Nitrite sensor using activated biochar synthesised by microwave-assisted pyrolysis

Abstract

Developing applications for the by-products obtained from waste processing is vital for resource recovery. The synthesis of ZnCl2-activated biochar with high electrocatalytic activity was carried out by the microwave-assisted pyrolysis of pineapple peel and subsequent chemical activation process. Activated biochar is employed in the electrochemical sensing of nitrite by drop casting in a glassy carbon electrode (GCE). The activated biochar exhibited a stacked carbon sheet, 254 m2 g−1 Brunauer, Emmett and Teller (BET) surface area, 0.076 cm3 g−1 pore volume, 189.53 m2 g−1 micropore area and oxygen-containing functional groups. The electrochemical impedance spectroscopy of the modified GCE showed a reduced charge transfer resistance of 61%. This is crucial to determine the electrochemical properties of biochar. The sensor showed a significant current response and an excellent limit of detection of 0.97 µmol L−1. The modified-activated biochar electrochemical sensor demonstrated high selectivity, reproducibility (RSD=2.4%), and stability (RSD=2.6%). Graphical abstract: [Figure not available: see fulltext.]