Modification Of Polymer Membranes Research Articles

Tuning of polymeric membranes to mitigate fouling and removal of dissolved compounds for wastewater treatment: a Review

Wastewater, referred to as sewage, has been a byproduct of human settlement since ancient times. An increase in human activities leads to more wastewater effluents, resulting in higher concentrations of organic compounds, which are harmful to all forms of living organisms and drinking water purposes. Traditional methods cannot satisfy this issue for higher concentrations. The advanced membrane process is an alternative to this conventional method for removing organic compounds and various effluents due to its high permeate quality and less toxicity. Moreover, the modification of polymeric membranes by increasing its content led to a higher flux thereby enhancing the fouling property for effective wastewater treatment. The processes, UF, RO, NF, and FO, ion exchange, MD, and pervaporation, were developed for more robust methods to improve the quality of the environment and lead to higher salt rejection. This review provides an overview of the fabrications, methods and modifications of substrates utilized in different processes with varying modules to achieve a higher flux rate, lowering the fouling. We discuss the materials used for various membrane modules in ceramic membranes under different operating circumstances and the methods to enhance the performance of membrane fouling. This review also aims to track the ongoing research works to broaden different process combinations for further research purposes, showcasing better antifouling performance and maximizing water quality in the future.

A catalytic membrane based on dopamine directional deposition biomimetically induced by immobilized enzyme for dye degradation

Dopamine-assisted deposition technology is widely used in functional modification of polymer membranes due to the advantages such as simple operation, mild reaction, and strong adhesion to materials. Limited by the major defects of spontaneous polymerization in an alkaline environment and non-selective adhesion, it is still challenging to achieve directional deposition, stability, and fast deposition rate at the same time. Herein, inspired by tyrosinase-induced melanin directional deposition on the skin, we present a biomimetic catalysis strategy for the directional deposition of dopamine on the target surface. By immobilizing laccase on the target surface, the oxidative self-polymerization of dopamine can be inhibited, and the biomimetic induced directional deposition on membrane can be achieved. The biomimetic catalytic membrane covered with a uniform and stable laccase-dopamine coating can be used for the degradation of azo printing and dyeing wastewater. Moreover, the degradation efficiency of the catalytic membrane for methyl orange can reach 19.8 μg/min, and the relative activity can still be maintained at about 81% after 6 cycles, showing high catalytic activity and stability.

Influence of Deposition Parameters of TiO2 + CuO Coating on the Membranes Surface Used in the Filtration Process of Dairy Wastewater on Their Functional Properties.

A novel approach of the deposition of two-component coating consisting of TiO2 and CuO on polymer membranes by MS-PVD method was presented in this work. This confirmed the possibility of using thin functional coatings for the modification of polymer membranes. The influence of technological parameters of the coating deposition on the membrane’s structure, chemical composition and functional properties (hydrophilic, photocatalytic and bactericidal properties) were analyzed using SEM. Model microorganism such as Escherichia coli and Bacillus subtilis have been used to check the antibacterial properties. The results indicated that doping with CuO highlights the potential of bactericidal efficiency. The surface properties of the membranes were evaluated with the surface free energy. For evaluating photocatalytic properties, the UV and visible light were used. The filtration tests showed that polymer membranes treated with two-component TiO2 + CuO coatings have a permeate flux similar to the reference material (non-coated membrane). The obtained results constitute a very promising perspective of the potential application of magnetron sputtering for deposition of TiO2 + CuO coatings in the prevention of biofouling resulted from the membrane filtration of dairy wastewater.

Co-deposition of pyrogallol/polyethyleneimine on polymer membranes for highly efficient treatment of oil-in-water emulsion

