In this work, compositions containing transparent glass bottles and banana leaves (desiccated and crushed), with different mass fractions (30-50%), were prepared for obtaining cellular materials for thermal insulation purposes. The formulated and prepared compositions were uniaxially pressed (10 MPa) and the compact powders fired between 700 and 850°C for 30 min in order to investigate the effect of the banana leaves on the formation of pores and on the thermal and mechanical properties of the processed glass foams. The results indicated that the obtained glass foams with porosities between 58.5 and 87.5%, compressive strength ranging between 1.17 and 3.50 MPa and thermal conductivity ranging between 0.06 and 0.15 W/mK, are potential candidates to work as thermal insulators with appropriate properties for a specific application.
Resumo Composições contendo dois diferentes tipos de resíduos, vidro de garrafas transparentes, VGT (50-70%), e lodo de estação de tratamento de efluentes, ETE (30-50%), e formador de poros, CaCO3 (2-10%), foram preparadas para a produção de isolantes térmicos para fins estruturais. As matérias-primas das composições formuladas foram, em uma etapa posterior, misturadas, compactadas uniaxialmente a 40 MPa e, após secagem (110 °C/2 h), queimadas entre 750 e 1000 °C com patamares de 15 a 60 min. As matérias-primas e os materiais obtidos foram caracterizados do ponto de vista de suas propriedades químicas, físicas e microestruturais. Os resultados obtidos mostraram que é possível produzir isolantes térmicos, a partir de composições otimizadas contendo 70% de VGT, 30% de lodo de ETE e 5% de CaCO3, queimados entre 750 e 1000 °C/60 min, os quais apresentaram porosidades entre 3 e 62% com condutividades térmicas entre 1,25 e 0,5 W/m.K e com resistência à compressão entre 8,7 e 5,4 MPa. Os materiais obtidos são fortes candidatos em aplicações estruturais tais como painéis para isolamento térmico, os quais requerem uma combinação adequada de condutividade térmica, porosidade e resistência mecânica.
The use of methylene blue (MB) by several industries generates contaminated industrial wastewaters that must be purified before discharge into the environment. Its removal can be achieved by adsorption, and low-cost and easily available materials should be used as adsorbents. Biomass fly ash (BFA) generated from biomass combustion, for heat and power generation, is increasing worldwide since the process is considered CO2 neutral. However, most of the ash is still landfilled. This study aims to evaluate the valorisation of BFA as a low-cost porous bulk adsorbent for MB removal from wastewaters. The monoliths were obtained after 14 days of curing just after adding water and a porogenic agent (aluminium powder) to the BFA, using the self-hardening ability of this waste. The BFA was characterised for chemical (XRF) and mineralogical (XRD) composition, particle size distribution (laser diffraction-COULTER) and morphology (SEM). The monolith sample cured for 14 days was characterised for density, porosity (total and open), microstructure, compressive strength, and MB removal ability (batch tests). The results showed that the addition of aluminium powder (0.09 wt.%) promoted an increase in interconnected porosity and the MB removal efficiency reached 80% for the most porous samples. The equilibrium data for the adsorption process were well characterised by a type 2 Langmuir isotherm equation with a monolayer adsorption capacity (qmax) that ranged from 0.22 to 0.66 mg/g.
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