CuO Nanoparticles Intermixed With Chemically Modified Multiwalled Carbon Nanotubes as a Novel Electrode for Cu2+ Ion Determination

A novel carbon paste electrode (CPE) was fabricated using 2-methoxy-6-(((3-(trimethoxysilyl) propyl) imino) methyl) phenol chemically bonded to multiwalled carbon nanotubes (MMSPIMP-MWCNTs) followed by intermixing with CuO nanoparticles, sodium tetraphenylborate (NaTPB), graphite powder, and Nujol oil. The MMSPIMP-MWCNT was characterized by Fourier transform-infrared spectroscopy (FT-IR) and other appropriate techniques. The influences of variables, including the amounts of NaTPB, modified MWCNT, CuO nanoparticles, graphite powder, and Nujol oil on the electrode response, were studied and optimized. Optimum composition of carbon paste was found to be a mixture of 120-mg Nujol with graphite powder: NaTPB-carrier with the mass (milligram) ratio of 150:9:60. Thus, the applied recipe for the construction of CPE, significantly enhanced its selectivity and sensitivity to Cu2+ ions over a wide concentration range of 4.09 × 10^-8 - 1 × 10^-2 mol L^-1 with detection limit of 1.6 × 10^-8 mol L^-1 and a Nernstian slope of 29.56 ± 0.56 mV/decade of Cu²⁺ concentration. The electrode response is independent of pH in the range of 3.5-5.5 with response time <;20 s. The potentiometric selectivity coefficients of the proposed Cu²⁺ ion, CPE, show its moderate selectivity for Cu²⁺ ion toward other metal ions. The MMSPIMP-MWCNT was found to be a suitable neutral carrier for the construction of a carbon paste electrode for the determination of Cu²⁺ ion in solution. Finally, from practical point of view, this electrode was successfully applied for the determination of Cu²⁺ ions content in real water sample.