High Oil Rejection Research Articles

Sulfonic nanohydrogelled surface-modified microporous polyvinylidene fluoride membrane with excellent antifouling performance for treating water-oil separation of kitchen wastewater

Kitchen wastewater containing high concentration of suspended solids, salt and oil is a comprehensive wastewater that requires urgent treatment. Organic fouling limits the use of membranes for treating kitchen wastewater. Herein, we propose a novel sulfonic nanohydrogel membrane with superhydrophilicity and underwater-superoleophobicity. A 32-nm-diameter sulfonic nanohydrogel Poly(SPP-co-MA-co-FLUORAL-P), developed by the polymerization technique in an aqueous medium, was grafted onto the polyvinylidene difluoride (PVDF) microfiltration membranes. The developed PVDF-g-Poly(SPP-co-MA-co-FLUORAL-P) membrane exhibited excellent antifouling properties for treating kitchen wastewater. The influence of organics (edible oil, surfactant, protein and humic acid) and salts on the membrane filtration was thoroughly investigated. The Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy techniques were used to confirm the successful surface modification. The experimental results revealed that the pure water flux was 2161 L m−2 h−1. A high oil rejection rate was achieved when the fabricated membrane was used for treating the simulated kitchen wastewater (˃99.7%). The excellent antifouling properties of the membrane significantly improved the circulation stability of the simulated kitchen wastewater filtration. The recovery rate of permeation flux was up to 100%. The chemical oxygen demand removal rate of the real kitchen wastewater was 61% and the flux recovery rate arrived at 98%. The PVDF-g-Poly(SPP-co-MA-co-FLUORAL-P) membrane can be potentially used for treating kitchen wastewater.

Selective grafting of morphologically modified poly(vinylidene fluoride) ultrafiltration membrane by poly(acrylic acid) for inducing antifouling property

Fouling propensity of a membrane depends on water wetting property and interaction of foulants with the surface. Surface initiated polymerization usually leads to the grafting of main membrane forming polymer. Herein, we report a process for the selective grafting of blend component of poly(vinylidene fluoride) (PVDF) membrane, and the effect of morphological feature on the water wetting behaviour and antifouling property. Polymerization of acrylic acid (AA) in contact with a morphologically modified blend membrane of PVDF leads to selective grafting of blend component by PAA chains. Polymerization causes formation of graft copolymer throughout the membrane matrix. Base membrane morphology and grafting time profoundly influence surface roughness, permeate flux and water wetting behaviour of the membranes. Grafting time window of 2–4 h produces membranes with high oil rejection (>99.5%), high flux recovery ratio (>95%) and low flux reduction (30–36%) during recovery of water from surfactant free and surfactant stabilized oil-in-water emulsions. The surface roughness and morphology of the base and grafted membranes are important factors to induce hydrophilic property, which in turn reduces the fouling propensity of the membranes. This work provides an insight regarding the influence of surface roughness on the water wetting behaviour and antifouling property of the membranes.

Ni-doped brochantite@copper hydroxide hierarchical structures on copper mesh with ultrahigh oil-resistance for high-efficiency oil/water separation

Design and preparation of materials with superhydrophilicity/underwater superoleophobicity are of great significance for high-efficiency oil/water separation. In this work, we prepared Ni-doped brochantite@copper hydroxide hierarchical structures on copper mesh using chemical oxidation and hydrothermal synthesis, in which the interleaved embedded hydrophilic Ni-doped brochantite nanosheets distributed around copper hydroxide nanoarrays on copper mesh. The Ni-doped brochantite@copper hydroxide hierarchical structures endowed the mesh with pore size of 10 μm and excellent superhydrophilicity/underwater superoleophobicity and ultrahigh oil resistance with great oil rejection (>99.99%) and extremely high flux of 28,543 L m−2 h−1 for various oil-water mixtures. Importantly, the mesh showed excellent cyclic performance for 20 times separation of pump oil/water mixture with stable high flux and oil rejection and survived conspicuous selective affinities to oil and water from harsh conditions. It is indicated that the hierarchical Ni-doped brochantite@copper hydroxide coated copper mesh (NBCHCM) is a potential membrane material for high-efficient and sustainable oil/water separation.

