Metta Penpolcharoen

pp. 85 - 95

Abstract

Bituminous fly ash, which is an industrial waste, was used as an adsorbent to remove dyestuff from
the textile-dye wastewater. The batch kinetic and isotherm experiments of the synthetic wastewater were
firstly conducted to determine the adsorption behavior and optimal conditions for adsorption. The optimal
conditions were then applied to the actual textile-dye wastewater. Under the original conditions of fly ash and
wastewater, the results indicated that the color could be removed up to 86.65% by 12 g of the fly ash /L of
the wastewater within 30 min. Its adsorption was described by the Freundlich isotherm. The dye-adsorbed
fly ash was further studied on its pozzolanic property in terms of compressive strength by using it as a partial
substitute to Portland cement type I to produce mortar. The result revealed that the highest compressive
strength was of the sample containing 10% by weight of the dye-adsorbed fly ash in replacement of cement.
It possessed 215 kg/cm² at 28 days, which is 92.67% of the sample containing 10% by weight of the original fly ash in replacement of cement, or 83.33 of the cement mortar. For the environmental concern, leachabilities
of lead (Pb), chromium (Cr), copper (Cu) and zinc (Zn) from all mortars were also carried out. No leaching
of the heavy metals from any samples could be detected. Hence, the dye-adsorbed fly ash can be used as an
environmental friendly construction material.

Keywords

• fly ash
• adsorption
• pozzolan
• compressive strength
• leachability
• textile-dye wastewater