Improved Removal of Neonicotinoid Insecticides from Real Water Matrices by Modified UF and NF Membranes

The removal of five neonicotinoid insecticides, acetamiprid, chlothianidin, imidacloprid, thiacloprid, and thiamethoxam, was explored using various commercial ultrafiltration (MW, PT, and GK) and nanofiltration (HL) membranes provided by GE Osmonics Labstore. Several modification techniques have also been applied to one ultrafiltration membrane, including immersion in hot water, sodium hydroxide, and ethanol solutions, as well as interfacial polymerization with monomers such as polyethyleneimine and trimesoyl chloride, to improve micropollutant retention while maintaining adequate permeability. The results show that only immersion in ethanol (60% solution or absolute ethanol) improved membrane performance. Among the reagents and conditions tested for membrane surface modification via polymerization, the sequential application of polyethyleneimine, trimesoyl chloride, oven curing at 60 °C, followed by immersion in a glycerol solution was the most efficient. The optimal modified membrane was tested with real water matrices (two secondary effluents from wastewater treatment plants and a surface water sample) in which the neonicotinoids were dissolved. The modified ultrafiltration membrane showed higher retention (80-95%) than commercial ultrafiltration (15-60%) and levels similar to nanofiltration membranes (70-95%), demonstrating greater efficiency in retaining neonicotinoids under real water conditions, although the permeability was about half that of the commercial nanofiltration membrane. Therefore, this modification process is a promising alternative to commercial membranes for removing micropollutants from urban wastewater and should be considered.