PENENTUAN POINT OF ZERO CHARGE (PZC) KULIT BUAH MANGGIS (Garcinia mangostana L.) DAN APLIKASINYA PADA ADSORPSI Au(III) DAN Cu(II); DETERMINATION OF POINT OF ZERO CHARGE (PZC) MANGOSTEEN RIND (Garcinia mangostana L.) AND ITS APLICATION IN ADSORPTION OF Au(III) AND Cu(II)

Saraswati, Dian Hana, Sri Sudiono

2015 | Skripsi | FMIPA

The aim of this research was to determine the point of zero charge (PZC) of mangosteen rind adsorbent, so that it could be applied to view about adsorption ability of Au(III) and Cu(II). This research was begun with the preparation of mangosteen rind. Mangosteen rind was dried and crushed then soaked for 24 hours with water as a solvent (maceration). Dry solid obtained from the maseration was used to determine point of zero charge by Potentiometric Mass Titrations methode. Determination of pH adsorption was done by mixing mangosteen rind adsorbent with solution of Au(III) or Cu(II) 20 ppm on pH variation 1, 2, 3, 4, 5, 6, and 7. Adsorption capacity was determined by interaction of mangosteen rind with varying concentration of standard solutions Au(III). The concentration of Au and Cu in the solutions were analyzed by AAS and the characterization of the mangosteen rind before and after interactions were characterized by FTIR, XRD, and microphotography. From the research, it was obtained that a point of zero charge of mangosteen rind located in pH 3.7. Result of pH optimum adsorption of Au(III) and Cu(II) were at pH 2 and pH 5. Adsorption of Au(III) with mangosteen rind adsorbent was tended to follow Langmuir equation, and the value of adsorption capacity (qmax) obtained was 333,33 mg/g. FTIR analysis results showed that the mangosteen rind has several functional groups including –OH phenolics, –C=C– aromatic, and ethers. Analysis with XRD showed amorphous structure of mangosteen rind before interaction, and when interacting with Cu(II), however the result of interaction with Au(III) shows 4 peaks characteristic of gold metal on 2?= 38o, 44o, 64o, and 77o that indicating mangosteen rind had been reduced from Au(III) to Au(0).

Kata Kunci : PZC; pH; adsorption capacity; mangosteen rind; adsorption, Au(III); Cu(II)