The removal of Pb2+ from aqueous solution using mangosteen peel activated carbon: Isotherm, kinetic, thermodynamic and binding energy calculation

Heavy metal ion such as lead(II) ion (Pb2+), contamination of drinking and waste water, is a serious and ongoing problem. Among available technologies, adsorption is here presented as an effective technology. The aims of this work were to investigate the adsorption capacity, kinetic, isotherm, thermodynamic, and adsorption energy of Pb2+ by activated carbon (AC) prepared from mangosteen peel (MPAC). Maximum Pb2+ adsorption equal 130 mg g(-1) was achieved when using Pb2+ concentration of 50 mg L-1, adsorbent dose of 0.67 mg mL(-1), pH of 5, contact time of 180 min, and temperature of 30 degrees C. The isotherm adsorption was found to fit well with the Langmuir isotherm. The kinetics adsorption behavior go along with the pseudo-second order model. Thermodynamic parameters (Delta G < 0 and Delta H degrees = -61.27 kJ mol(-1)) indicate that the adsorption process is spontaneous and exothermic. The Density-Functional Theory (DFT) calculation was also used to investigate the effect of AC pore size on binding efficiency to Pb2+. DFT calculations revealed that the 0.44 nm micropore AC model has a higher adsorption efficiency than that of the 0.71 nm micropore AC and graphene models due to the stronger ion-dipole interaction and suitable pore size for Pb2+ binding.

Automated summary

The study investigated the adsorption performance of activated carbon prepared from mangosteen peel on Pb2+ ions, showing a maximum adsorption capacity of 130 mg g(-1). The Langmuir isotherm and pseudo-second order model are suitable for describing the adsorption behavior, while thermodynamic parameters indicate a spontaneous and exothermic process. Density-Functional Theory calculations revealed that micropore size of activated carbon significantly affects its binding efficiency to Pb2+ ions.