A novel monolithic mullite microfiltration membrane for oil-in-water emulsion separation

Monolithic ceramic microfiltration membranes made up of an interlocking network of mullite crystals have been developed from low-cost raw materials, consisting of China clay, AlF3·3H2O and Al2O3. The characteristics of the developed membranes have been studied. The membrane made from clay+40 wt% AlF3·3H2O powder mixture with 10 wt% Al2O3 displayed excellent properties, with apparent porosity of 64%, median pore diameter of 0.3 μm, flexural strength of 43 MPa, and pure water permeance of 1031 L/m2 h bar. The membrane also displayed excellent pore connectivity and chemical stability owing to the crosslinked needle-like mullite microstructure. The performance of the mullite microfiltration (MF) membrane in oil-in-water emulsion separation was studied with three test solutions having oil concentrations of 200 mg/L, 500 mg/L and 1000 mg/L. The membrane showed excellent permeate flux of more than 200 L/m2. h at a transmembrane pressure of 2 bar and high oil rejection of more than 96% with all the feed concentrations. The fabrication of the monolithic mullite MF membrane in comparison to the conventional asymmetric ceramic MF membranes is highly economical and can be used as a cost-effective alternative for oil-in-water emulsion separation.

Bioinspired superwetting fibrous skin with hierarchical roughness for efficient oily water separation

Developing superwetting membranes with interconnected pore and multi-scale roughness for efficient oily water separation is significant but challenging owing to the limitations of low water flux and membrane fouling. Herein, we report a scalable method to develop superwetting membranes with superhydrophilicity and underwater superoleophobicity for oily water separation. This novel approach, composed of electrospinning/electrospraying of polyacrylonitrile (PAN), was to fabricate rough sphere membrane substrate, followed by in-situ polymerization of dopamine/polyethyleneimine (DA/PEI) to positively charge the fiber skin and then subsequent immersed into the negatively charged Ludox solution to construct rough membrane surface via electrostatic attraction. Benefiting from the rough sphere surface of the fibrous skin layer, the resultant membrane displayed micro/nanostructured surfaces with intriguing in-air superhydrophilicity of 0° and underwater superoleophobicity of 166° as well as robust oil-proof pressure of 83.55 kPa. As a proof-of-concept, the resultant membrane achieved high water flux and oil rejection efficiency as well as fantastic durability and antifouling performance toward the separation of highly emulsified oily water. The integration of electrospinning/electrospraying with bioinspired method is also expected to fabricate superwetting sphere surface membrane with interconnected pores for other selective separation applications.

Fabrication and characterization of graphene oxide–polyethersulfone (GO–PES) composite flat sheet and hollow fiber membranes for oil–water separation

AbstractBACKGROUNDIn this work, a series of graphene oxide–polyethersulfone (GO–PES) composite flat sheet (FS) and hollow fiber (HF) membranes were fabricated by blending 0.5 and 1.0 wt% of GO into the PES matrix and utilized for oil–water separation. GO was first prepared and characterized by using Fourier‐transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), X‐ray diffraction (XRD) and thermogravimetric analysis (TGA) before being used as membrane fillers.RESULTSInterestingly, although similar dope composition was used for the fabrication of HF and FS membranes, their morphology and pore size varied significantly owing to the way the membranes were fabricated. Significant enhancement of hydrophilicity was observed for both composite FS and HF membranes, where the water contact angle value decreased from 74.8° to 42.2° and 71.4° to 49.8°, respectively. The flux of the composite membranes increased up to 150% of the bare membranes especially when 1.0 wt% of GO was added. Although higher oil rejection (~99%) was observed for HF membranes that possess smaller pores, the permeation flux was maintained due to the improved flow dynamic. Lower oil rejection (up to 50%) was observed for FS membranes, which might be due to its big pore sizes particularly at the bottom surface. As more oil droplets formed on the membrane surface and prevented water molecules to pass through the membrane, fouling might occur rapidly.CONCLUSIONSThe results obtained in this work suggest that surface hydrophilicity, pore size of membranes and oil–water separation performances was greatly affected by membrane shape. Owing to many advantages of HF membranes, this type of membrane has great potential for commercial applications. © 2020 Society of Chemical Industry

Superwetting Oil/Water Separation Membrane Constructed from In Situ Assembled Metal-Phenolic Networks and Metal-Organic Frameworks.

