Membranes For Wastewater Treatment Research Articles

Simultaneous enhanced antibiotic pollutants removal and sustained permeability of the membrane involving CoFe2O4/MoS2 catalyst initiated with simple H2O2 backwashing

Membranes for wastewater treatment should ideally exhibit sustainable high permeate production, enhanced pollutant removal, and intrinsic physical rejection. In this study, CoFe2O4/MoS2 serves as a non-homogeneous phase catalyst; it is combined with polyether sulfone membranes via liquid-induced phase separation to simultaneously sustain membrane permeability and enhance antibiotic pollutant degradation. The prepared catalytic membranes have higher pure water flux (329.34 L m−2 h−1) than pristine polyethersulfone membranes (219.03 L m−2 h−1), as well as higher mean pore size, porosity, and hydrophilicity. Under a moderate transmembrane pressure (0.05 MPa), tetracycline (TC) in synthetic and real wastewater was degraded by the optimal catalytic membrane by 72.7 % and 91.2 %, respectively. Owing to the generation of the reactive oxygen species (ROS) during the Fenton-like reaction process, the catalytic membrane could exclude the natural organics during the H2O2 backwash step and selectively promote fouling degradation in the membrane channel. The irreversible fouling ratio of the catalyzed membrane was significantly reduced, and the flux recovery rate increased by up to 91.6 %. A potential catalytic mechanism and TC degradation pathways were proposed. This study offers valuable insights for designing catalytic membranes with enhanced filtration performance.

Study of novel Zn-MOF-II modified polymeric membrane in wastewater treatment containing oily waste and humic acid (NOM)

ABSTRACT The prime objective of the present work was to synthesise the polymeric membrane with Zn-MOF-II nanoparticles using the phase inversion method to purify oily wastewater and NOM. The dead-end filtration system was utilised to analyse the performance of fabricated membranes (without and with Zn-MOF-II), various feeds of 100 ppm concentration used, such as organic pollutants and oil effluent at 250 kPa and atmospheric temperature conditions. The following study involves the compaction factor, pure water flux, all mixed matrix membrane permeability, humic acid rejection, and oil–water emulsion rejection, contact angle, and liquid–liquid displacement porosimetry (LLDP). Scanning electron microscopy (SEM) and Fourier transforms infrared spectroscopy-attenuated total reflection (FTIR-ATR) goniometer were used to characterise the polymeric membranes. The FTIR-ATR spectra of the modified membrane exhibit a characteristic peak between 2,900 and 3,000 cm−1 associated with the presence of the –COOH group. The nanoparticles and polymer matrix were well compatible, as evidenced by SEM images of the polymeric membrane containing Zn-MOF-II nanoparticles. The maximum value of percentage rejection of oily wastewater (above 88.89%) and humic acid (above 86.88%) was obtained for the polymeric membrane containing Zn-MOF-II nanoparticles.

Chemistry of zeolites and zeolite based composite membranes as a cutting-edge candidate for removal of organic dyes & heavy metal ions: Progress and future directions

The quality of water has become a serious concern due to excessive industrial effluent production and poor wastewater treatment Membrane technology has received immense attention due to its mild operating conditions, and highly efficient process. Polymer-based membranes are generally applied in various separation operations for their highly reproducible fabrication and low-cost approaches. Fouling aspects and the trade-off between selectivity and permeability are the main disadvantages of polymeric membranes. In this regard, zeolites are an attractive and promising candidate with 3D crystalline microporous systems, large and medium pore molecular sieves, low-cost, and due to their distinct framework considered potential ceramics membranes for water treatment. Incorporating inorganic zeolite particles into the polymer matrix improves permeability while maintaining selectivity, and promotes mechanical strength in challenging environment and fouling conditions. Zeolite-based composite membranes can remove heavy metals and dye effluents from the aqueous medium thanks to their high adsorption capability and well-defined pore size. In this review, we focused on the significance of membranes in water treatment, structural/chemical features of zeolite-based membranes, their design, the various strategies involved in integrating zeolites to obtain composite based membranes, an overview of toxicity issues of dyes, heavy metals followed by an exploration of zeolite based composite membranes for the treatment of various dyes and heavy metal pollutants. Also, we tried to provide a cost analysis of zeolite-based membranes followed by commercial and industrial outlooks. Lastly, conclusions and future perspectives drawn for the zeolite-based composite membranes.

