Isotherm and thermodynamics adsorption of Au(III) ion by Mangosteen Rind (Garcinia mangostana L.)

The mangosteen rind has O-H, C=C aromatics, and ethers functional groups, its performance for Au adsorption become an interesting research to both environment and economic purpose. In this study, waste mangosteen rind as eco-friendly adsorbent had been used for Au(III) adsorption. Initiate by maceration for pre-treatment of biosorbent, the mangosteen rind’s perfomance was revealed. Crystalline structure of mangosteen rind was analyzed by X-ray diffraction, while after interaction with Au(III) ions gave three characteristic peaks indicated Au(III) reduction into Au(0). The adsorption followed isotherm Langmuir model and afforded spontaneous reaction that evidenced by enhancement of ΔG° by increasing of temperature (-1.7 at 30 °C to -8.4 at 60 °C). The value of ΔH° and ΔS° were 71.1 kJ mol-1 and 238.5 J mol-1 K-1, respectively. © 2020 Trans Tech Publications Ltd, Switzerland.