A comparative study of ozonation, iron coated zeolite catalyzed ozonation and granular activated carbon catalyzed ozonation of humic acid

- The performance of iron coated zeolite and granular active carbon for catalytic ozonation of humic acid was evaluated.
- The presence of ICZ and GAC significantly enhanced the degradation of HA.
- Ozonation and catalytic ozonation at pH 11 increased DOC and UV254 removals compared to ozonation at pH 6.5.
- Catalytic ozonation with ICZ at pH 11 showed the best catalytic activity for HA removal.
- DOC and UV254 removals in ozonation of <100 kDa fraction of HA were better than that of <50 kDa fraction of HA.

This study compares ozonation (O3), iron coated zeolite catalyzed ozonation (ICZ-O3) and granular activated carbon catalyzed ozonation (GAC-O3) for removal of humic acid from an aqueous solution. The results were evaluated by the removal of DOC that specifies organic matter, UV254 absorbance, SUVA (Specific Ultraviolet Absorbance at 254 nm) and absorbance at 436 nm. When ozonation was used alone, DOC removal was 21.4% at an ozone concentration of 10 mg/L, pH 6.50 and oxidation time of 60 min. The results showed that the use of ICZ or GAC as a catalyst increased the decomposition of humic acid compared to ozonation alone. DOC removal efficiencies were 62% and 48.1% at pH 6.5, at a catalyst loading of 0.75 g/L, and oxidation time of 60 min for ICZ and GAC, respectively. The oxidation experiments were also carried out using <100 kDa and <50 kDa molecular size fractions of humic acid in the presence of ICZ or GAC. Catalytic ozonation also yielded better DOC and UV254 reduction in both <50 kDa and <100 kDa fractions of HA compared to ozonation.

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