Sweet whey permeates, a lactose rich byproduct of whey protein manufacture, is currently underutilized; in the United States about 20% incorporated into food products, while most is fed to animals or discarded despite elevated biological oxygen demand BOD (35–50 g/L) and chemical oxygen demand COD (60–80 g/L). We evaluated liquefied dimethyl ether (L‑DME) drying against freeze drying for sweet whey permeate powder production. A two‑step L‑DME process (pre‑concentration, powder formation) was tested at 180–270 min (6–9 washes), with freeze drying (72 h) as control. One way ANOVA with Tukey’s post hoc (p<0.05) evaluated extraction efficiency, yield, moisture, and composition (minerals, protein, sugars, organic acids).At ambient temperature and pressure of about 70 psi, L‑DME removed 92.3% water and achieved 85.6% powder yield at 270 min, while retaining 99% lactose (74–75 g/L) as solids, and extracted circa 80% chloride into the aqueous fraction, lowering the pH of the extracted liquid from 6.7 to 3.4–3.7. Compared with freeze drying, extended L‑DME exposure increased yield and lowered moisture; significant differences (p<0.05) were found for moisture, minerals, lactose, and protein. Morphologically, L‑DME powders were crystalline, whereas freeze‑dried powders were spherical.L‑DME enables rapid, low‑energy, low‑pressure, non‑thermal SWPP production while improving water quality, offering a practical option for alternative method for powder production. Although demonstrated in batch process at laboratory scale, the approach shows promise for continuous processing and industrial deployment. Future work will optimize solvent recovery, continuous flow operation, and techno‑economic and life cycle performance relative to evaporation and spray drying.

Large-scale olefin separations from unreacted paraffins and other byproduct gases are primarily done by energy-intensive cryogenic distillation processes at refineries. Silver(I) supported liquid membranes (Ag SLMs) can be implemented at smaller production scales of ethylene (C2H4), a critical industrial chemical, such as its electrocatalytic (EC) production from CO2. Challenges of EC C2H4 production mainly stem from reducing gases like hydrogen (H2), where the redox reactions pertinent to Ag(I) facilitators diminish olefin transport. Herein we report that aqueous Ag(I) solution in a composite Ag SLM can operate in mixed-gas conditions containing H2 gas utilizing reduced titania compounds, such as titanium(III) oxide (Ti2O3). Embedding Ti2O3 in the polydimethylsiloxane layer of Ag SLM assisted in selectively separating C2H4 from mixed-gas feed streams related to CO2 electrolysis containing H2. The direct exposure of a mixed-gas stream containing C2H4, CO2, CO, N2, and CH4 with as high as 50 vol % H2 maintained excellent C2H4 separations for 7 days of continuous operation. The Ag SLM provided effective separations of C2H4 from CO (at detection limits), CH4 (selectivity ratio (alpha) = 20-30), and H2 (alpha = similar to 20), but C2H4 from CO2 (alpha = 2-4) revealed a slightly lower separation. These data show that aqueous Ag(I) solution(s) used in the SLMs can separate C2H4 for extended periods, even under highly reducing gas conditions. Also, we report C2H4 recovery from the gas mixture produced in the EC CO2 reduction process. The Ag SLM gave C2H4 selective separation from a five-component complex mixed-gas stream, relevant to tandem CO2 electrolysis.

To advance dimethyl ether -driven fractional crystallization (DME-FC), a more sustainable method of water treatment and mineral recovery, a range of chemical equilibria were measured. These include varying concentrations of miscible organic solvents (MOS) used to experimentally measure the solvent -induced solid -liquid equilibrium (SLE) of calcium sulfate (CaSO4) in water. Seven MOS, including dimethyl ether (DME), acetonitrile (MeCN), 1,4-dioxane, tetrahydrofuran (THF), acetone, ethanol, and diethylamine, were screened to establish trends associated with molecular volume, functional groups, and physical properties. The effect of MOS on CaSO4 removal differed at concentrations <0.15 mol fraction MOS; MOS with greater molecular volume (THF, 1,4dioxane, and diethylamine) induced greater CaSO4 precipitation on a per mole basis. The solvent -induced SLE for all MOS converged between 0.15 and 0.2 mol fraction MOS, reaching a CaSO4 concentration consistent with a water to MOS hydration ratio of 5:1 to 6:1, which may correspond to the solvent generating a solution -based pseudo-clathrate structure with continuity within the solution. Solution pseudo-clathrate structures provide a mechanistic basis for DME-FC.

