Highly Selective Molecular Recognition and Ultrasensitive Detection of 3,4-dichloroaniline Based on Molecularly Imprinted Sol-Gel Film Combined with Multi-Walled Carbon Nanotubes

This paper developed an electrochemiluminescence (ECL) method for detecting ultratrace levels of the highly toxic organic pollutant, 3,4-dichloroaniline (3,4-DCA), in water. This method has not been used previously for 3,4-DCA detection, and is based on a 96-well micro-plate modified with molecularly imprinted sol-gel films combined with multi-walled carbon nanotubes (MIF-MWCNTs). The increase in the ECL signal intensity was proportional to the 3,4-DCA concentration within a certain range, and an excellent response was obtained for 3,4-DCA concentrations ranging from 4 × 10−11 to 6 × 10−9 mol L−1, with a low detection limit (LOD) of 1 × 10−11 mol L−1. The detection sensitivity of the present method is higher than those of the most commonly used chromatography methods, with the recovery of 3,4-DCA from spiked samples of water ranging from 83.3 to 110.5%. Thermodynamic analysis showed that the adsorption of 3,4-DCA by the MIF-MWCNTs occurred spontaneously as an exothermic and entropy decreasing process (ΔH = −32.49 kJ mol−1, ΔS = −117.89 J mol−1). Kinetic equation fitting demonstrated that the adsorption of 3,4-DCA could be fitted by an intraparticle diffusion model, and that the adsorption isotherm data fitted the Freundlich model.