Membrane For Oily Wastewater Treatment Research Articles

WO3·H2O micro-flowers decorated PVDF/Ti3C2 MXene membrane for oily wastewater treatment

Purification of the complex wastewater mandates the fabrication of multi-functional membranes that can separate oil from emulsions and remove dangerous organic contaminants. Herein, we developed a new PVDF/Ti3C2/WO3·H2O fibrous membrane through the hydrothermal growth of WO3·H2O micro-flowers onto the porous PVDF/Ti3C2 electrospun mats. WO3·H2O micro-flowers showed similar growth spanning Ti3C2 MXene sheets having good interfacial contact, which regulated the wettability and enhanced the charge separation needed for boosting photo-reactivity. The fibrous PVDF/Ti3C2/WO3·H2O membrane displayed minimal oil adhesion, superhydrophilicity, and sustained underwater superoleophobic characteristics with outstanding separation effectiveness (∼99 %) and reusable nature. Notably, membrane had the ability to successfully separate a wide variety of oil/water emulsions with a permeation flux of 1431–1542 L.m- 2.h- 1. The composite membrane is 39 times more efficient than PVDF/Ti3C2 electrospun membrane with regard to RhB degradation (∼91 %) and has good recyclability and refreshing behaviour under LED light irradiation. Such bi-functional materials with outstanding oil/water emulsion separation and photocatalytic degradation properties pave the way for treating complex oily wastewater. The present study presents a scalable method for fabricating metal-oxide-based multi-functional membranes utilising 2D MXene.

Valorization of waste plastics and waste oases of Gabes-Tunisia to prepare polymeric membrane for oily wastewater treatment

Valorization of waste plastics and waste oases of Gabes-Tunisia to prepare polymeric membrane for oily wastewater treatment

Preparation of PVDF-PVP Composite Membranes for Oily Wastewater Treatment.

The oil and gas industry and related applications generate large quantities of oily wastewater, which can adversely affect the environment and human health if not properly handled. This study aims to prepare polyvinylidene fluoride (PVDF) membranes incorporated with polyvinylpyrrolidone (PVP) additives and utilize them to treat oily wastewater through the ultrafiltration (UF) process. Flat sheet membranes were prepared using PVDF dissolved in N,N-dimethylacetamide, followed by the addition of PVP ranging from 0.5 to 35 g. Characterization by scanning electron microscopy (SEM), water contact angle, Fourier transform infrared spectroscopy (FTIR), and mechanical strength tests were performed on the flat PVDF/PVP membranes to understand and compare the changes in the physical and chemical properties of the membranes. Prior to the UF process, oily wastewater was treated by a coagulation-flocculation process through a jar tester using polyaluminum chloride (PAC) as a coagulant. Based on the characterization of the membrane, the addition of PVP improves the physical and chemical properties of the membrane. The membrane's pore size becomes larger, which can increase its permeability and flux. In general, the addition of PVP to the PVDF membrane can increase the porosity and decrease the water contact angle, thereby increasing the membrane's hydrophilicity. With respect to filtration performance, the wastewater flux of the resultant membrane increases with increasing PVP content, but the rejections for TSS, turbidity, TDS, and COD are reduced.

Co-pressing and co-sintering preparation of cost-effective and high-performance asymmetric ceramic membrane for oily wastewater treatment

High-performance asymmetric ceramic membranes have shown great potential in wastewater treatment. Nevertheless, high production cost, which results from expensive raw materials, high energy consumption, and complicated preparation process, hinders their large-scale production and application. Herein, a simple and cost-effective co-pressing and co-sintering method was proposed to prepare thin defect-free asymmetric ceramic membranes. This method overcomes the bottleneck of preparing thin asymmetric ceramic membrane by co-pressing. The membrane with a cornstarch content of 20 wt% and sintered at 1300 °C possessed large water permeance (3640 L·m−2·h−1·bar−1), high permeability (steady-state feed permeance > 1000 L·m−2·h−1·bar−1) and selectivity (rejection rate > 99.6%), as well as excellent oil fouling resistance and regeneration performance. The fouling mechanism of the membrane was in accord with cake filtration for the whole separation process (3 h), although multiple fouling mechanisms might occur simultaneously in the initial filtration stage. This study indicates that co-pressing and co-sintering is a quite promising method for fabricating high-performance and cost-effective ceramic membrane.