Poly(vinylidene fluoride) (PVDF) has been widely used in the field of water treatment due to its outstanding chemical tolerance and excellent mechanical strength. However, PVDF membrane often suffers from oil fouling and low flux for separating oil/water emulsions because of low surface energy and strong hydrophobicity. In this work, we propose a bio-inspired biomimetic hydrophilic coating design strategy, in which pyrogallol (PG) and polyethyleneimine (PEI) are used as reactants, and NaIO4 (SP) is used as an oxidant to modify PVDF microfiltration membrane. This strategy realized the conversion of PVDF membrane surface wettability from hydrophobic to superhydrophilic. The membrane structures and performances were investigated by SEM, FT-IR/ATR, XPS, PMI, water contact angle, pure water permeability and oil rejection for toluene-in-water emulsion. The experimental results showed that the membranes deposited with a PG/PEI mass ratio of 1:1 exhibited the best hydrophilicity and water permeation flux. PVDF-PG/PEI-0.2/0.2 was used to treat surfactant-stabilized toluene-in-water emulsion with the highest flux of 1053 L·m−2·h−1 at 0.1 bar and the oil rejection of 98.3%. Moreover, the flux could be wholly restored after simple washing, indicating that the modified PVDF membrane possessed good reusability. Due to the robust adhesion of PG/PEI composite coatings, the proposed strategy for preparing hydrophilic coatings holds significant potentials in the hydrophilic modification of polymer membranes.

Simple approach for the plasma treatment of polymeric membranes and investigation of the aging effect

AbstractThe modification of the surface characteristics after treatment with plasma in polymeric materials, such as the aging phenomenon, calls the attention of research in the area of nonthermal plasma technology. In this work, a direct treatment with dielectric‐barrier discharge plasma was used on the surfaces of ultrafiltration membranes. The measurements of the contact angle with water, attenuated total reflectance accessory, zeta potential, atomic force microscopy and scanning electron microscopy‐MEV were performed on the surfaces to verify changes after plasma treatment and to understand the occurrence and timing of the plasma aging effect. In the analysis of the membrane performance, hydraulic permeation and protein retention tests were performed. The results showed an improvement in wettability and hydrophilic properties in the post‐treated membranes. The study of reversibility/aging of the post‐plasma surface is important for research that deals with the modification of polymeric membranes. Changes in surface morphology, topography and wettability of the membranes were observed up to seven days after treatment, with a tendency to return to the initial characteristics of the membranes.

Microfiltration Membranes Modified with Composition of Titanium Oxide and Silver Oxide by Magnetron Sputtering.

In this work, the authors present the possibility of modification of polymer membranes by TiO2 + AgO coating created by the magnetron sputtering method. The two-component TiO2 + AgO coating can improve and shape new functional properties such as bactericidal and photocatalytic properties. The influence of magnetron power changes on the structure of the membrane was investigated as well. The structure and elemental composition of TiO2 + AgO coatings were analyzed using SEM and EDS technique. All deposited coatings caused a total inhibition of the growth of two investigated colonies of Escherichia coli and Bacillus subtilis on the surface. The photocatalytic properties for membranes covered with oxide coatings were tested under UV irradiation and visible light. The filtration result show that polymer membranes covered with two-component TiO2 + AgO coatings have a permeate flux similar to the non-coated membranes.

State of the art and prospects in the development of proton‐conducting perfluorinated membranes with short side chains: A review

The review is devoted to key problems in the development of modern proton‐conducting membranes for hydrogen power assuming its progress for using in fuel cells working at enhanced temperatures without catalysts poisoning and providing stable high proton conductivity and improved mechanical properties. Modern trends in the synthesis approaches such as application of emulsion polymerization and novel efforts for the modification of polymer membranes by chemically stable nanoparticles, carrying protons, are discussed as compared to commercially used membrane materials such as Nafion and Aquivion. The crucial role of advanced structural methods to recognize subtle features of molecular ordering and formation of conducting channels in membranes is considered, focusing on neutron scattering as the most powerful instrument for the analysis of ionomers and other nanoscale structures by means of selective isotopic contrasting structural elements in membrane materials. The integration of novel methods of emulsion polymerization and use of nanodiamonds and other nanoparticles embedded into polymer matrices is prospective in the creation of new generations of membrane materials with higher functional properties.

Surface/Interfacial design and tailoring of polymeric membranes for liquid-phase separation

Synthetic polymer membranes are widely used in many applications, including, among others, water purification, protein separation, and medicine. However, the use of existing polymer membranes faces major challenges, such as the trade-off between permeability and selectivity, membrane fouling, and poor mechanical strength. To address these problems the authors have focused their research on surface/interfacial tailoring and the structure-property relationship of polymer membranes used in liquid separation systems. Progress has been made as follows: (1) a methodology for membrane surface functionalization and nanofiltration (NF) membrane preparation based on mussel-inspired catecholic chemistry was proposed and established; (2) a class of mechanically robust and environmentally-responsive composite membranes with hydrogel pore-filled in rigid macroporous supports was designed and developed; (3) a methodology for surface tailoring and antifouling modification of polymer membranes based on amphiphilic copolymers was created and the scientific implications for amphiphilic polymer membranes elaborated; (4) an adsorption membrane with both filtration and adsorption functions was designed and developed to achieve rapid removal of trace micropollutants, including heavy metal ions, organic dyes, plasticizer, antibiotics, and others. This mini-review briefly summarizes this work.

