Preparation and application of alumina/chitosan biocomposite

A new chitosan based biocomposite was prepared using alumina and used for the removal of chromium from the aqueous solution. The synthesized alumina/chitosan (AlCs) composite possesses an enhanced chromium sorption capacity (SC) of 8.62 mg/g than the original alumina and chitosan flakes that possess the SCs of 3.7 and 0.67 mg/g respectively, with a minimum contact period of 30 min. The sorption experiments were carried out in batch mode to optimize various parameters viz., contact time, initial chromium concentration, pH, co-ions and temperature that influence the sorption. The sorbents were characterized by FTIR, AFM, BET and SEM with EDAX analysis. The composite removes chromium by means of electrostatic adsorption coupled reduction and complexation. The adsorption data were fitted with Freundlich, Langmuir and Dubinin–Radushkevich (D-R) isotherms. The calculated values of thermodynamic parameters indicate the nature of chromium sorption. The dynamic studies demonstrate that the sorption process follows pseudo-second-order and intraparticle diffusion models.