Chemical Separation Processes Research Articles

Vapor-liquid equilibria for the CO2 + trimethoxymethylsilane and CO2 + triethoxymethylsilane systems under high-pressure conditions

New binary isotherms are crucial for designing chemical separation processes within supercritical carbon dioxide (CO2) + trialkoxysilane systems. Vapor-liquid equilibria (VLE) were investigated for two-component systems, trimethoxymethylsilane + CO2 and triethoxymethylsilane + CO2, at five temperatures (313.2, 333.2, 353.2, 373.2, and 393.2 K) and pressures up to 14.07 MPa using a synthetic high-pressure phase equilibria apparatus. The pressure-temperature (P-T) plot indicates that the critical mixture curve lies between the critical points of CO2 and the trialkoxysilane compounds. The solubility of trimethoxymethylsilane and triethoxymethylsilane in CO2 increased with increasing temperature at constant pressure, following a type-I phase behavior characteristic. The experimentally observed VLE values of the CO2 + trialkoxysilane systems were correlated using the Peng-Robinson equation of state with binary parameters (kij and ηij) in the conventional mixing rule. The model accuracy was validated by calculating the average relative deviation percentage for the pressure of the binary systems, resulting in values of 4.98% for the trimethoxymethylsilane + CO2 system and 3.64% for the triethoxymethylsilane + CO2 system. The estimated variables fell within reasonable limits and showed no significant differences between the predicted and observed VLE data for both systems.

Green recycling of end-of-life photovoltaic modules via Deep-Eutectic solvents

Sustainable End-of-life (EOL) photovoltaic (PV) modules recycling is essential for achieving resource conservation and alleviating environmental issues. Ethylene vinyle acetate (EVA) adhesive films separation is a prerequisite for the realization of valuable component recovery of PV modules. However, the conventional wet chemical separation processes are usually accompanied by the challenges of low separation efficiency, high toxicity and difficult multiple recycling. Herein, a green, biodegradable, low-cost and recyclable deep eutectic solvent (DES) is firstly developed to efficiently separate EVA films in EOL PV modules. The high temperature stability and the acidic characteristic of DES can facilitate the separation of EVA film between component layers. At 175 ℃, the warping effect caused by the differential thermal contraction between the module component layers creates favorable conditions for the efficient reaction and separation by the DES. Additionally, the acidic medium reacts with the aluminum electrode layer of PV cells, which further enhances the separation efficiency of EVA films. The EVA separation rate reached 100%, the separation rate of the EVA containing aluminum (Al) up to 98.4% after 12.5 h at 175 ℃. Moreover, the developed DES exhibits excellent recyclable performance, the EVA separation rate remained 100% after 10 cycles. Compared to the traditional solvent toluene, DES has advantages in terms of economics, environmental impact, and efficiency. This strategy of design a green, biodegradable, low-cost and recyclable solvent to replace traditional solvents, and provides a promising route to efficiently separate EVA films in EOL PV modules.

Realization for rapid extraction of citric acid from aqueous solutions using deep eutectic solvents

Citric acid is highlighted as a valuable chemical in the pharmaceutical and food industries. We present an extraction technique using hydrophobic deep eutectic solvents (HDES), which has emerged as an efficient and sustainable alternative solvent for the purification and recovery of this important compound from the production environment. HDES systems were formed by combining DL-Menthol as the hydrogen bond donor (HBD) and Tributyl Phosphate (TBP) as the hydrogen bond acceptor (HBA). HDES exhibited excellent performance as a hydrophobic medium for both physical and reactive extraction of citric acid. To demonstrate the effect of HDES composition over-extraction ability, HDESs with various DL-Menthol mole fractions (Xm) were prepared and tested. TOA molar concentration, initial citric acid concentration (CA0), and effect of temperature were also investigated as other effective parameters. The optimized HDES demonstrated remarkable extraction efficiency (E%) of over 90% using tri-n-octylamine (TOA) as the extractant, while offering rapid extraction rates within minutes. Our findings highlight the promising potential of these environmentally conscious HDES for sustainable chemical separation processes.

