This study evaluates the long-term operational performance of a full-scale reverse osmosis desalination plant treating highly mineralized water under real industrial operating conditions. Unlike conventional laboratory or pilot-scale investigations, the analysis is based on four years of operational data (2020–2024), providing a representative assessment of membrane system behavior under variable environmental and hydraulic conditions. Statistical analyses including descriptive statistics, time-series analysis, Pearson correlation, and inter-annual comparisons were performed using Python-based data-processing tools. An Operational Stability Index was also introduced to quantify process consistency over time. The results demonstrate stable desalination performance, with salt rejection exceeding 90%. Operational monitoring indicated effective pretreatment conditions, low SDI values, and controlled membrane fouling under long-term operation. Differential pressure evolution and cleaning-in-place performance further confirmed the effectiveness of the implemented fouling mitigation strategy. Membrane autopsy investigations revealed the coexistence of biological fouling, silica scaling, and localized oxidative degradation, highlighting the importance of integrated pretreatment and operational control. The findings demonstrate the value of long-term industrial monitoring for understanding membrane performance, fouling behavior, and operational stability in full-scale RO systems. This approach supports data-driven operational optimization and may contribute to the future development of predictive monitoring and intelligent desalination-management frameworks as a Digital Twin.
Herein, vinylbenzyl chloride (VBC)-grafted styrene-butadiene (SB) copolymers, with high contents of VBC (22–32 mol%), were synthesized and blended with low amounts (n = 3–10 wt%) of unfunctionalized poly(phenylene oxide) (PPO). Being well-known for its great chemical compatibility with polystyrene, PPO was selected as non-conductive, hydrophobic and mechanically robust component to be blended with graft copolymers in order to reduce their water uptake, thus improving their dimensional and mechanical stability after quaternization with trimethylamine. The resulting blend membranes were characterized in terms of thermal, mechanical, and ex situ electrochemical properties. Blend membranes generally presented improved mechanical properties, as well as reduced water uptake with respect to AEMs not containing PPO, while retaining ion conductivity values of 11.3–16.6 mS cm−1, higher than that of a commercial hydrocarbon-based benchmark. Among the investigated blend AEMs, g-VBC-32/PPOn membranes were found to have the highest conductivity values (>15 mS cm−1) and the best trade-off between water uptake, mechanical properties and hydrogen permeability. Overall, these results highlight pristine PPO blending as a cost-effective, simple and scalable route to improve the mechanical and dimensional stability of hydrocarbon-based AEMs.
Redox flow batteries (RFBs) are an interesting option for long-term energy storage. A well-performing membrane sits at the heart of the electrochemical battery cell and should effectively mitigate crossover of active species while minimizing resistance. However, current commercial membranes are rather expensive and demonstrate sub-optimal performance, leading to an extensive search for alternatives. Research on membranes for RFBs has long been dominated by dense ion-exchange membranes and porous membranes, both potentially with fillers. In recent years, increased interest in alternative morphologies such as thin-film composites (TFCs) has ignited new research directions. TFCs consist of a thin dense layer on top of a porous support, aiming to merge the advantages of both. Traditionally, TFCs are made using polyamide top layers. In this paper, a novel chemistry is developed with increased chemical stability for RFBs. Poly(vinylbenzyl chloride) is crosslinked interfacially with a diamine, demonstrating for the first time the potential of support-mediated interfacial crosslinking with two immiscible solvents. Optimization of the support, amine crosslinker, reaction time and synthesis procedure allowed a shift of the trade-off between vanadium crossover and proton transport, highlighting the opportunities for this promising TFC chemistry.
Upgrading biogas to pipeline-quality methane requires the efficient removal of CO2, yet conventional physicochemical routes remain energy-intensive. Coupling a CO2-selective membrane with microalgal photosynthetic fixation offers a green alternative, but is constrained by the low CO2/CH4 selectivity of common membranes and the poor adhesion of microalgae to hydrophobic membrane surfaces. Here, a dual-functional composite membrane was developed that simultaneously provides CO2/CH4 sieving and a biocompatible interface for microalgal attachment, and was integrated into a microalgae membrane bioreactor (MMBR). A cellulose acetate mixed-matrix membrane incorporating polyethyleneimine-grafted ZIF-8 (CA/PZIF-8(15)) achieved a mixed-gas CO2 permeability of 122.3 Barrer and a CO2/CH4 selectivity of 41.17. An ionic-liquid-modified chitosan (CS/IL) coating, first optimized on a commercial flat-sheet polyethersulfone (PES) membrane used as a model surface for the adhesion study, reversed the surface charge from −30.8 to +3.75 mV, lowered the water contact angle to 51.2°, and increased the day-7 adhesion of Scenedesmus obliquus by ~108%. Transferring the coating onto CA/PZIF-8(15) further raised the permeability to 138 Barrer and the selectivity to 57.31, placing the composite above the 2008 Robeson upper bound. In the MMBR, CH4 purity reached 95.13% after 48 h; a mass balance on the recirculating gas volume indicated that essentially all of the CO2 removed from the gas phase permeated the membrane, of which an estimated 2% was fixed into microalgal biomass while the remainder was retained in the liquid phase. This work offers a membrane-design strategy that bridges gas-separation functionality and microalgal carbon fixation for sustainable biogas upgrading.