Superwetting membranes with opposite wettability to oil and water have drawn intense attention in recent years for oil/water separation. Superhydrophilic and underwater superoleophobic membranes have shown unique advantages in the efficient treatment of oily wastewater containing oil-in-water emulsions. Facile interfacial engineering and microstructural design of the hierarchical architectures and the hydrophilic chemistry is of significance but still challenging. In this study, a hydrophilic hierarchical hybrid layer derived from metal-phenolic network (MPN)/metal-organic framework (MOF) synergy is constructed on the membrane surface via a proposed coordination-directed alternating assembly strategy. The assembly of MPN multilayers provides a hydrophilic chemical basis, and the assembly of MOF nanocrystals provides a hierarchical structural basis. Notably, the coordination interfacial interaction enables the formation of well-defined hydrophilic hierarchical architectures. The obtained membrane is thus endowed with robust superhydrophilicity, underwater superoleophobicity, and anti-oil-adhesion capability, which make it capable of highly efficient oil-water separation with high water permeance (above 6300 L/m2 h), high oil rejection (above 99.4%), and recyclable antifouling property. The high performance of the developed superwetting membrane makes it a competitive candidate for oil/water separation. Additionally, the demonstrated MPN/MOF assembly strategy may offer new prospects for the facile and versatile design of other superwetting materials.

Permeability behavior of silicon carbide‐based membrane and performance study for oily wastewater treatment

AbstractPorous SiC ceramic is considered as a suitable material for hot gas filtration, microfiltration, and many others industrial applications. However, full utilizations of porous SiC ceramics have been limited by high‐processing costs. In this study, mullite‐bonded porous SiC ceramics membranes were prepared using commercial SiC powder, alumina, clay, and different sacrificial pore formers. The effect of different pore formers on the microstructure, mechanical strength, porosity and pore size distribution, air, and water permeability of porous SiC ceramics were investigated. The average pore diameter, porosities, and flexural strength of the final ceramics varied in the range 3.7‐6.5 µm, 38‐50 vol. %, and 28‐38 MPa, respectively, depending on the characteristics of pore former. The Darcian (k1) and non‐Darcian (k2) permeability evaluated from air permeation behavior at room temperature was found to vary from 1.48 × 10−13 to 4.64 × 10−13 m2 and 1.46 × 10−8 to 6.51 × 10−8 m, respectively. All membranes showed high oil rejection rate (89%‐93%) from feed wastewater with oil concentration of 1557 mg/L. The membrane with porosity ~48 vol% and mechanical strength 31.5 MPa showed and highest pure water permeability of 13 298 Lm−2h−1bar−1.

Bio-inspired anchoring of amino-functionalized multi-wall carbon nanotubes (N-MWCNTs) onto PES membrane using polydopamine for oily wastewater treatment

The major problem that limits the utilization of PES membranes in treatment of oily wastewater is the drastic irreversible membrane fouling due to the attachment of oil droplets onto the membrane surface. The goal of this study was to develop a novel, fast and facile post-functionalization of polydopamine (PDA) coated membranes using pre-synthesized nanoparticles for fabrication of novel organic-inorganic hybrid recoverable membranes with high hydrophilicity and underwater oleophobicity. Here, bio-inspired technique was studied because the membrane technology could separate small oil droplets (even <10 µm) with high performance if faced little fouling phenomena during the treatment process.The amino-functionalized multi-wall carbon nanotubes (N-MWCNTs) were anchored onto the PDA coated PES membranes. The membranes characteristics, with specific focus on surface morphology and wettability were investigated. The newly developed PES/PDA/N-MWCNTs membranes showed an enhanced flux (~1086%) compared to the unmodified PES membrane. This enhancement was attributed to the high hydrophilic and underwater oleophobic properties, which were found to alleviate the effect of fouling. The total fouling ratio (Rt) of the PES/PDA/N-MWCNTs membrane was 22.35%, which was far lower than that of the unmodified PES membrane (98.38%). Meanwhile, most of the fouling was reversible for the former with the remaining (irreversible fouling) of 18.08%. It was concluded that cake filtration is the dominant fouling mechanism of the PES/PDA/N-MWCNTs membranes due to their average pore diameter. The modified membranes showed high oil rejection (>99%) so that the obtained clean water with oil concentration lower than 5 ppm met the wastewater discharge standard recommendations. Also, evaluation of the PES/PDA/N-MWCNT membrane in cross-flow filtration showed its antifouling properties in the long-term application (16 h).

