Assessment of the Energy Recovery of Aloe Vera Solid Residues by Pyrolysis and Hydrothermal Conversion

• Main Authors: A. Strubinger, A.A. Ruiz Oliveros, M.A. Araque, J. Guerra
• Format: Article
• Language: English
• Published: AIDIC Servizi S.r.l. 2017-03-01
• Series: Chemical Engineering Transactions
• Online Access: https://www.cetjournal.it/index.php/cet/article/view/2067

The renewable energy sources are being considered as an alternative to solve energy needs and reduce environmental problems. Compared with other renewable energy, biomass from different production processes are an interesting alternative. In particular, the Aloe Vera waste, because has increased their use in the cosmetic, pharmaceutical and food industry. Biorefining has now been introduced as a new concept that integrates conversion processes that allow sustainable treatment of biomass to be converted into products such as synthesis gas, bio-oils, charcoal and energy. Different thermochemical conversion processes have been used with biomass, in order to guarantee energy recovery and reuse. The four main processes used are pyrolysis, combustion, gasification and liquefaction. When these processes are carried out in the presence of water in sub-critical state, it is called hydropyrolysis or hydrothermal carbonization (HTC). When are executed at temperatures above 280°C is called hydrothermal liquefaction (HTL). In this research was studied the effect of HTC and HTL in neutral and basic medium. As well as the pyrolysis process, in performance and characteristics of products such as biochar and condensable on Aloe Vera leafs. The highest yield in biochar was observed for pyrolysis with 31±3 %w/w followed by the HTL in neutral medium with 28±3 %w/w. The biochars were characterized by Fourier transform infrared spectroscopy (FTIR), absorption indexes and scanning electron microscopy. The characterization by FTIR showed the presence of functional groups characteristic of aromatic compounds products of condensation processes after applying the thermal treatments. The higher carbon densification was observed for pyrolysis and HTL, while the presence of carbonyl groups is evidenced only for hydroconversion processes. The methylene blue index in the biochars of different thermochemical treatments was 80-100 mg/g, comparable with some commercial activated carbons. For iodine number, the highest value was 224 ± 13 mg/g that was obtained by HTL in a neutral medium. The yield of biofuels in hydrothermal conversion processes was 18 to 26 %w/w; while in the pyrolysis were over 50 %w/w. These were characterized by FTIR and could not identify significant differences in the functional groups existent. The results in the Aloe Vera leaf indicate that the pyrolysis treatment is a low-cost, environmentally friendly management of this biomass, and economic feasibility; with which the highest performance in biochar and condensable fuel is obtained with lower gas production. In addition, biochar obtained can be used for energy purposes due to its densification as well as for amendment in contaminated soil or production of activated carbon, nanostructured materials, and catalysts.