High Flux Rates Research Articles

Eco-friendly approach for the construction of biochar-based superhydrophobic membrane for effective oil/water separation

Abstract Researchers are looking at improved oil/water separation techniques due to the industry’s struggles with the separation of oily wastewater. One promising approach is to use superhydrophobic, SHP, membranes to separate oil from oily wastewater. In this study, we developed SHP textile fabric based on biochar, BC. The BC was synthesized from banana leaves by pyrolysis and then modified with nickel metal to produce Ni@BC. The textile fabric, TF, was submerged in an ethanolic solution of Ni@BC, and stearic acid, SA, to produce the SHP coating. The Ni@BC was utilized to improve the roughness of the surface of the pristine TF, and SA was utilized to reduce its surface energy. Scanning electron microscope, SEM, was used to investigate the surface morphology of the pristine and modified TF. The SEM results show that the modified TF shows a micro-nano structure. Atomic force microscopy, AFM, was utilized to study the surface roughness. The results show that the modified TF has a surface roughness greater than the pristine TF. The energy-dispersive x-ray spectroscopy techniques and Fourier transform infrared spectroscopy confirmed the structure of Ni@BC and the grafting of both SA and Ni@BC to the TF. The wettability finding demonstrated that the modified TF had a high degree of superhydrophobicity, with a high-water contact angle of 161° and a low water sliding angle of 1°. The modified TF showed excellent oil/water separation performance, with a separation efficiency of 99.9%. The oil absorption capacity of the TF was also high, with a capacity of 303 g g−1 for silicone oil, and it also has a high flux rate. The modified TF was also found to be mechanically and chemically stable, with no significant degradation after 10 cycles of use. The results of this study demonstrate that the biochar-based SHP TF is a promising material for oil/water separation.

Fabrication of high-performance MeI and HPEI assembled PES/CPES hollow fiber nanofiltration membranes with high positive charges for efficient removal of salt/heavy metal ions

Environmental protection and resource recovery require efficient separation of salts and heavy metal ions from wastewater. A new hollow fiber nanofiltration membrane (HFNM) with a highly positive charge was developed via Hyperbranched polyethyleneimine (HPEI) self-assembly and methyl iodide (MeI) quaternization on a polyethersulfone (PES) with carboxylic-PES (CPES) substrate. Effects of different layers on surface charge and roughness, wettability, and mechanical stability were evaluated. MgCl2 and ZnCl2 as representative of salts and heavy-metal ions, respectively, were used to investigate separating properties of the membranes in terms of feed temperature and concentrations, operating pressures, antifouling properties, and long-term stability. The relationship between salt/ions rejection and water flux, pore size, and surface positive charge degree was explained by comparing the structures and properties of the membranes. The 1wt.% HPEI and 0.5 wt.% GA solutions for 30 min crosslinking at pH of 11 and then 5 wt.% MeI solution could lead to the formation of the optimum membrane. Based on high hydrophilicity, low surface roughness, Donnan exclusion, and steric hindrance, the membrane could effectively exhibit superb rejection rates of Zn2+ (99.8 %), and Mg2+ (98.6 %), while showing high flux values (24.47 and 33.54 Lm−2h−1). The high flux rate (around 25.41 Lm−2h−1) during 4 cycles of regeneration, and high ions rejection (>98 %) were retained even after an 8-hour consistent operation. The prepared membrane, with high durability and structural stability, can introduce an effective solution for water purification from divalent ions.

Self-cleaning photoelectrocatalytic filtration based on Ca(OH)2/Ti3C2Tx composite nanofiltration membranes for synergistically enhanced separation and degradation of phenolic compounds

