Composite hollow fiber nanofiltration membranes for recovery of glyphosate from saline wastewater

A high performance versatile composite hollow fiber nanofiltration (NF) membrane is reported for the separation of glyphosate from saline waste streams. Preparation of SPEEK based on an amorphous poly (ether ether ketone, PEEK) was investigated. The membrane was prepared by coating sulfonated polyether ether ketone (SPEEK) onto a polyethersulfone (PES) ultrafiltration (UF) hollow fiber membrane. The composite membrane was characterized by water permeability, scanning electron microscopy, and rejection toward sodium sulfate (Na2SO4), sodium chloride (NaCl), and calcium chloride (CaCl2). About 90% rejection toward sulfate anions and only 10% rejection for calcium cations were obtained. A water permeability around 10–13 LMHBar and 90% rejection for polyethylene glycol (PEG) with a molecular weight of 4000–6000 Da were observed. In the separation of glyphosate from saline wastewater, the membrane rejected less than 20% of NaCl and higher than 90% of glyphosate at an operating pressure of 5 bars and pH = 11.0. An economic analysis indicated that the cost for recovery of glyphosate was comparably low to the value gained by an increase in the productivity. The results may lead to a new promising low energy solution for the environmental problem faced by the herbicide industry.

After coating the commercial ultrafiltration membrane with sulfonated poly (ether ether ketone), the membrane pores are blocked (as seen in the difference in SEM images of the inner surfaces and inner skins of PES ultrafiltration membrane before (A, C) and after coating (B, D)). The most interesting character of this composite membrane is the high water permeability and high rejection toward glyphosate, but low rejection to sodium chloride. The membrane shows potential for the separation of glyphosate from sodium chloride solution. The new type of nanofiltration membrane may provide an economic way for recovery of glyphosate from the highly saline wastewater in herbicide industry.Figure optionsDownload high-quality image (96 K)Download as PowerPoint slideHighlights
► A low pressure, negatively charged hollow fiber nanofiltration membrane.
► SPEEK nanofiltration membrane shows high rejection to glyphosate.
► Recovery of glyphosate from production wastewater using hollow fiber NF membrane.