Perpustakaan Digital ITB

Chromium and nickel are the common heavy metals in wastewaters. Their toxicity and tendency to bioaccumulation in food chain makes chromium and nickel disposal require special treatment. One of the most effective methods for chromium and nickel removal from wastewaters is adsorption. Synthesis zeolite from coal fly ash is a potential adsorbent for heavy metals removal. Coal fly ash from Suralaya power plant was activated at atmospheric pressure and 100 degrees C by hydrothermal treatment with NaOH 4 M solutions with varying liquid/solid (L/S) ratio and activation time. The L/S ratio (ml/gr) was 10 and 20 with activation time 6, 12, and 24 hours. During the activation, zeolite crystals phase was formed. The crystal phase was identified using X-Ray diffraction. The activated fly ash was used to removed Cr(VI) and Ni(II) from solution. The initial concentration of Cr(VI) and Ni(II) were 149 mg/l and 61 mg/l. The adsorption process was performed at atmospheric pressure and ambient temperature for 24 hours. The concentration of heavy metals was measured using Atomic Adsorption Spectrophotometer (AAS) method. The experiment shows synthesized zeolites remove up to 95% of nickel and 54% of chromium in the solution. The maximum adsorption capacity is found at L/S 20 and 6 hours activation time. The maximum adsorption capacity are 8 mg Cr(VI)/g and 6 mg Ni(II)/g. The activated fly ash with L/S 20 has greater adsorption capacity than L/S 10. The zeolitic product is sodalite.