Carboxylic acid modulated in situ growth of Zr-based MOFs on carboxylated cotton fabrics for removal of Cr(VI) from aqueous solutions

In this paper, carboxylated cotton fabric (CF-Ph-COOH) were obtained as active substrate by diazonium radical polymerization modification of cotton fibers. Then the MOF fabric composites were prepared by in situ growth of metal zirconium ions (Zr) and organic ligands on the surface of carboxylated cotton fabrics under carboxylic acid modifier. MOF fabric composites with controllable morphologies structures were achieved by regulating organic ligands, reaction time the type and dosage of regulator (formic acid and acetic acid). The prepared acetic acid regulated MOF fabric composites were designated as CF-HAc1-UiO-66, CF-HAc2-UiO-66, CF-HAc1-UiO-66-NH2, and CF-HAc2-UiO-66-NH2, respectively, and the formic acid regulated as CF-FA-UiO-66 and CF-FA-UiO-66-NH2. The fabricated carboxylic acid modulated MOF fabric composites were well characterized using SEM, TGA, XRD, FTIR, and XPS spectra. The adsorption experiment results show that carboxylic acid modulated Zr based MOF fabric composites can serve as adsorbent for effective removal of Cr(VI) from water, in which the CF-FA-UiO-66-NH2 was prepared under the ratio of ZrCl4 and BDC-NH2 is 1.006 and with 5.47 M formic acid regulator exhibits that the optimal adsorption efficiency and the removal efficiency is 79.5 %. In addition, the adsorption of Cr(VI) in water by CFA-UiO-66-NH2 showed a quasi-secondary kinetic model following the Langmuir adsorption model, showing a a typical of chemisorption. What’s more, the Cr(VI) removal efficiency and saturated adsorption capacity of CF-FA-UiO-66-NH2 was up to 80 % and 318.85 mg/g, respectively. The prepared CF-FA-UiO-66-NH2 MOF fabric composite was recyclable for removal of Cr(VI), and could be used as the potential adsorbent membrane for waste water treatment.

Computational analysis of MOF-functionalized polymeric membranes for wastewater treatment and applications

Contaminants in drinking water can cause several health issues. In this study, solution cast technology was used to create polycaprolactone (PCL) or graphene nanocomposite membranes with diameters ranging from 2 to 6 m. The industry of water purification has benefited greatly from the use of membrane separation processes. The membranes are also made of biocompatible, non-toxic, and environmentally friendly materials. We utilized PCL polymer solution that was dissolved in chloroform to create membranes, and we added graphene to the PCL polymer solution. Quantum espresso software was used to determine the band structure, DOS, and Fermi-energy. The results of this study’s inducible tests suggested that solution-cast PCL and polycaprolactone or graphene membranes might be a good choice for removing waste from water. According to the biological sensing component (enzymes, antibodies, entire cells, aptamers, tissues, molecularly imprinted polymers (MIPs) and DNA) or transducers (optical, electrochemical, piezoelectric, and thermal), biosensors are analytical devices. The transducer produces a signal corresponding to the concentration of the analyte when the target analyte interacts with the biological sensing component. A signal processor is used to boost the signal and display it. The industrial utilizations of Metal-Organic Frameworks (MOFs) have been a growing area of interest in recent years. Researchers are exploring the use of MOFs in various industrial applications such as gas storage, catalysis, drug delivery, and sensing.