Study on the Fabricated PC/PDA-Modified TiO2 Hybrid Membranes for Oily Wastewater Treatment in a Submerged Membrane System

Study on the Fabricated PC/PDA-Modified TiO2 Hybrid Membranes for Oily Wastewater Treatment in a Submerged Membrane System

Spray-assisted LBL assembly of chitosan/nanocellulose as coatings of commercial membranes for oil-in-water emulsion separation

Owing to the limitation of their wettability and pore size, lab filter membranes could not separate oil/water emulsions. Herein, we present surface modification of commercial membranes with chitosan/nanocellulose coatings via a spray-assisted layer-by-layer (LBL) assembly technology. By alternate spraying chitosan (CS) solution and TEMPO-oxidized tunicate cellulose nanofiber (TCNF) suspension, (CS/TCNF)n multilayers were obtained, where n denotes the number of bilayers. The (CS/TCNF)6 coated membrane possessed superhydrophilicity, underwater superoleophobicity, and outperforming anti-oil-fouling properties, which could effectively separate various oil-in-water emulsions. Importantly, the (CS/TCNF)6 coated membrane not only had stable permeate flux with nearly 100 % recovery ratio for the separation of pump oil-in-water emulsion, but also exhibited good harsh-environment-tolerant property. This work provided a novel strategy for designing and preparing stable anti-oil-fouling membranes for oily wastewater treatment.

Efficient oily wastewater treatment by a novel electroflotation-membrane separation system consisting a Ni-Cu-P membrane prepared by electroless nickel plating

Electroflotation-membrane separation system with a conductive membrane has recently emerged as a promising technology for oily wastewater treatment. However, the conductive membrane prepared by electroless plating often suffers the problems of low stability and high activation cost. To solve these problems, this work proposed a new strategy regarding surface metallization of polymeric membrane by surface nickel-catalyzed electroless nickel plating of nickel‑copper‑phosphorus alloys for the first time. It was found that, addition of copper source remarkably enhanced the membranes' hydrophilicity, corrosion resistance and fouling resistance. The Ni-Cu-P membrane had an underwater oil contact angle of up to 140°, and simultaneously possessed rejection rate > 98 % with rather high flux of 65,663.0 L·m−2·h−1 and excellent cycling stability when separating n-hexane/water mixtures under gravity drive. The permeability is higher than the state-of-the-art membranes for oil/water separation. The Ni-Cu-P membrane as the cathode can be assembled into an electroflotation-membrane separation system, allowing to separate oil-in-water emulsion with 99 % rejection. Meanwhile, the applied electric field significantly improved membrane flux and fouling resistance (flux recovery up to 91 %) when separate kaolin suspensions. Polarization curve and Nyquist curve analysis further confirmed that addition of Cu element obviously enhanced corrosion resistance of the Ni modified membrane. This work provided a novel strategy to make up high-efficiency membranes for oily wastewater treatment.

