Zeolitic imidazolate framework-8 (ZIF-8) was incorporated into polydimethylsiloxane (PDMS) to fabricate mixed matrix pervaporation membranes for furfural recovery from aqueous solutions. The effects of filler loading on membrane morphology, physicochemical properties, and separation performance were systematically investigated. ZIF-8 nanoparticles exhibited excellent dispersion within the PDMS matrix and enhanced both membrane hydrophobicity and furfural sorption capacity, resulting in increased furfural permeability with increasing filler loading. Surface modification of ZIF-8 with silane functional groups (SM-ZIF-8) further improved furfural affinity, preferentially promoting furfural transport across the membrane. Compared to pristine PDMS membranes, the incorporation of ZIF-8 and SM-ZIF-8 increased furfural permeability by approximately 270 and 550%, respectively, while the separation factor improved 2-2.5-fold. The best membrane performance was achieved at 15 wt % SM-ZIF-8 loading, yielding a furfural permeability of 37.14 × 105 Barrer and a separation factor of 26.84. This resulted in a 10-fold enrichment of furfural, elevating its concentration from 3 wt % in the feed to 31 wt % in the permeate. Permeation studies revealed that the separation mechanism was governed by sorption selectivity, which can be effectively tuned through appropriate filler selection and modification. This work demonstrates the promising potential of surface-modified ZIF-8/PDMS membranes for efficient furfural recovery via pervaporation.

Photothermal membrane distillation (PMD) offers a sustainable pathway for freshwater production, yet its progress depends on developing high-performance membranes made from environmentally benign materials. To address the growing concern over the environmental persistence of fluorinated polymers, this study utilizes non-fluorinated, postindustrial polyphenylsulfone (w-PPSU) waste as a sustainable polymer source for fabricating photothermal membranes. Electrospun w-PPSU nanofibers were surface-modified with magnetite/black titania (Fe3O4/b-TiO2) nanocomposites synthesized at varying b-TiO2 concentrations and subsequently sealed with a thin hydrophobic polydimethylsiloxane (PDMS) coating. The best-performing membrane (M-F/bT-50) demonstrated rapid solar-driven heating, elevating its surface temperature to 91.1 °C within 120 s under 1 kWm-2 irradiation. In desalination tests at a minimal temperature difference (ΔT = 15 °C), this membrane achieved a water flux of 3.27 Lm-2h-1, a salt rejection of 99.74%, and a photothermal conversion efficiency of 69.87%. Furthermore, the membrane maintained performance over multiple acidic cleaning cycles, demonstrating high flux recovery and regenerability. This work not only introduces an effective material system for efficient desalination but also establishes a viable pathway for valorizing industrial polymer waste into advanced, environmentally responsible technologies, contributing directly to the principles of a circular economy.

Membrane distillation (MD) is an emerging membrane-based thermal desalination technology for desalination. However, designing highly efficient MD membranes faces complication between large pore size for high flux and reduced pore size for excellent anti-wetting property. In this work, a unique composite nanofibrous membrane was developed using a simultaneous electrospinning and electrospraying technique. The membrane consisted of electrospun PVDF nanofibers and electrosprayed fluorinated TiO2-PVDF microclusters. The simultaneous dual-nozzle fabrication created an intertwined network of nanofibers and microclusters, resulting in a highly porous membrane structure with enhanced flux. The microclusters contributed to increased surface roughness and reduced surface energy, providing excellent liquid entry pressure and wetting resistance. The membrane achieved a flux of 22.5 kg m-2 h-1 and a salt rejection factor (SRF) of 0.999 for 24 h of MD operation with 3.5% NaCl. Additionally, it demonstrated good performance against surfactant-contaminated saline feed, maintaining a flux of 14.8 kg m-2 h-1 and SRF of 0.999. Compared to a conventional nanofibrous membrane, the composite membrane exhibited up to 55% increase in flux, highlighting its performance advantage. This work introduces a simple, scalable, and time-efficient fabrication strategy for producing high-performance MD membranes and offers valuable insights into membrane design for water desalination applications.

