Abstract
In this study, we have used a mild pyrolytic process for the synthesis of luminescent carbon material from phalsa (Grewia asiatica Linn) and utilized it for the photodegradation of methylene blue (MB) in aqueous solution under the irradiation of ultraviolet (UV) light. The carbon material was found to be graphitic in nature and with carbon dot-like properties as demonstrated by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), dynamic light scattering (DLS), and UV-visible techniques. The prepared carbon material was further studied for the elucidation of functional groups through Fourier transform infra-red (FTIR) spectroscopy. The carbon material exhibits the nanostructured phase which makes it a high surface area material for useful surface reactions. Different photodegradation aspects were investigated, such as initial dye concentration, catalyst dose, effect of pH of dye solution, reusability, electrochemical active surface area (ECSA), and charge transfer and scavenger. Optimum conditions of 15 mg carbon material, initial dye concentration of 2.3 x 10(-5) M solution, and pH 5 of dye solution gave the highest outperformance degradation efficiency. The degradation mechanism of MB in aqueous solution was dominated by the hydroxyl radicals as verified by the scavenger study. The reaction kinetics of MB degradation was followed by the pseudo first order kinetics and highest values of rate constants in the low initial dye concentration and the acidic pH of the MB solution. Significantly, the carbon material prepared from phalsa was found to be highly stable, as proven by the reusability experiments. Furthermore, the high ECSA and low charge transfer resistance of carbon material enabled it to have better performance. The use of mild pyrolytic process for the preparation of high performance luminescent carbon material from the biomass could be a great roadmap for the synthesis of a new generation of carbon materials for a wide range of applications including bio-imaging, catalysis, energy conversion and environmental applications.