Feed Solution Research Articles

Towards circularity in aquaculture systems: Environmental impact of Hermetia illucens meal inclusion in diets for rainbow trout reared in aquaponics

In advancing towards more sustainable aquaculture, the inclusion of insect meals in aquafeeds has significant potential to increase circularity and reduce environmental impacts, especially in aquaponics. Nevertheless, there is a lack of information regarding the environmental performance of these innovative feeding and management solutions. This study assessed the environmental impact associated with the dietary inclusion of Hermetia illucens (HI) meal (0%, 6% and 12%) in diets for rainbow trout (Oncorhynchus mykiss) reared in a low-tech aquaponic system characterised by nine independent experimental units (6.06 kg/m3 of fish and 14 strawberry plants per unit). A cradle-to-gate attributional life cycle assessment model was used to consider the impacts related to the whole aquaponic system (AQ-FISH) and those only related to the production and use of the aquafeed (AQ-FEED). The impact categories were 100-year global warming (kg CO2-eq) – with (GWP_LUC) and without (GWP) the emissions associated with land-use change (LUC), acidification (AP, g SO2-eq) and eutrophication (EP, g PO4-eq) potentials, cumulative energy demand (CED, MJ), land occupation (LO, m2/y) and water scarcity (WS, m3-eq). The functional unit was a 1 kg live weight increase of rainbow trout. Data originated from a previous 76-d fish performance trial. Data regarding HI meal were derived from an interview with the manufacturer. An economic method was used to partition the impacts between HI meal, HI fat and the frass (exhausted substrate). The effect of the HI meal inclusion level on the AQ-FISH and AQ-FEED impact values was tested using one-way analysis of variance.A 1 kg live weight increase of rainbow trout reared in the aquaponic system (AQ-FISH) produced 15.6 kg CO2-eq (GWP), 18.3 kg CO2-eq (GWP_LUC), 67 SO2-eq and 55 g PO4-eq and used 354 MJ, 3.5 m2/y and 311 m3-eq. The dietary inclusion of HI meal did not affect the AQ-FISH results, except for CED (+2%–5%). When considering the impact resulting from feed production (AQ-FEED), the inclusion of HI meal did not affect GWP_LUC, AP, EP and LO, but it negatively affected GWP (+13%–26%) and CED (+34%–68%). Results from AQ-FISH and AQ-FEED scenarios showed low sensitivity to the methodological choices. Overall, our findings suggest that general improvements to reduce the environmental impact associated with rainbow trout production in aquaponics should be concurrently directed towards both the system setting and management, as well as towards the HI meal production process, with a particular emphasis on enhancing energy efficiency. To minimise potential trade-offs, especially from an environmental perspective, future studies should prioritise the investigation of energy use and greenhouse gas emission associated with feed production. This requires a thorough evaluation of all changes in the diet formulation resulting from the inclusion of a new ingredient.

Research of the influence of the feed solution flow rate on the uranium refining in an extraction column cascade

Research of the influence of the feed solution flow rate on the uranium refining in an extraction column cascade

Explicit expression for water permeation flux in forward osmosis desalination process

Forward osmosis (FO) is a membrane process of water separation and purification. FO uses the osmotic pressure difference across a semipermeable membrane. The effective osmotic pressure at the membrane–solution interface on both the feed and permeate sides of the membrane is the main driving force for the generation of the water flux. The major hindrance to the permeation of the water flux is the prevalence of concentration polarization on both sides of the membrane. Concentration polarization inhibits permeate flux by increasing the osmotic pressure at the membrane active layer interface on the feed side of the membrane. This work focused on the development of a mathematical model for water flux in the FO process. Combined film theory model and diffusion transport through the membrane were utilized. The effect of internal concentration polarization and external concentration polarization on the flux was studied. Both internal and external concentration polarization were taken into consideration in both membrane orientations, i.e., active layer facing the feed solution and active layer facing the draw solution. The obtained explicit expression for water permeation flux in forward osmosis desalination process shows excellent agreement with the literature data.

