ABSTRACT
Size-controlled Pb0.06Fe0.7O3 nanoparticles (Pb-FeONPs) were fabricated by the thermal co-precipitation method and characterized by FE-SEM, EDX, XRD, and IR techniques. The SEM and XRD images showed the average size distribution and average crystallite size of 19.21 nm and 4.9 nm, respectively. The kinetic model of Congo Red (CR) adsorption onto Pb-FeONPs was verified and found to be a pseudo-second-order reaction. The Langmuir plot was better fitted (R2 = 0.990) than other isotherm models with a Qmax (mg/g) of 500 for Congo Red (CR) dye in 40 min. The double-layer statistical physics model based on two energies was used to calculate the significant parameters. The n (stoichiometric coefficient) values obtained from the statistical physics double-layer model were found to be 0.599, 0.593, and 0.565, which are less than 1, indicating the multi-docking process. The regeneration of Pb-FeONPs was used for up to 5 cycles effectively, making the material highly economical. The Pb-FeONPs were fruitfully applied for the removal of CR dye from wastewater on a laboratory and industrial scale.
Subject(s)
Congo Red , Water Pollutants, Chemical , Adsorption , Congo Red/analysis , Hydrogen-Ion Concentration , Kinetics , Lead , PhysicsABSTRACT
A Schiff-base 2-((E)-(3-(prop-1-en-2-yl)phenylimino)methyl)-4-nitrophenol (Receptor 1) colorimetric probe was synthesized and its UV-visible and fluorescence spectral properties for the sensing of Cu+ 2 ions in CH3OH/H2O (60:40,v/v) solvent system was explored. The Receptor 1 showed the discriminating spectral behavior with the addition of Cu2+ ions solution. The other metal ions showed no significant effect towards Receptor 1. Moreover, the addition of Cu2+ ions to the Receptor 1 demonstrated the shift in the peak towards longer wavelength of 405 nm due to the ligand to metal charge transfer (LMCT) effect. The red-shift and new peak at 405 nm are due to the deprotonation of the -OH group and formation of complex and O-Cu covalent bond, respectively. A slight increase in the Cu2+ ion concentration exhibited strong absorption and fluorescence properties, leading to the spontaneous change in color from pale yellow to orange. Additionally, Density Functional Theory (DFT) studies were performed to investigate the interaction of Cu2+ ions with Receptor 1. The decrease in the energies (3.59062 kcal/mol to 0.36028 kcal/mol) of Cu2+-Receptor-1 complex compared to Receptor 1 confirms the strong interaction with high stability. The association constant (Ka) of Cu2+-Receptor-1 complex was found as 175000 M- 1. The limit of detection (LOD) was calculated and noted as 179 nM.
