Valorization of Hemp-Based Packaging Waste with One-Pot Ionic Liquid Technology.

The range of applications for industrial hemp has consistently increased in various sectors over the years. For example, hemp hurd can be used as a resource to produce biodegradable packaging materials when incorporated into a fungal mycelium composite, a process that has been commercialized. Although these packaging materials can be composted after usage, they may present an opportunity for valorization in a biorefinery setting. Here, we demonstrate the potential of using this type of discarded packaging composite as a feedstock for biofuel production. A one-pot ionic liquid-based biomass deconstruction and conversion process was implemented, and the results from the packaging material were compared with those obtained from untreated hemp hurd. At a 120 °C reaction temperature, 7.5% ionic liquid loading, and 2 h reaction time, the packaging materials showed a higher lignocellulosic sugar yield and sugar concentrations than hemp hurd. Hydrolysates prepared from packaging materials also promoted production of higher titers (1400 mg/L) of the jet-fuel precursor bisabolene when used to cultivate an engineered strain of the yeast Rhodosporidium toruloides. Box-Behnken experiments revealed that pretreatment parameters affected the hemp hurd and packaging materials differently, evidencing different degrees of recalcitrance. This study demonstrated that a hemp hurd-based packaging material can be valorized a second time once it reaches the end of its primary use by supplying it as a feedstock to produce biofuels.

Hot Electrons Generated from Doped Quantum Dots via Upconversion of Excitons to Hot Charge Carriers for Enhanced Photocatalysis.

We show that hot electrons exhibiting the enhanced photocatalytic activity in H2 production reaction can be efficiently generated in Mn-doped quantum dots via the "upconversion" of the energy of two excitons into the hot charge carriers. The sequential two-photon-induced process with the long-lived Mn excited state serving as the intermediate state is considered as the pathway generating hot electrons. H2 production rate from doped quantum dots is significantly higher than that from undoped quantum dots and also exhibited the quadratic increase with the light intensity, demonstrating the effectiveness of the hot electrons produced in doped quantum dots in photocatalytic reaction. Due to the very long lifetime of Mn excited state (∼6 ms) in the doped quantum dots, the sequential two-photon excitation requires relatively low excitation rates readily achievable with a moderately concentrated solar radiation, demonstrating their potential as an efficient source of hot electrons operating at low excitation intensities.