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Nitrate removal or denitrification, involves reduction of nitrate into nitrogen and oxygen. The use of nanoparticles zero valent metals for denitrification receives great attention as they have been proven to be effective and environmentally safe. In this work, the nanoparticles were prepared by reducing the metals salts, dissolved in a mixed solution of water and ethanol, using sodium borohydrate. The nitrate reduction reaction took place in an ambient environment – room temperature, neutral pH and aerobic condition. Results from the experiments carried out showed that nitrate has been successfully reduced up to a maximum of 40% in all the samples without an increase in the pH of the solution, a strong indication that ammonia was not produced. As for the study on the reactivity of the recycled NZVI, the samples synthesized with 4:1 (v/v) ethanol/water and using 9: 1 (v/v) ethanol/water, the reactivity of the iron is similar to the fresh NZVI for the first two hours of the study.

The main objective of this paper is to reduce the amount of external heat penetrating the building wall, hence reducing the cooling load requirements and eventually the electricity consumption. Expanded polystyrene and wood sawdust were chosen as filler material to reduce the thermal conductivity in perforated bricks because both are commonly found waste products with good potential due to their lightweight, low thermal conductivity and high specific heat. It was found that bricks with polystyrene recorded the lowest temperature change. Although sawdust has a much higher thermal conductivity, the temperature change is almost similar to that of polystyrene. This could be attributed by the higher density of wood, which means more mass are occupying the same volume of space. Hence, the paper found that thermal conductivity, specific heat capacity and density of the filler material can influence the effective thermal conductivity of the perforated brick.

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