Combining photoelectrocatalytic (PEC) and nanofiltration (NF) membranes has emerged as an attractive technology for removing organic pollutants in wastewater treatment, however, the separation and degradation performance are still challenging. Herein, novel composite NF membranes were constructed by cross-linking a Ca(OH)2/Ti3C2Tx (CT) catalyst to a polyamide membrane using tannic acid (TA). In these CT@TA (CTTP) membranes, Ti3C2Tx reduces the charge-transfer resistance and recombination rate of CT, leading to enhanced PEC activity. The optimal CTTP membrane had a high water flux (27.9 L·m−2·h−1·bar−1) and excellent rejection rates for phenolic compounds (phenol: 85.1 %, 4-nitrophenol: 91.1 %, and bisphenol A (BPA): 94.6 %). Under visible-light irradiation with electrical assistance (3 V), the BPA degradation rate (92.2 %) was 13.7 % higher than that under light irradiation alone, and a higher flux recovery rate was achieved (94.1 %). Superoxide (O2−) and hydroxyl (OH) radicals were critical active species in catalytic BPA degradation, and the observed intermediates suggested that the degradation pathway involves oxidation, hydroxylation, and aromatic ring cracking. The developed NF membranes, which exhibit synergistic separation and degradation effects and self-cleaning properties, provide an innovative solution for the treatment of organic pollutants in wastewater.

Design of a mixed‐matrix polyether sulfone membrane with well self‐cleaning capability for oil/water separation

AbstractA self‐cleaning mixed‐matrix membrane was successfully developed and fabricated using the reverse thermally induced phase separation (RTIPS) method, incorporating modified particles. To achieve this, DA@CuFe2O4 particles were prepared by modifying CuFe2O4 with dopamine (DA) and then fed into the membrane matrix. The RTIPS method was employed to create hydrophilic membranes that exhibited remarkable stability and toughness. X‐ray diffraction, Fourier‐transform infrared (FTIR), transmission electron microscopy, and thermogravimetric analysis results showed that the particles were successfully modified. XPS, scanning electron microscopy, and FTIR proved that the modified particles were introduced into the film. The EDS spectra also showed that the self‐made CuFe2O4 particles with DA adsorbed on the surface were uniformly distributed in the organic matter. In addition, the results of the contact angle characterization, tensile test, water flux test, oil–water separation test, and cycle test showed that the material with a high water flux (1707.78 L/m2 h) and removal rate of >99.9% has good wettability, mechanical properties, corrosion resistance, and stain resistance. In addition, the photocatalytic performance of the modified membranes was demonstrated by studying the degradation of pollutants under visible light. Through photocatalysis, the membrane material obtained a higher utilization rate, which provided a new attempt to solve the membrane separation technology in the field of oily wastewater treatment.

Polysulfone-based mixed matrix membranes loaded with a multifunctional hierarchical porous Ag-Cu dendrites@SiO2 core-shell nanostructure for wastewater treatment

Eliminating pollutants from wastewater is a crucial approach to securing the global water supply. It is well known that membrane purification technologies are remarkably attractive due to their high efficacy and low energy consumption. The neat polysulfone (PSF) polymer membranes, though, are prone to be fouled by organic pollutants, causing pore blockage and waned separation performance. We herein report and describe the rational design of a hierarchical porous Ag-Cu dendrites@SiO2 core-shell nanostructure/PSF mixed matrix membranes (MMMs) by coupling heterogeneous dendritic Ag-Cu@SiO2 core-shell nanostructure with PSF polymer matrix using facile phase inversion method for efficient separation of the protein (Bovine Serum Albumin; BSA) and Rose Bengal (RB) dye removal. Besides, for the first time, a theoretical mapping of molecular electrostatic potential (MESP) maps for chemical structure has been used for studying the interaction between the compounds (membrane moieties and pollutants). Practically, the SiO2 nanoparticles provide excellent hydrophilicity causing a sequential efficient, antifouling protein and dye separation with an outstanding rejection rate of over 96 % for both BSA and RB. In addition, the porous hierarchical scaffold formed from the hydrophilic Ag-Cu nanosheets embedded with SiO2 nanoparticles greatly assists the rapid permeation of water with a high flux rate of up to 50 L m−2 h−1 bar−1 for pure water. Furthermore, the hydrophilic nature of Ag and Cu nanoparticles also renders this membrane with a high removal capability for dye blocking enabling it to remove soluble pollutants in molecular dimensions as well. This design strategy not only provides an outstanding membrane for water purification but also sheds light on the design of multi-purpose functional membranes for a variety of energy and environment-related applications.

