STUDI ADSORPSI ION MERKURI DAN TEMBAGA MENGGUNAKAN ABU DASAR BATUBARA TERMODIFIKASI DITIZON

SAHRI YANTI, Prof. Drs.Mudasir, M.Eng., Ph.D.

2015 | Tesis | S2 Ilmu Kimia

Telah dilakukan penelitian yang bertujuan mengetahui kemampuan adsorpsi abu dasar batubara teraktivasi (ADT) dan abu dasar batubara termodifikasi ditizon (ADTD) terhadap Cu(II) dan Hg(II). Modifikasi abu dasar batubara dilakukan dengan cara imobilisasi ditizon. Imobilisasi ditizon bertujuan untuk meningkatkan selektifitas dan kapasitas adsorpsi. Karakterisasi abu dasar batubara dilakukan dengan menggunakan SEM-EDS, FTIR, XRD, dan GSA. Kajian adsorpsi meliputi optimasi pH larutan, berat adsorben, waktu interaksi, dan konsentrasi larutan. Hasil karakterisasi SEM-EDS menunjukkan bahwa abu dasar batubara memiliki morfologi berbentuk bulat dan gumpalan yang tidak beraturan. Komposisi utama abu dasar batubara adalah SiO2 dan Al2O3. Hasil FTIR dari ADTD menunjukkan serapan baru pada 1319 dan 1489 cm1 yang karakteristik terhadap vibrasi tekuk –NH dan vibrasi ulur –CN dari ditizon. Data XRD menunjukkan basal spacing (d) ADTD yakni 4,28; 3,36; 3,72 Å. Sementara itu, basal spacing (d) ADT yakni 4,25; 3,69; 3,34 Å. Data tersebut mengindikasikan bahwa ADT dan ADTD didominasi oleh quarsa dan mullit. Analisis GSA memberikan hasil luas permukaan, jari-jari pori, dan volume pori ADT yaitu 126,66 m2/g, 15,22 Å, dan 0,10 mL/g, sedangkan untuk ADTD adalah 13,48 m2/g, 17,02 Å, dan 0,05 mL/g. Studi adsorpsi menunjukkan Cu(II) terikat secara fisik pada kedua adsorben, mengikuti pseudo orde dua dan isoterm Langmuir. Sementara itu, Hg(II) terikat secara kimia, mengikuti pseudo orde dua serta isoterm Freundlich. Adsorpsi optimum Cu(II) 500 ppm pada ADTD dan ADT yakni 51,362% dan 46,572%. Adsorpsi Hg(II) pada ADT sebesar 68,958% dengan konsentrasi awal Hg(II) 750 ppb, sedangkan pada ADTD yakni 96,531% dengan konsentrasi awal Hg(II) 1000 ppb. Kapasitas adsorpsi, tetapan kesetimbangan, energi adsorpsi, serta laju adsorpsi Cu(II) dan Hg(II) pada ADTD lebih besar dibandingkan ADT. Hal ini disebabkan ADTD memiliki jari-jari pori lebih besar, dan lebih banyak atom donor yang lebih mudah mendonorkan pasangan elektron.

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 : abu dasar, ditizon, adsorpsi, tembaga, merkuri