Unique Selectivity Reversal in the Complexation of Uranium(VI) and Plutonium(IV) with Two Novel C-Pivoted Tripodal Amide Ligands: Extraction and Liquid Membrane Transport Studies

ABSTRACT Two new carbon pivoted tripodal amide-containing ligands with different spacers (L I : -CH2- spacer; L II : -CH2-CH2- spacer) have been investigated for the liquid–liquid extraction of tetravalent plutonium and hexavalent uranium from nitric acid feed solutions. The studies were carried out using the ligand solutions prepared in 95% n-dodecane + 5% isodecanol. Pu(IV) extraction was higher than that of U(VI) at 3 M HNO3 for ligand L I which was just the opposite for ligand L II . Increase of the nitric acid concentration resulted in increasing extraction of both metal ions. Isodecanol variation studies exhibited decrease in the extraction of Pu(IV) and U(VI) with increasing isodecanol content in the organic phase. Greater that 98% stripping of Pu(IV) and U(VI) was obtained from the complexes of L I and L II using 0.5 M HNO3 + 0.1 M HEDTA and 1 M Na2CO3, respectively. The slope analysis study suggested the formation of 1:2 (ML2) species with Pu(IV) as well as U(VI) with both ligands at 3 M HNO3. Temperature variation studies showed that the extraction of U(VI) and Pu(IV) with both ligands is exothermic in nature. Supported liquid membrane transport experiments using 0.11 M ligands (L I and L II ) in 95% n-dodecane + 5% isodecanol indicated poor transport (<10% after 2 h) of U(VI) and Pu(IV).

Experimental Study on the Removal of Toluene from Water by PTFE Hydrophobic Microporous Membrane Using Air Gap Membrane Distillation Process

Toluene is used for various purposes such as a cleansing agent, paint thinner, lacquers, printing, and leather tanning process. However, it has an adverse effect on human bodies, such as skin irritation, leukemia, respiratory issues, mutagenicity, etc, when the chemical gets mixed in drinking and rainwater by the above routes. Therefore, there is a threat to the environment and society because of the presence of toluene in water bodies through industrial effluent. Henceforth, in this study, toluene is separated from water using the air gap membrane distillation (AGMD) process. The hydrophobic microporous poly-tetra- fluoro-ethylene has been employed for this purpose. Primarily, this work focussed on the study of operating parameters such as feed solution temperature and coolant temperature on the AGMD performance namely permeate flux and toluene selectivity. It was observed that the permeate flux increased exponentially from 2.07 kg/m2h to 9.23 kg/m2h, and 0.94 kg/m2h to 3.53 kg/m2h. However, it was found that the permeate flux decreased from 9.48 kg/m2h to 8.12 kg/m2h, and 3.78 kg/m2h to 2.42 kg/m2h on increasing the coolant temperature from 5°C to 25°C at 3 mm and 11 mm air gap, respectively. The membrane selectivity was found to be less than 1, which signifies the efficient toluene-water separation. In order to study the membrane performance in the long run, the permeate flux was estimated continuously till 60 h wherein the estimated flux was found to be almost constant. The membrane morphology before and after the 60 h experimental run was analysed using capture FE-SEM micrographs. The toluene concentration was estimated using a spectrophotometer at a wavelength of 264 nm.

Preparation of PVDF-nSiO2/PVSQ high-flux composite membrane by chemical grafting and separation of composite brine by membrane distillation

The large-scale application of membrane distillation (MD), an important method for desalting seawater, is limited due to membrane fouling. In this study, ethyl orthosilicate (TEOS) was polymerized to obtain different nSiO2 particles. Vinyl triethoxysilane (VTES) was hydrolysed and polycondensation was used to produce spherical polyethylene-sesquioxane (PVSQ) microparticles, which were modified to construct micro/nano particles. Then grafted on the surface of polyvinylidene fluoride (PVDF) composite membrane. The low-surface-energy hydrophobic groups present on the surfaces of the vinyl and ethoxy particles greatly enhanced the membrane hydrophobicity. The particle size of nSiO2 can change the properties of the membrane. The separation performance of the membrane was tested by direct contact membrane distillation (DCMD). In the separation of a constant concentration of feed solution (3.5 wt% NaCl), the membrane flux was relatively stable at 23.8 kg·m−2·h−1, and the salt interception rate reached 99.99 %. In the subsequent separation of a salt/humic acid solution, the flux remained stable and the good anti-fouling performance indicating that this system outperformed the unmodified membrane. Finally, the effect of different cations on the water diffusivity was studied using a molecular simulation method. Both Ca2+ and Mg2+ reduced the diffusion coefficient of water. However, when these two ions were present simultaneously, Ca2+ inhibited the binding of Mg2+ to water, and the diffusion coefficient of water increased. This study provides a novel approach for preparing hydrophobic membranes for the separation of complex brines.

