RESUMO

RESUMO Diferentes metodologias são descritas na literatura para tratamento de efluentes industriais. Entretanto, a maioria dos processos não são totalmente eficientes quando o efluente apresenta baixo conteúdo de partícula coloidal suspensa e alta concentração de matéria orgânica e detergentes. Entre os métodos que são estudados para eliminar detergente e matéria orgânica de efluentes industriais, o processo Fenton é uma estratégia atraente. No presente estudo, foi aplicada uma metodologia para remoção de detergente de efluentes líquidos utilizando processo Fenton com ultrassom e prego reutilizado. A otimização de parâmetros para tratamento do efluente foi realizada por meio das análises de pH, detergente, cor, turbidez, demanda química de oxigênio, demanda bioquímica de oxigênio, óleos e graxas, e sólidos suspensos. Os melhores resultados foram obtidos em pH 3,5, com 90 mg L−1 de peróxido de hidrogênio e um prego de ferro (2,7g) tanto para o processo Fenton como para o Fenton com ultrassom. Nessas condições, os valores de remoção de detergente foram de 99,4%. Em pH 2,5, 4,5 e 5,5, os valores obtidos para remoção de detergente foram menores, 75,2, 89,5, 68,4%, respectivamente. Resultados semelhantes foram obtidos para cor, turbidez, demanda química de oxigênio e demanda bioquímica de oxigênio. A reutilização dos pregos mostrou que a eficiência média na remoção de detergente até o quarto ciclo foi acima de 90%, e, a partir do quinto ciclo, observou-se uma diminuição gradativa, sendo a diferença entre o primeiro e o sexto ciclo em torno de 10%.

ABSTRACT Different methodologies are described in the literature for the industrial effluents treatment. However, most processes are not fully efficient when the effluent has low suspended colloidal particle content and high concentration of organic matter and detergents. Among the methods that are studied to eliminate detergent and organic matter from industrial effluents, the Fenton process is an attractive strategy. In the present study, a more sustainable methodology was applied to remove detergent and organic matter from liquid effluents using Fenton process with ultrasound and recycled nail. The optimization of parameters for effluent treatment was carried out through the analysis of pH, detergents, color, turbidity, chemical oxygen demand, biochemical oxygen demand, oils and greases, and suspended solids. The best results were obtained at pH 3.5, with 90 mg L−1 of hydrogen peroxide and an iron nail (2.7 g) both for the Fenton process and Fenton with ultrasound. Under these conditions, detergent removal values were 99.4%. At pH 2.5, 4.5, and 5.5, the values obtained for detergent removal were lower, 75.2, 89.5, and 68.4%, respectively. Similar results were obtained for color, turbidity, chemical oxygen demand, and biochemical oxygen demand. The reuse of the nails showed that the average detergent removal efficiency up to the fourth cycle was above 90%, and, from the fifth cycle, a gradual decrease was observed, with the difference between the first and sixth cycles being around 10%.

RESUMO

This work aims to evaluate the effects of feldspar substitution by basalt on porcelain tile composition with respect to its porosity, flexural strength, and pyroplastic deformation. Three ceramic formulations with different amounts of feldspar substituted with basalt, 50% (C1), 75% (C2), and 100% (C3), were evaluated at three different temperatures, 1200, 1220, and 1240 °C. Specifically, the effect of replacing feldspar with basalt on the pyroplastic deformation of ceramic bodies was analysed using optical fleximetry. The porosity of C1 at 1200 °C was 19.3 ± 2.9%, while that of composition C3 was 22.2 ± 0.7% at 1240 °C. The flexural strength was strongly influenced by the temperature. For C1 at 1200 and 1240 °C, flexural strengths of 11.1 ± 0.6 and 22.2 ± 1.9 MPa, respectively, were obtained. Regarding fleximetry, thermal deformation decreased with an increase in the amount of feldspar substituted with basalt. It was observed that C2 and C3 deformed less at high temperatures than the other combinations of compositions and temperature, probably owing to the lower amount of residual glass phase present during cooling. Compositions with higher substitution amounts of basalt (i.e., C2 and C3) exhibited more stable thermal behaviour than C0.