Competition between Hydration Shell and Ordered Water Chain Induces Thickness-Dependent Desalination Performance in Carbon Nanotube Membrane

Exploring new reverse osmosis (RO) membranes that break the permeability-selectivity trade-off rule is the ultimate goal in seawater desalination. Both nanoporous monolayer graphene (NPG) and carbon nanotube (CNT) channels have been proposed to be promising candidates for this purpose. From the perspective of membrane thickness, both NPG and CNT can be classified into the same category, as NPG is equivalent to the thinnest CNT. While NPG has the advantage of a high water flux rate and CNT is excellent at salt rejection performance, a transition is expected in practical devices when the channel thickness increases from NPG to infinite-sized CNTs. By employing molecular dynamics (MD) simulations, we find that as the thickness of CNT increases, the water flux diminishes but the ion rejection rate increases. These transitions lead to optimal desalination performance around the cross-over size. Further molecular analysis reveals that this thickness effect originates from the formation of two hydration shells and their competition with the ordered water chain structure. With the increase in CNT thickness, the competition-dominated ion path through CNT is further narrowed. Once above this cross-over size, the highly confined ion path remains unchanged. Thus, the number of reduced water molecules also tends to stabilize, which explains the saturation of the salt rejection rate with the increasing CNT thickness. Our results offer insights into the molecular mechanisms of the thickness-dependent desalination performance in a one-dimensional nanochannel, which can provide useful guidance for the future design and optimization of new desalination membranes.

Natural microfibrils/regenerated cellulose-based carbon aerogel for highly efficient oil/water separation

Cellulose-based carbon aerogels as biodegradable and renewable biomass materials have presented potential applications in oil/water separation. Herein, a novel carbon aerogel composed of natural microfibrils/regenerated cellulose (NM/RCA) was directly prepared by economical hardwood pulp as raw material using a novel co-solvent composed of deep eutectic solvent (DES) and N-methyl morpholine-N-oxide monohydrate (NMMO·H2O). In addition, the morphology and structure of the filiform natural microfibers could be remained after carbonized at 400 ℃, which resulted in a low density (8–10 mg cm−3), high specific surface area (768.89 m2 g−1) and high sorption capability. In addition, the aerogel exhibited high compressibility, outstanding elasticity, excellent fatigue resistance, and recyclability (80.5% height recovery after repeating 100 cycles at the strain of 80%). Due to the morphology and composition of the carbonized microfiber surface, the superhydrophobic materials with a water contact angle of 151.5°, could sorb various oils and organic solvents with 65–133 times its own weight and maintain 91.9% sorption capacity after 25 cycles. In addition, the aerogels could achieve the continuous separation of carbon tetrachloride (CCl4) from water with a high flux rate of 11,718.8 L m−2 h−1. Therefore, our prepared NM/RCA aerogels are anticipated to have broad potential applications in oil purification and contaminant remediation.

Fabrication of a new composite membrane consisting of MXene/PES /PEI for biofuel dehydration via pervaporation

A novel two-dimensional transition metal carbide with great potential for diverse applications is MXenes, which are synthesized and characterized in this paper. The study focuses on developing polyethersulfone (PES) and polyetherimide (PEI) mixed membranes and their modification with MXene nanoparticles for ethanol dehydration. X-ray diffraction (XRD), and Fourier transform infrared (FTIR) techniques confirmed that MXene and MAX were appropriately synthesized. The morphology and characteristics of the membranes were investigated by FTIR, field emission scanning electron microscopy (FE-SEM) imaging, and EDX map analysis. the result of contact angle analysis shows that the hydrophilicity of the MXene membrane is modified. Also the membrane's pervaporation ability evaluated for ethanol dehydration. The modified membrane, containing 5 wt% MXene, demonstrates superior performance with a high flux rate (>81.7 g/m2h) and a reasonable separation coefficient (112.67).

