Adsorption mechanism of hexavalent chromium removal using Amberlite IRA 743 resin

A commercially available chelating resin namely, Amberlite IRA 743 (AMB) is a macroporous polystyrene Nmethylglucamine with free base form used for the removal of chromium from aqueous solution. AMB resin possesses an enhanced chromium sorption capacity (SC) of 20.41 mg/g in a minimum period of 30 min contact time. The sorption experiments were carried out in batch mode to optimize various influencing parameters viz., contact time, initial chromium concentration, pH, co-ions and temperature. The resin is characterized by FTIR and SEM with EDAX analysis. The mechanism of chromium removal by the resin is by means of electrostatic adsorption coupled reduction and complexation. The adsorption data was fitted with Freundlich and Langmuir isotherms. The calculated values of thermodynamic parameters namely DG°, DH° and DS° indicate the nature of chromium sorption. The dynamic studies demonstrated that the sorption process follows pseudo-second-order and intraparticle diffusion models.