Ultrafiltration Membranes In Water Treatment Research Articles

Preparation and characterization of high flux cellulose acetate/hydroxyapatite composite ultrafiltration membranes for water treatment

In this study, we prepared cellulose acetate/hydroxyapatite (CA/HA) composite ultrafiltration membranes for water treatment. The organic-inorganic composite ultrafiltration membranes were prepared by doping different contents of HA nanoparticles into the CA by phase inversion method. The structure and morphology of the HA nanoparticles and membranes were characterized by X-ray diffraction, Fourier infrared spectroscopy and Scanning electron microscopy. Thermogravimetric analysis was used to describe thermal characteristics. The contact angle value and wettability test were used to determine the hydrophilicity of the polymer membrane. In addition, fluxes and rejection rates were tested at different pollutant concentrations and different pH values. The pore size and porosity gradually increased and the hydrophilicity and thermal stability of membrane were improved with the deposited HA content. With the addition of 5 wt% HA, the tensile strength of the membrane reached a maximum value of 2.80 MPa. The fluxes of pure water, CR, MB and BSA were 152.23, 111.25, 125.69 and 87.47 L/(m2·h), while the rejection rates of CR, MB and BSA were 99.99 %, 92.91 % and 99.99 %, respectively. In addition, the rejection decreased with increasing dye concentration and showed higher rejection under alkaline conditions. On the whole, the produced CA/HA composite membranes exhibited significantly higher permeability and rejection rates, offering them a lot of potential for water treatment applications.

Constructing quaternized graphene oxide filtration layer on PVDF membrane by a facile strategy via dopamine crosslinking and its performance

The increasing utilization of polyvinylidene fluoride (PVDF) ultrafiltration membranes in water treatment has necessitated the development of membranes with superior separation, antifouling performance and high pure water permeability. As a hydrophilic and antibacterial modifier, quaternized graphene oxide (QGO) has been successfully applied to improve the antifouling and antibacterial properties of the membranes simultaneously. Herein, we proposed a simple and effective strategy to fabricate a nanocomposite ultrafiltration membrane by coating the PVDF membrane surface with QGO and using polydopamine (PDA) as a “bio-glue”. The filtration followed by cross-linking method was utilized to construct a “brick-mud” structure on the membrane surface. The prepared QGO/PDA-PVDF membrane exhibited favorable separation and antifouling properties (79.5% of BSA rejection rate, 15.7% of irreversible fouling rate when filtering 0.5 g/L BSA solution, 97.2% of E. coli and 96.3% of S. aureus antibacterial rate), while maintaining a high pure water permeability of 1105.4 L.m−2.h−1.bar−1. QGO nanosheets were stably coated on the membrane surface, and the QGO/PDA-PVDF membrane prepared by this novel strategy also demonstrated application potential in the field of seawater desalination pretreatment. Besides, the possible mechanisms during modifications were also discussed. This research could serve as a reference for improving the comprehensive performance of PVDF ultrafiltration membrane through surface coating.

Recent Progress of Adsorptive Ultrafiltration Membranes in Water Treatment—A Mini Review

Adsorptive ultrafiltration mixed matrix membranes (MMMs) are a new strategy, developed in recent years, to remove harmful cations and small-molecule organics from wastewater and drinking water, which achieve ultrafiltration and adsorption functions in one unit and are considered to be among the promising technologies that have exhibited efficiency and competence in water reuse. This mini review concerns the research progress of adsorptive ultrafiltration MMMs for removing heavy metal ions and small-molecule organics. We firstly introduce the types and classifications of adsorptive ultrafiltration MMMs (their classifications can be established based on the type of the adsorbent used). Furthermore, we discuss the removal mechanism of adsorptive ultrafiltration MMMs, as well as summarizing the main fabrication techniques for adsorptive ultrafiltration membranes. In addition, we identified some of the issues and challenges of the practical application for adsorptive ultrafiltration.

Simultaneously enhanced permeability and anti-fouling performance of polyethersulfone ultrafiltration membranes by structural control and mixed carbon quantum dots

Assisted with a direct current (DC) electric field membrane forming device, the Polyethersulfone (PES) ultrafiltration (UF) membrane was fabricated by non solvent induced phase inversion method. The membrane morphology and performance were simultaneously changed because the PES polymer chains were polarized by the DC electric field. As a result, the M-0-DC membrane showed a porous and thinner separation layer structure with a water permeability of 280.1 L m−2 h−1·bar−1, which is ∼55% higher than that of M-0. Further, a novel antifouling PES membrane containing carbon quantum dots (CQDs) with a concentration of 0.5 was prepared combined with the electric field. The water permeability (∼164% higher than M − 0) of M-0.5-DC was substantially improved and the rejection rate for BSA was 98.4%. The M-0.5-DC also exhibited excellent antifouling property, that is, its BSA flux recovery rate reached as high as 95.3%. Apart from, the Congo red self-cleaning ability investigation of M-0.5-DC showed that the membrane became clean again after the irradiation of ultraviolet light for 2 h. The simultaneously enhanced water permeability and improved anti-fouling property by DC electric field and CQDs are promising advances that may promote the applications of UF membranes in water treatment.