Highly efficient dual-phase hydrogen-transporting membranes for NH3 decomposition coupling with CO2 reduction

Hydrogen-transporting membrane reactors play active roles in ammonia (NH3) decomposition and carbon dioxide (CO2) reduction by combining reaction and separation in one unit, simplifying the processes and reactor design and therefore saving the cost. These important reactions normally occur at high temperatures and in reducing and acidic atmosphere, thus posing great challenges on the membrane stability. Previous effort was devoted to thin Pd membranes, which however, suffer the shortcomings of hydrogen embrittlement, CO poisoning and high costs. Herein, we develop a H2-COx-tolerant and non-noble metal-ceramic dual-phase hydrogen permeable membrane reactors with a nominal composition of 60 vol% Ni-40 vol% La5.5WO11.25-δ (Ni-LWO). NH3 decomposition and hydrogen permeation was observed via the developed mixed protonic and electronic conducting membrane. A considerable production of CO in the sweep (CO2) side could also be achieved from CO2 reduction when the membrane was coupled by NH3 decomposition where the permeated hydrogen can consume the produced oxygen from favorable CO2 decomposition. Furthermore, we systematically investigated the performance of NiO–CeO2 catalyst coated Ni-LWO membrane reactor for CO2 reduction. Noteworthy that the CO generation rate obtained from Ni-LWO membrane reactor was increased in the presence of NiO–CeO2 catalysts. Hydrogen separation process coupled with surface reactions is jointly controlled by hydrogen surface exchange and bulk diffusion kinetics. These findings reveal a vital step towards the development of efficient hydrogen-transporting membrane reactor for the integration of chemical reactions and separation processes.

Sources of Cysteine-Based Pharmaceutical Drugs and Their Halal Aspects in Pharmaceutical Product Development

Indonesia is the country with the largest Muslim population in the world, so supplements and medicines consumed must be halal (permissible in Islamic law). Cysteine is an essential amino acid that is crucial to human biological functions. Cysteine can be used as a mucolytic agent to help thin mucus in respiratory diseases such as bronchitis or chronic obstructive pulmonary disease (COPD). It also serves as an antidote to acetaminophen for detoxification purposes or as an antidote to counteract paracetamol (acetaminophen) overdose, a commonly used drug to relieve pain and reduce fever. Additionally, it functions as a supplement. This research aims to comprehensively review the sources of cysteine, its production, and its use in pharmaceuticals, as well as the opinions of scholars regarding the halal aspects that need to be considered in developing pharmaceutical products containing cysteine. The methods employed include searching through references from research articles obtained from Google Scholar, ScienceDirect, NCBI, Elsevier, and the Qur'an, Hadiths, and other Islamic literature sources. The compound structures are depicted using the ChemSketch tool from ACD/Labs. Mucolytic and acetaminophen drugs, such as acetylcysteine, can be derived from both animal and plant sources through chemical and non-chemical separation processes. Cysteine is generally a precursor for the synthesis of acetylcysteine. Cysteine sourced from specific organs, such as pig hair, has differing opinions among various scholars regarding its permissibility. However, the prevailing view and fatwa tend to lean towards its prohibition, depending on the source, process, and urgency of its use.

Speciation and Organic Phase Structure in Nitric Acid Extraction with Trioctylamine.

Understanding chemical speciation and intermolecular interactions in multicomponent liquids is essential to understanding their phase and chemical equilibria, which underpin chemical separation processes, including solvent extraction. Here we report on the extraction of nitric acid from its aqueous solutions into organic solutions of trioctylamine (TOA) in toluene, investigated with spectroscopic, X-ray scattering, and computational tools to understand molecular speciation in the organic phase and its relationship with the nanoscale structure of the organic phase. Trends in acid and water extraction clearly show two and three regimes, respectively, indicating different stoichiometric relationships, but speciation of HNO3, water, and amine in these regimes is not apparent. 1H NMR of the organic phase shows that there are at least two distinct acidic protons in the organic phase while ATR-FTIR results show that the organic phase with excess acid extraction is a mixture of trioctylammonium-nitrate ion pairs (TOAH·NO3), and undissociated HNO3 molecules. Comparison with DFT-computed IR spectra show that the chain-like configurations of TOAH·NO3·HNO3·H2O are favored over TOAH·NO3·H2O·HNO3, i.e., direct interaction between the nitrate and HNO3 molecules is more favored compared to a water-mediated interaction. SAXS of the organic phases were modeled as sums of Ornstein-Zernike (O-Z) scattering and a prepeak feature in the higher Q region that corresponds to extractant packing. The extraction of undissociated HNO3 by the ion pairs leads to an increased X-ray scattering contrast in the organic phase without any significant change in the correlation length. These results show that the organic phase nanostructure is more sensitive to the concentration of TOAH·NO3 and is relatively unaffected by excess acid extraction. These findings will enable a molecular understanding of the mechanisms behind metal extraction from acidic media with basic extractants.

