Kinetics and TD-DFT calculations of base-catalyzed oxidation of acriflavine hydrochloride: Removal of dyes colors from wastewater

Abstract

The oxidation kinetics of acriflavine hydrochloride (AFH) to nitro-acriflavine (N-AFH) by KMnO4 as oxidizing agent in sodium hydroxide medium at a constant ionic strength of 0.5 moldm−3 was studied using spectrophotometric methods. It was found that the reaction went through two distinct steps that could be monitored. In the first stage, coordination species including transient blue pentavalent manganese and/or green hexavalent manganese species may be made quite quickly followed by the decomposition of intermediates in the second slow stage to produce soluble Mn (IV) and the nitroacriflavine as resulting products of oxidation. It has been investigated how several variables such as pH, ionic strength, permanganate ion concentration, and AFH substrate concentration affect oxidation rates. The experimental results demonstrated a first-order dependence in [MnO4−] and fractional first-order kinetics in each of [AFH] and alkali concentration under pseudo-first-order reaction conditions of [MnO4−] >>10 [AFH]. Sodium hydroxide concentrations accelerated the oxidation reaction, and as the alkali concentration rose, so the type of catalyzed is base-catalyzed. Evidence for the creation of a 1:1 intermediate complex was discovered using spectrophotometry and kinetics. In accordance with the kinetic findings, an efficient oxidation process that is compatible with the kinetic data obtained in terms of the activation parameters evaluated was analyzed, proposed, and debated. There are several techniques used to study the nanostructure thin films (AFH)TF and (N- AFH)TF, with using FT-IR, kinetic, isotherms of liquid-phase adsorption, and optical characteristics. A low deposition rate and a chamber pressure of 5 × 105 mbar are used in the PVD method to create (AFH)TF and (N-AFH)TF thin coatings with a 95 nanometer thickness. The isolated molecules (AFH)Iso and (N-AFH)Iso were additionally optimized using time-dependent density functional theory (TD-DFT) using TD-DFTD/Mol3 and Cambridge Serial Total Energy Bundle (TD-FDT/CASTEP). The optimized geometries, vibrational wavenumbers, intensity of vibrational bands, and various atomic charges of 9VC have all been investigated using DFT-B3LYP system using a 6-31G (d,p) basis set.