TERMODINAMIKA DAN ISOTERM ADSORPSI ION Au(III) OLEH KULIT BUAH MANGGIS (Garcinia mangostana L.); ADSORPTION ISOTERM AND THERMODYNAMIC OF Au(III) ION BY MANGOSTEEN RIND (Garcinia mangostana L.)

Harumi, Mellia, Sri Sudiono

2015 | Skripsi | FMIPA

Adsorption isoterm and thermodynamic of Au(III) ion on mangosteen rind (Garcinia mangostana L.) have been studied. The purpose of this research was to study adsorption Au(III) using mangosteen rind especially in the aspect of adsorption isoterm and thermodynamic. This research was started with preparation of mangosteen rind. Mangosteen rind was dried and crushed, then was soaked for 24 hours using aquades (maceration). Dry solid of maceration was determined it’s adsorption isoterm and parameter of thermodynamic at variations of concentration 0, 5, 10, 20, 30, 50, 75, and 100 ppm and variations of temperature 30, 40, 50, and 60 ?C. Mangosteen rind was characterized using FTIR, XRD, and photomicroscop. FTIR analysis results showed that the mangosteen rind has several functional groups including –OH, C=C aromatics, and ethers. Characteristics of the mangosteen rind with XRD showed that is amorphous, while difractogram mangosteen rind after interaction with Au(III) ions gave three characteristics peak Au that indicates the reduction of Au(III) into Au(0) has happened. The result shows that the adsorption follows adsorption isoterm Langmuir model. The value of ?G? increased more negative with the increasing of the temperature (-1.74 at 30 ?C to -8.42 at 60 ?C), indicates that adsorption proceed more spontaneous with the increasing of temperature. The value of ?H? and ?S? are 71.05 kJ mol-1 and 238.45 J mol-1 K-1, respectively.

Kata Kunci : mangosteen rind; adsorption; Au(III); adsorption isoterm; thermodynamic parameters.