Increasing utilisation efficiency of ferric chloride etchant in industrial photochemical machining

The environmental effects of photochemical machining (PCM) can be appreciable in view of the nature of the industry whereby various chemicals are used in the preparation and cleaning of metal surfaces, photographic processing of phototooling, coating and selective removal (development) of photoresists, etching through apertures in the resist stencils and stripping of resist after etching. This paper concerns the environmental impact of ferric chloride, the most commonly used etchant in PCM, and is believed to be the first quantitative analysis for the PCM industry. The findings showed that more than half of the PCM companies used regeneration of ferric chloride etchant and 76.3% of companies were prepared to use a more environment-friendly regeneration system at a higher overall cost. Regarding ferric chloride consumption, it was found that the performance of companies varies greatly: companies using regeneration were, on average, nearly seven times (340.8% compared with 51.1%) more efficient than those that do not regenerate, and the most efficient company used 135 times less etchant than the least efficient company. The findings of this study and the analysis carried out can be used by PCM companies as a benchmark in assessing their environmental performance with respect to etchant consumption efficiency.     

Assessment of spatial variability in some soil properties as related to soil salinity and alkalinity in Bafra plain in northern Turkey

The objectives of this study were to assess the variability in soil properties affecting salinity and alkalinity, and to analyze spatial distribution patterns of salinity (EC) and alkalinity (ESP) in the plain, which was used irrigation agriculture with low quality waters. Soil samples were collected from 0–30cm, 30–60cm, 60–90cm and 90–120cm soil depths at 60 sampling sites. Soil pH had the minimum variability, and hydraulic conductivity (Ks) had the maximum variability at all depths. The mean values of pH, EC, ESP and Ks increased while the mean values of CEC decreased with soil depth. Values pH, EC and ESP were generally high in the east and northeastern sides. Soil properties indicated moderate to strong spatial dependence. ESP and pH were moderately spatially dependent for three of the four depths, EC exhibited moderate spatial dependence for one of the four depths, CEC had a moderate spatial dependence at all depths, and Ks exhibited a strong spatial dependence. EC, CEC, and ESP were considerably variable in small distances. The spatial variability in small distances of EC, CEC, pH and ESP generally increased with depth. All geostatistical range values were greater than 1230m. It was inferred that the strong spatial dependency of soil properties would be resulted in extrinsic factors such as ground water level, drainage, irrigation systems and microtopography.