Superior separation of industrial oil-in-water emulsions utilizing surface patterned isotropic PES membranes

Developing polymeric membranes for oily wastewater treatment has attracted great interest over the last few years. However, the low permeance and poor fouling resistance are considered the most challenging issues. Introducing topographic patterns on the membrane surface to increase active area and surface roughness is one practical strategy for reducing membrane fouling. Here, isotropic polyethersulfone (PES) membranes with line patterns and continuous sponge-like porous structure were prepared using phase separation micro-molding processes. Various techniques were used to characterize the morphologies and physicochemical properties of the as-prepared membranes. The surface wettability of the membranes was evaluated by measuring contact angle of a water drop in air and of industrial crude oil under water. The as-prepared membranes separation and antifouling performance were assessed using water permeance, oil rejection, and flux recovery ratio after emulsion filtration. The results showed that the patterned PES membrane has superior hydrophilic and antifouling capabilities, with a lower static water contact angle (CA) of 32° as compared to a flat PES membrane (CA = 39°). Furthermore, the patterned membrane had pure water permeance (PWP) of 8036 ± 65 L·h−1·m−2·bar−1, which was ∼ 68 % greater than that of the flat PES membrane. This is mainly attributable to the discernible increase in the membrane pore size distribution and the enhancement in membrane surface hydrophilicity due to the increase in surface roughness as a result of micro-patterning. The patterned membranes showed superior separation efficiency (>99.0 %) and permeance (7031 ± 65 L·h−1·m−2·bar−1) for the oil-in-water emulsion of 0.1 g·L−1. At a higher concentration of crude oil-in-water emulsion (50 g·L−1), the patterned PES membranes achieved promising permeance of 90 L/h.m2.bar and 99.9 % rejection. Furthermore, the flux recovery ratio of the patterned membrane exceeded 91 % after three consecutive cycles of dead-end filtration and backwashing with water, demonstrating the benefit of using micro-patterned membranes for treating high concentration and industrial oil-in-water emulsions.

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.

Fabrication and Characterization of Polyphenylsulfone/Titanium Oxide Nanocomposite Membranes for Oily Wastewater Treatment

Fabrication and Characterization of Polyphenylsulfone/Titanium Oxide Nanocomposite Membranes for Oily Wastewater Treatment

Preparation of superhydrophilic poly(acrylonitrile/acrylic acid) electrospun membrane and its application in oil/water separation

Copolymer consisting of acrylonitrile (AN) and acrylic acid (AA) segments with different molar ratios were synthesized via a mixed-solvent precipitation polymerization method. The prepared polymer was then applied to fabricate nanofiber membrane via electrospinning technique. It was found that when the molar ratio of AN/AA was 80/20, the resultant membrane presented outstanding hydrophilicity with a water contact angle of 0° and water adsorption ratio of 17.10. In addition, the breaking force of optimized membrane was increased by more than 60% when comparing with those of pure PAN homopolymer counterpart due to the hydrogen bonding interaction resulting from the carboxyl groups in AA chain segments. The developed membrane possessed fascinating underwater oleophobicity with oil contact angle over 150° and could effectively separate oil/water mixture and oil-in-water emulsion with excellent separation efficiency beyond 95%, ascribing to the hydration layer on the membrane surface and size-sieving effect arising from the multi-scale pore size in the material. The current study provides a novel insight into the fabrication of hydrophilic membrane for oily wastewater treatment for practical applications.

An Overview of Recent Progress in Nanofiber Membranes for Oily Wastewater Treatment.

Oil separation from water becomes a challenging issue in industries, especially when large volumes of stable oil/water emulsion are discharged. The present short review offers an overview of the recent developments in the nanofiber membranes used in oily wastewater treatment. This review notes that nanofiber membranes can efficiently separate the free-floating oil, dispersed oil and emulsified oil droplets. The highly interconnected pore structure nanofiber membrane and its modified wettability can enhance the permeation flux and reduce the fouling. The nanofiber membrane is an efficient separator for liquid–liquid with different densities, which can act as a rejector of either oil or water and a coalescer of oil droplets. The present paper focuses on nanofiber membranes’ production techniques, nanofiber membranes’ modification for flux and separation efficiency improvement, and the future direction of research, especially for practical developments.