Electrospun nanofibrous membranes are highly valued for membrane distillation (MD) due to their inherent porosity and tunable structure. This study introduces a novel dual-nozzle electrospinning method to fabricate a multilayered Janus membrane, combining an omniphobic layer of PVDF fibers and fluorinated TiO2-PVDF microclusters with a hydrophilic layer of hydrolyzed PMA fibers. The resulting membrane demonstrated exceptional performance and durability. In a 21 h MD operation against oily saline solutions, it retained 80% of its initial flux while producing high-purity water (conductivity <5 μS/cm). Notably, the membrane exhibited complete underwater oil repellence, preventing fouling from oil droplet adhesion. Furthermore, in a 7 h test with highly saline feed, the membrane maintained 99% of its initial flux and permeate conductivity below 60 μS/cm. The success of the membrane is attributed to the dual-nozzle setup, which provides both improved processing efficiency and strong interlayer adhesion, enhancing structural integrity during prolonged MD operations and cleaning cycles. This work presents a robust and scalable method for fabricating high-performance Janus membranes, offering a significant advancement for treating challenging, oil-contaminated water via membrane distillation.

Poly(acrylonitrile-co-methyl acrylate) (PAN-co-MA) electrospun nanofiber (ENF) was used as the support for the formation of polyamide (PA) thin films. The ENF support layer was post-treated with heat-pressed treatment followed by NaOH hydrolysis to modify its support characteristics. The influence of heat-pressed conditions and NaOH hydrolysis on the support morphology and porosity, thin-film formation, surface chemistry, and membrane performances were investigated. This study revealed that applying heat-pressing followed by hydrolysis significantly enhances the physicochemical properties of the support material and aids in forming a uniform polyamide (PA) thin selective layer. Heat-pressing effectively densifies the support surface and reduces pore size, which is crucial for the even formation of the PA-selective layer. Additionally, the hydrolysis of the support increases its hydrophilicity and decreases pore size, leading to higher sodium chloride (NaCl) rejection rates and improved water permeance. When compared with membranes that underwent only heat-pressing, those treated with both heat-pressing and hydrolysis exhibited superior separation performance, with NaCl rejection rates rising from 83% to 98% while maintaining water permeance. Moreover, water permeance was further increased by 29% through n-hexane-rinsing post-interfacial polymerization. Thus, this simple yet effective combination of heat-pressing and hydrolysis presents a promising approach for developing high-performance thin-film nanocomposite (TFNC) membranes.

AbstractElectrospun nanofiber membranes (ENMs) have emerged as a cutting‐edge solution for membrane distillation (MD), recognized for their highly porous and interconnected architecture. This distinctive structure enables them to offer minimal mass transfer resistance, making them exceptionally suited for high‐efficiency membrane‐based separation processes. However, the very porosity that defines their strength also renders them vulnerable to fouling, scaling, and wetting during operation, which in turn compromises their performance. Current research efforts are geared toward overcoming these obstacles by refining the surface design and characteristics of ENMs. This review delves into the latest advancements in surface‐enhanced electrospun nanofiber membranes tailored for MD applications. It discusses the existing gaps in research and provides forward‐looking insights into the future of ENMs, spotlighting the development of membranes with precisely tunable surface attributes for optimized performance.

This work explored the use of biomass-derived cellulose nanofibers as an additive to enhance the separation performance of Pebax membranes for the removal of CO2 from biogas. Succinate functional groups were modified on the cellulose nanofiber (SCNF) to incorporate more CO2-attracting functional groups before they were added to the polymer matrix. A small addition of SCNF up to 0.5 wt % had no significant impact on the polymer chain packing of Pebax but significantly enhanced the tensile strength and separation performance in both CO2 permeability and CO2/CH4 selectivity. On the other hand, increasing the SCNF addition amount above 1 wt % resulted in a slight alternation of membrane microstructure, i.e., lowering crystallinity, stiffer structure, and reduced tensile strength. At high loading, the CO2 permeability and CO2/CH4 selectivity of the composite membrane were, however, found to decline. This behavior is explained by a greater propensity for interaction among the CO2-attracting functional groups of SCNF and Pebax at elevated SCNF loadings, leading to fewer functional groups available for CO2 sorption. The optimal 0.5% SCNF loading (Pebax/SCNF-0.5) demonstrated a CO2 permeability of 263.8 Barrer and selectivity of 19.9 under 4 bar pressure and an operating temperature of 30 °C. These separation performances increased by 29.69% permeability and 39.04% selectivity compared with those of pure Pebax. These highly impressive results corresponded to the increases in the levels of CO2 dissolution and diffusion via hydrophilic SCNF nanofillers in Pebax. This work could strongly advance the research and development of gas separation technology based on polymeric membranes with the utilization of biobased nanofillers for energy and environmental sectors.

