Enhancing Ibuprofen and 4-Isobutylacetophenone degradation: Exploiting the potential of Nb2O5 sol-gel catalysts in photocatalysis, catalytic ozonation, and photocatalytic ozonation

This study describes the synthesis of Nb2O5 by three sol-gel methods to be used as a catalyst in photocatalysis, catalytic ozonation and the synergistic effects of the two processes, photocatalytic ozonation in bath reactions for the degradation of ibuprofen and its degradation products, 4- Isobutylacetophenone and oxalic acid. The catalysts were prepared in three temperature ranges: non-calcined, calcined at 873 K and 1173 K, and were characterized using different techniques. The results demonstrate that the catalyst synthesized through Sol-gel Method 3 and heat-treated at 873 K achieved the highest pollutant removal in photocatalytic tests (92% with 95% TOC reduction) over 300 min of reaction, and in the catalytic ozonation tests (100% with 62% TOC reduction) over 30 min of reaction, due to the combination of the properties presented in the characterization analyzes. Thus, this catalyst was employed in photocatalytic ozonation reactions and demonstrated the capability to degrade 100% of ibuprofen in 12 min without 4-IBAP formation, resulting in a 98% reduction in TOC over 30 min of reaction. In addition, the photostability outcomes of this catalyst demonstrated no significant reduction in catalytic activity during the photocatalytic and catalytic ozonation processes and comparable results to P25. The toxicity tests validated the TOC results, showing an 8% effect vs. 90% of ibuprofen starting solution, and 43% effect vs. 95% of 4-IBAP starting solution.