Tannic acid (TA)-based coating modified membrane enhanced by successive inkjet printing of Fe3+ and sodium periodate (SP) for efficient oil-water separation

Wettability of membrane is of vital importance for treatment of oily wastewater. In recent years, hydrophilic modifications based on plant polyphenol have been widely investigated to enhance the anti-fouling property of membranes due to their mild conditions, versatility and low cost. However, there are still some problems in improving raw material utilization and hydrophilicity. Herein, a facile method was proposed to optimize tannic acid (TA)-based membrane modification process by synergistically inducing TA deposition by Fe3+ and SP with the assistance of inkjet printing. The hydrophobicity of polyvinylidene fluoride (PVDF) membrane was converted to hydrophilicity (WCA = 34.6°) and underwater oleophobicity (UOCA = 144.4°) in very short time (10 min). The optimum PVDF/Fe-TA-SP422 membrane possessed high flux (4968.4–7340.4 L m−2 h−1·bar−1) for a number of oil/water emulsions with high separation efficiency (>98%), outperforming most state-of-the-art membranes for oil-water separation. Furthermore, the optimized membrane displayed not only high antifouling property and reusability with flux recovery ratio of 89.1%–98.0% after eight-cycle filtration, but also desired stability under near neutral pH conditions during long-term running. The combination of inkjet printing method with these materials proposed in this study is convenient, efficient and low cost, and the prepared membranes are versatility, providing novel insights into preparation of high efficiency membranes for oily wastewater treatment.

Synergistic effect of GO@SiO2 and GO@ZnO nano-hybrid particles with PVDF-g-PMMA copolymer in high-flux ultrafiltration membrane for oily wastewater treatment and antifouling properties

In the Ultrafiltration (UF) region, the development of the membranes with ultra-water permeability and extraordinary oil rejection at the same time is highly desirable. Herein, a copolymer/nano-hybrid particles mixed matrix membrane was fabricated with high hydrophilicity and oil-in-water separation performance, originating from the synergistic effect between the prepared copolymer and nanoparticles. Accordingly, atom transfer radical polymerization (ATRP) method, especially considered as a promising grafting technique to modify polyvinylidene fluoride (PVDF), was utilized for the synthesis of the PVDF-g-PMMA copolymer. Furthermore, two different nano-hybrid particles including graphene oxide (GO) sheets separately decorated with ZnO and SiO2 were also synthesized. Then, different membrane compositions with various GO@ZnO and GO@SiO2 contents were fabricated, and then, the synergistic effect of each nano-hybrid particle with the PVDF-g-PMMA copolymer was evaluated. The prepared GO@ZnO and GO@SiO2 were used not only to modify ultrafiltration (UF) membranes for oil rejection but also to prevent protein BSA adsorption on the membrane surface based on their surface charge. The 4 wt.% PVDF-g-PMMA/0.3 wt.% GO@SiO2 and 4 wt.% PVDF-g-PMMA/0.3 wt.% GO@ZnO membranes provided outstanding separation performance (soybean oil rejections of 93.4% and 95.2%, respectively) and ultra- water permeability (312 and 326 L/m2.h.bar, respectively). Based on the results in terms of separation and filtration performances, the M5 membrane exhibited more efficient performance than M4 membrane. By increasing the amount of nano-hybrid particles, the overall finger-like voids, average pore size, and surface roughness of membranes decreased, making them ideal for application in the water treatment field. Also, the influence of hydrophilicity and charge density of GO@ZnO and GO@SiO2 nano-hybrid particles with the copolymer in the PVDF membrane was examined through conducting the antifouling experiment in two different pH values, in which a great performance was also obtained. Compared to previous researches, GO@ZnO and GO@SiO2 nano-hybrid particles with the copolymer in the PVDF membrane not only can generate ultra-high water permeability in low pressure but also provide >93% oil-in-water emulsion rejections.

State-of-the-Art Ceramic Membranes for Oily Wastewater Treatment: Modification and Application.