Due to their interfacial defects between inorganic fillers and polymer matrices, research into mixed matrix membranes (MMMs) is challenging. In the application of CO2 separation, these defects can potentially jeopardize the performance of membranes. In this study, aminosilane functionalization is employed to improve the nano-sized zeolite Y (ZeY) particle dispersion and adhesion in polyether block amide (Pebax). The performance of CO2/CH4 separation of Pebax mixed matrix composite hollow fiber membranes, incorporated with ZeY and aminosilane-modified zeolite Y (Mo-ZeY), is investigated. The addition of the zeolite filler at a small loading at 5 wt.% has a positive impact on both gas permeability and separation factor. Due to the CO2-facilitated transport effect, the performance of MMMs is further improved by the amino-functional groups modified on the ZeY. When 5 wt.% of Mo-ZeY is incorporated, the gas permeability and CO2/CH4 separation factor of the Pebax membrane are enhanced by over 100% and 35%, respectively.

The biorefinery concept is analogous to petroleum refinery (Petrorefinery) that utilizes nonrenewable petroleum to produce a wide range of products, mainly fuels, electricity, heat, chemicals, and various materials. Biorefinery processes employ renewable biomass to replace crude oil, natural gas, or other fossil energy resources. Like petroleum refinery, the biorefinery is composed of two main processes: upstream processing and downstream processing. The upstream processes include all activities for gathering the raw materials required to create the desired precursors. In the downstream process, the precursors derived from biomass can be converted into building blocks of biochemicals through five leading platforms: bio-syngas, sugar, lignin, lipids/oil, and protein. Although the drive toward utilizing renewable resources like biomass is well aware, the production of bio-derived products has been hindered by its economic uncompetitiveness compared to the fossil-based process. Therefore, improving the design for unit operations and processes to utilize process inputs and energy to maximum efficiency is the key to success for sustainable implementation of the biorefinery process. This chapter thus discusses the unit operations potentially used in the downstream process. The underlying principle for selecting proper unit operations, especially the reactor type and separation process in biorefinery, is provided.

Zeolitic imidazolate frameworks (ZIF-8) were incorporated into polydimethylsiloxane (PDMS), making a mixed matrix pervaporation membrane for furfural recovery. Effects of filler loading on morphology, properties, and separation performance of the membrane were investigated. ZIF-8 could disperse well in the polymer matrix and also increase the hydrophobic nature and furfural sorption ability of the membranes. The furfural permeability thus increased as the particle loading increased. Moreover, the surface modification of ZIF-8 (SM-ZIF-8) by a silane functional group could further enhance the furfural-affinity which preferably promoted the furfural transportation across the membrane. Furfural permeability of the membranes was improved by around 270% and 550% when ZIF-8 and the silane-modified ZIF-8 were incorporated, respectively. The furfural separation factor was also enhanced by 2-2.5 times. The best membrane performance was achieved when adding 15 wt.% of SM-ZIF-8, offering the furfural permeability of 37.14x105 barrer, separation factor of 26.84, and 10 times furfural product concentration. The separation mechanism of the prepared membranes was dominated by the sorption selectivity control which could be easily manipulated by incorporating a suitable filler. This study showcased the potential of furfural recovery by pervaporation when a promising furfural selective membrane is developed.