Oily wastewater commonly contains dissolved organic contaminants such as dyes, antibiotics, and phenolic compounds. Conventional stepwise treatment processes involve complex operation, high energy consumption, and severe membrane fouling. Multifunctional membranes integrating oil/water separation, pollutant adsorption or catalytic degradation, and membrane self-cleaning provide a promising solution for treating complex oily wastewater. This review summarizes recent advances in multifunctional membranes based on metal oxides, two-dimensional (2D) materials, three-dimensional (3D) porous structures, and biomass-derived materials. Key strategies, including micro and nanoscale structure regulation, wettability control, interlayer channel optimization, heterojunction construction, and active site engineering, are discussed together with the synergistic mechanisms involving oil/water separation, adsorption enrichment, photocatalysis, and Fenton reactions. Approaches for improving membrane flux, separation efficiency, degradation activity, antifouling performance, and cycling stability are also reviewed. Finally, challenges related to scalable fabrication, adaptability to real wastewater, long-term stability, and standardized evaluation are outlined, providing guidance for the design and practical application of multifunctional membranes.
This study investigates polymer/ionic liquid/polymer trilayer membranes for recovering aroma and fragrance compounds from a simplified synthetic model aqueous solution via pervaporation. The membranes featured organophilic polymer layers (PEBA and POMS) sandwiching an intermediate ionic liquid (IL) layer ([P1444][Tf2N] and [Bmim][Tf2N]), which were gelled with 12-hydroxystearic acid to ensure structural integrity. The trilayer architecture significantly enhanced separation performance compared with monophase membranes. The PEBA/[P1444][Tf2N]/PEBA configuration achieved the highest enrichment factors, reaching 1626 for hexanal and 963 for linalool. Meanwhile, the POMS/[P1444][Tf2N]/POMS system exhibited the highest selectivity relative to water. The introduction of the IL gel layer reduced overall mass transfer resistance while simultaneously suppressing water flux from 0.312 kg h−1 m−2 (in pure PEBA) to between 0.013 and 0.023 kg h−1 m−2. Overall, the results demonstrate that combining polymer matrices with gelled ILs in a trilayer design effectively optimizes mass transfer and selectivity, offering a promising strategy for the future valorization of aroma compounds from agro-industrial aqueous streams.
Diffusion against a concentration gradient, also called uphill transport, has been reported for magnesium and sulfate ions in solutions of NaCl and MgSO4 in reverse electrodialysis (RED). Here we derive transport equations for such systems and explain the observed uphill transport using non-equilibrium thermodynamics (NET). A set of Nernst–Planck equations was reformulated into a set of flux equations with neutral salt driving forces. By applying the condition of entropy production invariance to the sets of variables, we show how an ideal ion selectivity model provides Onsager coupling coefficients for the ion transport. These coupling coefficients can predict and explain the observed uphill transport of magnesium and sulfate. A linear fitting scheme is developed to fit the transport coefficients to experimental data for the ideal ion selectivity model and for a more general model. The results show that even the simplest ideal ion selectivity model captures the uphill transport, and the phenomenon occurs due to diffusional ion exchange, as in Donnan dialysis. Under open-circuit conditions, deviations are large, and the simplest model is no longer sufficient; co-ion leakage corrections are essential. The results provide a basis for future modelling of RED processes; in particular, one can determine and optimise the process efficiency, as the model gives direct access to the process’s local entropy production. Osmosis is identified as a potential source of error.
