Adsorption kinetics, isotherms, and thermodynamic studies for Hg2+ adsorption from aqueous medium using alizarin red-S-loaded amberlite IRA-400 resin

Alizarin red-S-modified amberlite IRA-400 resin (ARSA) was applied for Hg2+ removal from the aqueous medium which is a highly toxic metal ion. The adsorption process which was pH dependent, showed maximum adsorption of Hg2+ in the pH range 6–8. ARSA exhibited good monolayer adsorption capacity for Hg2+ (303.03 mg g−1) at 25°C and the isotherm was well fitted by the Langmuir model. Moreover, the adsorption was evaluated thermodynamically and the negative values of Gibbs free energy revealed the spontaneity of adsorption process. The practical applicability of ARSA was explored for the adsorption of Hg2+ metal ion from a real water sample. The values of ΔH and ΔS were found to be 79.87 kJ mol−1 and 0.26 J mol−1 K−1, respectively.