CO2 laser photoacoustic detection of ammonia emitted by ceramic industries.

A homemade photoacoustic spectrometer has been constructed for monitoring gas emission from several sources. Numerous air pollutant gases are emitted exhaust of industries, vehicles and power plants. The photoacoustic technique is extremely sensitive and selective in detecting various gases. This work focuses on the gas emitted by the ceramic industry in northern Rio de Janeiro State in Brazil, the ceramic industry plays a remarkable role in the economy activity of this region, in recent years, this region developed into a significant red ceramic complex. The potential impact on the atmospheric environment of the region due to gaseous pollutant emissions from these anthropogenic sources needs to be evaluated. In this work we identified NH3 present in the samples collected in the kiln of a ceramic plant, in the concentration range of 33-52 ppmV. The ammonia gas present in our collected samples might come from the excess nitrogen in the manure soil from where the ceramic material was extracted. This soil was used for the sugarcane culture which is another important economic activity of this region.

Oil spills debris clean up by thermal desorption.

Oil spills represent a significant environmental issue in Brazil. This paper presents the latest results of a comprehensive experimental programme aimed at understanding how the presence of spilled oil affects the properties of sands and at studying alternatives to remediate the affected shores. Results indicate that oil causes a slight increase in grain size and uniformity, and oiled debris presents a smaller void ratio but a larger unit weight. It was also observed that effective strength parameters for both the natural and oiled debris were the same although the undrained strength of a natural sand is much higher than that of the contaminated sand. At ambient temperature, oiled debris emits methane and ammonia, and these emissions tend to increase with rising temperatures. On the other hand, the oil and grease content from oiled debris decreases with rising temperature and prolonged exposure. Finally, in situ thermal desorption seems to be a promising method for cleaning debris from oil spills. It is simple, fast and avoids all the difficulties associated with digging up the soil for disposal or cleanup.

Photoresist resolution measurement during the exposure process.

The index-modulation evolution of a positive photoresist material was measured during the holographic exposure of sinusoidal patterns. The exposures were performed in a stabilized holographic setup that permits easy changes in the period. The results show the lowering of the recorded index modulation when the period decreases.