STUDI ADSORPSI ION MERKURI DAN TEMBAGA MENGGUNAKAN ABU DASAR BATUBARA TERMODIFIKASI DITIZON; ADSORPTION STUDY OF MERCURY AND COPPER IONS USING DITHIZONE-MODIFIED COAL BOTTOM ASH

Sahri Yanti, Mudasir

2014 | Disertasi | PROGRAM STUDI S2 KIMIA

The study of Cu(II) and Hg(II) adsorption on activated (ADT) and modified coal bottom ash (ADTD) had been conducted. A coal bottom ash modification was prepared by dithizone immobilization. The aim of dithizone immobilization was to increase adsorption selectivity and capacity. Coal bottom ash was characterized using SEM-EDS, FTIR, XRD, and GSA. The pH solution, adsorbent mass, interaction time, and solution concentration effect of adsorbat on the adsorption were also studied and optimized. Morphology of coal bottom ash was characterized using SEM-EDS shows spherical and irregular shapes. The coal bottom ash contained SiO2 an Al2O3 as the major component. FTIR spectra of ADTD show new peaks at 1319 and 1489 cm-1 which were characteristic for –NH stretching and –CN bending of dithizone. XRD data showed basal spacing (d) at 4.28, 3.36, 3.72 Å for ADTD. Meanwhile, ADT showed basal spacing at 4.25, 3.69, 3.34 Å. It indicated that both of adsorbent were dominated by quartz and mullit. GSA analysis showed the ADT surface area, pore volume, and pore radius respectively were 126.66 m2/g, 15.22 Å, and 0.10 mL/g, where ADTD gave 13.48 m2/g, 17.02 Å, and 0.05 mL/g. Adsorption study showed that Cu(II) was adsorbed physically and followed pseudo second orde and Langmuir isotherm. Meanwhile, Hg(II) was adsorbed chemically, and fitted well pseudo second orde, and Freundlich isotherm. The optimum adsorption of Cu(II) on ADTD and ADT respectively were 51.362% and 46.572% with initial concentration of adsorbat 500 ppm. Adsorption of Hg(II) on ADT was 68.958% with initial concentration of Hg(II) 750 ppb, and ADTD was 96.531% with initial concentration of Hg(II) 1000 ppb. The adsorption capacity, equilibrium constant, adsorption energy, and adsorption rate of Cu(II) and Hg(II) on ADTD was higher than those on ADT. This may be due to the fact ADTD has larger pore radius, and much more donating atom so that the electron pair can be easily donated.

Kata Kunci : bottom ash, dithizone, adsorption, copper, mercury.