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In-Situ Regeneration of Saturated Granular Activated Carbon by an Iron Oxide Nanocatalyst
Citation:
Chiu, C., K. Hristovski, S. Huling, AND P. Westerhoff. In-Situ Regeneration of Saturated Granular Activated Carbon by an Iron Oxide Nanocatalyst. WATER RESEARCH. Elsevier Science Ltd, New York, NY, 47(4):1596-1603, (2013).
Impact/Purpose:
Submitting to Water Research
Description:
Granular activated carbon (GAC) can remove trace organic pollutants and natural organic matter (NOM) from industrial and municipal waters. This paper evaluates an iron nanocatalyst approach, based on Fenton-like oxidation reactions, to regenerate spent GAC within a packed bed configuration after saturation by organic compounds. Specifically, we focus on regenerating GAC packed beds equilibrated with varying influent concentrations of phenol, a model organic compound. Iron nanocatalysts were synthesized using ferric chloride, a chemical already used as a coagulant at municipal WTPs, and reacted with hydrogen peroxide (H2O2) for the purpose of in-situ regeneration. Up to 95% of phenol adsorption capacity was regenerated for GAC equilibrated with 1000 mg/L of phenol. Using this technique, at least five adsorption-regeneration cycles can be performed sequentially for the same batch of GAC with fresh iron nanocatalysts while achieving a regeneration efficiency of 90 ± 5% between each loading. Moreover, the iron nanocatalyst can be recovered and reused multiple times. Lower initial adsorbate concentrations (10 to 500 mg/L) resulted in a slightly lower saturated adsorbent-phase concentration of phenol and lower regeneration efficiencies (72 ± 5%). Additionally, this catalytic in-situ regeneration was applied to GAC saturated by NOM. A slightly lower regeneration efficiency (60%) was observed for the Suwannee River NOM adsorption capacity of GAC. The next step is validation in a pilot-scale test that applies this regeneration technique to a GAC adsorber employed in NOM removal.