Advanced microcrystalline nanocellulose-based nanofiltration membranes for the efficient treatment of wastewater contaminated with cationic dyes

Advanced microcrystalline nanocellulose-based nanofiltration membranes for the efficient treatment of wastewater contaminated with cationic dyes

TiO2/AgBr nanocomposite as a novel hydrophilic and photocatalytic modifier in the fabrication of polyethersulfone membrane for wastewater treatment

Enhancing the performance of filtration membranes to improve their antifouling, permeability, and stability is a crucial objective. This can be acquired through the development of innovative materials and methods. With this in mind, the exertion of novel materials is considered a promising approach for modifying polymeric membranes. This study focuses on the potential of incorporating TiO2/AgBr photocatalytic nanocomposites to improve the hydrophilicity, antifouling, and permeability of polyethersulfone (PES) membranes. Following the synthesis of TiO2/AgBr, the study examines its impact on the performance of PES membranes by introducing various concentrations of TiO2/AgBr nanocomposite. Notably, the water contact angle significantly decreases from 68.5° to 44.2°, indicating an improvement in hydrophilicity. This enhanced overall porosity leads to almost a twofold increase in pure water permeability, with the bare membrane registering 78.3 L/m2h.bar and the membrane containing 0.2 wt% TiO2/AgBr achieving 152.4 L/m2h.bar. Due to the photocatalytic activity of TiO2/AgBr, the modified membranes demonstrate promoted antifouling performance, when UV irradiation is used in the washing step of the fouled membranes, as evidenced by the increased flux recovery ratio values, rising from 48 to 60.6 %. The rejection of two different dyes was assessed and the results of 83.9 % and 95.2 % rejection were obtained for Reactive Black 5 (RB5) and Lanasol Red 6G, respectively. Furthermore, the antibacterial activity of TiO2/AgBr was also indicated by confocal microscopy analysis. Thus, embedding TiO2/AgBr not only enhances antifouling properties but also improves the membranes’ ability to reject dyes effectively.

Constituents of Coliform Species Contained in the Permeate of Microfiltration Membranes in Wastewater Treatment

MBRs (Membrane bioreactors) have been increasingly employed for municipal and industrial wastewater treatment in the last decades for their small footprint and excellent effluent quality. However, microorganisms are often detected in the permeates of microfiltration (MF) membranes even with small pore sizes. Coliform bacteria are known for indicating the potential presence of pathogenic bacteria that cause infectious disease such as bacteremia, respiratory tract infections, and urinary tract infections. Thus, the retention of coliform bacteria by membrane processes is important when the membrane process is utilized in water reclamation. In this study, a microbial community of coliform bacteria in the permeates of MF membranes with different pore sizes (0.2, 0.4, and 0.8 µm) was identified. The results showed that the dominant coliform bacteria changed from Enterobacter spp. and Citrobacter spp. in the activated sludge to Enterobacter spp. and Klebsiella spp. in the permeate of MF membranes, while some pieces of membranes showed complete retention. The bacterial regrowth on the surface of the piping system on the permeate side could be a significant factor contributing to the frequent and exclusive detection of Enterobacter spp. and Klebsiella spp. in the case of membranes with small pore size (0.2 and 0.4 µm) after a long continuous filtration time. To indicate the public health-related risk of treated wastewater by MF, Escherichia coli may not be a suitable indicator species because E. coli is relatively retentive in MF compared to other coliforms.

Environmental remediation and the efficacy of ceramic membranes in wastewater treatment—a review

Environmental remediation and the efficacy of ceramic membranes in wastewater treatment—a review

Facile fabrication of MOF-based composite membranes with liquid crystal ordered microstructure for effective dyes separation

High-performance membranes for effective dye/water separation are urgently desired in chemical industrial manufacture, and Metal-organic frameworks (MOFs) with abundant microporous structures are considered suitable candidates for fabricating separation membranes. However, for MOF-based membranes, maintaining superior separation efficiency while ensuring high water flux remains a challenge. In this study, a series of novel MOF-based composite materials (TFNs) and membranes oriented by electric fields (fio-TFNs) were fabricated using NH2-MIL-53(Fe), a thermotropic liquid crystal, poly (styrene-4-sulfonic acid), and polytetrafluoroethylene. The fio-TFN membranes exhibited characteristics of orientation and uniform distribution, and showed higher water flux and dye rejection compared with ordinary TFN membranes. This highlights the significant role played by the ordered orientation of liquid crystal molecules induced by the electric field in effective dye/water separation. High porosity is the basis of dye absorption, and the electrostatic interaction among structural charges and dyes is the dominant driving forces in these dye/water separation systems. The prepared fio-TFN membranes exhibited excellent performance in effective dye separation. For instance, the fio-TFN-1 membrane demonstrated high water flux (up to 255.9 L·m−2 h−1 bar−1) and excellent dye rejection rates (≥97 %, 92 %, and 82 % for methyl blue, congo red, and rhodamine B, respectively). Moreover, these prepared membranes exhibited excellent long-term stability, reusability, and flexibility, indicating their potential as high-performance separation membranes for wastewater treatment.

