Newly developed cement–ground granite scraps composite for solidification/stabilization of radioactive wastes: characterization and evaluation of the mechanical durability

The core objective of the present study is to develop an added value cement–granite composite (CGC) based on granite (G) scraps and Ordinary Portland Cement (OPC). The granite scraps were collected, washed, ground, sieved, and the finest powder was used as an inorganic admixture for developing the CGC. Plain water was added to the granite–cement powder and thoroughly mixed. The obtained pastes were casted for 28 days prior to their physical, structural, thermal characterizations and their mechanical evaluation. Factors assumed, mostly, to affect the final properties of the CGC blocks, e.g. granite/cement and water: cement ratios were studied. The reached monolith cement–granite composite has many advantages, e.g. lower density, very low water absorption percentage, acceptable compressive strength values and significant radiation and thermal stability. Based on the experimental data reached it could be stated that: for its economical advantages, where the one of its basic components is a waste. In addition to the acceptable mechanical traits of the developed composite, it can be candidate properly as an inert matrix for some radioactive wastes containment, for application in many field including: construction sector (interior and exterior of household walls, floor tiles, etc.), and for many others. The environmental reward due to management the accumulated problematic solid granite scraps is, certainly, a gain.

Fifty years of solid-phase extraction in water analysis--historical development and overview

The use of an appropriate sample handling technique is a must in an analysis of organic micropollutants in water. The efforts to use a solid phase for the recovery of analytes from a water matrix prior to their detection have a long history. Since the first experimental trials using activated carbon filters that were performed 50 years ago, solid-phase extraction (SPE) has become an established sample preparation technique. The initial experimental applications of SPE resulted in widespread use of this technique in current water analysis and also to adoption of SPE into standardized analytical methods. During the decades of its evolution, chromatographers became aware of the advantages of SPE and, despite many innovations that appeared in the last decade, new SPE developments are still expected in the future. A brief overview of 50 years of the history of the use of SPE in organic trace analysis of water is given in presented paper.

On-line combination of aqueous-sample preparation and capillary gas chromatography

Methods currently in use to combine the preparation of aqueous samples on-line with capillary gas chromatography (GC) comprise heartcut-orientated reversed-phase liquid chromatography-GC and analyte-isolation-orientated analyte extraction-GC. These approaches either use techniques in which water is directly introduced onto the GC column, or an indirect approach in which water is eliminated, i.e., by solid-phase extraction, solid-phase microextraction or liquid-liquid extraction, prior to introduction of the analytes onto the GC column. The latter type of approach is much more successful and user-friendly, and many applications have been reported.

On-line combination of aqueous-sample preparation and capillary gas chromatography

An overview is presented of methods currently in use to combine the preparation of aqueous samples on-line with capillary gas chromatography. Two approaches can be distinguished: heartcut-orientated reversed-phase liquid chromatography-gas chromatography (GC) and analyte-isolation-orientated analyte extraction-GC. These approaches either use techniques in which water is directly introduced onto the GC column, or an indirect approach in which water is eliminated, i.e., by solid-phase extraction, solid-phase microextraction or liquid-liquid extraction, prior to introduction of the analytes onto the GC column. The latter type of approach is much more successful and user friendly, and many applications have been reported.

Modified on-column interface for coupled high-performance liquid chromatography-gas chromatography and its application to the determination of levamisole in milk

A modified on-column interface is reported for the coupling of high-performance liquid chromatography with gas chromatography, incorporating an adapted, commercially available multidimensional gas chromatography switching system. Novel features include cryogenic analyte focusing, total solvent exclusion from the analytical column and independent carrier gas supplies to the analytical GC column and uncoated pre-column. The instrumentation was used for the determination of the veterinary anthelmintic drug levamisole in milk with analyte detection by both flame ionisation and nitrogen-phosphorus detectors. Detection limits for the assay were 2.2 micrograms l-1 and 0.4 micrograms l-1 by flame ionisation and nitrogen-phosphorus detectors, respectively. The assay was applied to a survey of fourteen milk samples from different dairy outlets.