Retention of pesticides in filter membranes

The objective of this work was to determine the retention of pesticides in membrane filters used for the separation of suspended solids from solutions . Five types of filter materials were tested: cellulose acetate, nylon, pol yethersulfone, polyvinylidene fluoride (PVDF), and polytetra-fluorethylene (PTFE). Five aqueous solutions of pesticides with initial concentrations of 9.5 mu g/L were studied: atrazine (6-chloro-N-2-ethyl-N-4-isopropyl-1,3,5- triazine-2,4-diamine), isoproturon (3-(4-iso-propylphenyl)-1,1-dimethylurea ), mecoprop ((RS)-2-(4-chloro-o-tolyloxy)-propionic acid), 2,4-D ((2,4-dich lorophenoxy)acetic acid), and bentazone (3-isopropyl-1H-2,1,3-benzothiadiaz in-4-(3H)-one 2,2-dioxide). Detectable losses of pesticides were measured o n all the tested filter materials. Cellulose acetate filter, nylon filter, and polyethersulfone filter retained between 3 and 90% of all five tested p esticides. On PVDF filter and PTFE filter the retention was limited, as onl y two (isoproturon and mecoprop) out of five pesticides was retained with a maximum retention of 4.2% for isoproturon on the PVDF filter. In the prese nt study no correlation between retention by filters and pesticide solubili ty in water was observed. The results also demonstrate that pesticides with relatively high solubility and low octanol-water partition coefficient (K- ow values) can be strongly retained by synthetic filter materials.