Ionic liquid-containing polymer including membrane for the removal of cobalt: Synthesis, adsorption, transport, and modeling studies

This work describes synthesis of polymer inclusion membranes (PIMs), which is prepared by using varying ratios of polyvinylidene fluoride co-hexafluorophosphate (PVDF-HFP) as the base polymer and trioctyldodecylphosphonium bis(2,4,4-trimethylpentyl)phosphinate) (P88812BTMPP) as extractant carrier, and its utilization for the Co(II) sorption and transport. PIM with 40 wt% ionic liquid content showed a high sorption efficiency (>95 %) for 100 mg/L Co(II) feed with 0 and 5 mol/L HCl. Likewise, the transport experiment was achieved with Co(II) in 5 mol/L HCl as feed solution and 2 mol/L H2SO4, which exhibited excellent performance with a recovery factor of more than 85 %. The effect of various parameters on the efficiency of Co(II) sorption and transport was examined systematically. The kinetic and thermodynamic studies revealed that Co(II) sorption onto PIM was chemisorption in nature. Interestingly, the adsorption mechanism of Co(II) was found to be dependent upon the HCl concentration, resulting in two different mode of sorption mechanisms. Moreover, Co(II) desorption (>95 %) was achieved effectively, using 2 mol/L H2SO4. The recycling experiments suggested that PIM could be reused effectively without significant performance loss after six consecutive sorption-stripping cycles. Therefore, the reported PIM holds a good potential as a sorbent of critical metals, such as cobalt, due to its cost-effectiveness, excellent performance in batch-sorption and continuous transport processes, as well as good regeneration properties. To the best of our knowledge, this is the first report on Co(II) transport, employing a membrane transport system with a novel phosphonium-based ionic liquid.

Optimized preparation route for polyamide top-coated forward osmosis membrane for enhanced water flux using industrial wastewater as feed.

The forward osmosis (FO) process has recently gained significant interest in treating wastewater, brackish/seawater and concentrating feedstocks for various operations, including desalination. The study investigates the effect of different synthesis conditions of the polyamide-based thin-film composite (TFC) FO membranes on the membranes' final performance. Taguchi statistical analyses were used to fabricate and optimize the polyamide TFC FO membrane. The process parameters as factors were the amount of polyethersulfone (PES), polyethylene glycol 400 (PEG-400), polyvinyl pyrrolidone (PVP), m-phenylenediamine (MPD), and trimesoyl chloride (TMC), and TMC reaction-time (RT). The Taguchi method was adopted to investigate the optimal conditions and the significance of individual factors using an L16 (45) orthogonal array. Another Taguchi analysis (Taguchi 2) was adopted to investigate the influence of other important parameters like optimal conditions for MPD, TMC, and TMC reaction-time factors using an L9 (33) orthogonal array. Confirmation tests validated a maximum water flux of 46.4 ± 2.32 L/m2·h with a specific combination of control factors for membrane synthesis: PES/PEG/PVP/MPD/TMC/TMC RT-16/7/0.5/1/0.05/30. These tests demonstrated a high-water flux of 7.05 ± 0.35 L/m2·h when exposed to industrial wastewater (secondary effluent) as the feed solution (FS) and fertilizer as the draw solution (DS) in the FO process. The R2 values were more than 90%. The experimental validation confirmed the models' predictive ability with different FSs, including industrial wastewater.

