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Aproveitamento do resíduo de marmoraria (Lama) como substituinte parcial do cimento em pastas cimentícias

Fri, 19 Jun 2026 00:00:00 GMT

Título: Aproveitamento do resíduo de marmoraria (Lama) como substituinte parcial do cimento em pastas cimentícias Autor(es): Lima, Stephany Gonçalves; Araújo, Renato Costa; Sousa, Kawanny Lopes Galvão; Lemos, Francisco Ezequias Rodrigues; Coelho, Jéssica Azevedo Abstract: The Portland cement industry is responsible for a significant share of global CO2 emissions, making the search for sustainable substitute materials urgent. Simultaneously, the ornamental stone sector generates large volumes of marble waste (marble sludge), which is often disposed of improperly. This review article analyzes the state of the art regarding the use of marble powder as a supplementary cementitious material, based on a systematic survey of the ScienceDirect database. The literature demonstrates that the partial replacement of cement with marble powder at levels ranging from 5% to 20% is technically feasible, maintaining or increasing compressive strength while contributing to a reduction in the final material's carbon footprint. Beyond mechanical viability, the use of this waste enhances the dimensional stability and durability of cementitious pastes. It is concluded that incorporating this waste is a promising circular economy strategy, enabling cost reductions and lower environmental impacts in the construction industry through the large-scale repurposing of an industrial waste product. Editor: Associação Brasileira de Ciência dos Materiais e Tecnologias Não Convencionais Tipo: Resumo Expandido

Biofotocatalisadores a partir de microalgas e tio2 dopado com n para aplicação em fotocatálise solar

Fri, 07 Nov 2025 00:00:00 GMT

Título: Biofotocatalisadores a partir de microalgas e tio2 dopado com n para aplicação em fotocatálise solar Autor(es): Macedo de Lima, Paulo Henrique; da Penha Sousa, Lidiene; Ferraz Barbosa, Ana clara; Melo Carneiro, Fernanda; Santos, Lidiaine Maria Abstract: The growing concern over the environmental impacts caused by industrial effluents has driven the search for cleaner technologies¹. In this context, the development of biophotocatalysts based on Scenedesmus microalgae coated with TiO₂ and nitrogen-doped TiO₂ (TiO₂-N) stands out as a promising approach for application in solar-driven heterogeneous photocatalysis². The resulting composites were applied to the degradation of Ponceau 4R dye, aiming to achieve energy efficiency and economic feasibility³. The methodology involved the synthesis of the catalysts (TiO₂ and TiO₂-N) and the cultivation of microalgae in BG-11 medium. The analyses followed a four-day protocol involving sample collection, pH and temperature measurements, spectrophotometric analysis (200–800 nm), preparation of microscope slides, and cell counting⁴. The samples were classified into control groups (CI–CIII), pure TiO₂ groups (PI–PIX), and TiO₂-N groups (DI–DIX), using different catalyst amounts (15, 25, and 35 mg). Analysis of variance (factorial ANOVA) revealed a significant effect of the treatments on pH, absorbance (680 nm), transmittance (750 nm), and cell count (p < 0.05), highlighting the effectiveness of the catalysts. The results showed an average pH close to 10, with temperatures ranging from 26 °C to 28 °C. In the control samples, an increase in absorbance was observed, indicating cell growth. For the adsorption analysis, a TiO₂-N sample was used, and its spectrum showed only slight variations in absorbance among the samples, with no significant changes or evidence of chemical degradation. Under the experimental conditions investigated, direct photolysis was not sufficient to promote the degradation of Ponceau 4R dye, although the absorbance of the aliquots decreased over time. In the photocatalytic experiments using 25 mg and 35 mg of TiO₂-N, the absorbance spectra indicated degradation efficiencies of 80.33% for TiO₂-N (25 mg) and 87.64% for TiO₂-N (35 mg), demonstrating that higher photocatalyst loading was more effective at this stage and reinforcing the superior performance of nitrogen doping. Thus, the results support the feasibility of using biophotocatalysts for the sustainable and efficient removal of organic contaminants. Editor: Associação Brasileiro de Química Tipo: Pôster