Characterization of novel solar based nitrogen doped titanium dioxide photocatalytic membrane for wastewater treatment

The increasing presence of microbial and emerging organic contaminants pose detrimental effects on the environment and ecosystem such as diseases, pandemics and toxicity. Most of these synthetic pollutants are biorecalcitrant and therefore persist in the environment. Conventional water treatment methods are not effective thereby necessitating the development of advanced techniques such as photocatalysis and membrane processes. In this study, visible light-driven photocatalytic membrane was synthesized through the immobilization of nitrogen-doped nanoparticles onto the polyvinylidene fluoride (PVDF) membrane and performance evaluated with E.coli microbial contaminant removal. Characterization was done using Fourier transform infrared spectra, X-ray diffraction (XRD), water contact angle, Scanning Electron Microscopy-Energy Dispersive X-ray (SEM-EDX). The Nitrogen-doping of titanium dioxide red-shifted the light absorption to a visible range of 440 nm from 400 nm. Nitrogen dopant was detected at 1420 cm−1and 1170 cm−1 for nitrogen doped nanoparticles and 1346-1417 cm−1 for nitrogen doped titanium dioxide PVDF membrane. SEM-EDX confirmed presences of nitrogen in nitrogen doped titanium dioxide nanoparticles on membrane surface with nitrogen elemental composition of 0.01 % wt. The water contact angle reduced by 81.39o from 120.14o to 38.75o because of PVA immobilization of nitrogen-doped titanium dioxide and glutaraldehyde crosslinking. Nitrogen doping resulted in visible light active photocatalytic membranes with better hydrophilicity and fouling resistance. 8.42 E.coli log removal and a relative flux of 0.35 was obtained within 75 min. The developed photocatalytic membrane enables the use of sunlight hence a less costly method for decontamination of wastewater.

Anthropogenic gadolinium sources and remediation in highly urbanized river in the Beijing-Tianjin-Hebei (BTH) region, China: Insights from buffer zone and three-dimensional tracer system

As a newly emerging microcontaminant, rare earth elements (REEs), especially gadolinium (Gd) in surface water, are attracting great environmental concern in large urban cities. The Beijing-Tianjin-Hebei (BTH) region stands as the preeminent urban agglomeration in northern China, whereas the riverine Gd characteristics and environmental impacts on this region remain inadequate. This study analyzed 27 river water samples in BTH, all of which displayed evidently positive Gd anomalies ranging 1.44–290.75. Spearman correlation indicated the positively correlated REEs concentrations in river water with urban land and cultivated land. A three-dimensional tracing system was established involving anthropogenic Gd (Gdanth) and conventional ion ratios (NO3−/Na+, Cl−/Na+). This system effectively discerned the influences originating from sewage treatment plants, wastewater treatment plants, hospitals, and factories within the BTH region. Gd-based contrast agents (GBCAs) manifest notable potential ecological toxicity and adverse health effects when getting exposed. However, traditional wastewater treatment methods demonstrate limited efficacy in removing these pollutants completely from urban water. To deal with this challenge, this study proposed a new method by combining the latest GBCAs remediation technology with mixing membrane wastewater treatment. This technology may shed light on the potential of an economical and operational procedure of handling medical wastewater specifically in urban water.

