Highly Active Carbon Material Derived from Carica papaya Fruit Juice: Access to Efficient Photocatalytic Degradation of Methylene Blue in Aqueous Solution under the Illumination of Ultraviolet Light

Abstract

Herein, we describe a cost-effective, efficient, sustainable, and environmentally friendly pyrolytic method for the synthesis of highly active carbon materials from Carica papaya fruit juice for the photodegradation of various pollutants, such as methylene blue (MB), in aqueous solutions using ultraviolet (UV) light. Various analytical techniques were used to examine the morphology, crystal quality, functional group chemistry, particle size distribution, and optical properties of the materials. For evaluating the performance of the newly prepared carbon material, various photocatalyst parameters were investigated, including initial dye concentration, catalyst dose, pH of dye solution, cyclic stability, and scavenger studies. The obtained findings attest that the optimal degradation efficiency of carbon material for high MB concentrations (2.3 × 10−5 M) is around 98.08%, whereas at low concentrations of MB (1.5 × 10−5 M) it reaches 99.67%. Degradation kinetics indicate that MB degrades in a first-order manner. Importantly, as the pH of the dye solution was adjusted to ~11, the degradation rate increased significantly. The scavenger study indicated that hydroxyl radicals were the predominant species involved in the degradation of MB. In addition, active surface site exposure and charge transfer were strongly associated with efficient MB degradation. On the basis of its performance, this newly developed carbon material may prove to be an excellent alternative and promising photocatalyst for wastewater treatment. Furthermore, the synthetic approach used to produce carbon material from Carica papaya fruit juice may prove useful for the development of a new generation of photoactive materials for environmentally friendly applications, as well as for the production of hydrogen from solar energy.