Biodiesel como temática investigativa para uma abordagem experimental contextualizada: a síntese a partir do óleo de tilápia

Mon, 29 Jun 2026 00:00:00 GMT

Título: Biodiesel como temática investigativa para uma abordagem experimental contextualizada: a síntese a partir do óleo de tilápia Autor(es): Silva, Tatiana Aparecida Rosa da; Barbosa, Pedro Augusto Prata; Firmino, Cleisla Pereira Abstract: The search for renewable energy sources has intensified discussions on sustainability and alternatives to fossil fuels, making biodiesel a relevant topic for Chemistry education. This study presents an inquiry-based teaching proposal that uses biodiesel synthesis from residual tilapia viscera oil as a strategy to contextualize chemical and environmental concepts. The activity was structured around a problem related to the reuse of aquaculture waste and the production of biofuels, encouraging students to formulate hypotheses, analyze experimental evidence, and develop scientific explanations. During the investigation, participants carry out stages involving raw material preparation, transesterification reaction, and qualitative characterization of the biodiesel produced, establishing connections with concepts such as organic functions, stoichiometry, catalysts, mixture separation techniques, and sustainability. The proposal promotes the integration of scientific, technological, and social knowledge, contributing to scientific literacy and the development of critical thinking skills. The results indicate that inquiry-based experimentation associated with contemporary socio-environmental issues can foster more meaningful learning experiences, increasing students' interest in Chemistry and in discussions about sustainable energy systems. Editor: Instituto Federal de Educação, Ciência e Tecnologia de Goiás IFG Tipo: Pôster

Stencil printing of microfluidic paper-based analytical deevices to teach redox reactions for high school students

Tue, 04 Mar 2025 00:00:00 GMT

Título: Stencil printing of microfluidic paper-based analytical deevices to teach redox reactions for high school students Autor(es): Casanova, Monise; Neves, César; Gomes, Paulo; Silva, Ana Clara; Rocha, Danielly; Coltro, Wendell Abstract: Microfluidic paper-based analytical devices (μPADs) associated with colorimetric detection are attractive for applications in analytical chemistry due to their portability and instrumental simplicity. This kind of device has become popular to teach chemistry for high school students. This study describes the construction of μPADs using stencil printing technique dedicated to teaching redox reactions in high school classes. The layout with a circular sampling zone (5mm diameter) and 2 colorimetric detection zones (5-mm diameter) connected by 2 microfluidic channels (Y format) (2mm long) were drawn in Corel Draw graphics software. Then, a chromatographic paper substrate was laminated using polyester with the aid of a press at 140°C for 20s. Then, a layer of vinyl adhesive was added to the paper substrate using a spatula. The paper was cut by a paper cutter. Then, the adhesive edges of the device were removed, keeping the microfluidic geometry covered with the adhesive patterns. Finally, glass varnish was applied to create hydrophobic barriers and dried at 25°C for 30 min. The channel width was tested and optimal width was 2.5 mm wide. As a proof-of-concept, a redox reaction with sodium hypochlorite (SH) and N-N – diethyl p phenylenediamine (DPD) was chosen. The optimal volume of DPD chromogen was 1.6 µL. The complete filling of the device was achieved adding 18 µL of SH solution. The SH solution (colorless) reacts with the DPD solution (15 mmolL-1) (red) and generates a purple product. Then, 18 µL of a 1.1% v/v commercial SH solution was added into the sampling zone. After spontaneous transport through microfluidic channels, the analyte reacted with DPD reagent, generating a purple-colored product detected by naked eye. With successful preliminary results, the device will be explored to teach redox reactions and microfluidics and enables the demonstration of qualitative analysis, allowing the student to understand if the target analyte is present in the sample or not. Editor: Instituto federal de Goias - Campus Senador Canedo Tipo: Pôster