Mesoporous silica-grafted deep eutectic solvent-based mixed matrix membranes for wastewater treatment: Synthesis and emerging pollutant removal performance

Abstract Nano-enhanced membrane technology and deep eutectic solvents (DESs) have demonstrated effectiveness in addressing emerging environmental pollutants. This research centers on purifying water by removing heavy metals employing membranes enhanced with mesoporous silica and DES. Various DESs, including hexanoic acid, octanoic acid, and decanoic acid, were synthesized using tetrabutylammonium bromide (TBABr) as a base. The study combined a polysulfone-based membrane with mesoporous silica, aiming for efficient indigenous crafting to remove heavy metals. Mesoporous silica was blended with the synthesized DES solution, creating diverse membranes for heavy metal separation. The study characterized these membranes using various techniques such as scanning electron microscopy, atomic force microscopy, energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, and contact angle measurements. Surface mapping confirmed the integration of silicon-based DES, reducing the membrane surface roughness from 4 to 1.4 nm. By adjusting the carboxylic acid chain length with TBABr and adding mesoporous silica, leaching ratios were reduced from 4.2 to 2.3%. Silica-grafted DES-based membranes exhibited a progressive increase in flux from 2.6 to 26.67 L/m2 h. The synthesized silicon-based membranes demonstrated outstanding performance, achieving rejection rates exceeding 80% for chromium and arsenic, maintaining an impressive 90% flux recovery ratio even at high flux rates. This study will envision the potential of nano-enhanced membrane technology utilizing DES for sustainable water purification and wastewater treatment applications to achieve the sustainable development goal (SDG) of clean water and sanitation (SDG-6).

A synergistically enhanced photocatalytic 2D MXene nanofibrous composite membrane for wastewater treatment

Despite notable advancements in membrane technology, the efficacious separation of intricate oily wastewater via membrane filtration continues to pose formidable barriers for the industry. Recent methods, encompassing the integration of two-dimensional (2D) nanosheets to improve membrane properties, have demonstrated a propensity for encountering challenges like swelling, fouling, and operational instability during the filtration process. Herein, we meticulously designed a polyvinylidene fluoride (PVDF) nanofibrous membrane (NFM) tailored with a 2D nanostructured composite of MXene nanosheets and TiO2 nanofrost for the pioneering treatment of intricate oily wastewater. The resultant membrane exhibited remarkable separation performance concerning surfactant-stabilized emulsions while maintaining excellent water permeability. Additionally, the membrane demonstrated outstanding antifouling and self-cleaning capabilities while also showing high efficiency in removing metal cations from oily wastewater, which may be related to the intercalation of TiO2 nanofrost. Furthermore, in response to the synergistic impact of MXene nanosheets and TiO2 nanofrost, the TiO2@MX-PVDF NFM presented exceptional photocatalytic degradation ability for the breakdown of organic pollutants under visible irradiation. Consequently, present work unveils an advanced, reliable and remarkably efficient approach for developing a 2D multifunctional MXene composite membrane designed specifically for treating complex oily wastewater.

One-step fabrication of asymmetric alumina ceramic membranes with tunable pore parameters for oil-water separation

Porous ceramic membranes with low-cost and high performance are desirable in industrial filtration field. To improve the performance while reducing the production cost, various measures were developed, however, pre-sintering of supports, preparation of membrane-forming suspensions and adoption of extensive organic additives that involved were adverse to cost reduction. Herein, cost-effective one-step co-pressing and co-sintering technique was proposed to prepare asymmetric ceramic membranes. The results revealed that pore parameters and performance of the fabricated membranes could be adjusted by altering mole ratio of Al2O3 to SiO2 (Al2O3/SiO2) in the support and sintering temperature. The influence of supports on the permeation flux of membranes surpassed that of the parameters of membrane layer. Additionally, the oil rejection rate of the membranes exceeded 96 % within 2 min and even reached 100 % (~60 min), the water flux and steady-state feed flux were 1330–1730 L·m−2·h−1 and 470–620 L·m−2·h−1 at 1 bar, respectively. Moreover, cake filtration was the main fouling mechanism throughout the separation process. This research provides a feasible and simple method for preparing low-cost high-performance ceramic membrane for wastewater treatment.

