Absorptive removal of Pb2+, Cu2+ and Ni2+ from the aqueous solution by using groundnut husk modified with Guar Gum (GG): Kinetic and thermodynamic studies

• Groundnut husk was modified with Guar Gum (GG) for the removal of Pb2+, Cu2+ and Ni2+ ion.
• Adsorption follows Freundlich Isotherm and best fitted by Pseudo second kinetic order.
• Design procedure for single stage system was also reported.

In this study, the groundnut husk modified with Guar Gum (GG) is used for the removal of Pb2+, Cu2+ and Ni2+ from the aqueous solution. The maximum adsorption capacity for Pb2+, Cu2+ and Ni2+ is found to be in the order of 9.76 mg g−1, 9.26 mg g−1 and 6.74 mg g−1 respectively. The optimized adsorption parameters were: pH 5.0, equilibrium time 120 min and adsorption temperature 298 K for Pb2+, Cu2+ and Ni2+ ion. The adsorption data follows Freundlich Isotherm with regression coefficient (R2) of (0.987, 0.937, and 0.903).The data was further applied for various kinetic models and best fitted by Pseudo second order for all the metal ions. The negative value of Gibbs free energy shows the reaction is spontaneous and the positive value of enthalpy shows the adsorption process to be endothermic in nature for Pb2+ Cu2+ and Ni2+ ion. The adsorbent was characterized by FTIR, XRD, SEM and EDX. The design procedure for the batch process was also reported. The XRD spectra reveal that the adsorbent is semi-crystalline in nature.