The lipid and fatty acid composition of the little Baikal oilfish (Comephorus dybowskii Korotneff, 1905) was studied to identify the features of its biochemical adaptation to the environmental conditions of Lake Baikal. Multivariate analysis of lipid classes and FA profiles revealed reproducible clustering patterns in both muscle tissue and whole-body samples, indicating the presence of distinct physiological states differing in membrane organization and lipid metabolism. Lipid-class variability was primarily associated with sphingomyelin, cholesterol esters, phosphatidylinositol, and lysophosphatidylcholine, suggesting the coordinated regulation of membrane structure. The fatty-acid profiles were mainly presented by variations in saturated, monounsaturated, and long-chain polyunsaturated fatty acids, with muscle tissues characterized by a relatively longer carbon chain (ACL = 19 vs. 18 I whole body) and unsaturation (UI = 1.98–2.76 vs. 1.64–2.53 in whole body). At the same time, comparative analysis demonstrated low correspondence between lipid and FA profiles, indicating partially independent adaptive mechanisms. The experimental transfer of fish from their natural habitat to controlled conditions resulted in the significant remodeling of both lipid and FA compositions, including increases in acylglycerols, membrane phospholipids, and monounsaturated fatty acids, together with a decline in long-chain n-3 polyunsaturated fatty acids. The results suggest that lipid classes and fatty acids represent complementary but functionally distinct levels of biochemical adaptation contributing to the maintenance of membrane organization and metabolic homeostasis in C. dybowskii, revealing a previously undescribed multi-level organization of lipid-related adaptive responses in this endemic deep-water fish.
Extracting lithium from salt-lake brines boasts distinct advantages including low production cost, low energy consumption and low environmental risks, and will serve as a primary supply source of lithium salts in the future. This trend raises higher demands for the efficiency and cost-effectiveness of lithium extraction technologies. Nanofiltration (NF) membranes, renowned for their superior discrimination between monovalent and divalent ions, have been extensively utilized to obtain Li+ from Mg2+-rich saline brines. In this study, positively charged NF membranes aimed at Li+/Mg2+ fractionation were fabricated via surfactant-interlayer-assisted interfacial polymerization (SIAIP). Catechol (CA) and polyethyleneimine (PEI) were utilized to construct the CA/PEI interlayer, and oil-phase dodecyl phosphate (DDP) was used as an additive for interfacial polymerization (IP). The strongly bonded CA/PEI nanoaggregates improved interlayer stability and preserved the positive charge of the double-layer membrane. DDP adsorbed piperazine (PIP) at the two-phase interface through electrostatic interactions, accelerating PIP diffusion and forming a thick polyamide (PA) layer with uniform pores. The combination of CA/PEI interlayer and DDP synergistically enhanced size-sieving and Donnan effects. With MgCl2 and LiCl rejections of 97.9% and 36.2% respectively, the optimized membrane shows superior selectivity for Li+ over Mg2+. Moreover, the membrane exhibited weak electrostatic screening and concentration polarization, showing excellent operational stability under varied Mg2+-Li+ ratios and feed concentrations.
Rare earth elements (REEs) are critical for advanced manufacturing and clean energy, yet their separation remains extremely challenging due to the nearly identical ionic radii of adjacent lanthanides. Conventional solvent extraction, ion exchange, and precipitation methods are limited by their high reagent consumption, slow kinetics, poor selectivity, and environmental burdens. Nanofiltration (NF) offers a green and efficient alternative—operating in the aqueous phase with low energy demand and continuous high throughput. This review systematically summarizes NF-based REE separation. We first elucidate the fundamental mechanisms (size exclusion, Donnan exclusion, dielectric exclusion, and complexation enhancement), and discuss how lanthanide hydration chemistry underpins these synergistic effects. Membrane materials, from commercial to biomimetic, are critically surveyed, with an emphasis on strategies to overcome the trade-off between permeability and selectivity. The impacts of operating conditions and solution chemistry are analyzed, and NF applications ranging from single REE systems to real leachates are assessed. A comparative evaluation positions NF against conventional technologies. Key challenges remain: poor adjacent REE selectivity, membrane fouling, performance loss at high salinity, chemical instability, and a gap between model and real feeds. Future directions include designing high-selectivity membranes, integrating machine learning optimization, establishing standardized protocols, and realizing closed-loop process integration.
