Rare Earth Elements (REE) are essential ingredients of sustainable energy technologies ^1-5 , but separation of lanthanides is considered one of the hardest problems in chemistry today ⁶ . Biosorption, where molecules adsorb to the surface of biological materials, offers a sustainable alternative to environmentally harmful solvent extractions currently used for REE separations. The REE-biosorption capabilities of some microorganisms already allow for REE separations that under specialized conditions are competitive with solvent extractions ⁷ . Our recent work has discovered the genetic basis for REE biosorption selectivity ⁸ . However, it is unclear if the small changes to selectivity produced by changes to single genetic loci could allow biosorption to leapfrog existing REE separation technologies. In this article we present three models of lanthanide separation by biosorption and desorption. The first model shows that if a biosorbing microbe behaves as it if has a single type of binding site with small preference for one lanthanide, then the small changes in selectivity produced by changes to a single genetic locus could reduce the length of a separation process by ≈ 25%. Large multi-locus gene edits could reduce a separation process length by almost 90%. On the other hand, if the microbe contains multiple sites each with a distinct preference for an individual lanthanide, then separations become challenging and larger genetic edits would be needed to enable high purity. However, even if these large genetic edits are not possible, high purity separations could still be possible by combining multiple microbes, each with small increases in selectivity, with the first designed to enrich for the target lanthanide, while subsequent microbes are designed to remove contaminants.

Bacterial cellulose (BC) is a biodegradable, renewable material with exceptional mechanical properties, but its hydrophilicity and rigidity after dehydration limit its broader application in biobased materials including sustainable packaging and related flexible film and coating products. In this work, we report a two-step surface modification strategy to enhance the hydrophobic and thermal–mechanical performance of BC. First, carboxymethylation was performed using chloroacetic acid to introduce anionic carboxyl groups on the BC fibril surface. These negatively charged sites were then modified with cationic surfactants n-decylamine (C10), lauric arginate (LAE), or octadecylamine (C18). The resulting materials were characterized by using contact angle measurements, Fourier transform infrared spectroscopy (FTIR), dynamic mechanical analysis (DMA), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). Among the surfactants tested, MC18-modified BC showed an increased surface hydrophobicity (contact angle ∼95 vs 32° for unmodified BC), reduced storage modulus (0.5 from 4.8 GPa for unmodified BC) indicating enhanced flexibility, and improved T_max (314.5 vs 296 °C for unmodified BC). Surfactant-modified BC has the potential to be a more sustainable material that could be used as a substitute for high-density polyethylene (HDPE) films due to its comparable storage and loss moduli (0.8 and 0.8 GPa for storage modulus; 100 and 100 MPa for modified BC and HDPE, respectively).

Per- and polyfluoroalkyl substances (PFAS) coatings are widely used to impart water repellency to textiles, but their drawbacks, including the lack of biodegradability and potential effects on human health, underscore the need for fluorine-free alternatives. Current replacement products, such as PTFE (polytetrafluoroethylene) layers and wax applications, experience durability issues and require reapplication. In this study, a dual-surfactant coating comprising pentanoic acid (C5) and octadecylamine (C18) was developed to impart hydrophobicity to woven nylon 6,6 fabrics. The proposed mechanism involves thermal treatment after exposure to pentanoic acid to create carboxylate-rich surface sites, followed by electrostatic association of octadecylamine to form a non-polar monolayer. Process conditions were optimized by varying heating time, temperature, and pentanoic acid soaking time. Pristine nylon showed a water contact angle of 60.6°, whereas the fully coated fabric had a water contact angle of 118.8°. ATR-FTIR (Attenuated Total Reflectance Fourier Transform Infrared), FESEM (Field Emission Scanning Electron Microscope), and XPS (X-ray Photoelectron Spectroscopy) demonstrated successful coating on the nylon surface. Weight and color analysis indicated near-surface alkyl enrichment with minimal visible change to the fabric. The short-term durability has been confirmed by measuring water contact angle after aging and laundry cycles. These results present a simple fluorine-free strategy for producing hydrophobic nylon 6,6 textiles.