Molecular uptake of congo red dye from water on iron composite nano particles

The molecular uptake of congo red dye from aqueous solution onto the iron composite nano particles (ICNPs) is described in batch mode with respect to initial dye concentration, contact time, pH, adsorbent dose, and temperature. Adsorption data followed Langmuir, Freundlich, Temkin and Dubinin-Radushkevich models. The developed functionalized ICNPs were effective for the molecular uptake of congo red dye from aqueous solution with maximum 90%. The sorption was spontaneous and exothermic in nature. The optimized batch parameters were initial concentration 150 μg/L; contact time 25 min., pH 7.0, dose 0.5 g/L and 25 °C temperature. The thermodynamic parameters such as ΔG°, ΔH° and ΔS° were − 9.16, − 8.97 and − 8.84 kJ/mol at 20, 25 and 30 °C temperatures; − 3.35 kJ/mol and − 1.61 × 10− 4 kJ/mol K, respectively. Pseudo-first-order and liquid film diffusion mechanisms of the adsorption were proposed. The developed adsorption method was speedy, environmental friendly and inexpensive as may be used under natural water conditions. The method was capable to work at natural water resources pHs with low adsorbent and agitating time. The adsorption method may be applied for the removal of congo red dye from any water body at economic scale.