Activity assessment of direct synthesized Fe-SBA-15 for catalytic ozonation of oxalic acid

• Fe-SBA-15 was directly synthesised by hydrothermal method under weak acid.
• Surface reaction played a critical role for oxalic acid degradation.
• Fe-SBA-15 significantly accelerated the generation of hydroxy radical.
• Adsorption of oxalic acid on Fe-SBA-15 was a vital step for its degradation.
• Fe-SBA-15 maintained a good catalytic activity and stability after being used.

Highly ordered Iron-doped SBA-15 mesoporous material (Fe-SBA-15), which was synthesized via a direct hydrothermal method under weak acid condition, was used as heterogeneous catalyst for the ozonation of oxalic acid in aqueous solution. The results indicated that Fe doping significantly improved the catalytic activity of SBA-15, a high oxalic acid removal of 86.6% was achieved under the chosen condition, only 30.2% for SBA-15/O3 process. The major operating variables including Si/Fe ratio in catalyst, initial pH value and radical scavenger were also studied for catalytic reaction mechanism. The active sites of Fe-SBA-15 increased with iron doping content and Fe-SBA-15 significantly influenced ozone concentration in aqueous solution. The catalytic efficiency was mainly affected by radical scavenger and the pH value of solution, which illustrated that the catalytic ozonation process followed free radical mechanism, and the surface reaction played a critical role for oxalic acid degradation. The stability of Fe-SBA-15 was verified by the reused experiments. The XRD and BET tests also demonstrated that Fe-SBA-15 retained highly ordered 2D-hexagonal mesoporous structure and large surface area after reused. Fe-SBA-15 was a promising catalyst for catalytic ozonation of oxalic acid.

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