Modified maghemite nanoparticles as an efficient adsorbent for removing some cationic dyes from aqueous solution

A novel adsorbent, sodium dodecyl sulfate (SDS) modified maghemite nanoparticles (SDS–γ-Fe2O3), was used for removal of cationic dyes brilliant cresyl blue (BCB), thionine (Th) and janus green b (JG), from water samples. Prepared nanoparticles were characterized by TEM, SEM, XRD, BET and EDX measurements. The influences including initial pH, dosage of adsorbent, surfactant amount and contact time have been researched in order to find the optimum adsorption conditions. The experimental data were analyzed by the Langmuir and Freundlich adsorption models. Equilibrium data fitted very well with the Langmuir model signifying the energetic homogeneity of SDS-maghemite surface adsorption sites. The maximum predicted adsorption capacities for Th, BCB and JG dyes were obtained as 200.0, 166.7 and 172.4 mg g− 1, respectively. It was shown that the sorbent can remove more than 93% of the investigated dyes within the first 4 min of contact time. The desorption process of the adsorbed cationic dyes was also investigated using methanol and methanol–acetic acid mixture as the solvent. It was notable that both the adsorption and desorption of dyes were quite fast probably due to the absence of internal diffusion resistance.