Toxicological Effects of Leachates Extracted from Photocatalytic Concrete Blocks with Nano-TiO 2 on Daphnia magna .

The incorporation of titanium dioxide nanoparticles into concrete blocks for paving adds photocatalytic functionality to the cementitious matrix, providing self-cleaning and pollutant-degrading properties. However, wear and leaching from these pavements can release potentially toxic compounds into water bodies, affecting aquatic organisms. In this context, this study evaluated the toxicological effects of leachates from photocatalytic concrete containing nano-TiO 2 with an average size of 10 nm and anatase crystallinity on Daphnia magna . Acute and chronic toxicity tests on neonates were conducted with two leachate extracts: one from reference concrete and one from photocatalytic concrete (with 9% nano-TiO 2 added by mass of cement). In terms of acute toxicity, the reference concrete extract had an EC 50 of 104.0 mL/L at 48 h, whereas the concrete with TiO 2 had an EC 50 of 64.6 mL/L at 48 h. For chronic toxicity, the leachate from reference concrete had a significant effect ( p < 0.05) on the size parameter with an LOEC of 4 mL/L, whereas the leachate from concrete with 9% nano-TiO 2 did not have significant toxicological effects on any of the analyzed parameters (longevity, size, reproduction, and age of first posture) (LOEC > 6.5 mL/L). Furthermore, FTIR analysis indicated that TiO 2 nanoparticles were not detected in the leachates, suggesting efficient anchoring within the cementitious matrix. The results indicate that there was no increase in the chronic toxicity of the leachate from the cementitious matrix when nanoparticles were added at a 9% mass ratio of cement.