This paper describes the synthesis of a low-cost hybrid adsorbent from activation of fly ash and bentonite to remove 2-methylisoborneol (MIB) and geosmin from water. These substances produce objectionable taste and odor problems at levels as low as 4–10 ng/L and an effective, low-cost method of removal would be useful. The effect of the initial pH, contact time and adsorbent dosage on the adsorption process was investigated. In the range of 42–234 ng/L of MIB and geosmin, the maximal adsorption efficiency was obtained at the conditions of a dose level of 15 mg/L adsorbent, pH 8 and 60 min contact time, reaching 59.9 and 63.7%, respectively. Comparing to the natural fly ash and bentonite, the adsorbent showed higher surface area and micropores. The interlayer distance of the hybrid adsorbent was 0.59 nm, in accord with the molecular dimension of MIB and geosmin. The effect of humic acid, representative of natural organic matter (NOM), on MIB and geosmin adsorption was investigated for absorbent systems and indicated the presence of NOM would decrease adsorption slightly. The leaching experiments showed that the leaching of heavy metals from the adsorbent was negligible.
Keywords: adsorption, bentonite, fly ash, geosmin, 2-methylisoborneol