Carbon nitride nanoparticles modified carbon paste electrodes as potentiometric sensors for determination of nickel(II) and chromium(III) ions in tap water samples

Abstract

Chromium and nickel ions are two heavy metal ions with highly application in the various industries, and the entry of their effluents into the environment is the main cause of pollution. Therefore, new carbon paste electrodes (CPEs) were developed as potentiometric sensors to determine nickel(II) and chromium(III) ions. Carbon nitride nanoparticles were synthesized from melamine with a thermal procedure and used as a component in the CPE compositions. The percentage amounts of the CPE compositions, including graphite powder, paraffin oil, multiwalled carbon nanotubes, and carbon nitride nanoparticles, were optimized. The sensors showed a Nernstian behavior in the pH ranges of 3.4–6.0 and 3.6–6.8 for the Ni(II) and Cr(III) ion measurements. Besides, a response time of 20 S and a lifetime of 8 weeks was obtained for both sensors. The sensors have proper linearity of 2.05 × 10–8–1.0 × 10–1 and 3.54 × 10–8–1.0 × 10–1 M for the determination of Ni(II) and Cr(III) ions with correlation coefficients of 0.9921 and 0.9981, respectively. Limit of detections and relative standard deviations were lower than 1.16 × 10–8 M and 0.53% for both analytes, respectively. Study of selectivity coefficients for Ni(II) and Cr(III) determination is shown that all interfering species selected in the study have nonsignificant interferences with a small amount of selectivity coefficient. The proposed sensors were successfully used to analyze Ni(II) and Cr(III) ions in two tap water samples with a spiking technique showing the recoveries were in the range of 95.99–103.75%.