Microwave-assisted sequential extraction of fly ash:Studies on chemical speciation of zinc,copper,arsenic and manganese

摘要

Coal fly ash due to its light weight and better mobility,is a significant solid pollutant.A sequential extraction procedure has been applied to determine the environmental mobility of zinc,copper,arsenic and manganese in fly ash.The original procedure of Tessier et al.has been modified using the microwave-assisted technique.The results obtained by summation of extractable amounts of copper,arsenic and manganese obtained in each step by the microwave procedure range from 88 to 99% of the total content,by microwave-assisted method,as compared to the standard non-certified value of NIST fly ash.For zinc,however,we obtain 117% of the metal content,by microwave-assisted method,as compared to the standard non-certified value of NIST fly ash.The elemental analyses of the individual leachates have been done by flame atomic absorption spectrometry and hydride generation atomic absorption spectroscopy.A drastic reduction in time viz.from 68 h in the original Tessier to <3.5 h in the microwave-assisted method has been obtained.