Electrochemical determination of nitrites and sulfites by using waste-derived nanobiochar

In this work, the development of an electrochemical sensor based on nanobiochar for the determination of nitrites and sulfites is reported. Nanobiochar was obtained from orange peel waste derived hydrochar synthesized by hydrothermal carbonization 180 °C. This nanomaterial (NBC180) was characterized by SEM, FT-IR, PL, XRD analysis and its chemical, physical, morphological and microstructural properties were compared with the starting hydrochar material (HTC180). NBC180 was deposited on a commercial screen-printed carbon electrode (SPCE) and its electrochemical characteristics were investigated through CV and EIS analysis. The NBC180/SPCE sensor exhibits better electrochemical properties than the bare SPCE sensor for the detection of sulfites and nitrites in water, showing two well-defined and separated anodic peaks at +0.45 and +0.67 V, respectively. Linear correlations between anodic peaks and sulfites and nitrites concentration were found up to 3200 µM and 1400 µM, respectively. This study demonstrates, for the first time, the promising capability of nanobiochar derived from orange peels waste product for the simultaneous electrochemical oxidation of sulfites and nitrites in real samples.