From green tide to biochar: Thermal decomposition kinetics and TG-FTIR study of microalgae from Chaohu Lake

Every summer, algal bloom occurs in Chaohu Lake, causing the death of large numbers of aquatic animals, water pollution, and environmental pollution. Although Chaohu algae (CHA) is a pollutant, it represents a possible renewable energy source. This work aims to analyze the pyrolysis kinetics of CHA for the production of biochar and show the potential of the biochar for electrochemical applications. The thermal degradation features of CHA were studied using thermogravimetric and TG-FTIR analysis. Meanwhile, Flynn-Wall-Ozawa and Kissinger-Akahira-Sunose methods were applied for the evaluation of kinetic parameters. CHA was then pyrolyzed using the microwave-assisted method to obtain biochar. The biochar structure and components were characterized by SEM, XRD, and Raman spectra. And the electrocatalytic performance was measured via cyclic voltammetry (CV) test with the biochar-modified electrode. It was found that the volatile products mainly contained water, methane, carboxylic acid, ketones, aldehyde groups, and NH3 indicated by the real-time online FTIR spectra. And the comprehensive characterization showed that the CHA-derived biochar had unique properties as a superior functionalizing material for electrochemical applications. To sum up, we innovatively proposed to apply the biochar from the pyrolysis of CHA as an electrode functionalizing material and further evaluated the detection performance of the modified electrode.