| Summary: | Zeolite A was successfully synthesized from coal bottom ash of PLTU Paiton
East Java. Zeolite A was synthesized from bottom ash using the method of
alkaline fusion, continued with hydrothermal treatment. The fusion was done at
750�C for 1 hour, and the hydrothermal process was done with the temperature
variation of 100, 110, and 120�C for 3 hours. Bottom ash and the solid product of
synthesis were characterized by infrared spectrometry, X-ray diffraction, scanning
electron microscopy and gas N2 physisorption method based on the BET equation.
The synthesized zeolite A and bottom ash were applied as adsorbents of Ni2+ at
various pH, interaction time, and concentration of Ni2+.
Characterization using FTIR spectroscopy showed the presence of O-Si-O and
O-Al-O groups in bottom ash, sodium silicate and sodium aluminate in the result
of the fusion of bottom ash, and the vibration characteristic of zeolite A at solid
the product of synthesis. Both the XRD pattern showed hydrothermal treatment at
100�C for 3 hours resulted by zeolite A with the highest crystallicity. The result of
SEM showed the changes of shape that was more homogen on the product of
zeolite A. The result of physisorption analysis with BET method, showed that
surface area of zeolite A was higher than bottom ash. The optimum condition of
ion Ni2+ adsorption on synthetic zeolite A and bottom ash was observed at pH 4,
interaction time of 90 minutes. Adsorption of ion Ni2+ continually increased up to
50 ppm for synthetic zeolite A, and 40 ppm for bottom ash. The adsorption
kinetics study of Ni2+ on synthetic zeolite A and bottom ash can followed the first
order kinetic from Langmuir-Heinshelwood or Santosa modification (2007). The
synthetic zeolite A had greater adsorption capacity that was 18.3 x 10-5 mol/g,
compared with bottom ash which only 25.5 x 10-6 mol/g. The adsorption of Ni2+
continued chemically with adsorption energy of Ni2+ was 29.29 kJ/mol for the
sinthetic zeolite A, and 24.59 kJ/mol for bottom ash. The result of the study
showed that the modification of coal bottom ash becames zeolite A can increase
the adsorption of capacity for Ni2+.
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