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Solar collectors represent an attractive green technology for water heating, where sunlight is efficiently absorbed by a selective coating and the generated heat is transferred to water. In this work, the improvement and scale-up of an electrodeposited black nickel selective coating with a modified silica (MS) film deposited by spray pyrolysis are reported. The MS material was prepared by the sol–gel method using tetraethyl orthosilicate with the addition of n-propyl triethoxysilane to obtain a porous film with an adequate refractive index and enhanced flexibility. The reflectance of electrodeposited selective coatings was characterized with and without the MS film and compared to a commercially available coating of black paint. The MS film increased the solar absorptance from 89% to 93% while maintaining a much lower thermal emittance than the painted coating. The reflectance of the MS film remained unchanged after prolonged thermal treatment at 200 °C (200 h). The fabrication process was scaled up to 193 cm × 12 cm copper fins, which were incorporated in commercial-size flat-plate solar collectors. Three complete collectors of an area of 1.7 m2 were fabricated and their performance was evaluated under outdoor conditions. The results show that the electrodeposited selective coating with the MS film outperformed both the commercial black paint system and the system without the modified silica film. [ABSTRACT FROM AUTHOR]

Landfill leachate treatment is of utmost importance for pollution prevention. For this reason, in this study the performance of different types of activated carbons was monitored for applying in the Fenton-adsorption treatment of landfill leachate. Six carbon of different mesh and nature were studied, all of granular type. Only with the Fenton treatment a COD removal of >75% was achieved. Batch experiments were done to conduct adsorption isotherm studies and an adsorption column test was subsequently performed for Fenton-treated leachate. Granular coconut activated carbon revealed a better performance in removal of chemical oxygen demand (COD) and color during batch experiments. However, the activated carbon Gama L 8 × 30 (mesoporous) achieved removals >99% of COD and color in the adsorption column, removing 19.26 kg COD/kg carbon. Finally, it was found that the adsorption is carried out in multilayers with both carbons, having an adjustment with the models Temkin (80%) and Freunlich (96%) for granular coconut 12 × 40 and the Gama L 8 × 30, respectively. [ABSTRACT FROM AUTHOR]