Hydrocarbon Extraction with Ionic Liquids.

Separation and reaction processes are key components employed in the modern chemical industry, and the former accounts for the majority of the energy consumption therein. In particular, hydrocarbon separation and purification processes, such as aromatics extraction, desulfurization, and denitrification, are challenging in petroleum refinement, an industrial cornerstone that provides raw materials for products used in human activities. The major technical shortcomings in solvent extraction are volatile solvent loss, product entrainment leading to secondary pollution, low separation efficiency, and high regeneration energy consumption due to the use of traditional organic solvents with high boiling points as extraction agents. Ionic liquids (ILs), a class of designable functional solvents or materials, have been widely used in chemical separation processes to replace conventional organic solvents after nearly 30 years of rapid development. Herein, we provide a systematic and comprehensive review of the state-of-the-art progress in ILs in the field of extractive hydrocarbon separation (i.e., aromatics extraction, desulfurization, and denitrification) including (i) molecular thermodynamic models of IL systems that enable rapid large-scale screening of IL candidates and phase equilibrium prediction of extraction processes; (ii) structure-property relationships between anionic and cationic structures of ILs and their separation performance (i.e., selectivity and distribution coefficients); (iii) IL-related extractive separation mechanisms (e.g., the magnitude, strength, and sites of intermolecular interactions depending on the separation system and IL structure); and (iv) process simulation and design of IL-related extraction at the industrial scale based on validated thermodynamic models. In short, this Review provides an easy-to-read exhaustive reference on IL-related extractive separation of hydrocarbon mixtures from the multiscale perspective of molecules, thermodynamics, and processes. It also extends to progress in IL analogs, deep eutectic solvents (DESs) in this research area, and discusses the current challenges faced by ILs in related separation fields as well as future directions and opportunities.

The Catalytic Mechanism of [Bmim]Cl-Transition Metal Catalysts for Hydrochlorination of Acetylene

Ionic liquids (ILs) are green solvents involved in chemical reaction and separation processes. In this paper, four ILs-based metal catalysts were prepared by dissolving four transition metal chlorides into 1-butyl-3-methylimidazolium chloride ([Bmim]Cl). Their catalytic performance was measured, and the catalytic mechanism was studied via density functional theory (DFT) based on the analysis of the Mayer bonding order, Mulliken charge, molecular electrostatic potential (ESP), electron localization function (ELF), and partial density of states (PDOS). The results show that the catalytic activity follows the order [Bmim]Cl-RuCl3 > [Bmim]Cl-AgCl > [Bmim]Cl-CuCl2 > [Bmim]Cl-CuCl. [Bmim]Cl helps to dissolve and activate HCl, and the metal chlorides can greatly reduce the activation energy of the reaction. This study provides new insights into the catalytic mechanism of IL, transition metals, and their synergistic effect from a microscopic point of view and sheds light on the development of new catalysts for acetylene hydrochlorination.

Interfacial salt effect induced by competitive adsorption of coexisting ions: A new understanding of the mass transfer selectivity in the near-interface boundary layer

Specific ion effects are known to influence the interfacial behavior of ions in the aqueous phase and thus affect their extraction and separation. There are many studies on enhanced extraction and separation of the target ions based on the specific ion effects. A microscopic level understanding of the competitive mass transfer and selectivity of ions at the interface between heterogeneous phases is crucial importance for the precise control of numerous chemical reaction and separation processes. The conventional salt effect (i.e., background coexisting ions promoting the mass transfer of the target ions) are only observed at higher coexisting ion concentrations. However, the present work reveals an interesting phenomenon: the adsorption enrichment and competitive hydration of coexisting salt cations at the liquid–liquid interface can significantly influence the mass transfer rate of the target rare earth ions in the near-interface boundary layer. Notably, such a distinct interfacial salt effect can promote the separation between coexisting and target ions at lower coexisting ion concentrations, and it cannot be explained by the traditional theory for the salt effect. A thin-layer organic oil film extraction system was employed here as a simplified model experiment to investigate this new interfacial salt effect on the non-equilibrium extraction and separation of target rare earth ions. The results demonstrated that the diffusion rate of the target ions (Er3+) is subject to the local concentration gradient of coexisting salt cations (Mg2+) in the near-interface boundary layer. At the lower bulk concentrations, the Mg2+ ions enriched at the interface would compete for water molecules around the hydration shell of target Er3+ ions, resulting in the dehydration of Er3+ ions. Therefore, an enhanced diffusion rate of Er3+ ions and their adsorption affinity towards the interface were observed. However, at a higher bulk concentration of Mg2+ ions, the diffusion resistance of Er3+ ions increased due to the competitive adsorption and hydration of Mg2+ ions at the interface. The thickness of the organic oil film layer also plays an important role in the diffusion of Er3+ ions. In particular, a thinner oil layer makes it easier to perceive the interfacial salt effect, which enhances the separation between Er3+ and Mg2+ compared to the case of a thicker oil layer. A quantitative correlation between the diffusion rate of Er3+ ions and the concentration of coexisting Mg2+ ions was established to describe the interfacial salt effect. This work highlights the microscopic nature of the salt effect induced by the competitive adsorption kinetics of coexisting ions in the near-interface boundary layer on promoting the extraction and separation of target metal ions. The results will help the development of new approaches to control the separation selectivity and enhance the mass transfer of target metal ions in practical applications.

