N Nature Chemical Engineering · Dec 03, 2025 Selective partitioning and uphill transport enable effective Li/Mg ion separation by negatively charged membranes Efficient separation of lithium (Li+) and magnesium (Mg2+) is critical for enhancing sustainable lithium extraction from natural brines, which is vital for battery production and renewable energy technologies. Here we present a method for highly selective Li+/Mg2+separation driven by concentration gradients across negatively charged membranes with high charge densities. In contrast to typical electric field-driven transport in negatively charged membranes, where divalent cations generally permeate faster than monovalent cations, Li+ions in our system permeate the membrane at substantially higher rates than Mg2+ions. This unexpected selectivity stems from the selective ion partitioning properties of the membrane and the uphill transport of Mg2+ions against their external concentration gradient. We demonstrate the efficacy of this separation approach through bench-scale dialysis experiments using a model Atacama brine solution, achieving efficient separation of monovalent and divalent cations. The high separation efficiency observed in this study suggests a promising approach for monovalent/divalent ion separations, offering higher selectivity compared to current technologies. Chemical engineering Polymers other
N Nature Chemical Engineering · Nov 27, 2025 Passive direct air capture via evaporative carbonate crystallization Direct air capture of CO2is needed to mitigate past emissions and those of persistent and difficult-to-abate sources. Current liquid-sorbent-based direct air capture relies on large-scale air handling and coupled sorbent–solid chemical loops, but the complexity and cost of this approach are barriers to scaling. Here we report a departure from established capture mechanisms in which ultraconcentrated KOH solutions (>9 M) achieve rapid CO2-to-carbonate crystallization at the air interface. On the basis of this finding, we develop a carbonate crystallizer that leverages evaporation to concentrate KOH on a wicking substrate, enabling the stable, passive capture of atmospheric CO2directly into a solid form. This approach achieves a capture flux over sixfold that of conventional systems, with regeneration demonstrated via a subsequent electrochemical step. A module with 100 such crystallizers achieved an average capture flux over threefold that of conventional contactors, with sustained operation over seven cycles and 25 days. This passive, single-chemical-loop approach has the potential to reduce capital and levelized costs by approximately 42% and 32%, respectively, compared with conventional liquid-based direct air capture systems. Carbon capture and storage Chemical engineering Metabolism Climate Engineering Carbon Capture Electrochemistry
N Nature Chemical Engineering · Nov 19, 2025 An industrial automated laboratory for programmable protein evolution Current methods for protein engineering are constrained by limited understanding of sequence–function relationships, the difficulty of designing complex properties by artificial intelligence methods and labor-intensive directed evolution. Here, to enable continuous and scalable protein evolution and systematic exploration of protein adaptive landscapes, we established an industrial-grade automation platform featuring high throughput, high efficiency, enhanced reliability and minimal human intervention (operational for ~1 month). We then developed new genetic circuits for the OrthoRep continuous evolution system to achieve growth-coupled evolution for proteins with diverse and complex functionalities. This included improving lactate sensitivity of LldR via dual selection and increasing operator selectivity for LmrA using the NIMPLY circuit. We integrated these components into an all-in-one laboratory, iAutoEvoLab, and evolved proteins from inactive precursors to fully functional entities, such as a T7 RNA polymerase fusion protein CapT7 with mRNA capping properties, which can be directly applied to in vitro mRNA transcription and mammalian systems. Our system represents a versatile tool for protein engineering and expands the scope for investigating the origins and evolutionary trajectories of protein functions. Biomedical engineering Biotechnology Proteins Protein Engineering Automation Directed Evolution Genetic Circuits
N Nature Chemical Engineering · Nov 17, 2025 Water dissociation efficiencies control the viability of reverse-bias bipolar membranes for CO2electrolysis Bipolar membranes operated under reverse-bias (r-BPM) provide the only potential route to use anodes free of platinum group metals in CO2electrolyzers when paired with the oxygen evolution reaction. Under 100% water dissociation efficiency (WDE) conditions, the OH−generated by a r-BPM fully replenishes the OH−consumed by the oxygen evolution reaction, maintaining an alkaline anolyte. However, unwanted co-ion crossover leads to <100% WDEs, gradually causing anolyte acidification and nickel-based anodes to corrode over time. Here we experimentally measured the WDE of r-BPMs in a membrane–electrode assembly configuration as a function of the current density, anolyte concentration and cation identity, finding that the highest measured WDE of 98% is insufficient to maintain an alkaline environment over extended operation. We further highlight through modeling that WDEs >99.8% are required to operate for >10,000 h with reasonable anolyte volumes. Our results show that r-BPMs CO2electrolyzers require additional strategies, such as reverting to platinum group metal anodes or regenerating the anolyte, to operate stably at an industrial scale. Chemical engineering Electrocatalysis other
