PENENTUAN KAPASITAS ADSORPSI DAN ENTALPI ADSORPSI Au(III) OLEH ASAM HUMAT; DETERMINATION OF ADSORPTION CAPACITY AND ADSORPTION ENTHALPY OF Au(III) BY HUMIC ACIDS

Lestari, Mita, Sri Sudiono

2015 | Skripsi | FMIPA

Determination of adsorption capacity and adsorption enthalpy of Au(III) by humic acids has been conducted. Humic acid was isolated from peat soil, Rawa Pening, Ambarawa, Central Java. Isolation was conducted by dissolving peat soil into NaOH 0.1 M solution under nitrogen atmosphere, then precipitated by acidifying it using HCl 1 M until pH = 2. Humic acid was purified by dissolving it into HCl 0.1 M: HF 0.3 M (1:1 v/v). The adsorption capacity and adsorption enthalpy was conducted by interacting humic acid and Au(III) solution at several concentration and temperature. Au(III) concentration was analyzed by using AAS and humic acid both before and after interaction were characterized by using FTIR spectrofotometer, XRD and microscopic photos. The results obtained show that Au(III) adsorption by humic acid followed Langmuir isotherm models and in the region of chemisorption. The adsorption capacity of Au(III) by humic acid increased with increasing the temperature. Interaction in the temperature 30, 40, 50 and 60 ?C obtained qm 13.27; 21.88; 34.36 and 79.37 mg g-1, respectively also ?G? values 5.67; 3.99; 2.57 and -2.50 kJ mol-1, respectively. ?S? and ?H? values computed from plots of ln K vs 1/T were 255. 41 J mol K-1 and 83.61 kJ mol-1, respectively.

Kata Kunci : humic acid; capacity; enthalpy; adsorption; isotherm.