NAR2 family proteins are involved in the uptake of nitrate by plant roots as partners of high-affinity nitrate transporters of NRT2 family. In this study, we cloned the coding sequence of a gene, which encodes a protein consisting of 196 amino acids with a calculated molecular weight of 21.7 kDa, from the euhalophyte Suaeda altissima. The protein was characterized in terms of structure and phylogeny. On the phylogenetic tree of NAR2 family proteins, the protein from S. altissima is located in a clade with proteins from the NAR2.2 subfamily found in species within the Amaranthaceae. Therefore, on the basis of phylogenetic relationships, we named it SaNAR2.2. According to a prediction of cellular localization and protein topology, SaNAR2.2 is a likely resident of the plasma membrane. We detected the interaction between SaNAR2.2 and putative partner proteins SaNRT2.1 and SaNRT2.5, which are members of the high-affinity nitrate transporter family NRT2 in S. altissima, using the bimolecular fluorescence complementation (BiFC) assay in Nicotiana benthamiana leaves and the yeast mating-based split-ubiquitin system (mbSUS). SaNAR2.2 was expressed predominantly in roots of S. altissima. The level of SaNAR2.2 transcripts significantly increases at low nitrate concentrations in the medium at the background of high NaCl concentrations (up to 0.5 M). These findings point to the important role of SaNAR2.2 as a participant in the high-affinity nitrate transport system under saline conditions.
Polyamide nanofiltration (NF) membranes offer a scalable and energy-efficient pathway for lithium concentration from lake brines and battery leachates, but practical implementation hinges on achieving high selectivity of Li+ over Mg2+. The active layer of these membranes can be positively or negatively charged, carrying both amine groups that can be protonated and carboxyl groups that can be deprotonated with an ionization state that is set by the feed pH. Here, molecular dynamics simulations are used to elucidate how pH-dependent charged functional groups within the polymeric nanostructure of NF membranes govern Li+/Mg2+ selectivity, arising from electrostatic charge interactions between ions and functional groups at the molecular scale as well as steric size exclusion within the membrane pore structure. Although single-salt Li+ or Mg2+ feed solutions exhibit similar ion penetration behavior, mixed Li+/Mg2+ feeds show markedly enhanced Li+/Mg2+ selectivity at low concentrations when the membrane is positively charged. This selectivity arises because Mg2+ interacts more strongly than Li+ with repulsive protonated amine (NH2+) groups, suppressing divalent ion transport, an effect that emerges specifically when the two cations compete for the same Cl− ions in a mixed feed. In contrast, for negatively charged membranes, attractive interactions with deprotonated carboxylate (COO−) groups strongly hinder the transport of both ions, resulting in poor selectivity. Ion clustering within membrane pores further reduces transport through steric effects. These results provide molecular-level insight into how charged functional groups control mono/divalent ion selectivity when competing ions are present and highlight positively charged membranes as optimal platforms for lithium separation applications.
The lack of freshwater in the world requires a paradigm shift from linear water consumption to resilient and low-energy desalination technologies. Although reverse osmosis (RO) is the standard in the industry, its usefulness is essentially constrained by concentration polarization (CP) and non-useful hydraulic pressure losses. This paper applies a high-fidelity computational model in ANSYS Fluent 2022 R1 to conduct a comparative parametric evaluation of hexagonal and sinusoidal feed-spacer geometries relative to a baseline grid configuration. The solute concentration gradients at the fluid–membrane interface were solved using a 3D species transport model, which was optimized using one-micron near-wall inflation layers. The hexagonal configuration produced the lowest maximum membrane-surface salt mass fraction, decreasing it from 0.1127 kg/kg for the baseline grid to 0.0429 kg/kg, corresponding to a 61.9% reduction. Although the hexagonal design required an inlet pressure of 205.7 Pa, it produced a more favorable normalized mass-transfer–friction trade-off than the sinusoidal configuration (447.8 Pa), with a System Performance Index (η) of 2.53. These results demonstrate comparative micro-scale improvements in concentration polarization control and hydraulic performance under the simulated conditions. Experimental testing and system-level modeling are required before conclusions can be drawn regarding full-module energy consumption, photovoltaic integration, long-term fouling behavior, or economic feasibility. This study is consistent with the emerging Concepts and design for sustainability, whereby a circular and energy-efficient water economy is facilitated through an innovative mechanical design.
