Preparation of Biochar Derived From Lychee Shell and Its Application in Simultaneous Detection of Catechol and Hydroquinone

Abstract

Four biochars were prepared from lychee shell with or without phosphoric acid activation under one- or two-stage heating, and characterized by scanning electron microscopy, transmission electron microscopy, infrared spectroscopy and Raman spectroscopy, respectively. Their adsorption capacities were evaluated by methylene blue adsorption test. Their electrochemical properties were depicted by electrochemical impedance spectroscopy and cyclic voltammetry. The biochar prepared by two-stage heating and phosphoric acid activation (LSC-THP) exhibited a high porosity, the best adsorption capacity, lowest electric resistance and largest electrochemically active surface, was applied to modify a glassy carbon electrode (GCE) after mixed with chitosan (CS), to fabricate the sensing electrode LSC-THP/CS/GCE for the simultaneous detection of catechol (CC) and hydroquinone (HQ). Square wave voltammetry and differential pulse voltammetry measurements indicated that LSC-THP/CS/GCE exhibited the best response current signal at pH 6.6, with the linear detection range of 10–2000 μmol·L⁻¹ and limit of detections of 1.23 and 0.44 μmol·L⁻¹ for CC and HQ detections, respectively. LSC-THP/CS/GCE also exhibited a good anti-interference ability and could be applied to the simultaneous detection of CC and HQ in real samples. This study provides a promising approach to improve the electrochemical performance of biochars for the development of novel electrochemical sensors.