Amanda Pontes Maia Pires Alcantara

Improving air quality is a significant environmental challenge. This research explored the potential of asphalt mixtures functionalized with a chitosan–TiO₂ composite (CS-TiO₂) to reduce high NO₂ concentrations and improve durability. For the assessment of the photocatalytic efficiency of the new CS-TiO₂ composite, a low-cost reactor adapted to accommodate asphalt Marshall-type specimens and high pollutant concentrations encompassing a passive sampling module was developed. The CS-TiO₂ was synthesized using a wet impregnation method at a concentration of 2%, and asphalt mixtures were treated with aqueous solutions of the photocatalysts at 2.5 g/m² and 5.0 g/m². Laboratory tests using the photocatalytic reactor and passive sampling of NO₂ revealed pollutant reductions of 21% with TiO₂ and 28% with CS-TiO₂. CS-TiO₂ achieved 15% efficiency in visible light, reducing NO₂ levels and offering UV protection to the asphalt mixtures. Additionally, the chitosan improved the photocatalyst’s adhesion by about 18%, as confirmed by tape test results, suggesting enhanced durability on pavement surfaces. The results achieved showcase the relevance of the proposed methodological improvements for supporting further research.

Os pavimentos asfálticos são comumente utilizados em grandes centros urbanos no Brasil. No entanto, vários contaminantes do ar são emitidos durante o ciclo de produção desses pavimentos devido, principalmente, a necessidade de uso de altas temperaturas durante esse processo. Esta pesquisa visa avaliar os níveis de poluição durante o processo de produção (usinagem) de misturas asfáltica em contexto real. Para avaliar tal aspecto, foram analisadas emissões de poluentes atmosféricos geradas em uma usina de misturas asfálticas durante seu período de operação em comparação com o seu estágio de inatividade. Utilizaram-se os métodos de amostragem passiva para a quantificação do dióxido de nitrogênio (NO2) e do dióxido de enxofre (SO2) e amostragem ativa para a quantificação de Material Particulado de tamanho aerodinâmico inferior a 10 µm (MP10), nas quais foram realizadas as suas especiações químicas quanto aos Compostos Orgânicos Voláteis (COVs), aos Hidrocarbonetos Policíclicos Aromáticos (HPAs) e ao Níquel (Ni). Comparando os resultados encontrados no contexto da usina em operação com aqueles obtidos durante o seu estágio de inatividade, houve um aumento na concentração de todos os poluentes analisados, dos quais destaca-se o MP10 com COVs, HPAs e Ni adsorvido.

In this work, the catalytic performance of clinoptilolite (CLIN) and SBA-15 catalysts, doped with Fe and Cu, was evaluated in the selective catalytic reduction of NO using NH₃ as a reducing agent (SCR-NH₃). Both Cu-CLIN and Fe-CLIN were obtained by ion-exchange using natural clinoptilolite zeolite originating from the Hrabovec deposit (northeast Slovakia region). Cu-SBA-15 and Fe-SBA-15 were prepared by impregnation into SBA-15 mesoporous synthesized silica. Standard catalytic activity tests were carried out on a bench-scale laboratory apparatus using a reaction mixture of a standard test. GHSV of 48,000 h⁻¹ was adopted based on the space velocity of a real NH₃-SCR catalyst for diesel vehicles (100–550 °C). All Cu-doped samples showed better NO conversion values than Fe-doped samples. Clinoptilolite catalysts were more active than those based on SBA-15. Maximum NO conversions of about 96% were observed for Cu-CLIN and Fe-CLIN at 350–400 °C, respectively. Moreover, Fe-CLIN also showed higher stability in the presence of SO₂ and water steam at 350 °C. These results demonstrate the potential of metal-doped natural clinoptilolite to be used as cost-effective catalysts applied to the abatement of NOx emissions generated in automotive combustion processes.

Aging by oxidation of asphalt roadway material promotes changes in its physical, chemical, and rheological properties, affecting its hardening and accelerating the degradation of its corresponding asphalt mixture. Titanium dioxide (TiO₂) has been applied in engineering investigations to promote anti-aging and photocatalytic properties. In this study, a commercial binder was modified with nano-TiO₂ (using contents of 0.1, 0.25, 0.5, 1, 2, 3, and 6%). It was evaluated by physicochemical and rheological tests (penetration, softening point, mass loss, dynamic viscosity, rheology, and Fourier transform infrared spectroscopy—FTIR) before and after aging by rolling thin-film oven test (RTFOT) and pressure aging vessel (PAV). The results indicated that incorporating nano-TiO₂ mitigates binder aging, pointing out 0.25% as an optimum modification content for the investigated asphalt binder.