DOI: 10.3303/CET2184025 Paper Received: 13 July 2020; Revised: 19 November 2020; Accepted: 9 March 2021 Please cite this article as: Russo C., Cerciello F., Senneca O., Ciajolo A., Apicella B., 2021, Formation of Fluorescent Carbon from Fast Pyrolysis of Lignocellulosic Biomass, Chemical Engineering Transactions, 84, 145-150 DOI:10.3303/CET2184025 CHEMICAL ENGINEERING TRANSACTIONS VOL. 84, 2021 A publication of The Italian Association of Chemical Engineering Online at www.cetjournal.it Guest Editors: Paolo Ciambelli, Luca Di Palma Copyright © 2021, AIDIC Servizi S.r.l. I SBN 978-88-95608-82-2; I SSN 2283-9216 Formation of Fluorescent Carbon from Fast Pyrolysis of Lignocellulosic Biomass Carmela Russo, Francesca Cerciello, Osvalda Senneca, Anna Ciajolo, Barbara Apicella* Istituto di Scienze e Tecnologie per l’Energia e la Mobilità Sostenibili, STEMS- CNR P.le Tecchio 80, 80125 Napoli, Italy* barbara.apicella@stems.cnr.it Fluorescent carbon was produced from fast pyrolysis of lignocellulosic biomass in a modified wire-mesh reactor named heated strip reactor (HSR). The metal grid, usually employed as a sample holder in a wire- mesh reactor, is replaced in the HSR by a pyrolytic graphite foil. HSR can achieve temperatures up to 2073 K with a high heating rate (104 K/s). The volatiles produced by the HSR pyrolysis of a lignocellulosic biomass sample were immediately quenched in the surrounding low temperature environment, so avoiding the occurrence of secondary reactions of the volatiles. Volatiles were condensed in form of a tar-like material on a pyrex glass bridge located above HSR, whereas the residue solid (char and soot) remained on the strip. The tar-like material recovered and separated with different solvents in fractions of various characteristics showed blue and/or green fluorescence typical of fluorescent carbon dots (CDs). It was thus shown that fast pyrolysis of carbon resources as biomasses, can be employed as one-step approach to synthesize different classes of carbon materials, assimilable to CDs. The different CDs could be separated and isolated choosing appropriate organic solvents and constitute very promising materials for applications in photonics, electro-optics, chemical sensing, and other material science areas. 1. Introduction Carbon dots (CDs) are a new type of carbon-based zero-dimensional material and have drawn significant attention since the discovery of carbon fluorescent nanoparticles into arc discharge soot in 2004 [Xu et al. 2004]. CDs are eco-friendly candidates aiming at replacing both the semiconductor quantum nanodots and the organic dyes for biolabeling and bioimaging, as they offer great advantages due to their low toxicity and high biocompatibility, chemical stability and quantum yield. The synthesis of CDs from renewable biomass is especially attractive due to its sustainable and cost-efficient feature, therefore there is a growing research work on this topic, collected in some recent reviews [Kang et al 2020; Meng et al 2019; Zhao et al. 2020; Li et al. 2021]. Due to its versatility and simple experimental setup, hydrothermal carbonization has now become the most common procedure adopted for the production of CDs from natural biomass or other readily available carbon sources [Meng et al 2019]. However, hydrothermal methods are generally considered time-consuming and present disadvantages regarding the use of commodity chemicals [Heidari et al 2019; Kang et al 2020]. The present paper shows for the first time that fluorescent carbon featuring CD properties can be produced from fast pyrolysis (reaction times of order of seconds) of a lignocellulosic biomass in a modified wire-mesh reactor named heated strip reactor (HSR). Specifically, in this work fluorescent carbons produced in N2 and CO2 atmosphere from the pyrolysis of hemicellulose, one of the major components of lignocellulosic biomass, were analysed. 2. Experimental Figure 1 shows a picture of the experimental apparatus used for treating the hemicellulose sample at severe heating conditions in N 2 or CO 2 atmosphere using a special heated strip reactor (HSR), where the metal grid, usually employed as a sample holder, is replaced by a pyrolytic graphite foil thermally stabilized for use up to 145