The Effectiveness Adsorption of Au(III) and Cu(II) Ion by Mangosteen Rind (<i>Garcinia mangostana </i>L.) Using Point of Zero Charge Calculation

Abstract

Adsorption of Au(III) and Cu(II) by mangosteen rind adsorbent had been carried out. Mangosteen rind has several functional groups including –OH phenolics, ‒C=C‒ aromatics, and ethers. Dried mangosteen rind which was obtained from maceration was used to determine Point of Zero Charge (PZC). The most effective pH adsorption was determined by mixing adsorbent with Au(III) or Cu(II) solutions with various pH. The adsorption capacity was affected by the interaction between adsorbent and adsorbate. The solid adsorbent before and after interaction was characterized by FTIR, XRD, and microphotography. The PZC pH value of adsorbent was 3.7 while the optimum pH for Au(III) and Cu(II) were at pH 2 and pH 5, respectively. The adsorption capacity (qmax) value was 333.33 mg/g by following the Langmuir isotherm equation. The crystalline structure of adsorbent was analyzed using XRD and gave 4 peaks characteristics of gold metal on 2ϴ = 38º, 44º, 64º, and 77º after adsorption which indicated the reduction of Au(III) ions into Au(0).

Preparation and evaluation of a niosomal delivery system containing G. mangostana extract and study of its anti-Acanthamoeba activity

“…GME has a net negative charge, it may electrostatically repel other negatively charged groups on the nanoparticle surface, causing them to become more exposed and contributing to a more negative charge. 39–42 Fig. 2D showed that the GME-loaded niosomes were stable at room temperature on the day of production.…”

Study of Mangosteen Peel (<i>Garcinia mangostana</i> L.) Waste Capability to Recover Au(III) and Ag(I) in Aqueous Solution

“…The optimum pH of Au(III) and Ag(I) adsorption were 2 and 6, respectively. Our previous research showed that the Point of Zero Charge (pH PZC) of mangosteen rind adsorbent was 3.7 [26]. Below the pH of PZC, the adsorbent tends to be positively charged and could interact electrostatically with AuCl4at pH = 2 condition.…”

“…At pH = 2, Au(III) is negatively charged in the form of tetrachloroaurate(III) ions ([AuCl4] -), while the adsorbent surface is protonated and has a positively-charged surface. In an acidic solution, the possibility of electrostatic interaction between the functional group of adsorbent and [AuCl4]increases [26]. Ag(I) has a positive charge at a pH of 2-6.…”