Preparation of longan shell biochar and its application in fabrication of nitrite electrochemical sensing electrode

Abstract

Longan shells were treated with or without phosphoric acid activation in different pyrolysis processes, to obtain four biochar materials including direct pyrolysis-longan shell biochar (D-LSB), stage pyrolysis-longan shell biochar (S-LSB), phosphoric acid activation with direct pyrolysis-longan shell biochar (PD-LSB), and phosphoric acid activation with stage pyrolysis-longan shell biochar (PS-LSB). This study is to screen out the LSB with the best electrochemical property, being applied in the fabrication of nitrite sensing electrode. A series of structural and electrochemical characterizations revealed that PD-LSB featured hierarchically porous structures, the largest specific surface area and pore volume as well as the best conductivity, and was applied to modify the glassy carbon electrode (GCE) after mixed with chitosan, to fabricate the electrochemical sensing electrode PD-LSB/CS/GCE for nitrite detection. The operating condition and performance of the fabricated nitrite sensing electrode were investigated, and the results indicated that it showed the optimal response signal for nitrite detection at pH=3.0, with a linear detection range of 200.0–30000.0 μM and a limit of detection (LOD) of 1.08 μM. The fabricated nitrite sensing electrode also exhibited a good reproducibility, reproducibility and stability as well as good anti-interference ability, and was applied for the nitrite detection in real aqueous samples successfully. This study provides useful reference information for the preparation of novel biomass materials, and an innovative electrochemical analytical technique for the quick and accurate detection of nitrite in aqueous samples.