Effect of temperature on synthesis of carbon quantum dots and biochar through one-step hydrothermal treatment of distillers’ grains
Wanting Wu, Lan Mu, Xinyu Luo, Yanhong Zhang, Jialiang Huang, Hao Peng, Junyu Tao
Abstract
In seeking new pathways for the efficient utilization and high-value conversion of distillers’ grains (DG), this study adopted a hydrothermal method to process the material. The aim was to simultaneously prepare fluorescent carbon quantum dots (CDs) and biochar (BC), while thoroughly exploring the impact of hydrothermal temperature on the luminescent properties of the CDs and the burning characteristics of the BC. The results indicated that the average particle size of the CDs produced at different hydrothermal carbonization temperatures ranged from 1.78 to 2.80 nm, with a relatively uniform particle size distribution and excellent storage stability. The QY of CDs gradually increases with the rise in hydrothermal temperature, reaching its peak at 220°C, with a value of 7.23 %. Under ultraviolet excitation at 435 nm, the CDs emitted blue fluorescence, and their emission spectra exhibited a dependency on the excitation wavelength. The CDs prepared at a hydrothermal carbonization temperature of 220 °C demonstrated the highest fluorescence intensity and exhibited a high specificity for Fe 3 + , showing a linear range between 100 and 2000 μM. As the hydrothermal carbonization reaction temperature increased, the yield of BC decreased; however, at a reaction temperature of 220 °C, its HHV reached its peak. The combustion process of the BC was divided into three stages, with the decomposition and combustion of cellulose being the primary weight loss phase, demonstrating good combustion stability and sustainability, showcasing potential as a high-quality fuel.