In this work, polyhedral oligomeric silsesquioxane (POSS) with two different functional groups, octa(nitrophenyl)silsesquioxane (ONPS) and octa(aminophenyl)silsesquioxane (OAPS), was incorporated with polydimethylsiloxane (PDMS), forming composite membranes for furfural recovery via pervaporation process. The addition of POSS had enhanced the hydrophobicity of the PDMS and improved the affinity of furfural with membranes. At the same filler loading, OAPS/PDMS membrane showed a superior separation factor to the bare PDMS and the ONPS/PDMS composite. The effects of OAPS loading on property and pervaporation performance of the membrane were also investigated. The loading at 15 wt% was found to be the optimum value that could improve water contact angle to 116 degrees and furfural affinity to achieve over 20% improvement in both furfural flux and separation factor. The PDMS membrane with 15 wt% of OAPS could provide 7-fold concentrated furfural solution compared to the feed. The newly developed OAPS/PDMS membrane showed great potential for furfural recovery as the alternative separation method with improved energy-effectiveness and low chemical footprint.

5-Hydroxymethylfurfural (HMF) derived from cellulosic sugars has become increasingly important as a platform chemical for the biorefinery industry because of its versatility in the conversion to other chemicals. Although HMF can be produced in high yield from fructose dehydration, fructose is rather expensive because it requires multiple processing steps. On the other hand, HMF can be produced directly from highly abundant glucose, which could reduce time and cost. However, an effective and multifunctional catalyst is needed to selectively promote the glucose-to-HMF reaction. In this work, we report a bifunctional phosphated titanium dioxide as an efficient catalyst for such a reaction. The best catalyst exhibits excellent catalytic performance for the glucose conversion to HMF with 72% yield and 83% selectivity in the biphasic system. We achieve this by tuning the solvent system, controlling the amount of Brønsted and Lewis acid sites on the catalyst, and modification of the reaction setup. From the analysis of acid sites, we found that the addition of phosphate group (Brønsted acid site) onto the surface of TiO2 (Lewis acid site) significantly enhanced the HMF yield and selectivity when the optimum ratio of Brønsted and Lewis acid sites is reached. The high catalytic activity, good reusability, and simple preparation method of the catalyst show a promise for the potential use of this catalytic system on an industrial scale.

5-Hydroxymethylfurfural (HMF) is one of the main chemical building blocks to generate other high value-added biofuels and biochemicals. This study aimed to produce HMF from fructose dehydration under a biphasic system using various organic acids as catalytic promoters, such as formic acid, acetic acid, lactic acid, succinic acid, and levulinic acid. Among these organic acids, the acetic acid was found to be the best promoter in this system. The experimental results showed a prominent correlation between the HMF formation and the pK_a – the higher pK_a gave rise to greater HMF yield and lower activity toward side reactions. Response surface methodology was performed to identify the optimum reaction temperature, time, and promoter concentration for fructose dehydration. Among the three variables, the reaction temperature played the most significant role in fructose conversion and HMF yield. The optimum condition to achieve the highest HMF yield at 72.5

Produced water (PW) generated from oil and gas production is a threat to the environment if not treated properly. Conventional methods for PW treatment are often accompanied by a series of treatments to fulfill the discharge standard. Forward osmosis (FO) is a promising option due to its high solute retention, less irreversible fouling, low energy footprint and potentially used as a standalone unit. However, FO still suffers from the low flux and fouling when treating highly contaminated feeds. This study investigated fouling control in the FO system for concentrating PW by using seawater as a draw solution (DS). A multi-stage filtration system (via via replenishments of the DS) with an aeration and module inclination for fouling mitigation was proposed to improve concentration factor (CF) and flux. Results showed that the multi-stage concentration offered higher fluxes range of 1.72-15.48-1.72 L/(m(2)h) (LMH) and four times of CF than the single-stage one with fluxes range of 0.39-9.49 LMH corresponding to CF of 1.75. The aeration was effective to enhance the water flux and suppress the fouling, and showed a significant impact at the rate of 0.4 L/min, reaching flux increment by 11 times at a rate of 1 L/min. The impact of aeration was enhanced by inclining the filtration cell up to 5 times at the inclination angle (0) of 90 degrees due to the improved contacts of air bubbles with the membrane surface. The contribution of the aeration and cell inclination on the water flux can be explained through the forces acting on moving air bubbles.