Membrane-based microfluidic systems for medical and biological applications.

Microfluidic devices with integrated membranes that enable control of mass transport in constrained environments have shown considerable growth over the last decade. Membranes are a key component in several industrial processes such as chemical, pharmaceutical, biotechnological, food, and metallurgy separation processes as well as waste management applications, allowing for modular and compact systems. Moreover, the miniaturization of a process through microfluidic devices leads to process intensification together with reagents, waste and cost reduction, and energy and space savings. The combination of membrane technology and microfluidic devices allows therefore magnification of their respective advantages, providing more valuable solutions not only for industrial processes but also for reproducing biological processes. This review focuses on membrane-based microfluidic devices for biomedical science with an emphasis on microfluidic artificial organs and organs-on-chip. We provide the basic concepts of membrane technology and the laws governing mass transport. The role of the membrane in biomedical microfluidic devices, along with the required properties, available materials, and current challenges are summarized. We believe that the present review may be a starting point and a resource for researchers who aim to replicate a biological phenomenon on-chip by applying membrane technology, for moving forward the biomedical applications.

Polyamide composite membrane with 3D honeycomb-like structure via acetone-regulated interfacial polymerization for high-efficiency organic solvent nanofiltration

High-performance organic solvent nanofiltration (OSN) membranes play an indispensable role in chemical separation processes. However, conventional OSN membranes such as thin-film composite polyamide (TFC-PA) membranes exhibit insufficient perm-selectivity. In this study, we developed a high-performance TFC-PAOSN membrane on a porous polyketone (PK) support by regulating interfacial polymerization (IP) with acetone as an organic co-solvent. The effect of the acetone co-solvent on the IP reaction and PA nanofilm morphology was investigated. Acetone serves as a regulator to mediate the IP reaction by facilitating the convective diffusion of monomers at the aqueous/organic interface. Furthermore, experimental results and molecular dynamics (MD) simulation analysis confirmed that the addition of acetone increases the width of the IP reaction zone, facilitates more violent exothermic reactions, and induces aggravated vaporization of acetone, resulting in the formation of a 3D honeycomb-like structure with an ultrahigh specific surface area. Compared with the TFC-PA membrane prepared by the conventional IP method, the TFC-PA-acetone membrane prepared by acetone-regulated IP (ARIP) exhibited 2.6 times higher methanol solvent permeance (7.0 LMH/bar) and comparable methyl orange rejection (94.6%). This work explores the underlying mechanism of acetone-regulated IP, providing a facile strategy for tailoring the membrane morphology with high-efficiency organic solvent nanofiltration.

Shear flow induced specific ion interfacial effect on enhanced difference in mass transfer in the boundary layer

