Model of Corncob Biochar Modified Carbon Paste Electrode for Nitrite Detection

The ability of corncob biochar as a modifier of carbon paste electrodes for nitrite sensing was investigated and compared to unmodified carbon paste electrodes. Nitrite standard solutions in 0.1 M phosphate buffer solution (pH 7.0) were measured using cyclic voltammetry with a potential range of 0.1 to 1 V and a scan rate of 100 mV s^{– 1}. The corncob biochar-modified carbon paste electrode provided better performance than the unmodified electrode, with an anodic peak of 20 mg L^{– 1} nitrite appearing at a potential of 0.84 V, indicating nitrite oxidation. In contrast, the unmodified carbon paste electrode did not show any significant peak. To confirm that the observed peak is indeed the anodic peak of nitrite, we conducted measurements at different nitrite concentrations of 0, 20, and 50 mg L^{– 1}. In the absence of nitrite, no significant peak was observed. However, in nitrite solutions, the anodic peak increased with higher concentrations of nitrite. Additionally, the corncob biochar-modified carbon paste electrode demonstrated good selectivity for nitrite detection, as cyclic voltammetric measurements of some interference components did not produce redox peaks in the potential range of nitrite oxidation. These findings suggest that corncob biochar has significant potential for the development of electrochemical nitrite sensors.