Efficient removal of chromium from leather waste and flyash using supercritical fluid extraction technology

摘要

A number of alternative solutions have been examined in detail throughout the world for the extraction of contaminant metal ions from industrial and waste materials. Chemical processing using wet digestion and solvent extraction methods have been studied, alongside combustion and biological methods. Supercritical fluid extraction (SFE) using carbon dioxide, is an environmentally friendly technology, which avoids the hazards and costs of organic solvent handling or excessive water consumption and can be non-destructive to the waste material. Thus, instead of carrying out liquid-liquid extractions or solid phase extractions for the pretreatment and preconcentration of metal ions from solid and liquid matrices, it is possible to send ina selective courier molecule to permeate through the sample, grab onto the targeted metal and deposit it in concentrated form into a collection vessel for further analysis or recovery. This approach utilises the solvating power of supercritical CO_2 and the metal ion complexing power and selectivity of organic ligands. This use of metal ion selective reagents in supercritical CO_2 for the extraction of targeted ions from waste, environmental and industrial samples offers a host of potential advantages and applications.