| Popis: |
Municipal solid waste incineration (MSWI) fly ash was regarded as one kind of hazardous waste due to the enrichment of heavy metals (Zn, Pb, Cd and Cu), which should be removed from the ash or stabilized prior to final landfill disposal. Extraction with phosphoric acid is a conventional method of safe treatment of fly ash. In this work, influence of phosphoric acid concentration and liquid to solid ratio on removal efficiency of the four heavy metals was investigated. It was found that phosphoric acid was efficient in removing Pb, Zn and Cu but less efficient in removing Cd. Removal ratio followed the decreasing sequence of Pb >Zn > Cd > Cu for acid extraction using phosphoric acid, quite different with that for sulfuric acid. In comparison with sulfuric acid, phosphoric acid was more effective in removing the four heavy metals. |