Understanding the nature of specific ion effect on mass transfer in boundary layer near liquid–liquid interface is of crucial importance in modern precise and controllable chemical reaction and separation processes. In present work, a new phenomenon was noticed that aqueous shear flow near the boundary layer of oil-aqueous interface exhibits a significant influence on mass transfer selectivity of target ions. Mass transfer rate of target ions in the background aqueous solutions containing strongly hydrated or weakly hydrated ions was obviously different. A thin-layered oil film based laminar flow experiment model was employed to detect the specific effect from two typical background cations, Mg2+ and Al3+, on mass transfer of Er3+ ions in laminar boundary layer. It was revealed that competitive hydration and mass transfer of background ions is subject to aqueous shear flow rate and results in the difference in mass transfer rate of Er3+ ions. Aqueous shear flow increases mass transfer resistance of weakly hydrated Mg2+ ions towards the interface, while strongly hydrated Al3+ ions are more likely to be squeezed into the stagnant region in the boundary layer, because of its stronger interaction with the hydration shell around Er3+ ions. As a result, the influence from the interaction of extractant molecules with strongly hydrated Al3+ ions on mass transfer of Er3+ ions are significantly larger than that of weakly hydrated Mg2+ ions. It appears an obvious shear flow induced specific ion effect on enhanced difference in mass transfer of Er3+ ions. This work suggests a novel perspective to understand the essence of specific ion interfacial effect under shear flow. It is aimed to develop new strategies for achieving controllable reaction and separation on the flowing surface of fluids.

Ideal Conductor Model: An Analytical Finite-Size Correction for Nonequilibrium Molecular Dynamics Simulations of Ion Transport through Nanoporous Membranes.

Modulating ion transport through nanoporous membranes is critical to many important chemical and biological separation processes. The corresponding transport timescales, however, are often too long to capture accurately using conventional molecular dynamics (MD). Recently, path sampling techniques, such as forward-flux sampling (FFS), have emerged as attractive alternatives for efficiently and accurately estimating arbitrarily long ionic passage times. Here, we use non-equilibrium MD and FFS to explore how the kinetics and mechanisms of pressure-driven chloride transport through a nanoporous graphitic membrane are affected by its lateral dimensions. We not only find ionic passage times and free energy barriers to decrease dramatically upon increasing the membrane surface area but also observe an abrupt and discontinuous change in the locus of the transition state. These strong finite size effects arise due to the cumulative effect of the periodic images of the leading ion entering the pore on the distribution of the induced excess charge at the membrane surface in the feed. By assuming that the feed is an ideal conductor, we analytically derive a finite size correction term that can be computed from the information obtained from a single simulation and successfully use it to obtain corrected free energy profiles with no dependence on the system size. We then estimate ionic passage times in the thermodynamic limit by assuming an Eyring-type dependence of rates on barriers with a size-independent prefactor. This approach constitutes a universal framework for removing finite size artifacts in molecular simulations of ion transport through nanoporous membranes and biological channel proteins.

Phase Behavior of Ionic Liquid-Based Aqueous Two-Phase Systems.

As an environmentally friendly separation medium, the ionic liquid (IL)-based aqueous two-phase system (ATPS) is attracting long-term attention from a growing number of scientists and engineers. Phase equilibrium data of IL-based ATPSs are an important basis for the design and optimization of chemical reactions and separation processes involving ILs. This article provides the recent significant progress that has been made in the field and highlights the possible directions of future developments. The effects of each component (such as salting-out agents and ILs) on the phase behavior of IL-based ATPSs are summarized and discussed in detail. We mainly focus on the phase behavior of ATPSs by using ILs, expecting to provide meaningful and valuable information that may promote further research and application.

Review of 2D Graphitic Carbon Nitride-Based Membranes: Principles, Syntheses, and Applications

Membrane separation is a central area of research in chemical engineering because of its important status as the key technology in chemical separation and water treatment processes. Recently, polymeric graphitic carbon nitride (g-C3N4) has emerged as a candidate material for membrane applications because of its appealing physiochemical properties and ease of fabrication. Herein we review the progress of g-C3N4-based membranes, including the peculiarity of two-dimensional (2D) g-C3N4, the tailoring of functionality, and integration into membrane stacks for practical applications in gas separation, water purification, pervaporation, photocatalytic water filtration, oil-in-water separation, and polymer electrolyte membranes. Moreover, possible development directions of g-C3N4-based membranes are discussed along with the current challenges and future perspectives.

Applications of Ionic Liquids in Carboxylic Acids Separation.

Ionic liquids (ILs) are considered a green viable organic solvent substitute for use in the extraction and purification of biosynthetic products (derived from biomass—solid/liquid extraction, or obtained through fermentation—liquid/liquid extraction). In this review, we analyzed the ionic liquids (greener alternative for volatile organic media in chemical separation processes) as solvents for extraction (physical and reactive) and pertraction (extraction and transport through liquid membranes) in the downstream part of organic acids production, focusing on current advances and future trends of ILs in the fields of promoting environmentally friendly products separation.

