PENGARUH pH TERHADAP ADSORPSI Au(III) DAN Cu(II) OLEH ASAM HUMAT TERETERIFIKASI; THE EFFECT OF pH ON ADSORPTION OF Au(III) AND Cu(II) ONTO ETHERIFIED HUMIC ACID

Nugroho, Aditya Dwi, Sri Sudiono

2016 | Skripsi | FMIPA

Isolation and etherification of humic acid and its application for adsorption of Au(III) and Cu(II) have been conducted. Humic acid was isolated from peat soil from Rawa Pening, Jawa Tengah by dissolving humic acid in NaOH 0.1 M and precipitated with HCl 1 M until pH 2. The result of humic acid was purified by 0.1 M HCl/0.3 M HF (1:1 v/v). Etherification of humic acid was performed by reacting humic acid with dimethyl sulfate and K2CO3 in methanol solvent. Solution of Au(III) and Cu(II) with molar ratio 1:1 was interacted with humic acid and etherified humic acid at pH 1, 2, 3, 4, 5, 6 and 7. The effect of pH and Cu(II) metal ion in adsorption-reduction of Au(III) by humic acid and etherified humic acid was studied from the concentration data Au(III) and Cu(II) before and after interaction, these were analyzed using AAS. Humic acid and etherified humic acid before and after interaction were characterized by FT-IR, XRD and photo microscope. The result showed that the adsorption-reduction of Au(III) on humic acid was optimum at pH 2 while the adsorption of Cu(II) was optimum at pH 5. The adsorption-reduction of Au(III) on etherified humic acid was optimum at pH 5 while the adsorption of Cu(II) was optimum at pH 5.5. The existence of Cu(II) at low pH did not show a significant effect in adsorption-reduction of Au(III) on humic acid as well as on the etherified humic acid. Characteristics of the humic acid and etherified humic acid with XRD showed that is amorphous, while difractogram after interaction gave four characteristic peaks Au that indicates the reduction of Au(III) into Au(0) has occured.

Kata Kunci : humic acid, etherified humic acid, pH, adsorption, Au(III), Cu(II)