A molecular dynamics simulation model was developed to comprehensively understand carbon dioxide over nitrogen (CO2/N2) selectivity through polyphosphazene-based membrane comprising of poly[bis((methoxyethoxy)ethoxy)phosphazene] (MEEP) selective layer at the molecular level. The effects of temperature, pressure, and initial feed gas composition on the CO2 transport on a polymer membrane were studied. The computed free energy and density profile of the permeating gas mixture exhibited that CO2 molecules express higher interactions with the membrane than N2 molecules, resulting in higher CO2/N2 selectivity. Statistical analysis of gas molecules (CO2, water (H2O), and N2) transportation suggested that hydro- and CO2-philic functional groups in the membrane significantly impact CO2 permeability and CO2/N2 selectivity. This study suggested that Lewis acid-base and hydrogen bonding combinations contribute to CO2 permeation and CO2/N2 selectivity. An equal CO2/N2 selectivity was observed with and without water vapor in the feed gas suggesting that water does not hinder CO2 transport through the membrane.

ABSTRACT This research tested the treatment efficacy of an Energy Savings Nanofiltration 1 Low Fouling (ESNA 1-LF) nanofiltration (NF) and an Energy Saving Polyamide 2 (ESPA2) reverse osmosis (RO) membrane for removing malathion from water. Both membranes are of composite polyamide construction. The study included measuring malathion rejection using both pristine membranes and membranes exposed to a simulated secondary wastewater effluent foulant before and after two types of clean-in-place procedures. Across all conditions studied, malathion rejection ranged from 84 to 95% for the ESNA1-LF NF membrane and 77 to 94% for the ESPA2 RO membrane. Contact angle measurements were also collected for each membrane exposure condition. While the contact angle measurements indicated changes to the hydrophobicity of the selective layer of the membranes, they did not correlate to changes in the performance of malathion rejection. As expected, it was observed that malathion rejection improved with the introduction of foulant. Also, the clean-in-place procedures helped restore flux while maintaining malathion rejection.

Rising carbon dioxide (CO2) levels in the atmosphere lead to global warming, causing climate change. As such, carbon capture has become necessary to slow the increase and reduce CO2 levels in the atmosphere. Point source emissions have a wide range of CO2 concentrations, but emissions below 3% CO2 have mostly been ignored because Carbon capture from these sources has been viewed as costly and economically unsustainable. Membrane technologies are considered the most viable solution by virtue of more energy-efficient operation. Our group at Idaho National Laboratory (INL) has developed poly[bis((2-methoxyethoxy)ethoxy)phosphazene] (MEEP)-based carbon dioxide selective membranes with CO2/N2 selectivity greater than 40 and CO2 permeability greater than 450 Barrer. To understand the economics of carbon capture, a spreadsheet-based technoeconomic analysis (TEA) model was developed to consider multiple parameters, including selectivity and permeability of the membranes, performance conditions such as the number of stages, module material, electricity price, membrane price, and capital financing. The cost of carbon capture in US$/metric ton was calculated at various purities and compared with other membrane processes, cryogenic capture, solvent-based capture, and pressure swing adsorption-based capture. It was determined that a MEEP-based three-stage process had a capture cost of US$ 50.1/metric ton for 99.8% purity CO2 from a 1% CO2 feed source in nitrogen (N2). The capture cost using the best performing Pebax-based membrane was 464% higher, cryogenic capture was 60%-140% higher, pressure swing adsorption was 55%-165% higher, and chemical absorption was - 10%-110% higher than MEEPbased membrane capture, respectively.

Thin solid oxide films are crucial for developing high-performance solid oxide-based electrochemical devices aimed at decarbonizing the global energy system. Among various methods, ultrasonic spray coating (USC) can provide the throughput, scalability, quality consistency, roll-to-roll compatibility, and low material waste necessary for scalable production of large-sized solid oxide electrochemical cells. However, due to the large number of USC parameters, systematic parameter optimization is required to ensure optimal settings. However, the optimizations in previous literature are either not discussed or not systematic, facile, and practical for scalable production of thin oxide films. In this regard, we propose an USC optimization process assisted with mathematical models. Using this method, we obtained optimal settings for producing high-quality, uniform 4 × 4 cm2 oxygen electrode films with a consistent thickness of ∼27 μm in 1 min in a facile and systematic way. The quality of the films is evaluated at both micrometer and centimeter scales and meets desirable thickness and uniformity criteria. To validate the performance of USC-fabricated electrolytes and oxygen electrodes, we employ protonic ceramic electrochemical cells, which achieve a peak power density of 0.88 W cm-2 in the fuel cell mode and a current density of 1.36 A cm-2 at 1.3 V in the electrolysis mode, with minimal degradation over a period of 200 h. These results demonstrate the potential of USC as a promising technology for scalable production of large-sized solid oxide electrochemical cells.

