Hydrothermal carbon microspheres and their iron salt modification for enhancing biohydrogen production

Enhanced mechanical, thermal, and degradation properties of zein composite films by citrate ester composite elastomer based on hydrothermal carbon microspheres

Improving the toughness and strength of zein films simultaneously by a sustainable way is an urgent need. In this study, it is proposed to use hydrothermal carbon microspheres (HCM) and citrate ester (CE) to prepare hydrothermal carbon microspheres/citrate ester (HCE) to meet the inherent mechanical challenges of zein films. The results showed that the HCE with excellent structure and properties was obtained by ester bond and hydrogen bond, which also achieved the simultaneous improvement of zein film strength and toughness. Introducing HCM to HCE accelerated the degradation of zein whether for in water, orthophosphate solution, or soil environment. Additionally, the HCE increased the thermal decomposition residue, delayed the maximum decomposition peak temperature, and thus improved the thermal stability of zein. As a comparison, 3% HCM added CE exhibited the best performance improvement effects to zein film with the tensile strength of 2.37 MPa, tensile modulus of 0.81 GPa, elongation at break of 45.81%, hydrolysis rate of 44.12%, PBS degradation rate of 47.35%, buried degradation rate of 87.58%, and maximum decomposition peak temperatures of 270°C and 385°C. Having excellent properties and sustainability of the HCE provides a promising strategy for developing sustainable and high-performance zein composites.

Enhancing dark fermentative hydrogen production from wheat straw through synergistic effects of active electric fields and enzymatic hydrolysis pretreatment

Hydrogen, a clean and sustainable energy source, faces challenges from energy-intensive pre-processing technologies. This study explores the synergistic enhancement of active electric fields on enzymolysis of wheat straw and hydrogen production through dark fermentation. The active electric field enzymolysis system improved the adsorption capacity of wheat straw to cellulase, increasing cellulase activity by 18.0 %, causing a 39.1 % increase in reducing sugar content. In the active fermentation system, Clostridium_sensu_stricto_1 activity was enhanced in the first stage, increasing hydrogenase activity by 23.0 %, prolonging the first hydrogen production peak. Elevated reducing sugars were observed in the second stage, with Prevotella_9 and Bacteroides becoming the dominant hydrogen-producing bacteria in the third stage, leading to a second hydrogen production peak. Overall, cumulative hydrogen production was enhanced by 50.9 % compared to the control. The synergistic pretreatment with an active electric field and cellulase provides a novel approach for efficiently utilizing wheat straw.

Light energy utilization and microbial catalysis for enhanced biohydrogen: Ternary coupling system of triethanolamine-mediated Fe@C-Rhodobacter sphaeroides

This study investigated the mediating effect of Triethanolamine on Fe@C-Rhodobacter sphaeroides hybrid photosynthetic system to achieve efficient biohydrogen production. The biocompatible Fe@C generates excited electrons upon exposure to light, releasing ferrum for nitrogenase synthesis, and regulating the pH of the fermentation environment. Triethanolamine was introduced to optimize the electron transfer chain, thereby improving system stability, prolonging electron lifespan, and facilitating ferrum corrosion. This, in turn, stimulated the lactic acid synthetic metabolic pathway of Rhodobacter sphaeroides, resulting in increased reducing power in the biohybrid system. The ternary coupling system was analyzed through the regulation of concentration, initial pH, and light intensity. The system achieved the highest total H2 production of 5410.9 mL/L, 1.29 times higher than the control (2360.5 mL/L). This research provides a valuable strategy for constructing ferrum-carbon-based composite-cellular biohybrid systems for photo-fermentation H2 production.