Adsorption of Congo Red on Pb doped FexOy: experimental study and theoretical modeling via double-layer statistical physics models

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. HIGHLIGHTS Pb-FeONPs of 19.21 nm size material were synthesized.; Pb-FeONPs utilized as an efficient adsorbent for removal of Congo Red dye from water samples.; High specific surface area of Pb-FeONPs indicated favorable adsorption behavior for dyes.; The Pb-FeONPs was successfully applied for the removal of CR dye from laboratory and industrial waste.;

Keywords

• double-layer model
• isotherm modeling
• pb-feonps
• statistical physics model