Modification of Polymeric Membranes by Corona Discharge

A brief review of the literature data on the treatment of polymer membranes by alternating and unipolar corona discharge is presented in this work. Treatment by corona discharge in air leads to the formation of ozone, which contributes to the formation of oxygen-containing groups (C–O–C, C–OН, C(O)OН, C–O, and C=O) on the membrane surface of carbon-chain polyolefin, polysulfone, polyethersulfone, polyetherketone, polyvinyl chloride, and other polymers, as confirmed by IR spectroscopy. This contributes to an increase in hydrophilic characteristics, wettability, and polarity of the membranes, and an increase in the roughness of the latter by burning, as shown by atomic force microscopy, scanning electron microscopy, and the sessile drop technique. Hydrophilization of polymeric membranes after corona treatment results in improved performance during the ultrafiltration of media containing microorganisms, albumin, oil-water and petroleum-water emulsions, etc.

Fabrication of a novel hollow fiber composite membrane with a double-layer structure for enhanced water treatment

In surface modification of polymer membranes, permeate flux is normally decreased with the enhancement of rejection and antifouling properties. Herein, a new method is proposed to beat the permeability–selectivity trade-off and endow polymer membranes with more functions: a double-layer polypropylene/styrene–maleic anhydride (SMA) copolymer hollow fiber composite membrane was fabricated via interfacial suspension copolymerization. The pore structure of the hydrophilic SMA layer was optimized by manipulating the polymerization and phase separation in the mixed solvents. The formation mechanism of the pores was systematically investigated. Phase separation, the length of the SMA molecular chain, and its selective swelling in the mixed solvents were the key factors for pore formation. Compared with the pristine membrane, the water flux of the optimized membrane PPM2 was significantly increased from 105.5 to 570.0 L/m2h, and rejections were highly elevated from 81.4% to 97.2% for bovine serum albumin (BSA), 49.8% to 96.5% for Congo red, and 17.6% to 68.9% for methylthionine chloride. The antifouling properties were simultaneously strengthened, and the flux recovery ratio was increased from 68.6% to 95.2% for the BSA solution and 71.5% to 92.8% for the oil/water (O/W) emulsion. The separation efficiency of the O/W emulsion was up to 99.9% because of the double-layer structure with asymmetric wettability.

The Recent Progress in Modification of Polymeric Membranes Using Organic Macromolecules for Water Treatment

For decades, the water deficit has been a severe global issue. A reliable supply of water is needed to ensure sustainable economic development in population growth, industrialization and urbanization. To solve this major challenge, membrane-based water treatment technology has attracted a great deal of attention to produce clean drinking water from groundwater, seawater and brackish water. The emergence of nanotechnology in membrane science has opened new frontiers in the development of advanced polymeric membranes to enhance filtration performance. Nevertheless, some obstacles such as fouling and trade-off of membrane selectivity and permeability of water have hindered the development of traditional polymeric membranes for real applications. To overcome these issues, the modification of membranes has been pursued. The use of macromolecules for membrane modification has attracted wide interests in recent years owing to their interesting chemical and structural properties. Membranes modified with macromolecules have exhibited improved anti-fouling properties due to the alteration of their physiochemical properties in terms of the membrane morphology, porosity, surface charge, wettability, and durability. This review provides a comprehensive review of the progress made in the development of macromolecule modified polymeric membranes. The role of macromolecules in polymeric membranes and the advancement of these membrane materials for water solution are presented. The challenges and future directions for this subject are highlighted.

