Construction of Highly Efficient Fe3O4@AlOOH Lamellar Adsorbent for Removal of Congo Red

Fe3O4@AlOOH adsorbent with high efficient adsorption capacity was successfully synthesized by controlling the hydrolysis rate for aluminum isopropoxide (AIP) and introducing inductive agent thioglycolic acid (TGA). Al(OH)3-TGA clusters played a key role in the formation of Fe3O4@AlOOH adsorbent with lamellar structure. Morphology characterization revealed that magnetic Fe3O4 nanoparticles were uniformly deposited on the surface of AlOOH. The lamellar structure of AlOOH and the strong magnetic intensity of Fe3O4 were helpful for its rapid separation from solution under external magnetic field. Hence, the sample could be regenerated easily and reused in the later adsorption–desorption cycles. The as-prepared sample exhibited ultrafast adsorption rate and high adsorption capacity in the removal of Congo Red (CR) from aqueous solution. The maximum adsorption capacity of Fe3O4@AlOOH towards CR was 280.90 mg/g and CR was completely removed from the aqueous solution within 60 seconds. The adsorption process was well described by the Langmuir isotherm model. Electrostatic adsorption was considered as the main adsorption mechanism. Moreover, Fe3O4@AlOOH sample tended to adsorb CR more effectively in the neutral and acidic solution.