Cationic surfactant modified iron nanoparticles for removal of orange II in batch mode: Kinetics, isotherms, mechanistic, and thermodynamic approach

The interaction of cetyltrimethylammonium bromide (CTAB) with orange II has been studied spectrophotometrically. CTA-Orange II complex was isolated from an aqueous solution with chloroform. The results indicate that the CTAB interacts in 1:1 stoichiometry with orange II. CTAB capped FeNPs were used as an adsorbent to the removal of CTA-Orange II complex. Energy dispersive x-ray spectroscope (EDX), Fourier transform infrared spectroscope (FTIR), surface scanning microscope (SEM), and transmission electron microscope (TEM) were used to determine the morphology of FeNPs. The effect of contact time, pH, and concentration of orange II were examined on the removal of dye and surfactant. The removal of orange II followed pseudo-second-order kinetic and Langmuir isotherm model. The maximum adsorption capacity (Q_max) of CTAB-FeNPs for orange II was 1288.9 mg/g at 30°C. CTA-Orange II complex was adsorbed onto the adsorbent through several types of interaction (e.g., electrostatic attractions, van der Waals interactions, hydrogen bonding and n-π stacking interactions). The sorption of orange G was also studied at different CTAB concentrations. The results implied that the maximum sorption amount was almost half of the orange II adsorption. The findings reveal the feasibility of CTAB capped FeNPs to be used as an excellent and low-cost adsorbent for the removal of various water pollutants, more specifically anionic dyes.