Amphiphilic cellulose for enhancing the antifouling and separation performances of poly (acrylonitrile-co-methyl acrylate) ultrafiltration membrane

Membrane fouling results in short membrane life and high operating costs, which is a major obstacle in membrane filtration technology. Here, an amphiphilic cellulose (MCC-C16) was synthesized and used as an additive to mix with poly (acrylonitrile-co-methyl acrylate) (P(AN-MA)) copolymer. P(AN-MA)/MCC-C16 composite membranes were formed via non-solvent induced phase separation, which exhibited excellent antifouling ability, hydrophilicity, and permeability compared with the control sample P(AN-MA) membrane. The P(AN-MA)/MCC-C16 composite membranes exhibited higher pure water flux, bovine serum albumin (BSA) flux, and flux recovery rate (FRR) than those of the pristine membrane when 5 wt% MCC-C16 was added. The pure water flux increased from 284 to 459 L/m2 h, BSA rejection was up to 95.2%, and the highest flux recovery ratio was up to 86.7%. The lowest irreversible fouling was depressed to 13.5% after three cycles of permeation. MCC-C16 is valuable in fabricating PAN-based ultrafiltration membranes for water treatment and is low cost, and environmentally friendly with excellent antifouling performance.

Development of Hybrid Ultrafiltration Membranes with Improved Water Separation Properties Using Modified Superhydrophilic Metal-Organic Framework Nanoparticles.

Metal-organic frameworks (MOFs) are being intensively explored as filler materials for polymeric membranes primarily due to their high polymer affinity, large pore volumes, and alterable pore functionalities, but the development of MOF-based ultrafiltration (UF) membranes for water treatment lags behind. Herein, poly(sulfobetaine methacrylate) (PSBMA)-functionalized MOF UiO-66-PSBMA was developed, and incorporated into polysulfone (PSf) casting solution to fabricate novel hybrid UF membranes via phase-inversion method. The resultant UiO-66-PSBMA/PSf membrane exhibited significantly improved water flux (up to 602 L m-2 h-1), which was 2.5 times that of the pristine PSf membrane (240 L m-2 h-1) and 2 times that of UiO-66-NH2/PSf membrane (294 L m-2 h-1), whereas the rejection of UiO-66-PSBMA/PSf membrane was still maintained at a high level. Moreover, UiO-66-PSBMA/PSf membrane exhibited improved antifouling performance. The improvement of membrane performances could be attributed to the well-tailored properties of UiO-66-PSBMA. On one hand, the excellent dispersion and compatibility of UiO-66-PSBMA ensured the formation of a uniform structure with few defects. On the other hand, the superhydrophilicity of UiO-66-PSBMA could accelerate the exchange rate between solvent and nonsolvent, resulting in a more hydrophilic surface and a more porous structure. Besides, UiO-66-PSBMA nanoparticles in the thin layer provided additional flow paths for water permeation through their hydrophilic porous structure as well as the tiny interspace between PSf matrix. This study indicates the great application potential of UiO-66-PSBMA in fabricating hybrid UF membranes and provides a useful guideline to integrate other modified hydrophilic MOFs to design UF membranes for water treatment.

Consider Microfiltration and Ultrafiltration Membranes for Water Treatment

Microfiltration and ultrafiltration have gained rapid acceptance as processes that provide reliable and high‐level particle, turbidity, and microorganism removal.

Recent Advanced Technologies in the Processing of Hybrid Reinforced Polymers for Applications of Membranes

This review presents a comprehensive introduction to recent advances in the field of blends of the natural and synthetic polymers as new material for biodegradable membranes. These materials and several blends have attracted industrial attention because they exhibit improvements in properties which are required in membrane technology. In the current review, the structure, preparation coating method and properties of the blends of natural and man-made polymer are discussed. We focus on the applications of blend materials for membrane technology like fuel cells, membrane electrolytes and ultrafiltration membranes for water treatment. From the literature, it is found that the most common natural polymers: collagen, chitosan, chitin, cellulose, starch and poly(lactic acid) are used as components of blends with man-made polymers. We have also studied the introduction of nano-fibrous and nano-particles to improve the mechanical properties of these membranes.

Evaluation of Membrane Ultrafiltration and Residual Chlorination as a Decentralized Water Treatment Strategy for Ten Rural Healthcare Facilities in Rwanda.

There is a critical need for safe water in healthcare facilities (HCF) in low-income countries. HCF rely on water supplies that may require additional on-site treatment, and need sustainable technologies that can deliver sufficient quantities of water. Water treatment systems (WTS) that utilize ultrafiltration membranes for water treatment can be a useful technology in low-income countries, but studies have not systematically examined the feasibility of this technology in low-income settings. We monitored 22 months of operation of 10 WTS, including pre-filtration, membrane ultrafiltration, and chlorine residual disinfection that were donated to and operated by rural HCF in Rwanda. The systems were fully operational for 74% of the observation period. The most frequent reasons for interruption were water shortage (8%) and failure of the chlorination mechanism (7%). When systems were operational, 98% of water samples collected from the HCF taps met World Health Organization (WHO) guidelines for microbiological water quality. Water quality deteriorated during treatment interruptions and when water was stored in containers. Sustained performance of the systems depended primarily on organizational factors: the ability of the HCF technician to perform routine servicing and repairs, and environmental factors: water and power availability and procurement of materials, including chlorine and replacement parts in Rwanda.

An economic analysis on ultrafiltration membranes in water treatment: Brazilian cases

An economic analysis on ultrafiltration membranes in water treatment: Brazilian cases

Inge secures €5 million in venture capital funding

Inge Watertechnologies AG, a German company that specialises in ultrafiltration membranes for water treatment, has secured venture capital funding of €5 million.