Rejection properties of pesticides with a hollow fiber NF membrane (HNF-1)

Abstract

NF membranes are potentially useful to remove residual hazardous organic pollutants such as pesticides and alkyl phthalates in drinking water treatment processes. In this study, the rejection properties of a hollow fiber NF membrane (HNF-1) for 8 kinds of pesticides were investigated using a bench scale cell: the membrane consisted of polyamide skin layer and polysulfone support membrane with a nominal desalting degree fo 35% at 0.3 MPa. In addition, hydrophilic organic compounds (molecular weight: 74.1–504.5), i.e. alcohols and saccharides, were also used as reference solutes. The hydrophilic compounds were rejected at rates of 9.0–97.8%, revealing that the molecular sieving effect was significant since the logarithm of solute permeability, log B, correlated linearly with the molecular width parameter, MWd, of the solute. Phenylic pesticides, such as alachlor, metolachlor, methoxychlor, and thiobencarb, were rejected at 88.7–99.3%. However, non-phenylic pesticides, such as aldicarb, simazine, atrazine, and pirimicarb, were rejected at lower degrees: 42.2–89.9%. The batch type sorption experiments indicated that all of the pesticides were adsorbed on the membrane, and the adsorption properties were controlled mainly by the hydrophobic property of the pesticides. Sorption properties based on solute recovery rates in the separation experiments, however, were different from those in the batch type experiments.