Flow thermohydraulic characterization of open diverging microchannel heat sink for high heat flux dissipation

The future fusion reactor puts forward higher demand for the heat dissipation capability of the divertor, which requires to withstand ultra-high heat flux of up to 20 MW/m2. Our previous study demonstrated that microchannel cooling technology is a promising strategy to remove high heat loads on the target plate of the divertor. However, the high pressure drop of the straight rectangular microchannel limits its practical implementation. In this study, we propose an open diverging microchannel heat sink (ODMHS) to reduce the pressure drop under high heat flux and high flow rate conditions. The effects of the width and height of expanding channel on the heat transfer performance and pressure drop were first studied numerically. The results indicated that expanding channel width resulted in a reduction of heat transfer coefficient, whereas the expansion of the channel height led to the enhancement of heat transfer performance. Regardless of the divergence of channel width or height, the enlargement of the channel dimension can effectively reduce the pumping power. Subsequently, experimental tests were carried out in ODMHS with a width ratio and a height ratio of 1.33 and 1.30, respectively. The results demonstrated that the ODMHS can withstand heat flux of up to 15.6 MW/m2 at 3 L/min. This study provides important insights for high heat flux dissipation on the target plate of the divertor by rational design of microchannel structures.

Plant phenology and species-specific traits control plant CH4 emissions in a northern boreal fen.

Aerenchymatic transport is an important mechanism through which plants affect methane (CH4 ) emissions from peatlands. Controlling environmental factors and the effects of plant phenology remain, however, uncertain. We identified factors controlling seasonal CH4 flux rate and investigated transport efficiency (flux rate per unit of rhizospheric porewater CH4 concentration). We measured CH4 fluxes through individual shoots of Carex rostrata, Menyanthes trifoliata, Betula nana and Salix lapponum throughout growing seasons in 2020 and 2021 and Equisetum fluviatile and Comarum palustre in high summer 2021 along with water-table level, peat temperature and porewater CH4 concentration. CH4 flux rate of C. rostrata was related to plant phenology and peat temperature. Flux rates of M. trifoliata and shrubs B. nana and S. lapponum were insensitive to the investigated environmental variables. In high summer, flux rate and efficiency were highest for C. rostrata (6.86 mg m-2 h-1 and 0.36 mg m-2 h-1 (μmol l-1 )-1 , respectively). Menyanthes trifoliata showed a high flux rate, but limited efficiency. Low flux rates and efficiency were detected for the remaining species. Knowledge of the species-specific CH4 flux rate and their different responses to plant phenology and environmental factors can significantly improve the estimation of ecosystem-scale CH4 dynamics in boreal peatlands.

Brackish water treatment by Ceramic TiO2 Low-Pressure Nanofiltration Membranes

<p>The application of ceramic Nanofiltration (NF) membrane in brackish water treatment is increasing due to strict water quality standards. Ceramic NF is a widely used membrane process and has replaced reverse osmosis (RO) membranes in many applications due to lower energy consumption and higher flux rates. This work aims to study the separation performance of tubular ceramic TiO2 Nanofiltration membrane at low-pressure (2 bar) for single and tertiary salt mixture separation. The results showed that the rejection of ions is ordered as follows: R (Cl1-) ion size > R calcium (Ca2+) ion size > R sodium (Na1+) ion size > R magnesium (Mg2+) ion size. Moreover, the highest Cl1- rejection was about 46%, the highest Ca2+ and Mg2+ rejection was about 44%, and the highest Na1+ rejection was about 37%. The pure water flux through the investigated ceramic NF membrane for distilled water was calculated to be 5.29 x 10-7 m3 s-1 m-2 bar-1, and this flux was dropped down for the salt mixture feed to 2.56 x 10-7 m3 s-1 m-2 bar-1 due to the presence of salt particles in the feed.</p>

Desalination behavior of composite membrane with petal shaped pore—formed by superimposition of covalent organic framework with large aperture difference

Covalent organic frameworks (COFs) are promising materials for developing the new generation of reverse-osmosis membranes owing to their unique structure with well-defined nanoporosity and highly tunable pore-wall chemistry. In this work, a new separation membrane was developed using the molecular dynamics (MD) simulation method by superimposing two COF-based films: HPB-COF (0.577 nm) and TpPa-1 (1.582 nm), with a large difference in aperture. The results showed that the new double-layer superimposition membrane could overcome the trade-off effect, and achieve a high water flux and salt rejection rate. According to the membrane model microanalysis, the HPB-COF divided TpPa-1 into six “petals”, thus endowing the first layer and second layer of the membrane with a larger accessible surface area and smaller effective pore diameter, respectively. As a result, the new composite membrane simultaneously had combined advantages of the two COF materials. The water permeance of the TpPa-1/HPB-COF composite membrane was 1.85 times higher than that of the AB-stacked HPB-COF membrane, which was two orders of magnitude higher than that of other conventional reverse-osmosis membranes. The salt rejection rate was 100%, which was higher than that of AB-stacked TpPa-1 membrane (39.42%). Furthermore, the microanalysis revealed that the hydrophilic CO in TpPa-1 positively improved the water flux.

