Conversion of industrial orange peel waste by an integrated Hydrothermal and Electrochemical sustainable approach to NanoCarbon Materials for Catalysis Applications

In 2021, in Southern Italy two million tons of oranges were produced. Every year, the industry of orange juice generates a huge amount of orange peel waste (OPW) that requires suitable management, taking into consideration the high orange processing waste biodegradability that causes its fast fermentation.[1] Therefore, the direct disposal of this secondary product using traditional disposal strategies, without previous processing, raises serious environmental issues and economic loss for the citrus industry. The aim of this work is the conversion OPW into new and useful chemicals. The OPW waste has been transformed into carbon dots (CDs) by a simple, scalable, and ecofriendly hydrothermal [2] and electrochemical (EC) approach. The use of the EC method on waste material represents a recent innovative method. [3] The EC routes operate through consolidated devices for nanomaterials production and offer advantages of mild reaction conditions, high yields, and purity, simple instrumentation, and cost containment for mass production. The choice to synthesize the CDs by EC method is linked to the envisioned use of green precursors which originate from biological materials, the OPW, to make sure the as-prepared CDs are non-toxic and biocompatible. The carbon nanoparticles have been characterized by SEM, the functional groups on the surface has been determined by FT-IR analysis and optical properties and quantum yield have been evaluated by UV-Visible and PL measurements. Since CDs have been used as reusable catalysts, the synthetized bio-based CDs have been tested as heterogeneous catalyst in carbon-carbon bond reactions, relevant in organic synthesis.