Electrospun Nylon 6,6/ZIF-8 Nanofiber Membrane for Produced Water Filtration

This study develops electrospun nylon 6,6 nanofiber membrane (NFM), incorporating zeolitic imidazolate framework-8 (ZIF-8) as the additive for produced water (PW) filtration. Electrospun NFM is suitable to be used as a filter, especially for water treatment, since it has a huge surface area to volume ratio, high porosity, and great permeability compared to the conventional membranes. These properties also enhance its competitiveness to be used as reverse osmosis pre-treatment, as the final stage of PW treatment water reuse purpose. However, the fouling issue and low mechanical strength of NFM reduces hydraulic performance over time. Therefore, this study employs ZIF-8 as an additive to improve nylon 6,6 NFM properties to reduce fouling and increase membrane tensile strength. Results show that the optimum loading of ZIF-8 was at 0.2%. This loading gives the highest oil rejection (89%), highest steady-state pure water permeability (1967 L/(m2·h·bar)), 2× higher than untreated nylon 6,6 NFM with tensile strength 5× greater (3743 MPa), and a steady-state permeability of 1667 L/(m2·h·bar) for filtration of real produced water.

Ultra-thin titanium carbide (MXene) sheet membranes for high-efficient oil/water emulsions separation

Oily wastewater from oil spill and industrial water discharge poses danger to human body and the environment. Fouling is the bottleneck of membrane for oily wastewater separation. Here, an ultra-thin 2D titanium carbide MXene membrane (about 30 nm) supported on porous polyethersulfone (PES) as substrate with high performance and excellent stability for oil-in-water emulsion separation is designed. The high antifouling resistance, promising oil/water separation and excellent recyclability of the MXene membranes are originated from their inherent hydrophilicity, low adhesion of oil droplets as well as the regular stacking of the 2D lamellar structure. Molecular Dynamics simulations further confirm that the hydrophilic MXene membranes with low oil adhensive force. Moreover, for salt-containing oily wastewater, the MXene membranes exhibit even higher oil rejection with low compromised water permeance due to the reduced d-spacing because of ion intercalation. Such ultra-thin MXene 2D membranes with outstanding recyclability and high separation performance pave an avenue for a broad oil/water separation.

Expanded Graphite-Polyurethane Foams for Water-Oil Filtration.

Herein, expanded graphite is successfully combined with waterborne polyurethane to develop porous foams with underwater oleophobic properties for the separation of surfactant-free, oil-in-water mixtures and emulsions. To obtain foams with different pore sizes and therefore with different performances in the oil-water filtration process, two solvent-free fabrication processes are adopted. In the first one, the expanded graphite granules are mixed with the waterborne polyurethane (PUEGr), and in the second method, calcium carbonate is introduced to the two-component mixture (PUEGr_t). In both cases, the obtained foams exhibit hydrophilicity and oleophilicity in air and oleophobicity underwater, and they have porous interconnected networks, while their pore size distribution differs significantly. The foams can be used as 3D filters, able to separate, through gravity, surfactant-free, oil-in-water mixtures (10% w/w oil in water) with high oil rejection efficiencies and flow rates that depend on the type of foam. In particular, in the gravity-driven filtration process using 100 mL of the feed liquid, the PUEGr foams have an oil rejection efficiency of 96.85% and flow rate of 9988 L m-2 h-1, while for the PUEGr_t foams the efficiency is higher (99.99%) and the flow rate is lower (8547 L m-2 h-1) due to their smaller pore size. Although the PUEGr_t foams have slower separation performance, they are more efficient for the separation of surfactant-free emulsions (1% w/w oil in water) reaching an oil rejection efficiency of 98.28%, higher than the 95.66% of the PUEGr foams of the same thickness. The foams can be used for several filtration cycles, as well as in harsh conditions without deteriorating their performance. The nature of raw materials, the simple solvent-free preparation method, the effective gravity-driven filtration even in harsh conditions, and their reusability suggest that the herein engineered foams have great potential for practical applications in oil-water separation through highly energy-efficient filtration.