3D printing titanium dioxide-acrylonitrile-butadiene-styrene (TiO2-ABS) composite membrane for efficient oil/water separation

The oily water treatment is becoming one of the hottest topics due to that increase of offshore oil transportation and the various accident oil leakages. In this study, a functional TiO2-ABS composite membrane was generated through the three-dimensional (3D) printing strategy for the first time and was conducted to simulated oily water treatment. The TiO2-ABS composite membrane demonstrated a significant promotion in hydrophilicity and oleophobicity which were evidenced by the water contact angle of 14.8° and the underwater oil contact angle of 144.7°, respectively. The optimal modified membrane had both exceedingly high flux (1.8 × 105 L m−2·h−1) and oil rejection rate (99.5%). Moreover, the results of filtration cycles of 10 days and extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory demonstrated that the modified membranes took possession of excellent stability and antifouling property. What was more, the TiO2-ABS composite membrane revealed over 99% rejection to all five types of oil/water systems. The interestingly experimental results indicated that the prepared membrane possessed a broad development trend and application prospect in the field of oily water treatment.

Towards superior permeability and antifouling performance of sulfonated polyethersulfone ultrafiltration membranes modified with sulfopropyl methacrylate functionalized SBA-15

A non-solvent induced phase separation (NIPS) process was used to fabricate a series of sulfonated polyethersulfone (SPES) membranes blending with different concentrations of SBA-15-g-PSPA with the applications in the ultrafiltration (UF) process. SBA-15 was modified with 3-methacrylate-propyltrimethoxysilane (MPS) to form SBA-15-g-MPS. It was further modified with the charge tailorable polymer chains by reacting with 3-sulfopropyl methacrylate potassium salt. The nanoparticles were uniformly dispersed and finger-like channels were developed within the membrane. The adding of surface modified SBA-15-g-PSPA nanoparticles has significantly improved membrane water permeability, hydrophilicity, and antifouling properties. The pure water fluxes of the composite SPES membranes were significantly higher than the pristine SPES membrane. For the membrane containing 5% (mass) of SBA-15-g-PSPA (MSSPA5), the pure water flux was increased dramatically to 402.15 L∙m –2 ∙h –1 , which is ∼ 1.5 times that of MSSPA0 (268.0 L∙m –2 ∙h –1 ). The high flux rate was achieved with 3% (mass) of SBA-15 nanoparticles with retained high rejection ratio 98% for natural organic matter. The results indicate that the fashioned composite membrane comprising SBA-15-g-PSPA nanoparticles have a promising future in ultrafiltration applications.

A Comparison between Various Polymeric Membranes for Oily Wastewater Treatment via Membrane Distillation Process.

Oily wastewater (OW) is detrimental towards the environment and human health. The complex composition of OW needs an advanced treatment, such as membrane technology. Membrane distillation (MD) gives the highest rejection percentage of pollutants in wastewater, as the membrane only allows the vapor to pass its microporous membrane. However, the commercial membranes on the market are less efficient in treating OW, as they are prone to fouling. Thus, the best membrane must be identified to treat OW effectively. This study tested and compared the separation performance of different membranes, comparing the pressure-driven performance between the membrane filtration and MD. In this study, several ultrafiltration (UF) and nanofiltration (NF) membranes (NFS, NFX, XT, MT, GC and FILMTEC) were tested for their performance in treating OW (100 ppm). The XT and MT membranes (UF membrane) with contact angles of 70.4 ± 0.2° and 69.6 ± 0.26°, respectively, showed the best performance with high flux and oil removal rate. The two membranes were then tested for long-term performance for two hours with 5000 ppm oil concentration using membrane pressure-filtration and MD. The XT membrane displayed a better oil removal percentage of >99%. MD demonstrated a better removal percentage; the flux reduction was high, with average flux reduction of 82% compared to the membrane pressure-filtration method, which experienced a lower flux reduction of 25%. The hydrophilic MT and XT membranes have the tendency to overcome fouling in both methods. However, for the MD method, wetting occurred due to the feed penetrating the membrane pores, causing flux reduction. Therefore, it is important to identify the performance and characteristics of the prepared membrane, including the best membrane treatment method. To ensure that the MD membrane has good anti-fouling and anti-wetting properties, a simple and reliable membrane surface modification technique is required to be explored. The modified dual layer membrane with hydrophobic/hydrophilic properties is expected to produce effective separation in MD for future study.

