Removal of picloram herbicide from an aqueous environment using polymer inclusion membranes

Abstract

The picloram (4-amino-3,5,6-trichloro-2-pyridinecarboxylic acid) herbicide is widely applied to control the growth of woody plants and it has been frequently detected in aqueous environments due to its poor adsorption by soils and high leaching potential. Consequently, the removal of picloram from contaminated environmental waters is of major concern due to its adverse impacts on aquatic organisms, soils and animals. The development of a method for the extraction and transport of picloram from aqueous solutions using a polymer inclusion membrane (PIM) composed of cellulose triacetate, trioctylmethylammonium chloride (Aliquat 336) and 2–ni- trophenyl octyl ether (NPOE) is reported. The experimental method was optimized for the PIM composition, and the type and concentration of stripping reagent. The optimized method demonstrated good performance in- dicators of flux and transport efficiency for picloram during non-competitive and competitive transport ex- periments. The PIM was also successfully applied in a passive sampling device to recover picloram at the maximum permissable concentration of 500 μg/L from a complex matrix of natural water. Findings from this study demonstrate that PIMs can serve as a potential alternative method for the removal and recovery of pi- cloram and related herbicides from contaminated aqueous solutions.