Preparation of an electrochemical sensor utilizing graphene-like biochar for the detection of tetracycline

Tetracycline (TC), which is ubiquitous in the aquatic environment, can cause ecological imbalance and adversely affect human health. Therefore, a quick, inexpensive, and easy method for the detection of TC in water systems is highly desirable. This study reports the development of a novel electrochemical sensor from waste peanut shell for the quick detection of TC in water. Raman and TEM lattice mapping analyses confirmed the successful preparation of graphene -like biochar from waste peanut shells (PSs) via hydrothermal and pyrolysis processes. An electrochemical sensor, PS@glassy carbon electrode (PS@GCE), was then developed by coating the prepared graphene-like biochar on the surface of a glass electrode to enhance its conductivity. The feasibility of using this sensor for the detection of TC in the aqueous system was investigated. The PS@GCE sensor exhibited excellent sensitivity with a low detection limit of 3.6 × 10^--9 nM and a linear range of 10^-10-10² μM. These results were attributed to the large specific surface area and high conductivity, of the PS biochar. The stability of the PS@GCE sensor was also investigated in the presence of TC (10^-4 M) and interfering species (10^-2 M) and recovery rates in the range of 86.4%-116.0% were achieved, thus indicating the absence of an interference range of range of 84.3%-98.2% with relative standard deviation lower than 6% were achieved upon the detection of TC in natural water samples using the designed sensor, thus confirming the superior repeatability of the PS@GCE sensor. Consequently, the designed electrode has a high potential for application in the detection of TC in natural aqueous systems.