Modification of Polymer Membranes for Use in Organic Solvents

The chemical stability of polymer membranes, i.e., their ability to preserve the size, shape, and pore structure in contact with aggressive organic solvents, largely determines their separation characteristics in filtration of organic media. Methods for enhancing the stability of porous membranes based on commercial polymers (polysulfone, polyphenylsulfone, polyacrylonitrile) by chemical and/or physical modification are considered. Chemical modification consists in covalent cross-linking of matrix polymer chains; in some cases, cross-linking of macromolecules requires their preliminary functionalization. Physical modification involves blending of a matrix polymer with another polymer. A promising way to stabilize various membranes is combining a matrix polymer with a chemically cross-linked additional polymer, i.e., forming a semi-interpenetrating network.

Nanotechnology in water and wastewater treatment. Graphene – the nanomaterial for next generation of semipermeable membranes

In recent decades, novel and promising graphene-based materials (i.e., carbon nanotubes, nanoporous graphene and graphene oxide) suitable to be used in preparation of high-capacity membranes for water desalination and water and wastewater treatment have been developed. After detail recognition of properties of nanoporous graphene and graphene oxide-based materials, the general conclusion on preparation of membranes made of only graphene or only graphene oxide as well as other composite materials involving these nanomaterials has been given. Novel composite membranes containing nanoporous graphene and, first of all, graphene oxide can be divided into two groups: (i) freestanding membranes made only of graphene or only of graphene oxide, and (ii) polymeric/ceramic membranes modified with the use of graphene-based nanomaterials. The modification of polymeric membranes can be achieved either by introduction of a nanomaterial onto a membrane surface or its addition to a membrane casting solution followed by membrane formation from a polymer and a nanomaterial mixture. Membranes based on nanomaterials enable to obtain significantly higher water/permeate fluxes than currently used thin film composite polyamide membranes. The future prospect of membranes based on nanoporous graphene and graphene oxide in regard to the final separation efficiency and commercial scaling up has been discussed.

Modification of polymeric membranes with unipolar corona discharge to intensify the separation of oil-in-water emulsions

The data on the unipolar corona treatment of polymer membranes made of polyethersulfone and polyacrylonitrile and their use for the separation of a 20% model oil-in-water emulsion based on an “I-20A” industrial oil stabilized by a “Kosintol-242” surfactant are given.It is shown that corona treatment of polymer membranes contributes to an increase in membrane productivity and the efficiency of separation of water-oil emulsion.It has been determined that corona discharge treatment leads to a decrease in the degree of crystallinity of the membranes, roughness due to oxidation of the surface with ozone produced during corona processing and the edge wetting angle, which indicates an increase in hydrophilic characteristics.

Carbon nanostructures for advanced nanocomposite mixed matrix membranes: a comprehensive overview

Abstract The highly progressive membrane separation technology challenges conventional separation processes such as ion exchange, distillation, precipitation, solvent extraction, and adsorption. The integration of many desired properties such as low energy consumption, high removal efficiency, affordable costs, suitable selectivity, acceptable productivity, ease of scale-up, and being environmentally friendly have made the membranes capable of being replaced with other separation technologies. Combination of membrane technology and nanoscience has revolutionized the nano-engineered materials, e.g. nanocomposites applied in advanced membrane processes. Polymer composites containing carbon nanostructures are promising choices for membrane fabrication owing to their enhanced chemistry, morphology, electromagnetic properties, and physicochemical stability. Carbon nanostructures such as carbon nanotubes (CNTs), nano graphene oxides (NGOs), and fullerenes are among the most popular nanofillers that have been successfully applied in modification of polymer membranes. Literature review shows that there is no comprehensive overview reporting the modification of mixed matrix membranes (MMMs) using carbon nanofibers, nano-activated carbons, and carbon nanospheres. The present overview focuses on the applications of carbon nanostructures mainly CNTs and NGOs in the modification of MMMs and emphasizes on the application of CNTs and NGO particles.

