Removal of organophosphate pesticides from wastewater by supercritical carbon dioxide extraction.

Organophosphate pesticides including fenitrothion chlorpyrifos, diazinon, methamidophos, edifenphos, mevinphos, fenthion, and acephate present in agro-wastewater can be effectively removed by supercritical carbon dioxide (SC-CO2) extraction. Near quantitative removal of the pesticides from the aqueous solution can be achieved by SC-CO2 at 90 degrees C and 325 atm for 20 min of static extraction followed by 40 min of dynamic extraction. The extracted pesticides were collected in a small amount of Fenton's solution. The pesticides in Fenton's solution were degraded completely within an hour after the collection. A combination of SC-CO2 extraction and subsequent degradation by Fenton's reagent may provide an alternative water purification strategy for treating organophosphate pesticides in agro-wastewater.