Inhibition of Quorum Sensing to Mitigate the Risks of Membrane Biofouling in Biological Wastewater Treatment

Membrane-based systems play a pivotal role in various applications, providing efficient separation, purification, and filtration processes across diverse industries such as water purification and desalination. However, this system faces major challenge of membrane biofouling impacting the efficiency and sustainability of such systems. Biofouling occurs when various microorganisms like bacteria, fungi, etc. adheres to the surface of membrane and form biofilm which results in reducing membrane permeability and increasing its operational cost. Various physical, chemical and biological strategies are known to prevent biofouling. Inhibition of quorum sensing is a recent trend based on the researches that shows quorum sensing as an integral part of biofilm formation. Bacteria’s uses cell to cell communication mechanisms known as Quorum sensing, plays an important role in formation of virulence factors, biofilm. It is regulated by quorum sensing signalling molecules known as autoinducers like Autoinducing peptides, acyl homoserine lactones, Autoinducer-2. Various strategies can be adopted to inhibit quorum sensing: inhibition of Autoinducer synthase which is responsible for synthesizing autoinducers; inhibition/degradation of autoinducers and interfering with signal receptors. This article provides deeper knowledge of Quorum sensing (QS), methods of QS inhibition: Quorum quenching which involves the enzymatic degradation of QS signaling molecules, and the use of Quorum sensing inhibitor compounds in preventing membrane biofouling are discussed in detail. This article delves into the potential of disrupting quorum sensing pathways to prevent or reduce biofilm formation, thereby enhancing the performance and longevity of membranes in wastewater treatment. The mitigation of biofouling can revolutionize membrane-based systems, ensuring their sustainability and efficacy in water treatment processes

Measuring the Thickness of Fiber Mats Using Light Transmittance via Image Processing

Fiber materials possess unique properties, including a large active surface area, high surface-to-volume ratio, high porosity, high mechanical performance, and low density. Consequently, they serve as key components in various applications such as energy production and storage cells, batteries, wastewater treatment membranes, sensors, drug-releasing band-aids, and protective clothing. Electrospinning is a simple and versatile method for producing fiber materials. Despite its simplicity in terms of working principles, it faces challenges in achieving homogeneous thickness (evenly on the entire surface) throughout fiber mats due to inherent bending instability during the process. Non-uniform thickness not only diminishes the efficiency of these mats in applications but also adversely impacts their mechanical functionality. In this study, the aim is to develop a thickness measurement system based on image processing and the principle of light transmittance as a solution to the issues encountered in achieving uniform thickness and thickness control of fiber mats produced by electrospinning devices. To accomplish this, a closed mechanism with a light-impermeable encapsulation method was established. Various fiber mats, produced at different times were placed on the acetate floor built on LED lighting on the base of the mechanism. Using a camera with the adjusted settings positioned at the focal point on top of the mechanism, images of the fiber mats were captured, and image processing techniques were employed to determine threshold value ranges for the mat thicknesses. The actual thicknesses of the fiber mats were verified using an optical microscope, revealing that regions defined with the same color in different samples exhibited similar thicknesses.

Electrochemical synthesis of ultra-flexible PES/HKUST-1 composite membranes for wastewater treatment

Electrochemical synthesis of polymer/MOF composite membranes holds great potential for practical applications, yet the preparation of flexible and dense MOF layers remains a challenge, which is crucial for achieving practicality. Herein, a novel ultra-flexible polyethersulfone (PES)/Cu-based metal–organic framework (HKUST-1) composite membrane has been fabricated via an electrochemical synthesis method. Various reaction conditions, including voltage, stirring speed, and reaction time, were systematically investigated to elucidate their influence on crystal growth and the resulting membrane uniformity. The characterization results showed that high voltage and moderate stirring as well as are conducive to obtaining uniform fine crystals. Additionally, a relatively extended reaction time is advantageous for achieving a more continuous and denser MOFs membrane with outstanding flexibility. The optimized membrane possesses an excellent separation flux (2.81 × 103±32 L m−2 h−1·bar−1) and efficiency (99.7 ± 0.3%) for n-hexane/water mixtures, as well as excellent photodegradation efficiency (>99%) for methylene blue (MB). Remarkably, the optimized membrane exhibits remarkable scalability and stability, maintaining superior separation performance even after being rolled up 10 times with a curvature of 200 m−1. This suggests that it has great potential for practical applications in complex environments.