As primary feedstocks deplete across the world, raw material extraction becomes increasingly expensive. Awareness of the environmental impact of primary extraction has motivated the development of energy- and reagent-efficient methods for material reuse. This work confronts an emblematic challenge of modern recycling: the soiled pizza box. While the fibers constituting corrugated cardboard are generally recyclable, pizza contaminants such as sauces and oils complicate their reuse, resulting in municipal prohibitions on the recycling of used pizza boxes in cardboard recycling streams and a representative of 275 kg/year per US household of food waste that is directed to landfill. This challenge is common to many materials, and engineering strategies must be developed to tackle complex/mixed feedstocks. To address the mixed composition of the pizza box (and similar materials), an environmentally benign, non-toxic organic solvent is applied to remove and fractionate components from mixed materials. The solvent employed in this process, dimethyl ether (DME), is a condensable hygroscopic gas, which facilitates its removal and recovery for reuse. The results of this study indicate that 1) DME is capable of solubilizing and extracting components from soiled cardboard and other materials, (resulting in cardboard drier than new/unused cardboard) facilitating its recycling, and 2) the DME-soluble components of the system phase separate into aqueous and fatty acid/oil fractions (potentially similar to 27.5 kg/year per US household). Condensable solvent-driven washing and extraction enable the efficient separation of multiple intermediate product streams, suggesting a pathway to enable technology development necessary for achieving clean production in a circular economy.

Carbon capture has been an important topic of the twenty-first century because of the elevating carbon dioxide (CO2) levels in the atmosphere. CO2 in the atmosphere is above 420 parts per million (ppm) as of 2022, 70 ppm higher than 50 years ago. Carbon capture research and development has mostly been centered around higher concentration flue gas streams. For example, flue gas streams from steel and cement industries have been largely ignored due to lower associated CO2 concentrations and higher capture and processing costs. Capture technologies such as solvent-based, adsorption-based, cryogenic distillation, and pressure-swing adsorption are under research, but many suffer from higher costs and life cycle impacts. Membrane-based capture processes are considered cost-effective and environmentally friendly alternatives. Over the past three decades, our research group at Idaho National Laboratory has led the development of several polyphosphazene polymer chemistries and has demonstrated their selectivity for CO2 over nitrogen (N-2). Poly[bis((2-methoxyethoxy)ethoxy)phosphazene] (MEEP) has shown the highest selectivity. A comprehensive life cycle assessment (LCA) was performed to determine the life cycle feasibility of the MEEP polymer material compared to other CO2-selective membranes and separation processes. The MEEP-based membrane processes emit at least 42% less equivalent CO2 than Pebax-based membrane processes. Similarly, MEEP-based membrane processes produce 34-72% less CO2 than conventional separation processes. In all studied categories, MEEP-based membranes report lower emissions than Pebax-based membranes and conventional separation processes.

Waste plastic presently accumulates in landfills or the environment. While natural microbial metabolisms can degrade plastic polymers, biodegradation of plastic is very slow. This study demonstrates that chemical deconstruction of polyethylene terephthalate (PET) with ammonium hydroxide can replace the rate limiting step (depolymerization) and by producing plastic-derived terephthalic acid and terephthalic acid monoamide. The deconstructed PET (DCPET) is neutralized with phosphoric acid prior to bioprocessing, resulting in a product containing biologically accessible nitrogen and phosphorus from the process reactants. Three microbial consortia obtained from compost and sediment degraded DCPET in ultrapure water and scavenged river water without addition of nutrients. No statistically significant difference was observed in growth rate compared to communities grown on DCPET in minimal culture medium. The consortia were dominated by Rhodococcus spp., Hydrogenophaga spp., and many lower abundance genera. All taxa were related to species known to degrade aromatic compounds. Microbial consortia are known to confer flexibility in processing diverse substrates. To highlight this, we also demonstrate that two microbial consortia can grow on similarly deconstructed polyesters, polyamides, and polyurethanes in water instead of medium. Our findings suggest that microbial communities may enable flexible bioprocessing of mixed plastic wastes when coupled with chemical deconstruction.

Protonic ceramic electrochemical cells (PCECs) offer promising paths for energy storage and conversion. Despite considerable achievements made, PCECs still face challenges such as physiochemical compatibility between componenets and suboptimal solid-solid contact at the interfaces between the electrolytes and electrodes. In this study, a novel approach is proposed that combines in situ electrochemical characterization of interfacial electrical sensor embedded PCECs and machine learning to quantify the contributions of different cell components to total degradation, as well as to predict the remaining useful life. The experimental results suggest that the overpotential induced by the oxygen electrode is 48% less than that of oxygen electrode/electrolyte interfacial contact for up to 1171 h. The data-driven machine learning simulation predicts the RUL of up to 2132 h. The root cause of degradation is overpotential increase induced by oxygen electrode, which accounts for 82.9% of total cell degradation. The success of the failure diagnostic model is demonstrated by its consistency with degradation modes that do not manifest in electrolysis fade during early real operations. This synergistic approach provides valuable insights into practical failure diagnosis of PCECs and has the potential to revolutionize their development by enabling improved performance prediction and material selection for enhanced durability and efficiency.