Influence of Dispersed TiO2 Nanoparticles via Steric Interaction on the Antifouling Performance of PVDF/TiO2 Composite Membranes.

Herein, the influence of various contents of polyethylene glycol (PEG) on the dispersion of TiO2 nanoparticles and the comprehensive properties of PVDF/TiO2 composite membranes via the steric hindrance interaction was systematically explored. Hydrophilic PEG was employed as a dispersing surfactant of TiO2 nanoparticles in the pre-dispersion process and as a pore-forming additive in the following membrane preparation process. The slight overlap shown in the TEM image and low TSI value (<1) of the composite casting solution indicated the effective dispersion and stabilization under the steric interaction with a PEG content of 6 wt.%. Properties such as the surface pore size, the development of finger-like structures, permeability, hydrophilicity and Zeta potential were obviously enhanced. The improved antifouling performance between the membrane surface and foulants was corroborated by less negative free energy of adhesion (about -42.87 mJ/m2), a higher interaction energy barrier (0.65 KT) and low flux declination during the filtration process. The high critical flux and low fouling rate both in winter and summer as well as the long-term running operation in A/O-MBR firmly supported the elevated antifouling performance, which implies a promising application in the municipal sewage treatment field.

Construction of self-healing polyethersulfone ultrafiltration membrane by cucurbit[8]uril hydrogel via RTIPS method and host-guest chemistry

In this work, the self-healing polyethersulfone ultrafiltration membrane constructed by host-guest chemistry between cucurbit [8]uril (CB [8] is a family of macrocyclic compounds comprising 8 glycoluril units) and two guest molecules based on reverse thermally induced phase separation (RTIPS) method was developed, which had excellent self-healing performance, better mechanical properties, and high permeation flux and BSA rejection rate. The membrane autonomously restored it BSA rejection rate up to about 89% from rejection rate levels as low as 21% after damage. The observed self-healing performance were attributed to the swelling of pore-filled CB [8] hydrogel into the damage position, the molecular interdiffusion of the hydrogel chains, the strong hydrogen bond of the hydrogel chains and the host-guest interaction between CB [8] and two guest molecules (HEC-Np and PVA-MV). SEM morphologies illustrated that the prepared pore-filled membrane via the RTIPS method had homogeneous and porous skin surface and sponge-like cross-section, which imparted the prepared membranes with improved permeability and better mechanical properties. Properties of MR-CB [8] membranes, which varied with increased content of CB [8], were evaluated by permeability, water contact angle, thermogravimetric analysis (TGA), mechanical properties, FRR, scanning electron microscope (SEM) and atomic force microscopy (AFM). The contact angle water showed that CB [8] hydrogel enhanced the surface hydrophilicity of the prepared membrane. TGA illustrated that the thermal stability improved with the increased content of CB [8]. The optimal pore-filled CB [8] hydrogel membrane (MR-CB [8]2) exhibited that the pure water flux reached 2100.5 L/m2 h, while the BSA rejection rate remained at 86.0%. The results of this work suggested pore-filled CB [8] hydrogel membrane was a more promising way to develop polyethersulfone ultrafiltration membranes with self-healing performance.