Preparation of CuO-PdO-Pd/Ti electrocatalytic membrane and its performance in treating oily wastewater

Developing multifunctional, efficient, and long-lasting membranes for long-term use in treating complicated oily wastewater is highly desirable, but it remains a challenge due to severe membrane fouling and the difficulty of separating contaminants smaller than the membrane pores. In this work, we fabricate a CuO-PdO-Pd/Ti membrane with self-cleaning for small sized pollutants removal by introducing electrocatalytic oxidation to membrane filtration. In order to improve the electrocatalytic performance of the membrane, we prepared a high-performance CuO-PdO-Pd electrocatalyst-coated Ti-based electrocatalytic membrane by introducing the Pd、PdO into CuO. The prepared CuO-PdO-Pd/Ti membrane (CuO-PdO-Pd/Ti) has superior removal ability over the original Ti membrane (Ti) and the conventional CuO/Ti membrane (CuO/Ti). The emulsified oil and COD removal efficiency of the CuO-PdO-Pd/Ti reach 94% and 80.18%, respectively,which are about 1.2–2.15 times and 1.16–1.26 times higher than that of the Ti and the CuO/Ti. Meanwhile, CuO-PdO-Pd/Ti shows higher permeability (13,021 (L m-2 h−1 bar−1)) over Ti (8077 (L m-2 h−1 bar−1)) and CuO/Ti (9829 (L m-2 h−1 bar−1). In addition, CuO-PdO-Pd/Ti has good sustainability because the emulsified oil and COD removal efficiency maintain above 91% and 80% after six repeated tests, respectively. The extensive applicability of the CuO-PdO-Pd/Ti is also proven by the high removal efficiency (all above 82%) when treating real oily wastewater and organic wastewater. Thus, the prepared CuO-PdO-Pd/Ti shows great potential for emulsified oil and small-sized organic pollutants removal with both high permeability and removal efficiency. CuO-PdO-Pd/Ti is high-performance electrocatalytic membrane for wastewater treatment.

ZCS-TiO2 modified bacterial cellulose multifunctional membranes for highly effective and antibacterial oil-water separation

Oil-water separation has given superhydrophilic/underwater superoleophobic (SUS) membrane technology a lot of attention. However, manufacturing multifunctional membranes to meet the complexities of oily wastewater treatment remains a huge challenge. In this work, a multifunctional SUS membrane based on bacterial cellulose (BC) was designed for oil-water separation. ZnCo2S4 (ZCS) was coupled to the surface of TiO2 nanoparticles to form ZCS-TiO2 by the simple hydrothermal synthesis method, and then BC nanofibers were mixed with ZCS-TiO2 to prepare a membrane. Oil/water (o/w) separation is accomplished by the composite membrane at a low drive pressure (0.2–0.3 bar). Its flux is 8232.81 ± 212 L.m−2 h−1, and the separation efficiency can exceed 99.9%. In addition, the composite membrane also has good photocatalytic performance, the degradation rate of 20-BC/ZCS-TiO2 for dye within 2 h was 80%. The composite membrane's antibacterial efficacy against gram-positive and gram-negative pathogens was also investigated at the same time, the BC/ZCS-TiO2 membrane with the lowest content of ZCS-TiO2 reduced the bacterial viability of Staphylococcus aureus and Escherichia coli by 40.32% and 30.64%, respectively. With the increase of ZCS-TiO2 content, the bacteriostatic activity also increased; 20-BC/ZCS-TiO2 completely eradicated both strains (no viable colonies). This work may shed some light on the manufacture of a new generation of multifunctional membranes for wastewater treatment, especially water contaminated with oily wastewater, dyes, and microorganisms.