Solvent-driven water extraction (SDWE) has promising applications in hypersaline brine desalination, including zero-liquid discharge processing for industrial wastewaters, and resource recovery, such as the extraction of lithium and rare earth elements from solution mining leachates. In this study, we develop a computational thermodynamic framework to analyze the liquid–liquid extraction of water from hypersaline brines using dimethyl ether (DME), an aprotic solvent that is partially miscible with water. The high volatility of DME enables its rapid separation from water–DME mixtures after water absorption, while its low polarity minimizes the organic-phase solubility of electrolytes, such as sodium chloride (NaCl). We first build a thermodynamic model based on the LIQUAC excess Gibbs free energy model for water–DME–NaCl mixtures. Maximum likelihood estimators for water–DME–NaCl interaction parameters are calculated through the nonlinear regression of fluid phase equilibrium and osmotic coefficient data using metaheuristic global optimization techniques. A multistage counter-current liquid–liquid separator (LLS) model is then developed to explore the water recovery and brine concentration ratios achievable as a function of feed molality and DME to feed water flow rate ratio. For a saline feed with a molality of 2.0molkg−1 (over three times the salinity of seawater) our analysis demonstrates that a one-stage LLS can achieve a water recovery ratio of 0.51 with an initial DME to saline feed molar flow rate ratio of 4.0, rising to 0.63 with a second equilibrium stage. We conclude by quantifying the amount of DME required to reach zero-liquid discharge brine salinities and analyzing the impact of staging and temperature on separation performance. Our thermodynamic model enables the rapid evaluation of SDWE systems for emerging hypersaline brine desalination and valorization applications.

This work reports a dimethyl ether-driven fractional crystallization process for separating rare earth elements and transition metals. The process has been successfully applied in the treatment of rare earth element-bearing permanent magnet leachates as an atom-efficient, reagent-free separation method. Using ~5 bar pressure, the solvent was dissolved into the aqueous system to displace the contained metal salts as solid precipitates. Treatments at distinct temperatures ranging from 20–31 °C enable crystallization of either lanthanide-rich or transition metal-rich products, with single-stage solute recovery of up to 95.9% and a separation factor as high as 704. Separation factors increase with solution purity, suggesting feasibility for eco-friendly solution treatments in series and parallel to purify aqueous material streams. Staged treatments are demonstrated as capable of further improving the separation factor and purity of crystallized products. Upon completion of a crystallization, the solvent can be recovered with high efficiency at ambient pressure. This separation process involves low energy and reagent requirements and does not contribute to waste generation.

Renewable organic precursors, including olefinic compounds such as isoprene, have attracted interest from the polymer and pharmaceutical industries. Biologically-derived processes can generate these target compounds; however, their gaseous product streams are complex mixtures of condensable organic vapors (COVs), water vapor, carbon dioxide (CO2), and/or nitrogen (N-2). Because COVs, CO2 and water vapor are known to alter polymer membranes, mixed gas separations data at ambient and elevated temperatures are limited. This study focused on two classes of polymer membranes, glassy [polyetherimide (Ultem (R))] and a rubbery [polydimethylsiloxane (PDMS)] with results indicating that isoprene separation is possible in humidified gas environment (2-4 vol% water). Gas permeabilities of these membranes did not noticeably change in the presence of humidity; however, the selectivity of these membranes was significantly lower compared to their performance under dry conditions. The role of water vapor in gas transport was derived from the energy of activation of permeation (E-p) for PDMS and Ultem (R) from 30-80 degrees C in humidified mixed gas streams. For both polymers, E-p data shows a slight decrease in selectivity with the other gases (hydrogen, N-2, CO2, and methane) at elevated temperatures in the presence of water vapor. Thus, these COVs separations are feasible with polymer membranes in the presence of humidified gas streams, even in the case of glassy and rubbery membranes in series.

Polyphosphazenes gain much of their physical and chemical properties from the substituents attached to the phosphorus atoms in the backbone. Poly(phosphazenes) that have short-chain polyether containing substituents, such as, 2-(2-methoxyethoxy)ethanol, have high CO2 permeability and selectivity over N-2 as well as resistance to degradation under humidification at 60 degrees C. However, the principal shortcomings of this polymer are the poor mechanical and surface characteristics. Blending of an example of this polyphosphazene (MEEP-80) with poly(bis-phenoxyphosphazene) (PPOP) has yielded more durable materials that have a non-adhesive surface. In this work, the blended polymer membranes were found to have increased CO2 permeability with higher selectivity over N-2. Thermal analysis and the application of transport models support a structure of the blends that is not either an intimate blend or phase separated bulk structure, but one where PPOP domains retain their crystallinity and are dispersed within an amorphous MEEP-80 phase.