Membrane filtration is considered to be one of the most promising methods for oily wastewater treatment. Because of their hydrophilic surface, ceramic membranes show less fouling compared with their polymeric counterparts. Membrane fouling, however, is an inevitable phenomenon in the filtration process, leading to higher energy consumption and a shorter lifetime of the membrane. It is therefore important to improve the fouling resistance of the ceramic membranes in oily wastewater treatment. In this review, we first focus on the various methods used for ceramic membrane modification, aiming for application in oily wastewater. Then, the performance of the modified ceramic membranes is discussed and compared. We found that, besides the traditional sol-gel and dip-coating methods, atomic layer deposition is promising for ceramic membrane modification in terms of the control of layer thickness, and pore size tuning. Enhanced surface hydrophilicity and surface charge are two of the most used strategies to improve the performance of ceramic membranes for oily wastewater treatment. Nano-sized metal oxides such as TiO2, ZrO2 and Fe2O3 and graphene oxide are considered to be the potential candidates for ceramic membrane modification for flux enhancement and fouling alleviation. The passive antifouling ceramic membranes, e.g., photocatalytic and electrified ceramic membranes, have shown some potential in fouling control, oil rejection and flux enhancement, but have their limitations.

Enhanced separation performance of microfiltration carbon membranes for oily wastewater treatment by an air oxidation strategy

An air oxidation strategy was developed for the first time to modify the microstructure and separation performance of microfiltration carbon membranes (MFCMs) for oily wastewater treatment. The structure and property of MFCMs were characterized by the techniques of Fourier transform infrared spectroscopy, scanning electron microscope, pore size distribution, porosity, X-ray diffraction, nitrogen adsorption and water contact angle. The results have shown that the oxidation can effectively modulate the porous structure, surface property and separation performance of MFCMs by varying air oxidation temperature and holding time. The optimal separation performance was respectively achieved to 554.5 kg m−2 h−1 for water permeation flux and 99.0% for oil rejection when MFCMs were oxidized at 80 °C for 30 min. Meanwhile, the anti-fouling ability of MFCMs was substantially improved by two-fold for the flux recovery ratio after oxidation modification. In brief, the work has been proved that the air oxidation is one of the most promising strategies for tailoring MFCMs to efficiently remove the emulsified oil from wastewater.

Fabrication and evaluation of a biopolymer-based nanocomposite membrane for oily wastewater treatment

In recent years, discharging a large amount of untreated oily wastewater has become an environmental issue because of the hazardous nature of its oil contents. Membrane separation can be considered an effective method for the treatment of these types of effluents. In this study, polymeric membranes were synthesized to separate oil/water emulsion in Esfahan’s Mobarakeh steel company’s effluent, Iran. The membranes were prepared based on polylactic acid (PLA) physically blended with Polybutylene succinate (PBS), polypropylene carbonate (PPC), and polyhydroxybutyrate (PHB) biopolymers with and without silica nanoparticles (SNPs). Prepared membranes were characterized using methods such as atomic force microscopy (AFM), field emission scanning electron microscopy (FE-SEM), thermogravimetric analysis (TGA), and X-ray diffraction analysis (XRD). An experimental membrane module was also made to evaluate the filtration separation performance of membranes. The results showed that the membranes have suitable properties such as porosity and thermal stability. The membrane containing SNPs showed better separation performance, so that the amount of oil&grease (O&G), manganese, iron, total dissolved solids (TDS), and turbidity in the feed, were removed by 98.6%, 14.17%, 22.56%, 11.33%, and 89.15% respectively, using this membrane.