Mozliwosci wykorzystania plazmowych technik inzynierii powierzchni do modyfikacji membran polimerowych

Mozliwosci wykorzystania plazmowych technik inzynierii powierzchni do modyfikacji membran polimerowych

Controllable modification of polymer membranes by LDDLT plasma flow: Grafting acidic ILs into PPF membrane for catalytic performance

This article focused on the membranes covalent bearing ionic liquid for catalytic performance. The polypropylene fibrous (PPF) membranes was activated by long-distance and dynamic low-temperature plasma flow. Thereafter, it was successfully grafted with 1-vinylimidazole acidic ionic liquids (ILs) through free radical polymerization. The membranes formed were characterized through Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, bubble pressure method filter membrane pore size analyzer, electronic universal testing machine and contact angle meter. Catalytic hydrolysis of inulin polysaccharide into fermentable reducing sugars using the ILs grafted PPF (ILs-g-PPF) membranes was also evaluated by the DNS method. The results confirmed the successful and steady grafting onto the surfaces and the pore walls of PPF membranes. The resulting ILs-g-PPF membrane exhibited high catalytic activity for hydrolysis of inulin and could be easily separated from the reaction mixture. After two rinses and six times of hydrolysis for the same feed, the hydrolysis ratio was close to 100%. Moreover, the spent ILs-g-PPF membrane was of good reusability and stability. Catalytic PPF membranes obtained by the ILs immobilization have advantages over the ILs themselves for chemical industrial application.

Effects of polyethyleneimine molecular weight and proportion on the membrane hydrophilization by codepositing with dopamine

ABSTRACTMussel‐inspired chemistry has attracted widespread interest in the surface modification of polymer membranes. We have previously demonstrated a dopamine (DA) assisted codeposition process of polyethyleneimine onto polypropylene microfiltration membranes (PPMMs) for surface hydrophilization. In this work, we further investigate the effects of PEI molecular weight and DA/PEI mass ratio on the codeposition process and membrane performance. The results indicate that only low‐molecular‐weight PEI bring a distinct promotion in both surface wettability and water permeation flux for PPMMs. On the other hand, either excess DA or PEI is detrimental to the surface hydrophilicity of the studied membranes. The optimized PEI molecular weight is 600 Da and the corresponding mass ratio is 1:1 for the surface hydrophilization of PPMMs. These results are beneficial to understand those codeposition processes of dopamine with other polymers. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43792.

Polypropylene microfiltration membranes modified with TiO2 nanoparticles for surface wettability and antifouling property

TiO2 nanoparticles have attracted much attention in the surface modification of polymer membranes for antifouling purpose due to their excellent hydrophilicity. In this work, a polydopamine/polyethyleneimine (PDA/PEI) intermediate layer was fabricated on the polypropylene microfiltration membrane via a co-deposition method and then TiO2 nanoparticles (NPs) were modified on the membrane surfaces through a sol–gel process. TiO2-modified membranes with various Ti/C ratios were prepared and their surface structures and properties are compared with those of the nascent and PDA/PEI-deposited ones. Results indicate that the TiO2 NPs modification increases both the surface wettability and the water permeation flux of the membranes remarkably. TiO2 NPs also endow the membranes with promoted protein resistance properties. The relative flux reduction and flux recovery ratio are 31±3% and 82±5% for bovine serum albumin solution, while 26±4% and 86±3% for lysozyme solution. The TiO2 NPs are also stable on the membrane surfaces under a wide range of pH value.

PROTON-EXCHANGE MEMBRANES BASED ON HETEROPOLY COMPOUNDS FOR LOW TEMPERATURE FUEL CELLS

The review has analyzed the papers relative to heteropoly compounds, as solid proton conductors, for modification of polymer proton exchange membranes for their usage as low temperature fuel cells. The electrolyte functions and requirements, the structure and transport properties of perfluorinated proton exchange membranes which are the main candidates for practical applications are briefly considered. The main disadvantages of these membranes limiting their use are also highlighted. A special attention is given to the structure and properties of heteropoly compounds. The properties of heteropoly acids (phospho- and silicotungstic) containing anion with Keggin structure are discussed in details. In the main part of the review the methods of the preparation of the composite membranes based on perfluorinated and aromatic polymers and heteropoly compounds, the influence of the nature and content of the heteropoly compounds on their transport properties are analyzed. It is shown that the modification of polymer membranes by heteropoly compounds is one of the most promising methods to improve membranes performance. Due to its own high proton conductivity introduction of heteropoly compounds into polymer electrolytes in some cases can significantly improve proton conductivity, particularly at elevated temperatures, and reduce the methanol permeability. In the final part of the review the data on the use of composite polymer electrolytes with heteropoly compounds in the fuel cells and the influence of heteropoly compounds on the performance of the electrochemical devices are analyzed. It is shown that introduction of dopants inside of membrane can significantly increase both the operating temperature and performance of the fuel cell.