Polyaniline nanoparticles for the selective recognition of aldrin : synthesis, characterization, and adsorption

Abstract

We report the preparation, characterization, and property evaluation of molecularly imprinted polyaniline nanoparticles that can be used for the selective recognition of aldrin. The molecularly imprinted polyaniline nanoparticles were prepared by inverted emulsion polymerization using aldrin as a template and aniline as a functional monomer. The prepared nanoparticles were characterized using UV–vis spectroscopy, Fourier transform infrared spectroscopy, and nuclear magnetic resonance spectroscopy. The spectral data confirmed that aldrin was successfully incorporated into the polymer matrix. Atomic force microscopy and scanning electron microscopy analyses revealed that the prepared nanoparticles were spherical in nature with sizes ranging from 60 to 100 nm for nonimprinted particles and from 500 to 1500 nm for imprinted particles. The surface morphology changed from smooth to rough upon the incorporation of aldrin molecules. The electrical properties were evaluated using a four-point probe coupled to a source meter. The nonimprinted nanoparticles showed an electrical conductivity of 4.149 S/cm, which was reduced to 0.546 S/cm in molecularly imprinted polyaniline. The equilibrium dissociation constant and free equilibrium concentration were found to be 0.6 and 0.799 ng/μL, respectively. The adsorption characteristics of aldrin and dichlorodiphenyltrichloroethane (DDT) were investigated to determine the selectivity of the imprinted nanoparticles. The distribution coefficients for DDT and aldrin were 0.76 ng/ng and 1.31 μL/ng, respectively, indicating that the imprinted nanoparticles had a stronger affinity for aldrin than for DDT.