Surface modification for enhanced Anti‐Wetting properties of electrospun omniphobic membranes in membrane distillation

AbstractMembrane wetting caused by substances in the feed solution with low surface tension has posed serious issues for membrane distillation (MD). Omniphobic membranes could be helpful when dealing with this problem because they strongly repel liquids with a wide range of surface tensions. We fabricated electrospun omniphobic membranes containing PVDF‐TEOS‐PFDTMS, PVDF‐HFP‐TMOS‐PFDTMS, and PVDF‐HFP‐TEOS‐PFDTMS. All electrospun membranes have shown contact angles &gt;90°, but the electrospun membrane containing PVDF‐HFP‐TEOS‐PFDTMS has shown super repellence with a contact angle &gt;150° and maintains stable salt rejection and water flux in direct contact MD processes in the presence of sodium dodecyl sulfate surfactant (up to 0.3 mM). Furthermore, the morphology and crystallinity of the electrospun membranes were studied by scanning electron microscopy and Fourier‐transform infrared spectroscopy, and the percentage composition of elements was analyzed by x‐ray photoelectron spectroscopy. liquid entry pressure, mechanical strength, and the porosity of the electrospun omniphobic membranes were also studied.

Characterization of the Aroma Profile of Ginger Powder Produced by a Split-Stream Spray-Drying Process.

Freeze-dried ginger (Zingiber officinale) is renowned for its high quality, but it is expensive. As an alternative, spray drying can be explored for producing ginger powder. However, sugar rich feed solutions can lead to stickiness development during the process. Adding carrier materials increases costs and labeling. Accordingly, a split-stream spray-drying process was developed, where ginger fibers in their natural composition were reintroduced as a carrier material into the spray-drying process. The inlet and outlet temperatures were set at 220 and 80 °C, respectively, for optimal aroma retention. Using a stir bar sorptive extraction-gas chromatography-mass spectrometry-olfactometry, the results revealed that reintegrating ginger fibers significantly increased the concentration of eight key odorants. Although freeze-dried ginger retains more aroma, the total concentration of twenty-seven odorants in the developed spray-dried ginger was 1.9 times higher compared to frozen ginger.

Pervaporation recovery of aniline using the degradable material poly(butylene adipate‐terephthalate): Experiment and molecular simulation

AbstractPervaporation has been considered a promising technique in the recovery of organic matter in low concentrations. Developing new and efficient pervaporation membrane materials remains the main challenge. In this study, the biodegradable poly (butylene adipate‐terephthalate) (PBAT) membrane was used to recover aniline by pervaporation for the first time. The PBAT membrane showed a good pervaporation performance due to its unique affinity with aniline by the surface adsorption energy calculations. When the aniline concentration in the feed solution was 0.4 wt%, the separation factor of the PBAT membrane exceeded 80. Besides, the results showed that the flux rose with the aniline concentration increasing, which was because of the incremental free volume of PBAT membrane. Moreover, the H‐bond length between aniline and PBAT (1.947 Å) was shorter than that between water and PBAT (2.091 Å) according to the density functional theory (DFT) calculations, which could account for the low diffusion coefficient of aniline from the result of molecular dynamics (MD) simulations. In addition, PBAT membranes displayed excellent stability in pervaporation experiments of more than 80 h. It is anticipated that the PBAT membrane may have great potential in pervaporation recovery of valuable chemicals from dilute aqueous solutions.Highlights Biodegradable PBAT membrane was first used to recover aniline by pervaporation. Low diffusion coefficient of aniline was further explained combining MD and DFT. The PBAT membranes exhibited excellent performance for aniline recovery.

