Impact of Solute Properties and Water Matrix on Nanofiltration of Pesticides

Abstract

The application of different nanofiltration membranes for the separation of pesticides, i.e., atrazine and dimethoate, from aqueous solutions is described. The nanoflitration membranes DK, NF270, NF200, and NF90 were tested for the pesticide retention performance in a stirred dead-end filtration system. NF90 demonstrated the best pesticide retention with over 95 % for atrazine and approximately 80 % for dimethoate. All membranes consistently showed better retention of atrazine than of dimethoate. Dissolving the pesticides in river or tap water amplified the overall pesticide retention performance, indicating that filtration in water treatment plants could render superior pesticide retention. However, a lower flux was obtained for the filtration of tap and river water.

Critical Evaluation of Thin Film Composite Membrane on Pesticide Removal

“…Similar trend was observed in another study by Tan et al [32] in which river water with the most ions displayed the highest retention and lowest permeate flux of atrazine and dimethoate pesticides using DK, NF270, NF200 and NF90 membranes. For instance, the retention and permeate flux of atrazine in deionised water 50% and 2.1×10 -5 m 3 /m 2 •s, respectively.…”

“…Like positively charged molecules, micropollutants with larger dipole moment could adsorb onto the charged membrane surface, making it possible for them to diffuse through the membrane. Hence, there was a lower retention of large dipole moment solutes [31,32].…”

“…However, Tan et al [32] claimed otherwise despite both studies were carried out using NF90 membrane. They mentioned that pesticides with higher hydrophobicity exhibited better removal in which atrazine (log Kow of 2.34) was rejected better at 99 % than dimethoate (log Kow of 0.70) which showed only 81% rejection.…”

Nanofiltration & Reverse Osmosis Technical Assessment for Pesticides Removal

“…These membranes are usually targeted towards softening of water, being partially effective in removing dissolved ions [19]. Previous studies have reported pesticide removal e ciencies ranging from 30.00% to greater than 90.00% for phenylurea, phenoxyacetic acid, triazines, dithiolane pesticides organophosphate or synthetic auxin classes [20][21][22][23][24]. Meanwhile, reverse osmosis membranes have a molecular cut-off smaller than 100 Da [25] and are the standard on desalination processes.…”