Decoding the Impact of Injection-Induced Fractures on the Sweep Efficiency of a Mature Polymer Flood through Pressure Falloff Analysis

Summary Polymer flooding is one of the most popular chemical enhanced oil recovery processes in the world, with many large-scale commercial field implementations. It improves mobility ratio and sweep efficiency over waterflooding. However, injection of high volumes of viscous fluid at high injection pressures almost inevitably induces fractures. Induced fractures are not necessarily negative for the flood, and they are documented to improve injectivity and reduce shear degradation of polymer. The big question is on their effect on areal and vertical sweep efficiency. Mangala is one of the largest and most commercially successful polymer floods in the world. The FM-1 unit has the highest stock tank oil initially in place among all the layers of Mangala. Polymer flood sweep efficiency in FM-1 is excellent despite the presence of injection-induced fractures and geological layering. Pressure falloff (PFO) studies are an important and inexpensive source of monitoring the growth of induced fractures in mature polymer floods. Extensive work has been done in the past to derive analytical solutions and numerically assisted solutions for polymer PFOs for non-Newtonian rheology and induced fractures with variable storage. There is also extensive and sometimes contradictory literature on polymer rheology in porous media at both high and low flux rates. Most of the work on polymer PFOs have published a few field examples or synthetic examples and addressed specific issues in depth. We have interpreted 40 PFOs carried out over a period of 1 year. All relevant data sources in the field on geomechanics, polymer rheology in core and rheometers, temperature logs, and saturation logs were integrated to get a consistent estimate for fracture half-length. The results provide insight into the role of induced fractures in improving the sweep efficiency of FM-1. The arguments are backed with literature survey. The work can be used by operators around the world to manage mature polymer floods. The observations mentioned in the work can be used by researchers to fine tune their work. Secondary hypothesis on polymer rheology in porous media is also derived out of the work, which may be of academic interest and merit further work. There are other important aspects of polymer flood PFOs, such as impact of suspended solids and rock dilation near wellbore, which have not been explored in the paper.

Metal-organic framework/H2O2-exfoliated g-C3N4/poly(vinylidene fluoride) composite nanofiltration membranes

In this current work, a proper membrane was fabricated via vapor induced phase separation (VIPS) coupled with the non-solvent induced phase separation (NIPS). First, synthesized hydrogen peroxide treated exfoliated graphitic carbon nitride (H2O2-g-eC3N4) nanosheets were incorporated into the mixed matrix membrane (MMM). Then, synthesized NH2-MIL-101(Al) nanoparticles were incorporated into the MMM. In the next step, the synergistic effect of NH2-MIL-101(Al) and H2O2-g-eC3N4 was investigated systematically, and the optimized proportion of each modifier was acquired. The optimized membrane elucidated a high flux rate that reached as high as 20.7 ± 1.01 L m−2 h−1.bar−1, which was almost 62% higher than pristine PVDF membrane. It came across that the optimum membrane could provide a high dye rejection properties (99.9%, 99.8%, 99.7%, 99.3%) for orange G (OG), sunset yellow FCF (SY), naphthol yellow S (NYS), and Martius yellow (MY), respectively. Significant antifouling feature (96% for the optimum membrane), and outstanding long-term stability. Moreover, it was found that the synergistic effect of used dual nanoparticle/nanosheet caused promising long rejection stability even after 12 days.

Fabrication of a biological metal–organic framework based superhydrophobic textile fabric for efficient oil/water separation

In response to the industry's difficulty in properly separating oily wastewater discharge, researchers are investigating enhanced oil/water separation materials. In this work, a cost-effective and environmentally friendly superhydrophobic textile fabric was fabricated for effective oil–water mixture and emulsion separation. A biological metal–organic framework consisting of copper as a core metal and aspartic acid as a linker (Cu-Asp MOF) was used to improve the surface roughness of the pristine textile fabric, and stearic acid was used to lower its surface energy. The thermal gravimetric analysis investigated the prepared Cu-Asp MOF's thermal stability. X-ray spectroscopy and Fourier-transform infrared spectroscopy studied the crystal orientation and chemical composition of the Cu-Asp MOF, Cu-Asp MOF@SA, pristine textile fabric, and superhydrophobic textile fabric, respectively. The surface morphology of the pristine and modified textile fabric was studied by scanning electron microscope. The wettability results showed that the prepared superhydrophobic textile fabric has a water contact angle of 158° ± 1.3 and water sliding angle of 2° ± 0.2°. The prepared superhydrophobic textile fabric showed excellent oil–water mixture and emulsion separation performance, oil absorption capacity, chemical stability, mechanical abrasion resistance, and a high flux rate. These outstanding characteristics of the prepared superhydrophobic textile fabric greatly increase the possibility for practical applications.