Accumulation of Particles in an Annular Centrifugal Contactor Cascade and the Effect upon the Extraction of Nitric Acid

Centrifugal contactors (CCs) are a technology candidate for the development of advanced reprocessing flowsheets. While they offer many advantages, such as process intensification, there are still uncertainties regarding their industrial deployment. The presence of particles in the process streams in particular may present a challenge to both performance and operability. Preliminary studies have been undertaken to evaluate the accumulation of particles in the contactors and the effect upon the extraction behaviour of nitric acid. Aluminium oxide (Al2O3) particles were suspended in the aqueous feed solution during the operation of a three-stage, 40 mm diameter CC cascade. The presence of insoluble solid particles in the aqueous feed, up to 7 g/L, were not observed to affect phase separation and entrainment under the experimental conditions investigated. The particles were centrifuged out of solution and accumulated as a thin cake/bed in the rotors of each stage. This work also illustrates that particles do entrain through the cascade. The predominant effect on the rate of accumulation was particle concentration in the aqueous feed solution, and increasing solids loading was observed to have an impact upon the extraction of nitric acid across the cascade.

Controlling amine monomers via UiO-66-NH2 defect sites to enhance forward osmosis membrane performance for lithium recovery

The excessive thickness of the separation layer and the presence of cracks cause low water flux and poor lithium recovery in conventional forward osmosis (FO) membranes. According to the influence of the diffusion behavior of amine monomers in interfacial polymerization, the use of an interlayer optimizes the separation layer structure of traditional thin-film composite FO membrane. However, it is difficult to accurately control the separation layer structure by simply adjusting the amount of the interlayer material loaded. Herein, FO membranes with defect-containing metal–organic framework (MOF) interlayers were constructed. By adjusting the concentrations of competitive ligands, the MOFs showed different degrees of linker loss, which exposed the metal ions in the MOFs to different extents. The defective sites of the constructed MOFs increased the interaction between the interlayer and m-phenylenediamine (MPD), and density functional theory (DFT) simulations also revealed an increase in the binding energy of the two materials. Therefore, MPD attachment and diffusion were controlled by changing the proportion of defects in the MOFs, thereby finely regulating the separation layer structure. Additionally, tannic acid (TA) was predeposited to improve the stability of the interlayer. The prepared membrane exhibited water fluxes of 33.84 and 65.81 LMH and reverse salt fluxes of 0.58 and 2.38 gMH in the active layer facing feed solution (AL-FS) and active layer facing draw solution (AL-DS) modes, respectively. Excellent lithium ion recovery and fouling resistance was also demonstrated in battery wastewater treatment.

PVDF-HFP-based polymer inclusion membrane functionalized with D2EHPA for the selective extraction of bismuth(III) from sulfate media

This study is the first application of a PVDF-HFP-based polymer inclusion membrane incorporating the poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) and di(2-ethylhexyl)phosphoric acid (D2EHPA) as the base polymer and extractant for the extraction of bismuth(III), respectively. It is demonstrated that the PIM comprised of 60 wt% PVDF-HFP and 40 wt% D2EHPA is the most effective in the extraction of bismuth(III) from feed solution containing 20 mg L−1 bismuth(III) and 0.2 mol L−1 sulfate adjusted to pH 1.4. The extracted bismuth(III) ions are back-extracted quantitatively to the receiving solution containing 1 mol L−1 sulfuric acid. The stoichiometry experiments reveal that the Bi: D2EHPA ratio in the bismuth(III) extracted complex is 1:6, and D2EHPA is dimer. Moreover, it is shown that the studied PIM has high selectivity in the extraction of bismuth(III) over other interfering ions such as Mo(VI), Cr(III), Al(III), Fe(III), Ni(II), Zn(II), Cd(II), Co(II), Cu(II), and Mn(II). The interference of Fe(III) is also eliminated by masking with fluoride, leading finally to a nearly pure extraction of bismuth(III).