To overcome the limitations of insufficient driving force in traditional microbial desalination batteries, this paper constructs a microbial anode-membrane capacitive deionization (B-MCDI) coupling system. For the first time, direct coupling between extracellular electron transfer in Shewanella oneidensis and double-layer adsorption at the MCDI cathode is achieved at the circuit and material levels, realizing self-driven, low-energy desalination. High-specific-surface-area carbon felt is used as the anode, and a stable electrogenic biomembrane (output voltage >400 mV) is formed after directional domestication with Shewanella oneidensis MR-1. Activated carbon is used as the cathode to construct the MCDI electrode. In the three-chamber reactor, the desalination chambers are separated by cation and anion exchange membranes. Under the drive of the bioelectric field, Na+ and Cl− selectively permeate into the cathode and anode chambers, respectively, effectively suppressing the co-ion effect. Under optimal operating conditions (external resistance 1000 Ω, initial NaCl concentration 2.0 g/L), the system achieved a cumulative desalination rate of 85.1% after 12 h of operation, with a salt adsorption capacity of 162.1 mg/g, an average desalination rate of 13.51 mg/(g·h), and an energy consumption of only 0.58 kWh/m3. This demonstrates that bioelectric energy can effectively provide targeted power to drive capacitive adsorption and desalination. Under initial NaCl concentrations of 1.0 g/L and 3.0 g/L, the highest desalination rates reached 78% and 68%, respectively. The maximum instantaneous desalination rate occurred within 0.5–1.0 h (64 mg/h under 2.0 g/L conditions), exhibiting a three-stage kinetic characteristic of “fast-slow-equilibrium”. The energy consumption in this study was only 0.51 kWh/m3, further demonstrating the high energy efficiency of bioelectrically coupled MCDI in low-salinity treatment areas. Therefore, this B-MCDI can serve as a theoretically feasible proof-of-concept technology for desalination of brackish water that meets the requirements of self-driven, low-energy consumption, and has promising applications in decentralized water supply systems in areas with limited energy supply or no available electricity.
The membrane dipole potential (Ψd) is a critical modulator of ion transport and protein function, making the ability to accurately predict its modifications essential for rational drug design and membrane biophysics. While molecular dynamics (MD) simulations offer a powerful alternative to challenging in vitro experiments, their predictive accuracy is often hampered by sensitivities to simulation setups and force field parameterization. In this study, we provide a systematic evaluation of how system composition, box size, water models, and small-molecule parameterization protocols influence the calculated membrane potential. Using the CHARMM36m and AMBER (Lipid21) force fields, we demonstrate that CHARMM is notably more sensitive to box composition and finite-size effects than AMBER. We further show that the ~100 mV shift induced by 4-site water models is purely systematic; therefore, computationally efficient 3-site models remain reliable for predicting relative potential changes. Finally, we compare multiple parameterization strategies for three Ψd-modifying flavonoids (baicalein, chrysin, luteolin) and show that standard CGenFF protocols fail to capture experimental trends, whereas ffTK-refinement and AMBER-based protocols (GAFF2 and Espaloma) significantly improve accuracy. Notably, the neural network-based Espaloma demonstrated surprisingly high predictive power, marking this approach as a promising, automated alternative for future studies. Our findings provide a set of practical recommendations for establishing reliable MD protocols to predict dipole potential modifications.
It is essential for quinoa’s rapid expansion in the global market to comply with the circular economy to become a green agro-food industry. For this purpose, in this work, bioactive added-value compounds, specifically saponins and phenolic antioxidants, were extracted and purified from quinoa by-products (QbP), namely hulls, using green solvent extraction (60 wt% ethanol-water) and nanofiltration (NF). So far, research published on the implementation of NF in the treatment of QbP, or modelization and optimization of the membrane performance focusing on fouling minimization and control, is scarce. Centrifugation and microfiltration were conducted as separation-purification pretreatments before NF. A three-level factorial design was successfully applied to optimize NF membrane operation in terms of saponins and phenolic compound recovery, as well as permeate flux, comprising operating pressure and tangential velocity as key input factors. Membrane fouling, critical for stable process operation scale-up, required intensive multifactorial analysis. Optimization at 4 bar and 15 m/s permitted the recovery of up to 84.5% saponins and 84.3% phenolic compounds in the permeate stream. Moreover, NF dynamic performance modeling and optimization ensured fouling build-up minimization and maximization of membrane productivity almost ten-fold, up to a stable value as high as 175.4 L/hm2, ensuring full recovery of the membrane performance after each operating cycle, key for the technical–economic viability of the proposed process to obtain standardized purified extract products.
Membrane technologies are a key technique in modern separation because of their flexibility and the intrinsic modularity of membrane processes, which can reduce energy consumption compared to conventional thermal separations and enable separations that are difficult to achieve with other processes [...]
