raziq Rahimi Kooh
This study reports the efficacy of adsorbents synthesized by thermal (TT-GMH) and chemical (CT-GMH) modification of great millet husk (GMH) for the treatment of synthetic wastewater containing Cr(VI). The chemical modification of raw GMH was done by concentrated H2SO4 to increase the porosity and heterogeneity on the surface. The comparative investigations of physicochemical properties of synthesized adsorbents were examined by point of zero charge (pHpzc), BET surface area, SEM-EDX, FTIR, and XRD analyses. The results revealed that CT-GMH had around three times higher surface area and more porous structure as compared to TT-GMH. The adsorption experiments were executed in batch mode to examine the impact of parameters governing the adsorption process. For Cr(VI) solution of 25 mg/L, adsorbent dose of 4 g/L, temperature of 25°C, and shaking speed of 150 RPM, the maximum removal for TT-GMH was attained at pH 1 and contact time 150 min, while for CT-GMH, maximum removal was attained at pH 2 and contact time 120 min. The experimental results fitted to the rate kinetic equations showed that for both TT-GMH and CT-GMH, adsorbents followed the quasi-second-order kinetic model during the adsorption process. Further, results revealed that the adsorption process was endothermic and Sips isotherm model was followed for both TT-GMH and CT-GMH. Based on the Sips isotherm, maximum uptake capacity for TT-GMH and CT-GMH was noted to be 16 and 22.21 mg/g, respectively. Among the tested mass transfer models, liquid film diffusion model was followed during the adsorption process of both the adsorbents. The desorption study revealed that TT-GMH and CT-GMH give 69.45% and 74.48% removal, respectively, up to six cycles. Copyright © 2022 Anuj Kumar Prajapati et al.
Emerging nanocomposites as highly efficient materials for photocatalysis of dyes: Synthesis routes, characterization, and reaction mechanism
(Elsevier, 2021) Anuj Kumar Prajapati; Monoj Kumar Mondal
Organic pollutants in water stream are the foremost concern, due to the high concentration of various coloring components known as dyes or dyestuffs. Industries such as textiles, leather, plastic, etc. are the primary sources of dyes and these are undesirable for our environment and human life. There are various techniques for dye contaminated wastewater treatment, such as photocatalysis, adsorption, membrane filtration, etc. Among these techniques, photocatalysis is preferred due to the high degradation rate, less formation of by-products, etc. Nanocomposites are the new trend photocatalyst materials used in dye photocatalysis due to high degradation of dye, fast kinetic rate, less by-product formation, and easy regeneration. The primary objective of this chapter is to address the synthesis process, surface and morphology characterization, and photocatalysis effects of nanocomposite, and also discuss the degradation/removal efficiency of various hazardous dyes by photocatalysis processes using nanocomposites. The common reaction mechanism related to the photocatalysis of dye degradation by nanocomposite was also discussed. © 2021 Elsevier Inc. All rights reserved.