8-Hydroxyquinoline intercalated montmorillonite composite: characterization and application for copper ion determination as potentiometric electrode.

The intercalation of 8-hydroxyquinoline (HQ) organic chelating ligand onto the structure of Na+-montmorillonite (MMT) was prepared and investigated by using Fourier transform infrared spectrometry (FT-IR), X-ray diffraction spectrometry (XRD), elemental analysis, and scanning electron microscope with energy X-ray dispersive (SEM–EDS) techniques; the results indicated that 8-hydroxyquinoline was successfully intercalated in the interlayer space of montmorillonite. This intercalation compound was used to construct a potentiometric electrode. Potentiometric results showed the best response to Cu2+ ion with a slope of 30.45 ± 0.36 mV decade−1 (R2 = 0.9987) and provided a good linearity within a concentration range of 10−5–0.5 M. The limit of detection of the electrode was determined as 1.99×10−6 mol L−1. The selectivity coefficient of electrode was evaluated by a separate solution method (SSM), and the resulting values of the selectivity coefficient were small which indicated the electrode gave the best response to Cu2+ ion. This electrode also showed good precision, repeatability, durability, fast response time, and selective to copper ion. Cyclic voltametry and electrochemical impedance spectroscopy (EIS) analysis exhibited that 8-hydroxyquinoline could help enhance the specificity of the montmorillonite to form with Cu2+ ion in solution. The proposed potentiometric electrode was successfully applied to determine Cu2+ in a real micronutrient fertilizer sample by the standard addition method. [ABSTRACT FROM AUTHOR]