Mapping Nanocellulose- and Alginate-Based Photosynthetic Cell Factory Scaffolds: Interlinking Porosity, Wet Strength, and Gas Exchange.

To develop efficient solid-state photosynthetic cell factories for sustainable chemical production, we present an interdisciplinary experimental toolbox to investigate and interlink the structure, operative stability, and gas transfer properties of alginate- and nanocellulose-based hydrogel matrices with entrapped wild-type Synechocystis PCC 6803 cyanobacteria. We created a rheological map based on the mechanical performance of the hydrogel matrices. The results highlighted the importance of Ca2+-cross-linking and showed that nanocellulose matrices possess higher yield properties, and alginate matrices possess higher rest properties. We observed higher porosity for nanocellulose-based matrices in a water-swollen state via calorimetric thermoporosimetry and scanning electron microscopy imaging. Finally, by pioneering a gas flux analysis via membrane-inlet mass spectrometry for entrapped cells, we observed that the porosity and rigidity of the matrices are connected to their gas exchange rates over time. Overall, these findings link the dynamic properties of the life-sustaining matrix to the performance of the immobilized cells in tailored solid-state photosynthetic cell factories.

Effect of Enzymatic Depolymerization of Cellulose and Hemicelluloses on the Direct Dissolution of Prehydrolysis Kraft Dissolving Pulp.

Prehydrolysis kraft (PHK) pulps account for more than half of the global market of dissolving pulp. Characterized by high reactivity toward dissolution, their performances can still be improved by activation treatments. This study compares the dissolution kinetics in cupriethylenediamine of a hardwood and a softwood PHK pulps before and after their activation by high-solid-content mechano-enzymatic treatments. Three enzyme combinations were tested: endoglucanase (E), xylanase and mannanase (XM), and endoglucanase, xylanase, and mannanase (EXM). Xylanase and mannanase reduced the hemicellulose content of only hardwood (by max. 2.4%). Mixing and carbohydrate depolymerization decreased the dissolution time of hardwood and softwood pulps by a maximum of 63 and 30% with E, 37 and 16% with XM, and 44 and 30% with EXM, respectively. The shortening of the dissolution time was partially hindered by hornification, which increased with hemicellulose degradation. Interestingly, XM accelerated the dissolution while preserving a high weight-average molecular mass.

Highly Porous Willow Wood-Derived Activated Carbon for High-Performance Supercapacitor Electrodes.

In this study, we present willow wood as a new low-cost, renewable, and sustainable biomass source for the production of a highly porous activated carbon for application in energy storage devices. The obtained activated carbon showed favorable features required for excellent electrochemical performance such as high surface area (∼2 800 m2 g-1) and pore volume (1.45 cm3 g-1), with coexistence of micropores and mesopores. This carbon material was tested as an electrode for supercapacitor application and showed a high specific capacitance of 394 F g-1 at a current density of 1 A g-1 and good cycling stability, retaining ∼94% capacitance after 5 000 cycles (at a current density of 5 A g-1) in 6 M KOH electrolyte. The prepared carbon material also showed an excellent rate performance in a symmetrical two-electrode full cell configuration using 1 M Na2SO4 electrolyte, in a high working voltage of 1.8 V. The maximum energy density and power density of the fabricated symmetric cell reach 23 W h kg-1 and 10 000 W kg-1, respectively. These results demonstrate that willow wood can serve as a low-cost carbon feedstock for production of high-performance electrode material for supercapacitors.