Biogas production has been globally promoted due to the need for renewable energy. Membrane gas separation is one of the most potential technologies for separating impurity and inert gases from the biogas to meet the fuel standard. Membranes with high selectivity and high permeability are most desirable in membrane gas separation. This study aims to develop the composite hollow fiber membrane for CO2 separation from CO2/CH4 mixture. The synthesized composite membranes were composed of a support layer of polysulfone (PSF) and a selective layer, containing poly-block-amide (PEBAX1657) and modified zeolite Y as the filler. The effects of filler loading at 0, 5, 10, 15, and 20 on membrane properties and performance were investigated. The defect-free composite membranes were successfully obtained in all filler loadings.

Highly stable, well suspended TiO2 nanoparticles (NPs) were synthesized by a sol-gel method and directly mixed with an aqueous amine solution to react at the interface with trimesoyl chloride, forming polyamide (PA) thin film nanocomposite (TFN) membranes with a uniform distribution of the nanoparticles in the PA film. Besides the presence of TiO2 NPs, the influence of remaining chemicals such as ethanol and acid from the synthesis of the TiO2 colloids on the film formation was also investigated. The residual ethanol and acid were found to play a role in thin film formation and properties of the final membranes. The presence of TiO2 NPs, ethanol, and acid had a positive impact on membrane wettability, water flux, and salt rejection. Compared to the unmodified membrane, the TiO2-TFN membranes achieved a good separation performance with around 12% and 19% improvement in water permeability and NaCl rejection, respectively. In addition, the developed TFN membranes possessed an improved anti-fouling property with low flux decay and high flux recovery up to 94%. This simple one-pot synthesis procedure of TiO2 NPs combined with the in-situ integration during the interfacial polymerization showed great potential for economic scaling up in industrial production of high-performance TFN membranes.

Membrane separators are one of the critical components in zinc–air batteries (ZABs). In the control of mass transfer, and hence, electrochemical reaction, membrane separators have an important role to play. This work addresses the issue of battery performance in a ZAB via a new composite membrane separator based on polyvinyl alcohol (PVA). To enhance the electrolyte uptake and ionic conductivity, mesoporous Mobil Composition of Matter No. 41 (MCM-41) is incorporated as a filler in the membrane while maintaining its integrity. The presence of MCM-41 is seen to reduce the number of cycles of secondary ZABs due to the uninvited drawbacks of increased zincate crossover and reduced triple phase boundary at the air cathode, which is pivotal for oxygen reduction reaction. Overall, results suggest that the application of the MCM-41/PVA composite has the potential for use as a separator in high-capacity primary ZABs.

Membrane fouling is a major bottleneck of almost all pressure-driven membrane filtration processes that limits their widespread applications. Improvement of hydrodynamics conditions is one of the most effective methods for membrane fouling control. This paper assesses a rotating biological contactor (RBC) integrated with membrane (RBC-MI) filtration that potentially offers inherent membrane fouling control as well as enhances biological performance, in which the membrane is placed inside the RBC bioreactor. Results show that the RBC-MI system achieves 84% of COD, 96.7% ammonium, 74% total nitrogen, 89% total phosphorus, and 96% turbidity removals. The integration of membrane placed inside the bioreactor doubles the permeability as compared to the external placement. Higher hydraulic performance is achieved at the low membrane-to-disk gap and higher disk rotational speed. The energy analysis shows that the RBC-MI consumes only 0.18 kWhm−3 signifying its viability as promission option to the energy-intensive conventional treatment systems.

The selectivity of thin film composite membranes supported by a sulfonated polyetheretherketone (sPEEK) hydrophilized polyethersulfone (PES) layer was enhanced by introducing a more volatile co-solvent, i.e. tetrahydrofuran (THF), and by using an alternative simplified preparation method (SIM), which combines the coagulation step of the phase inversion process and the impregnation of the amine monomer of the interfacial polymerization process. The addition of THF to the polymer casting solutions produced TFC membranes with higher retention but lower permeance. The lowest structural parameter (similar to 383 mu m) was found for the TFC membrane with a -10% sPEEK 10% THF support and led to water fluxes of 23 LMH in PRO mode and 11 LMH in FO mode using a DI water feed solution and a 0.5 M NaCl draw solution. A minimal membrane bottom surface porosity was necessary to accomplish satisfying water fluxes in FO. The SIM method resulted in TFC membranes with comparable selectivity but significantly higher permeance and smoother polyamide selective layers.