Fabrication of mullite ceramic-supported carbon nanotube composite membranes with enhanced performance in direct separation of high-temperature emulsified oil droplets

The direct treatment of high-temperature oil-in-water (O/W) emulsions is a challenging energy-saving water treatment issue for membrane technology, where thermally resistant separation membranes are required. This work proposes the rational design and facile fabrication of a thermally resistant mullite-CNT (carbon nanotube) composite membrane with a hierarchical structure for the high-temperature direct removal of tiny oil droplets from O/W emulsions. CNTs were grown in situ on/inside robust mullite ceramic hollow fibers by chemical vapor deposition (CVD), where hydrogen gas was produced as by-product with a concentration as high as 5.5% at 600 °C. After structural characterization, the high-temperature separation capability of mullite-CNT composite ultrafiltration membranes was assessed. The membranes exhibited excellent performance with high oil rejection of 100%, 99.99%, 99.99% and 99.99% and increased initial permeate fluxes from 6.5, 9.7, 12.8–15.7 L m−2 h−1 at the investigated temperatures of 25, 50, 80 and 100 °C. A simple cleaning method using dilute aqueous NaOH without energy consumption was used to effectively accomplish membrane regeneration. Our results indicate that ceramic-CNT membrane is promising for highly efficient direct separation of high-temperature O/W emulsions without the necessity of including a cooling process, thus providing recovered hot water with intensive energy saving in practical industrial applications.

Synergistic effect of Cloisite 15A and 30B nanofillers on the characteristics of nanocomposite polyethersulfone membrane

Considering the environmental risks of oily wastewater and the impressive role of membrane technology in refining these wastes, preparation of a highly durable well performed polymeric membrane with improved antifouling properties was taken into account in this study. For this purpose, two different clay-based nanofillers i.e., Cloisite 15A and 30B organoclays were examined as nanofiller in polyethersulfone membrane matrix. The synergistic effect of hybrid nanofiller addition on the membrane efficacy was probed using oily water filtration, morphological and mechanical characterization tests as well as the fouling investigations. It was found that embedding equal amounts of Cloisite 15A and 30B resulted in the most preferred membrane among all the prepared samples with different ratios of two nano-additives. Hybrid nanofiller resulted in higher oil rejection (99.1%), acceptable water permeability, high flux recovery (95%) after getting fouled with oil as well as higher mechanical resistance compared with bare PES and also single filler nanocomposite membranes.

Low cost palm oil fuel ash based ceramic membranes for oily water separation

Ceramic membranes have been gaining so much interest for oily water separation due to their superior characteristics such as good anti-fouling property, superhydrophilic, as well as excellent thermal and chemical stabilities. However, ceramic membranes are very expensive which hinders their uses in large scale applications. Therefore, the aim of our study is to develop a low cost palm oil fuel ash (POFA) based ceramic hollow fiber ceramic membrane for oily water separation application. An asymmetric membrane structure consisting of sponge-like and macrovoid layers were acquired using a combined phase inversion and sintering technique. The membranes were sintered at different temperatures ranging from 1000 to 1150 °C. The sintered membranes were characterized in terms of morphology, mechanical strength, porosity, permeate flux and oil rejection performance. A high oil rejection efficiency of up to 96.0% was obtained for the membrane sintered at 1050 °C with the permeate flux of 185.42 L/m2h at the applied pressure of 3 bar. Based on the comparison with other ceramic membranes reported in the literature, it can be concluded that POFA based ceramic hollow fiber membrane showed a comparable performance and thus can be a promising low cost alternative ceramic membrane for oily water separation application.

Modification of hydrophobic commercial PVDF microfiltration membranes into superhydrophilic membranes by the mussel-inspired method with dopamine and polyethyleneimine

Polymeric membranes have not been widely used to treat oily wastewater due to their susceptibility to fouling. The aim of the present work is to develop a low-cost, facile modification technique to achieve superhydrophilicity and fouling resistance of hydrophobic PVDF membranes in oil-water separation applications. PVDF microfiltration membranes with 0.1, 0.2 and 0.45 µm pore size were modified with mixtures of different concentrations of dopamine (DA) and polyethyleneimine (PEI) using different deposition times (6, 12 and 24 h). The modified membranes were characterized for their surface physicochemical properties, pH tolerance, and performance in filtration of a model oil emulsion. The PDA/PEI coating was shown to produce superhydrophilic membrane surfaces with very high oil rejection (>98% with 1 µm nominal pore size), and greatly reduced irreversible fouling by oily wastewater. The excellent oil rejection and fouling resistance is attributed to the hydration water layer formed by the PDA/PEI coating both on the membrane surface and inside membrane pores.