Application of Artificial Neural Network in Chemical Separation Process

The chemical separation process is a necessary unit operation to obtain qualified purity products. The design and operation control of the separation device are very important. Due to the numerous parameters that affect the separation efficiency and product purity, it is very difficult to optimize by traditional methods. Artificial neural network (ANN) has strong fault tolerance because of its self-learning, self-organization, self-adaptive and strong nonlinear function approximation ability. ANN can be used to map the complex nonlinear relationship between dependent variables and independent variables, and can be used for the design and control of chemical separation devices. This paper summarizes the characteristics of artificial neural network and several important artificial neural network models, and discusses the application of artificial neural network in different chemical separation processes.

Tailoring the CO2 selective adsorption properties of MOR zeolites by post functionalization

A wide range of organic molecules covering benzene, dimethylbenzene, methoxybenzene, and dimethoxybenzene, isopropylbenzene with different molecular diameters were covalently attached to the interior micropore walls of mordenite (MOR) zeolites to enable the systematic tuning of adsorption properties. The formation of covalent bonds between internal oxygens of MOR and benzene carbon atoms were confirmed via Rietveld refinement. The adsorption properties of the functionalized MORs were studied using CO2, CH4, and N2 adsorption isotherms under static conditions, and ideal adsorbed solution theory was used to predict MOR selectivities for CO2 over CH4 and N2. The results showed that post-functionalization with organics remarkably improved CO2/CH4 and CO2/N2 selectivities, albeit at the expense of a slight concomitant partial loss of CO2 adsorption capacity. Among the functionalized zeolites, the MOR functionalized with isopropylbenzene (the bulkiest moiety introduced) exhibited the highest selectivities (CO2/CH4 = 18.3, CO2/N2 = 59.9), which were 2.8 and 4.3 times higher, respectively, than those of pristine MOR (CO2/CH4 = 6.6, CO2/N2 = 14). Reduction of effective micropore diameters by isopropylbenzene is responsible for the improved CO2 adsorption selectivity. We believe that the concept of tailoring the molecular-sieve properties of zeolites by organic functionalization will open new opportunities for developing efficient molecular sieves for chemical separation processes.

Physical and chemical separation of Ti, rare earth elements, Fe, and Al from red mud by carbothermal reduction, magnetic separation, and leaching.

In this study, a combination of physical and chemical separation processes was used to recover the metallic components of red mud. At first, the impact of carbothermal reduction on magnetic separation of iron was studied. Low magnetic properties of iron minerals resulted in insignificant separation of iron from other components in the non-carbothermally reduced sample. Various carbothermal reduction parameters were optimized to maximize iron separation from other components. The optimum conditions were found T = 1350°C, t = 120min, coal/red mud ratio of 3, reaction time of 120min, and the soda ash/red mud ratio of 0.2. Under the optimum condition, the iron recovery of the magnetic product was observed 91% with 81% Fe content, while the non-magnetic product has contained 90% of Ti and Al and 80% of rare earth elements (REEs). Following the physical separation of iron, the chemical separation of remaining red mud components was investigated using leaching with sulfuric, hydrochloric, and nitric acids. The leaching experiments were performed on two samples, treated red mud with carbothermal reduction and an untreated sample. The untreated sample had a higher dissolution efficiency for Ti and REEs than the carbothermally reduced sample. Different dissolution behavior of the red mud components was explained by samples' mineralogy. In the end, considering the obtained results, various scenarios for the recovery of red mud components were evaluated from technical and environmental aspects.

Tunable organic solvent nanofiltration in self-assembled membranes at the sub-1 nm scale.

Organic solvent–stable membranes exhibiting strong selectivity and high permeance have the potential to transform energy utilization in chemical separation processes. A key goal is developing materials with uniform, well-defined pores at the 1-nm scale, with sizes that can be tuned in small increments with high fidelity. Here, we demonstrate a class of organic solvent–stable nanoporous membranes derived from self-assembled liquid crystal mesophases that display such characteristics and elucidate their transport properties. The transport-regulating dimensions are defined by the mesophase geometry and can be controlled in increments of ~0.1 nm by modifying the chemical structure of the mesogen or the composition of the mesophase. The highly ordered nanostructure affords previously unidentified opportunities for the systematic design of organic solvent nanofiltration membranes with tailored selectivity and permeability and for understanding and modeling rejection in nanoscale flows. Hence, these membranes represent progress toward the goal of enabling precise organic solvent nanofiltration.