Leaching properties, evaluation

Van der Sloot, H.A. (1998) Quick techniques for evaluating the leaching properties of waste materials their relation to decisions on utilization and disposal, Trends in Analytical Chemistry 17, 298-310. 

The first example of biphasic catalysis was actually described for an ionic liquid system. In 1972, one year before Manassen proposed aqueous-organic biphasic catalysis [1], Par shall reported that the hydrogenation and alkoxycarbonylation of alkenes could be catalysed by PtCh when dissolved in tetraalkylammonium chloride/tin dichloride at temperatures of less than 100 °C [2], It was even noted that the product could be separated by decantation or distillation. Since this nascent study, synthetic chemistry in ionic liquids has developed at an incredible rate. In this chapter, we explore the different types of ionic liquids available and assess the factors that give rise to their low melting points. This is followed by an evaluation of synthetic methods used to prepare ionic liquids and the problems associated with these methods. The physical properties of ionic liquids are then described and a summary of the properties of ionic liquids that are attractive to clean synthesis is then given. The techniques that have been developed to improve catalyst solubility in ionic liquids to prevent leaching into the organic phase are also covered. 

Mai.ow, G. 1982. The mechanisms for hydrothermal leaching of nuclear waste glasses properties and evaluation of surface layers. In Lutze, W. (ed)... 

Another approach is to categorize hydrocarbon compounds into surrogate fractions characterized by similar chemical and physical properties (EA Engineering 1995). Compounds are assigned to a given fraction on the basis of similar leaching and volatilization factors. Correlation to Carbon Number Index was used because it closely follows GC behavior. This method has the potential to provide realistic evaluation of potential risks however, a full set of parameters is not available for all the compounds of interest (EA Engineering 1995). 

Test methods used in the evaluation should Include (a) tests to evaluate changes in the physical and mechanical properties of the specimens, (b) chemical analyses to determine the depth and rate of penetration of the aggressive solutions, and (c) tests to monitor and control the treatment solutions and to analyze them for materials being leached from the test specimens. 

The major emphasis of this discussion centered on the importance of surface and subsurface soil characteristics in influencing deep pesticide leaching. Some factors, such as the depth to groundwater and the amount of incipient rainfall or irrigation, are clearly important factors that do affect the probability of pesticide residues reaching groundwater. Similarly, properties of the pesticide itself (especially its inherent mobility and chemical/biological stability) correlate closely with pollution potential, but their evaluation is outside the scope of this review. 

Xanthos and co-workers [12] did some research in which LDPE was melt blended with either automotive shredder residue, carpet hacking residue or mixtures of the two and prototype blocks were intrusion moulded from them. These blocks were evaluated for use as a wood substitute for the building industry by conducting tests to determine their short-term and long-term mechanical properties, flammability, thermal conductivity and heavy metal and total organic carbon leaching behaviour. The performance of these prototypes was compared with that of wood and the composites containing carpet residue were found to be favourable as replacements for wood thermal barrier components in a steel-based stud assembly. 

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