Synthesis of urea-modified MnFe₂O₄ for aromatic micro-pollutants adsorption from wastewater: Mechanism and modeling

Amine-terminated MnFe₂O₄, using urea solution (UMF-MNPs) fabricated by a combined ultrasonic/microwave technique, was characterized and applied as a magnetic adsorbent to remove catechol, phenol, and benzene micro-pollutants from wastewater solutions. The simultaneous effect of solution pH, TDS, micro-pollutants concentrations, UMF-MNPs dose, and temperature was investigated and optimized using D-optimal design in a batch experiment. The quadratic regression, as the best-structured simulated model, predicted the maximum adsorption rates at pH 6.0, TDS 1855 mg/l, UMF-MNPs dose of 0.73 g/l, and temperature 320 K for 50 mg/l micro-pollutant concentrations. Kinetic and isotherm models, through linear and nonlinear regression methods, reflected an excellent correlation (R ² ≈ 0.83 to 1) to simulate the adsorption data. The column breakthrough curves were tested using the equivalent length of the unused bed approach, which well fitted the Thomas model equation. The film diffusion, consequently with Lewis acid–base, is the major rate-controlling adsorption mechanism, and recovered by alkali ethanolic solution.