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Microfluidic solvent extraction (microSX) of metal ions from industrial grade mineral leach solutions was studied. In conventional bulk-scale SX, partially hydrophobic nanoparticles that are present in the leach solution readily adsorb at the liquid-liquid interface of the dispersed droplets, causing delayed or incomplete phase separation and reduce efficiency. In contrast, microSX employs continuous microscopic streams of aqueous and organic phases (without mixing the phases) and, in this way, bypasses the need for a conventional phase separation stage. This makes the technique promising for handling complex leach solutions. The stability of the two-phase flow is considered in terms of the surface wettability and guiding geometry of the microchannel, which determines the Laplace pressure window that stabilizes the liquid-liquid interface. We show that careful characterization of the microchannel wettability, including contact angle hysteresis, is essential to predict long-term flow stability.

The effect of a 3% Pd/C catalyst on the depolymerization of the ethanol organosolv lignin (EOL) was studied in ethanol at 300–400 °C and 10–50 bar H2 pressure. The EOL depolymerized to monoaromatic compounds, oligomers and larger lignin fragments in both catalytic and non‐catalytic experiments. In addition, char was formed simultaneously due to repolymerization. The commercial Pd/C catalyst influenced the content of the bio‐oil and gas fraction through the secondary reactions of the smaller product molecules. However, the EOL decomposition occurred mainly thermally and possibly autocatalytically due to the inert nature of the catalyst support. The effect of the catalyst on the monoaromatic product distribution was remarkable. With the catalyst, most of the identified products contained a saturated side chain produced by hydrogenation, whereas without the catalyst, the product distribution was wider, with a large portion of products exhibiting unsaturated and carbonyl side chains. Additionally, the monoaromatic compounds formed in the presence of the catalyst had longer side chains than the components formed in non‐catalytic experiments.

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