Concentration properties of biopolymers via dead-end forward osmosis

Extracellular polymeric substances (EPSs) in excess sludge of wastewater treatment plants are valuable biopolymers that can act as recovery materials. However, effectively concentrating EPSs consumes a significant amount of energy. This study employed novel energy-saving pressure-free dead-end forward osmosis (DEFO) technology to concentrate various biopolymers, including EPSs and model biopolymers [sodium alginate (SA), bovine serum albumin (BSA), and a mixture of both (denoted as BSA-SA)]. The feasibility of the DEFO technology was proven and the largest concentration ratios for these biopolymers were 94.8 % for EPSs, 97.1 % for SA, 97.8 % for BSA, and 98.4 % for BSA-SA solutions. An evaluation model was proposed, incorporating the FO membrane's water permeability coefficient and the concentrated substances' osmotic resistance, to describe biopolymers' concentration properties. Irrespective of biopolymer type, the water permeability coefficient decreased with increasing osmotic pressure, remained constant with increasing feed solution (FS) concentration, increased with increasing crossing velocity in the draw side, and showed little dependence on draw salt type. In the EPS DEFO concentration process, osmotic resistance was minimally impacted by osmotic pressure, FS concentration, and crossing velocity, and monovalent metal salts were proposed as draw solutes. The interaction between reverse diffusion metal cations and EPSs affected the structure of the concentrated substances on the FO membrane, thus changing the osmotic resistance in the DEFO process. These findings offer insights into the efficient concentration of biopolymers using DEFO.

Diffusion-driven fed-batch fermentation in perforated ring flasks

PurposeSimultaneous membrane-based feeding and monitoring of the oxygen transfer rate shall be introduced to the newly established perforated ring flask, which consists of a cylindrical glass flask with an additional perforated inner glass ring, for rapid bioprocess development.Methods A 3D-printed adapter was constructed to enable monitoring of the oxygen transfer rate in the perforated ring flasks. Escherichia coli experiments in batch were performed to validate the adapter. Fed-batch experiments with different diffusion rates and feed solutions were performed.ResultsThe adapter and the performed experiments allowed a direct comparison of the perforated ring flasks with Erlenmeyer flasks. In batch cultivations, maximum oxygen transfer capacities of 80 mmol L−1 h−1 were reached with perforated ring flasks, corresponding to a 3.5 times higher capacity than in Erlenmeyer flasks. Fed-batch experiments with a feed reservoir concentration of 500 g glucose L−1 were successfully conducted. Based on the oxygen transfer rate, an ammonium limitation could be observed. By adding 40 g ammonium sulfate L−1 to the feed reservoir, the limitation could be prevented.Conclusion The membrane-based feeding, an online monitoring technique, and the perforated ring flask were successfully combined and offer a new and promising tool for screening and process development in biotechnology.

Sensitive 236U/238U Isotopic Analysis of Trace Uranium in Safeguards Environmental Samples Using Multicollector Inductively Coupled Plasma Mass Spectrometry.

A sensitive analytical technique was developed for determining a 10-7 level low 236U/238U ratio using multicollector inductively coupled plasma mass spectrometry. This analytical technique can determine the subnanogram amount of uranium in safeguards environmental samples. To increase the sensitivity of the 236U/238U ratio, (1) the feed solution was concentrated to one-tenth of that in the conventional method and (2) data acquisition was started from the beginning of the solution uptake until all of the solution was exhausted. All signal intensities were recorded. This technique was applied to the IRMM-184 uranium isotopic standard solution with a 1.2410 × 10-7 236U/238U ratio. The IRMM-184 uranium solution (0.2 mL of 1 ng g-1 uranium) was prepared, and the 236U/238U ratios were determined using our new data collection method. The 236U/238U ratios were in agreement with the certified value within the uncertainty (k = 2) evaluated using the Guide to the Expression of Uncertainty in Measurement (GUM) workbench. The uncertainties obtained with this new technique (32% on average) were revised to be 10 times smaller than those obtained with the conventional method using 0.1 ng g-1 IRMM-184. The tailing effect from the 238U intense peak was determined using 10 times higher concentrations of NBL CRM U0002 uranium isotopic standard solution (10 ng g-1 uranium) to improve its uncertainty. Approximately 1-2% of the uncertainties of 236U/238U could be further reduced using this improved correction factor.

