Green synthesis of mesoporous Ni-Co layered double hydroxide and its application for removal of 2, 4-dinitrophenol from water: A theoretical study complemented by the first principle density functional theory-Monte-Carlo approach. Issue 5 (October 2022)

• Record Type: Journal Article
• Authors: Sangtam, Apuchu R.; Saikia, Pinky; Goswamee, Rajib Lochan; Sinha, Dipak; Sinha, Upasana Bora
• Is Part Of: Journal of environmental chemical engineering. Volume 10:Issue 5(2022)
• Publication Date: 2022-10
• Subjects: Layered double hydroxide (LDH) -- Soft-chemical synthesis -- Adsorption models -- Density Functional Theory (DFT) -- Monte-Carlo Simulation -- Regeneration study; Chemical engineering -- Environmental aspects -- Periodicals; Environmental engineering -- Periodicals; Chemical engineering -- Environmental aspects; Environmental engineering; Periodicals; 660.0286
• DOI: 10.1016/j.jece.2022.108378
• Languages: English
• ISSNs: 2213-2929

Abstract

Abstract: This paper describes the synthesis of a novel mesoporous Ni-Co layered double hydroxide(LDH) and its application for the adsorptive removal of 2, 4-dinitrophenol(2, 4-DNP) from an aqueous solution. A green synthetic method was used involving a non-aqueous 'soft chemical' ethanol: acetone mixture in order to avoid intercalation or interlayer contamination by CO2 gas, which is responsible for carbonate formation. The synthesized material was characterized using PXRD, HR-TEM, FESEM, XPS, FT-IR, TGA-DTA, etc. The experimental and model fitting results of adsorption studies showed that equilibrium Freundlich adsorption isotherm and kinetic pseudo-second-order were the best-fitting models. Also, thermodynamic adsorption parameters ∆ H o, ∆ S o an d ∆ G o were found to be favorable, non-spontaneous, and endothermic. Furthermore, theoretical molecular dynamic simulation (MD) revealed that the nature of adsorbate-substrate (2, 4-DNP- Ni-Co LDH) interactions were favorable hydrophobic interactions. DFT-based DMoL 3 approach showed that the adsorbate-substrate energy gap (eV) increases with the increase in the interfacial region, explaining the high chemical stability after the adhesion of adsorbate molecules. The regeneration adsorption cycles showed that the Ni-Co LDH acts with an excellent removal affinity towards the 2, 4-DNP molecule within 150–180 min from cycles 1–4. Highlights: Synthesis of mesoporous Ni-Co LDH was achieved using a non-aqueous 'soft chemical ' Sol-Gel method. PXRD, FT-IR, FESEM, HRTEM, XPS, TGA-DTA etc., were used to characterize the synthesized compounds. Adsorption Frendulich isotherm and kinetic pseudo-second order were the best-fitting models. Also, thermodynamic adsorption parameters ∆ H o, ∆ S o and ∆ G o were found to be favorable, non-spontaneous, and endothermic. DFT-Based DMoL 3 proved the adsorbate(2, 4-DNP)-substrate(Ni-Co LDH) energy gap increase in interfacial region. MD simulation studies showed the nature of adsorbate-substrate interactions were favored by hydrophobic nature. Regeneration cycles showed that the Ni-Co LDH acts with an excellent removal affinity towards the 2, 4-DNP from cycles 1–4.