| Summary: | Isolation of peat soil humic acid and its application for adsorption
reduction of Au(III) have been conducted. Humic acid was isolated from peat soil
that was collected from Rawa Pening, Central Java. Isolation of humic acid from
peat soil was based on conventional alkaline extraction. Humic acid was extracted
from peat soil with NaOH 0.1 M, then precipitated with 0.1 M HCl, and purified
with 0.1 M HCl/0.3 M HF 1/1. Esterification and etherification of humic acid
were also studied. Esterification was performed by reaction with ethanol in acidic
conditions. Etherification of humic acid was performed by reacting humic acid
with dimethylsulfate and methanol-water solvent. The isolated humic acid,
esterified humic acid, and etherified humic acid was characterized by FTIR
spectroscopy, XRD, ash content, total acidity, -COOH content, and �OH content,
then applied for adsorption reduction of Au(III). The Effect of pH adsorption,
adsorption kinetics, and adsorption isotherm on adsorption reduction process of
Au (III) also were studied. The gold metal formed was confirmed by XRD
diffractogram, and photo optical microscope.
The isolated humic acid has 7.46 % ash content and after purification has
0.19% ash content. The isolated humic acid after purification has total acidity of
799 cmol/kg, -COOH content of 406 cmol/kg, and -OH content of 393 cmol/kg.
Humic acid after esterification has 0.78% ash content, total acidity of 1022
cmol/kg, COOH content of 217 cmol/kg, and -OH content of 805 cmol/kg. Humic
acid after etherification has 0.89% ash content, total acidity of 699 cmol/kg, -
COOH content of 486 cmol/kg, and �OH content of 213 cmol/kg. The adsorption
capacity with Langmuir isotherm model for humic acid, esterified humic acid,
and etherified humic acid is 92 mg/g, 625 mg/g, and 158 mg/g, respectively. The
adsorption rate constant (k) with Ho kinetic model for humic acid, esterified
humic acid, and etherified humic acid are 5.29.10-4 g/mg min., 1.50.10-3 g/mg
min., and 8.06.10-3 g/mg min., respectively. Peaks of gold particles in the
difractogram are 2θ = 38, 44, and 64.
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