Nitrogen-doped porous carbon with regulated pore structure and surface wettability as flow electrodes for efficient capacitive deionization

Nitrogen-doped porous carbon with controlled pore structure and wettability was synthesized using spent mushroom substrate (SMS) via physical activation process. The nitrogen-rich feature of precursor enables the carbon material to possess both electrical conductivity and surface wettability, creating an effective conducting network in flow electrodes. These materials have been proven to be highly efficient for deionization due to their ability of maintaining surface wettability and electrical conductivity. Our results show that the SMS-1.5 sample has a high adsorption capacity of 8.38 mg/g, which is 1.8 times greater than the commercial YP-50. The corresponding charge efficiency was up to 90.66 % after being exposed to 1.6 g/L NaCl feed solution for 120 min in flow electrode capacitive deionization device. This study highlights the significance of the inherent nitrogen element in biomass for the synergistic promotion of electrical conductivity and surface wettability, providing a strategy for designing porous carbons with excellent desalination performance.

Investigating the impact of the sulfonation degree in sulfonated polyphenylsulfone (sPPSU) on PES/sPPSU polymer blend membranes

Polyethersulfone (PES) has widespread applications due to its excellent processability, mechanical strength, and chemical resistance. Nevertheless, its hydrophobic nature often leads to severe fouling and permeance decline. To improve the hydrophilicity of PES membranes, polymer blending is one of the most common methods. In this work, a series of sulfonated polyphenylene sulfones (sPPSU) with 1.9, 4.5, 8.2, 12.7, 19 degrees of sulfonation (DS) were synthesized and used to blend with PES. The PES/sPPSU blends were found to be compatible by calculating their theoretical enthalpy of mixing and measuring their glass transition temperatures (Tg's) at a blend weight ratio of 1:1. Ultrafiltration (UF) membranes were cast using the nonsolvent-induced phase separation (NIPS) method. It was found that 50/50 PES/sPPSU blend membranes with a DS equaling to or exceeding 8.2 eliminated finger-like macrovoids, resulting in a thinner and tight cross-sectional structure. A higher DS of sPPSU rendered the blend membranes with more hydrophilicity and oleophobicity as well as a more negatively charged surface. The unmodified PES membrane had rejections of 87.47 % and 91.5 % in ultrafiltration tests using feed solutions containing BSA and oil/water emulsion, respectively. The rejections could be further increased to 99.37 % and 97.17 % respectively by the blend membranes. The blend membranes consisting of a higher DS of sPPSU also exhibited a higher permeance, lower BSA absorption and better anti-fouling properties than the PES membrane.

Unlocking Direct Lithium Extraction in Harsh Conditions through Thiol-Functionalized Metal-Organic Framework Subnanofluidic Membranes.

Metal-organic framework (MOF) membranes with high ion selectivity are highly desirable for direct lithium-ion (Li+) separation from industrial brines. However, very few MOF membranes can efficiently separate Li+ from brines of high Mg2+/Li+ concentration ratios and keep stable in ultrahigh Mg2+-concentrated brines. This work reports a type of MOF-channel membranes (MOFCMs) by growing UiO-66-(SH)2 into the nanochannels of polymer substrates to improve the efficiency of MOF membranes for challenging Li+ extraction. The resulting membranes demonstrate excellent monovalent metal ion selectivity over divalent metal ions, with Li+/Mg2+ selectivity up to 103 since Mg2+ should overcome a higher energy barrier than Li+ when transported through the MOF pores, as confirmed by molecular dynamics simulations. Under dual-ion diffusion, as the Mg2+/Li+ mole ratio of the feed solution increases from 0.2 to 30, the membrane Li+/Mg2+ selectivity decreases from 1516 to 19, corresponding to the purity of lithium products between 99.9 and 95.0%. Further research on multi-ion diffusion that involves Mg2+ and three monovalent metal ions (K+, Na+, and Li+, referred to as M+) in the feed solutions shows a significant improvement in Li+/Mg2+ separation efficiency. The Li+/Mg2+ selectivity can go up to 1114 when the Mg2+/M+ molar concentration ratio is 1:1, and it remains at 19 when the ratio is 30:1. The membrane selectivity is also stable for 30 days in a highly concentrated solution with a high Mg2+/Li+ concentration ratio. These results indicate the feasibility of the MOFCMs for direct lithium extraction from brines with Mg2+ concentrations up to 3.5 M. This study provides an alternative strategy for designing efficient MOF membranes in extracting valuable minerals in the future.