Fast and highly efficient removal of methylene blue by a novel EDTAD-modified magnetic chitosan material

A novel adsorbent, ethylenediaminetetraacetic dianhydride (EDTAD)-modified magnetic chitosan (EMC) complex, was fabricated using glutaraldehyde as a cross-link agent. The obtained EMC was characterized by SEM, XRD, potentiometric titration, and FTIR. The results showed that nano-Fe3O4 with granular morphology were steadily integrated with chitosan and EDTAD was successfully modified on the surface of chitosan. The adsorption properties of EMC for methylene blue (MB) were then evaluated. Factors affecting the uptake behavior such as pH, contact time, initial concentration of MB, and temperature were investigated. The optimal adsorption conditions were determined as pH 6.0, MB concentration 300mg L-1, contact time 30min, and temperature 35 degrees C. The adsorption capacity in the optimal condition was 113.257mgg(-1). The adsorption process followed the Sips isotherm model and the pseudo-second-order kinetic model. Desorption and regeneration experiments were conducted and the adsorption/desorption cycles of MB were repeated three times. The EMC regeneration efficiency and the MB recovery efficiency were 82.82% and 80.72%, respectively, in the third cycle by using HCl as the eluent solution.