Transformation of waste thermocol into activated carbon for electrochemical detection of ammonia in an aqueous solution

In this study, waste thermocol sheets are used to synthesize activated carbon (AC) for the electrochemical detection of ammonia in an aqueous solution. The AC is characterized for its morphology, structure, and chemical composition via standard characterization techniques. AC shows promise for detecting ammonia in aqueous solutions due to its high adsorption capacity from large surface area and porosity. The electrochemical approach used to detect ammonia (NH3) in electrolyte solutions uses an AC electrode and is based mostly on the electro-oxidative conversion of ammonia species at the electrode's interface. AC electrodes fabricated on flexible conductive fabric (CF) are used for the electrochemical detection of ammonia at pH 6. The electrochemical sensing of ammonia in aqueous solutions involves its oxidation on the electrode's surface. Cyclic Voltammetry (CV) experiments were conducted over a pH range of 5 to 8, revealing optimal current responses at pH 6. Therefore, phosphate-buffered saline (PBS) at pH 6.0 was employed for all electrochemical analyses. Various concentrations of ammonia (10-100 ppm) were investigated within a voltage window of -0.3 V to 0.3 V, with current signals increasing proportionally with ammonia concentration. The limits of detection (LOD) and quantification (LOQ) were determined to be 28.55 ppm and 86.54 ppm, respectively. An incubation period of 3 min was observed for ammonia concentrations ranging from 0 to 40 ppm. Selectivity evaluations were conducted by assessing interference effects from ethanol (E), methanol (M), toluene (T), and uric acid (UA), revealing ammonia's distinctive peak, indicative of superior selectivity. Notably, the electrode exhibited remarkable stability, retaining approximately 95 % of the original signal over a 5-week duration. The reproducibility of the fabricated electrodes shows significant results. The repeatability was performed at room temperature in a buffer solution of pH 6 and at a 40-ppm concentration of ammonia and has shown almost similar results. Therefore, the fabricated AC sensing electrode has shown prominent stability, reproducibility, and repeatability. These sensing electrodes can be very beneficial for sensing applications.