Novel silica sand hollow fibre ceramic membrane for oily wastewater treatment

Hollow fibre ceramic membranes are well-known to have unique characteristics, including superior thermal, chemical, and mechanical stabilities. The main drawback of ceramic membranes that limits their commercialisation is their high cost of raw materials. To overcome this disadvantage, a low-cost silica sand-based hollow fibre ceramic membrane (SS-HFCM) was successfully fabricated via combined phase inversion/sintering technique. Prior to fabrication, silica sand powder was first characterised using X-ray fluorescence (XRF), X-ray diffraction (XRD), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET), and Fourier transform infrared spectroscopy (FTIR) analyses. Furthermore, the morphology and mechanical strength were investigated using scanning electron microscopy (SEM) and three-point bending test, respectively. The effects of two major fabrication process parameters (i.e., sintering temperature and ceramic content) on the mechanical strength, morphology, pure water flux (PWF), and oily-water separation of the SS-HFCM were examined. Based on the findings, the most suitable sintering temperature was 1300 °C. Satisfactory morphological structure and strength of sponge- and finger-like voids at 55 wt% ceramic powder loading was found to be advantageous for the characteristics of the fabricated SS-HFCM. The mechanical strength of 210 MPa was obtained at the sintering temperature and content loading of 1300 °C and 57.5 wt%, respectively. The mechanical strength of SS-HFCM obtained at 1300 °C in this work is significantly higher than those reported in previous studies. Furthermore, enhanced oil-water separation performance was obtained with the highest oil rejection rate of 99.7%. This SS-HFCM has a satisfactory structure with functional inner and outer layers of separation, which can be beneficial for water treatment applications, such as microfiltration, ultrafiltration, membrane distillation, and membrane contactor.

PES electrospun fibrous membrane for oily wastewater treatment: Fabrication condition optimization using response surface methodology

Dependence of the polyethersulfone electrospun fibrous membrane (EFM) performance on direct and interactive effects of electrospinning parameters and post heat‐treatment conditions were studied using RSM technique. A designed number of 29 EFM samples with different average fiber thickness and average pore radius were prepared. Modified quadratic models were developed based on the experimental results to predict the membrane performance in oil‐in‐water (O/W) emulsion separation. The low error of permeation flux (7.6%) and oil rejection (11.3%) models guaranteed accuracy of the modeling results. The optimum values of the studied parameters resulting in the membrane with promising performance, including polymeric solution flow rate, hot‐pressing duration, temperature, and pressure were 0.8 mL/h, 1.5 hours, 210°C, and 0.14 bar, respectively. The polymeric solution flow rate and hot‐pressing temperature were found as the most effective parameters on water permeation flux and oil rejection, respectively. The maximum predicted permeation flux and oil rejection of this EFM were 708 LMH and 89%, respectively.

Fabrication of blend hydrophilic polyamide imide (Torlon®)-sulfonated poly (ether ether ketone) hollow fiber membranes for oily wastewater treatment

Blend hydrophilic polyamide imide (PAI)-sulfonated poly (ether ether keton) (SPEEK) hollow fiber membranes were fabricated for oil-water emulsion separation. The structure and performance of the membranes were examined by FESEM analysis, N2 permeation, overall porosity, collapsing pressure, water contact angle, pure water flux, molecular weight cutoff (MWCO), and oil rejection tests. By studying ternary phase diagrams of polymer/solvent-additive/water system, the higher phase-inversion rate was confirmed for the solutions prepared at higher PAI/SPEEK ratio. A more open structure with larger finger-likes was observed by increasing PAI/SPEEK ratio. Mean pore size of 81 nm, overall porosity of 79% and water contact angle of 58° were obtained for the improved membrane prepared by PAI/SPEEK ratio of 85/15. Increasing SPEEK ratio resulted in lower mechanical stability in terms of collapsing pressure. Pure water flux of about 2.5 times of the plain PAI membrane was found for the improved membrane. MWCO of 460 kDa was found for the improved blend membrane. From oil rejection test, all the membranes demonstrated an oil rejection of over 95%. The improved membrane showed a lower rate of permeate flux reduction compared to the plain membrane which was related to the smaller fouling possibility. Less fouling resistance of the improved membrane was related to the higher flux recovery ratio (about 92%). For all the membranes, the dominant fouling mechanism was found to be the cake filtration. The improved PAI-SPEEK hollow fiber membranes was found to be practical for ultrafiltration of oily wastewaters.