Energy and exergy analyses were conducted on a triple-pass seawater reverse osmosis desalination system to evaluate thermodynamic performance and identify primary sources of irreversibility. A comprehensive simulation model, developed in IPSEpro (Version 7.0) and validated against manufacturer data, demonstrated strong agreement with the reported values. Exergetic efficiency of the reverse osmosis (RO) units increased across the passes, from 57% in the first pass to 80% and 78% in the second and third passes, respectively, while exergy destruction decreased correspondingly from approximately 375 kW in the first pass to 120 kW and 130 kW in the second and third passes. The pumping system, particularly the main high-pressure pump, was responsible for 49% of total exergy destruction, followed by the first RO unit at 23%. The impacts of feed water temperature, high-pressure pump pressure, and water recovery ratio (RC) on exergetic efficiency, specific energy consumption, and permeate flow rate were systematically assessed. Increasing the feed water temperature from 15 °C to 33 °C enhanced exergetic efficiency from 27.8% to 29.9% and reduced total exergy destruction from 1622 to 1582 kW, supporting the integration of hybrid RO-thermal desalination systems. The first-pass recovery ratio emerged as the most influential operational parameter overall, with exergetic efficiency rising from 25.1% to 33.7% as RC1 increased from 0.35 to 0.60. Analysis of the overall recovery ratio identified RC = 0.39 as a practical operating target that balances specific energy consumption of 4.05 kWh/m3 and exergy destruction of 1700 kW, offering the most favourable compromise between energy efficiency and thermodynamic performance. The results presented here provide practical guidance and recommendations for the optimization of the performance of large-scale multi-pass reverse osmosis seawater desalination plants.
The extensive use of plastics in everyday life has exerted a significant influence on the environment, with the release of micro- and nanoplastics posing even greater ecological threats. Plastic contamination, particularly in these smaller forms, has emerged as a pressing environmental concern due to its persistence, bioaccumulation, and potential hazards. Traditional treatment systems are generally ineffective at removing such micro- and nano-scale complex pollutants. Recently, micro- and nanofiber-based materials have emerged as promising candidates due to their large surface area, porous structure, and adjustable functionality, enabling efficient adsorption, filtration, and photocatalytic degradation. The term micro/nanofibers in this study encompasses both electrospun nanofibrous membranes and nanofiber-based functional layers or additives incorporated into pre-existing membrane structures for performance enhancement. The incorporation of photocatalysts enables these materials to promote photocatalytic oxidation, degrading plastics into smaller, less toxic compounds. This paper outlines recent progress in developing micro- and nanofiber systems for environmental remediation, highlighting their design approaches, removal mechanisms, and multifunctional capabilities. Ultimately, the discussion explores emerging directions, existing limitations, and future opportunities, highlighting how these advanced materials can contribute to sustainable and efficient pollution control strategies.
The emergence of biological membranes was a critical step in the origin of cellular life because compartmentalization enabled molecular concentration, selective interactions, and increasingly complex chemical evolution. While fatty acids are widely considered the primary constituents of primitive membranes, the origin of the hydrophilic molecular scaffolds required for more stable amphiphilic systems remains unresolved. In this review, we propose a new conceptual framework in which low-molecular-weight polyols—including ethylene glycol, glycerol, tetritols, and related sugar alcohols—served as key molecular intermediates linking abiotic carbohydrate chemistry with the emergence of proto-lipids and protomembranes during a pre-phosphate stage of Earth history. Experimental and theoretical studies indicate that abiotic carbon chemistry can generate abundant polyols capable of esterification, etherification, hydrogen bonding, and reversible complexation with borate species. We hypothesize that borate-mediated stabilization of sugars and polyols promoted molecular selection, while sulfur-rich geochemical environments supplied chemically diverse amphiphiles and redox-active reaction networks. Building upon these observations, we propose a pH-dependent evolutionary model in which acidic sulfur-rich environments favored sulfo-protolipids, near-neutral environments promoted mixed polyol–fatty acid membranes, and alkaline boron-rich systems facilitated borate-associated amphiphiles and dynamic supramolecular membrane organization. We further suggest that borate-cross-linked polyol hydrogels acted as transitional soft-matter systems connecting molecular synthesis, membrane self-assembly, compartmentalization, and the emergence of proto-informational assemblies. Modern glycolipids, sulfolipids, archaeal ether lipids, and calditol-containing tetraether membranes are discussed as structural analogues, rather than direct evolutionary descendants, supporting the chemical versatility of polyol-based membrane architectures. Although the proposed evolutionary framework remains hypothetical, it integrates current knowledge from prebiotic organic chemistry, membrane biophysics, boron coordination chemistry, sulfur geochemistry, and systems chemistry into a unified and experimentally testable model for the evolution of proto-lipids, protomembranes, and early protocellular organization.
