A molecularly imprinted membrane for specific removal of 2,4-Dichlorophenoxyacetic acid (2,4-D) was synthesized by gamma-initiated polymerization using N-vinyl imidazole as functional monomer and ethylene glycol dimethacrylate (EGDMA) as a crosslinker in methanol:water (1:4 by volume) mixture at room temperature. Functional monomer to template molecule ratio was kept as 4:1. The binding capacity of molecularly imprinted membranes was obtained as 75% within 100 min for 5 mg/L 2,4-D solution (on 25 mg of imprinted polymer). Binding characteristics in various template molecule concentrations and pH values were studied. Furthermore, the selectivity of the imprinted membranes was evaluated by using structurally similar herbicides such as (R)-2-(2,4-dichlorophenoxy) propanoic acid (2,4-DP) and 4-chlorophenoxyacetic acid (4-CPA). The binding capacity of membrane was investigated by using real water samples. In order to investigate the free volume size of the membranes positron annihilation lifetime spectroscopy (PALS) experiments were carried out.