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Gonçalves Oliveira Valente da Cruz-Lopes, Luísa Paula
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- Enhancing Liquefaction Efficiency: Exploring the Impact of Pre-Hydrolysis on Hazelnut Shell (Corylus avellana L.)Publication . Cruz-Lopes, Luísa; Duarte, Joana; Dulyanska, Yuliya; Guiné, Raquel; Esteves, BrunoHazelnut shells (HS), scientifically known as Corylus avellana L. shells, are waste produced by companies that process nuts. The main objective of this study was to find an efficient way to maximize the chemical potential of HS by solubilizing the hemicelluloses, which could then be used to recover sugars and, at the same time, increase the lignin content of this material to produce adhesives or high-strength foams. In order to optimize the pre-hydrolysis process, two different temperatures (160 and 170 °C) and times varying from 15 to 180 min were tested. All the remaining solid materials were then liquefied using polyalcohols with acid catalysis. The chemical composition of hazelnut shells was determined before and after the pre-hydrolysis. All of the process was monitored using Fourier Transform Infrared Spectroscopy with Attenuated Total Reflectance (FTIR-ATR) by determining the spectra of solids and liquids after the pre-hydrolysis and liquefaction steps. The highest solubilization of hazelnut shells was found for 170 °C and 180 min, resulting in a 25.8% solubilization. Chemical analysis after the hydrolysis process showed a gradual increase in the solubilization of hemicelluloses as both the temperature and time of the reactor were increased. Simultaneously, the percentages of α-cellulose and lignin in the material also increased with rises in temperature and duration. FTIR-ATR allowed for the detection of significant spectral changes in the hazelnut shells from their initial state to the solid residue and further into the liquefied phase. This confirmed that pre-hydrolysis was effective in enhancing the chemical composition of the material, making it more suitable for the production of adhesives, polyurethane foams, or in the production of bioplastics and composite materials, combined with other biopolymers or synthetic polymers to enhance the mechanical properties and biodegradability of the resulting materials.
- Influence of Pre-Hydrolysis on the Chemical Composition of Prunus avium Cherry SeedsPublication . Cruz-Lopes, Luísa; Dulyanska, Yuliya; Domingos, Idalina; Ferreira, José; Fragata, Anabela; Guiné, Raquel; Esteves, BrunoDuring the industrial processing of sweet cherry fruits, the seeds are considered agricultural waste and must be disposed of, typically through burning. In this context, it is intended to contribute to the scientific development of the ecovalorization of by-products and to provide new strategies for their transformation into value-added products obtained from sweet cherry seeds (SCS). This work aimed to establish the chemical characterization of SCS before and after several pre-hydrolysis steps in order to allow the solubilization of hemicelluloses that can later be used for the recovery of sugars. The higher percentage of cellulose and lignin remaining in the solid phase will allow its further processing for an integral valorization of the raw material. The temperature (160 and 170 °C) and time (0 and 180 min) of pre-hydrolysis were optimized to obtain the best liquefaction. The percentage of liquefied material was determined from the solid waste obtained at the time of filtration. The best liquefaction by the hydrolysis of SCS was obtained at 170 °C and 180 min, with a yield of 26.7%. The chemical analyses of SCS throughout hydrolysis showed the solubilization of hemicelluloses with increases in the time and temperature of the reactor. α-cellulose and lignin showed an increase both with temperature and time, increasing the material’s potential for further processing in adhesives. FTIR analysis showed that there were significant changes in the spectra between the initial SCS, the solid residue, and the liquefied material. Pre-hydrolysis was proven to be an efficient process to improve the chemical composition of the material for further processing into adhesives or higher-mechanical-strength polyurethane foams