WO3/TiO2 superhydrophilic and underwater superoleophobic membrane for effective separation of oil-in-water emulsions

Tungsten trioxide (WO3) and titanium dioxide (TiO2) decorated commercial stainless steel meshes (SSM 304) were fabricated by chemical deposition and dip coating. WO3 and TiO2 particles were firmly and uniformly coated on the membrane surfaces, forming rough micro-nano double structures with underwater superoleophobicity, large contact angles and low oil-adhesion characteristic. Furthermore, the as-prepared membranes achieved effective oil-in-water (O/W) emulsions separation with high efficiency up to 98.5% or more. The separation of O/W emulsions was easily implemented under gravity with water fluxes of >200 L m−2 h−1 or low pressure with water fluxes up to 1300 L m−2 h−1 or more. In addition, the superhydrophilic membranes with WO3/TiO2 coatings were demonstrated for high oil rejection, stable underwater superoleophobic properties after abrasion treatment and steady water permeation flux after several cycles.

Amphiphobic PFTMS@nano-SiO2/ePTFE Membrane for Oil Aerosol Removal

Synthetic expanded polytetrafluoroethylene (ePTFE) membrane has a wide range of applications, including aerosol and dust removal, and exhibits high dust-removing efficiency, high air permeability, and cost-effectiveness. However, the intrinsic oleophilic surface of ePTFE limits its application in the oil-bearing gas–solid separation process. Herein, we report a surface modification method to prepare amphiphobic ePTFE membranes via coating of a layer of 1H,1H,2H,2H-perfluorooctyltrimethoxysilane (PFTMS) – modified nano-SiO2 onto the surface of ePTFE fibers. The oil contact angle of the modified ePTFE membranes was increased from 0 to 123°, while retaining the initial water contact angle of 142°. The amphiphobic membrane shows excellent oil aerosol filtration efficiency with a comparative low pressure drop and high oil rejection rate of 99.5%. Remarkably, the membrane can be reused after simple rinsing with water. The oil aerosol filtration efficiency of membrane remained as high as 98.5% after five cycles of filtration and cleaning.

Fabrication, characterization, and performance evaluation of polyethersulfone/TiO2 nanocomposite ultrafiltration membranes for produced water treatment

In the present work, development of neat and nanocomposite polyethersulfone membranes composed of TiO2 nanoparticles is presented. Membranes are fabricated using nonsolvent phase inversion process with the objective of improving antifouling, hydrophilicity, and mechanical properties for real and synthetic produced water treatment. Membranes are characterized using scanning electron microscopy, Fourier‐transform infrared, contact angle, porosity measurement, compaction factor, nanoparticles stability, and mechanical strength. The performance of prepared membranes was also characterized using flux measurement and oil rejection. Fourier‐transform infrared spectra indicated that noncovalence bond formed between Ti and polyethersulfone chains. The contact angle results confirmed the improved hydrophilicity of nanocomposite membranes upon addition of TiO2 nanoparticles owing to the strong interactions between fillers and water molecules. The increased water flux for nanocomposite membranes in comparison with neat ones can be due to coupling effects of improved surface hydrophilicity, higher porosity, and formation of macrovoids in the membrane structure. The membrane containing 7 wt% of TiO2 nanoparticles was the best nanocomposite membrane because of its high oil rejection, water flux, antifouling properties, and mechanical stability. The pure water flux for this membrane was twice greater than that of neat membrane without any loss in oil rejection. The hydrophilicity and antifouling resistance against oil nominates developed nanocomposite membranes for real and synthetic produced water treatment applications with high performance and extended life span.

Robust Tunicate Cellulose Nanocrystal/Palygorskite Nanorod Membranes for Multifunctional Oil/Water Emulsion Separation

Nanoporous membranes with superhydrophilic and underwater superoleophobic surfaces have shown excellent performance in oil/water emulsion separation due to their low oil adhesion and good oil/water selectivity. However, fabrication of membranes from low cost raw materials through green and sustainable routes for multifunctional separation of oily water still remains a challenge. Herein, we reported a facile strategy to prepare robust membranes from renewable tunicate cellulose nanocrystals (TCNCs) and low-cost palygorskite (PGS) for multifunctional oil/water emulsion separation. The TCNC/PGS membranes possess nanoporous structure with tunable thickness, and superhydrophilic and underwater superoleophobic surface, which could effectively separate micro/nanoemulsions with high water flux and oil rejection. Moreover, the resulting membranes exhibited high mechanical strength, excellent recyclability, and good stability under harsh conditions. More importantly, TCNC/PGS membranes could remove water-soluble co...