The transition toward low-carbon fuels demands efficient routes for converting renewable feedstocks into drop-in hydrocarbons. In this work, we report an alternative, metal-free photodecarboxylative protocol for the production of hydrocarbons within the Sustainable Aviation Fuel (SAF) range, starting from N-hydroxyphthalimide-derived redox-active esters obtained from C10-C18 fatty acids. The methodology relies on the in situ formation of an electron donor-acceptor (EDA) complex between the redox-active ester and the Hantzsch ester, which simultaneously acts as a hydrogen atom donor and photochemical activator, thereby eliminating the need for metal catalysts and molecular hydrogen. Under visible-light irradiation, at ambient temperature and atmospheric pressure, using isopropyl alcohol as solvent, saturated substrates achieved conversions exceeding 99% and afforded the corresponding n-alkanes (Cn-1) in yields of up to 83%. Chain-length variation influenced the overall efficiency, providing C9-C17 alkanes in yields ranging from 52 to 83%. Unsaturated C18 substrates furnished the corresponding olefins in moderate yields (up to 48%). The one-pot strategy maintained conversions above 90% and enabled the direct application of the protocol to a range of real lipidic biomasses, delivering overall yields between 31 and 79%. The protocol operates under mild conditions, tolerates open-air atmosphere, and can be driven by solar irradiation, representing a promising alternative to conventional SAF production pathways.
The growing demand for bio-based materials has stimulated the development of sustainable alternatives to conventional plastics, among which polyhydroxyalkanoates (PHAs) stand out due to their biodegradability and biocompatibility. In this context, the present study evaluated the production, recovery, and characterization of poly(3-hydroxybutyrate) [P(3HB)] synthesized by Bacillus megaterium ATCC 14581 using rice parboiling wastewater (RPW) and confectionery industry effluent (CIE) as agro-industrial substrates. P(3HB) production was carried out in a fed-batch bioreactor under controlled conditions employing two nitrogen-feeding strategies: continuous supplementation (Strategy I) and intermittent supplementation (Strategy II). The recovery of P(3HB) was investigated using ultrasound-assisted extraction, employing chloroform and 1,2-dichloroethane as solvents. The P(3HB) recovered under the selected conditions was characterized by Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and biodegradability assays. Strategy II showed superior performance, reaching a maximum biomass concentration of 6.48 g/L at 27 h and a P(3HB) accumulation of 2.35 g/L, corresponding to 67.74% of cell dry mass, at 21 h of cultivation. Ultrasound-assisted extraction resulted in recovery yields of 6.16% for chloroform. Biodegradation tests demonstrated mass losses exceeding 80% after 84 days under controlled conditions, confirming the environmentally favorable behavior of the biopolymer. Overall, the results demonstrate that agro-industrial residues can be successfully valorized as low-cost substrates for P(3HB) production and that ultrasound-assisted technology represents a promising alternative for polymer recovery.
Sugar beet pulp (SBP) is an abundant polysaccharide-rich agro-industrial residue with distinctly low lignin and significant pectin content. Suitable pretreatment strategies tailored to SBP constituents are thus critical for its valorisation to diverse products. We developed two novel pretreatments, hydrogen peroxide-tween 80 (PS) and polypropylene glycol (PPG) and benchmarked them against dilute hydrochloric acid pretreatment (DAP). The process development includes response surface optimization, sequential pectinase-cellulase hydrolysis, and a techno-economic analysis (TEA). DAP achieved 75% theoretical arabinose yield (28.59 g/L) while solubilizing 80% of pectin, recovered via ethanol precipitation. A subsequent cellulase hydrolysis released 45.1 g/L glucose at 83% theoretical yield. PS removed 62-67% lignin through oxidative delignification with minimal sugar loss (less than 2 g/L), and PPG substantially improved enzyme accessibility through solvent-mediated surface disruption with negligible PPG loading. Sequential enzymatic hydrolysis produced 59.4 g/L and 55.3 g/L total sugars (ara + GalA dominant) from the pectinase stage, and 69.6 g/L and 81.7 g/L (glucose dominant) from the cellulase stage, for PS and PPG, respectively. TEA, using 100 MT SBP/day as plant capacity, showed that the production costs per kg of sugar mixtures were $0.41, $1.03, and $0.96 for DAP, PS, and PPG, respectively. However, DAP's apparent cost advantage is contingent on pectin co-product revenue. Without this credit, its production cost rises to $1.05/kg. This work validates PS and PPG as viable novel pretreatments and establishes a comparative framework linking process chemistry, enzymatic performance, and economics for pretreatment selection in SBP-based 2G biorefinery.
Selecting a biomass pyrolysis facility location requires reconciling site conditions with the priorities of affected stakeholders. This study develops an integrated Multi-Actor Multi-Criteria Analysis (MAMCA) framework combining the Pivot-Linked Elicitation Best-Worst Method (PILE-BWM) and Multi-Attribute Value Theory (MAVT) to evaluate four organized industrial zones for a tea- and hazelnut-residue bioenergy and biochar hub in Trabzon, Türkiye. A common nine-criterion performance matrix was constructed from documented regional sources, historical district-level information, and transparent screening assumptions, while separate consensus weights were elicited for farmers, residents, public-sector representatives, and private-sector actors. Farmers and the private sector assigned the greatest importance to resource and supply, whereas residents and the public sector emphasized environmental and accessibility considerations. Arsin ranked first for farmers and the private sector, while Akçaabat-Şinik ranked first for residents and the public sector. Although biomass-weighted inbound haul distance received the public sector's largest criterion weight, it favoured Arsin; Akçaabat-Şinik's narrow public-sector lead was driven by its settlement-separation advantage. The four rankings showed relatively high descriptive concordance (Kendall's W = 0.78), and minimax regret identified Akçaabat-Şinik as the compromise alternative (maximum regret = 0.47). Extended sensitivity analyses showed stable winners for farmers, residents, and the private sector, whereas the public-sector winner changed under selected circuity-factor and reference-anchor scenarios. The findings show that preserving stakeholder-specific preferences reveals trade-offs that would be obscured by aggregated weighting.
