Liquid phase membrane extraction of targeted pesticides from manufacturing wastewaters in a hollow fiber contactor with feed-stream recycles

A two-phase membrane extraction in a hollow fibre contactor with feed-stream recycle was applied to remove selected pesticides (tebufenozide, linuron, imidacloprid, acetamiprid and dimethoate) from their mixed aqueous solutions. The contactor consisted of 50 polypropylene hollow fibers impregnated with 5% tri-n-octylphosphine oxide in di-n-hexyl ether. For low polar pesticides with log P ˃ 2 (tebufenozide and linuron), the maximum removal efficiency increased linearly from 85 to 96% with increasing the feed flow rate. The maximum removal efficiencies of more polar pesticides were significantly higher under feed recirculation (86%) than in a continuous single pass operation (30%). It was found from the Wilson's plot that the mass transfer resistance of the liquid membrane can be neglected for low polar pesticides. The pesticide removals from commercial formulations were similar to those from pure pesticide solutions, indicating that built-in adjuvants did not affect the extraction process.