Cu-BTC Metalâ\u88\u92Organic Framework Modified Membranes for Landfill Leachate Treatment

In this study, Cu-BTC (copper(II) benzene-1,3,5-tricarboxylate) metal-organic frameworks (MOFs) were incorporated into the structure of polysulfone (PSf) ultrafiltration (UF) membranes to improve the membrane performance for landfill leachate treatment, whereby different concentrations of Cu-BTC (0.5, 1, 1.5, 2 wt%) were added to the PSf casting solution. The successful incorporation of Cu-BTC MOFs into the modified membranes was investigated by field emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray (EDX). The Cu-BTC-modified PSf membranes showed higher performance in terms of flux and rejection, as compared to the neat PSf membrane. For example, the pure water flux (PWF) of neat membrane increased from 111 to 194 L/m2h (LMH) by loading 2 wt% Cu-BTC into the membrane structure, indicating 74% improvement in PWF. Furthermore, the flux of this membrane during filtration of landfill leachate increased up to 15 LMH, which indicated 50% improvement in permeability, as compared to the neat membrane. Finally, the modified membranes showed reasonable antifouling and anti-biofouling properties than the blank membrane.Bio4Energ

A Critical Review on Ultrasonic-Assisted Fouling Control and Cleaning of Fouled Membranes

Fouling is one of the most challenging problems impacting the performance of membrane-based separationtechnology. In recent years, ultrasound have been widely applied as an unconventional method to controlmembrane fouling, as well as to enhance membrane cleaning. The aim of the present work is to review thecurrentliteratureandtherecentdevelopmentsrelatedtotheuseofultrasoundasaninnovativeandalternativeapproachtoimprovethefoulingbehaviorofmembraneseparationprocesses.Thetheoryunderlyingultrasonic-assisted phenomena is reviewed, together with operational factors that influence the effectiveness of the ul-trasound treatment, such as frequency, power intensity, pressure, temperature, pH, and operation mode.Ultrasoundirradiationeffectivelyaidsthecleaningofcontaminatedsurfacesandenhancesthepermeateflux,owingtocavitationphenomenaandpowerfulconvectivecurrents,associatedwithsecondaryphenomena,suchas microstreamers, shock waves, and heating. However, the lifetime of the membranes should be carefullyevaluatedwhenapplyingultrasonicationasatechniqueofcleaningorcontrollingmembranefouling.Indeed,theintegrityofmembranesaftersonicationandthecontroloferosionproducedbyhighultrasonicintensitiesarekeyissueshinderingthescale-upofthisapproachinthemembraneindustry.Thisreviewshighlightsthetopicsrequiringmoreinvestigations,specificallytoevaluatetheeconomicaspectsofultrasonicassistedfoulingcontrolandcleaninginmembraneproces

Effective strategy for UV-mediated grafting of biocidal Ag-MOFs on polymeric membranes aimed at enhanced water ultrafiltration

Ultrafiltration membranes with antifouling and antibacterial properties are greatly beneficial for all industrial applications and to supply safe water worldwide. Improving these properties while maintaining both high productivity and high water quality remains a challenge. This work proposes the surface functionalization of an ultrafiltration membrane obtained via UV-initiated grafting polymerization of acrylic acid (AA) and silvercontaining metal–organic frameworks (Ag-MOFs), with the goal to achieve combined bactericidal and hydrophilic properties. The effectiveness of different modification pathways is evaluated, including Ag-MOFs blending into the AA solution followed by grafting, as well as in-situ synthesis of Ag-MOFs over the surface of AA-grafted membranes, with in-depth characterization of the resulting materials. The steady-state water fluxes with a feed water laden with organics are improved from two to three-fold for the functionalized membranes compared to the commercial one, while the rejection of macromolecules is maintained at greater than 99%. Significantly, fouling is partly reversible with all enhanced surfaces: the flux recovery ratio following cleaning varies between 3.8% and 20% compared to near zero for the pristine membrane. Noteworthy bacterial inactivation reaches up to 90% for E. coli and 95% for S. aureus, respectively, for surface-grafted membranes. Silver leaching and surface characterization analyses indicate a strong immobilization of Ag-MOFs on membranes and imply long-lasting antimicrobial as well as antifouling activities

In-Situ Ag-MOFs Growth on Pre-Grafted Zwitterions Imparts Outstanding Antifouling Properties to Forward Osmosis Membranes

In this study, a polyamide forward osmosis membrane was functionalized with zwitterions followed by the in-situ growth of metal-organic frameworks with silver as metal core (Ag-MOFs) to improve its antibacterial and antifouling activity. First, 3-bromopropionic acid was grafted onto the membrane surface after its activation with N, N-diethylethylenediamine. Then, the in-situ growth of Ag-MOFs was achieved by a simple membrane immersion sequentially in a silver nitrate solution and in a ligand solution (2-methylimidazole), exploiting the underlying zwitterions as binding sites for the metal. The successful membrane functionalization and the enhanced surface wettability were verified through an array of characterization techniques. When evaluated in forward osmosis tests, the modified membranes exhibited high performance and improved permeability compared to pristine membranes. Static antibacterial experiments, appraised with confocal microscopy and colony-forming unit plate count, resulted in a 77% increase in the bacterial inhibition rate due to the activity of the Ag-MOFs. Microscopy micrographs of the E. coli bacteria suggested the deterioration of the biological cells. The antifouling properties of the functionalized membranes translated into a significantly lower flux decline in forward osmosis filtrations. These modified surfaces displayed negligible depletion of silver ion over 30 days, confirming the strong immobilization of Ag-MOFs on their surface

Nanocomposite membranes for water separation and purification: Fabrication, modification, and applications

Water pollution is one of the greatest challenges around the world. Nanocomposite membranes are a promising modified version of traditional polymeric membranes for water treatment, with three main characteristics of enhanced permeation, improved rejection and reduced fouling. For novel nanocomposite membranes, there is a strong connection between the membrane fabrication method, the properties of fabricated membranes, and membrane performance. This article, first, reviews the different nanocomposite membrane fabrication and modification techniques for mixed matrix membranes and thin film membranes for both pressure driven and non-pressure driven membranes using different types of nanoparticles, carbon-based materials, and polymers. In addition, the advanced techniques for surface locating nanomaterials on different types of membranes are discussed in detail. The effects of nanoparticle physicochemical properties, type, size, and concentration on membranes intrinsic properties such as pore morphology, porosity, pore size, hydrophilicity/hydrophobicity, membrane surface charge, and roughness are discussed and the performance of nanocomposite membranes in terms of flux permeation, contaminant rejection, and anti-fouling capability are compared. Secondly, the wide range of nanocomposite membrane applications, such as desalination and removal of various contaminants in water treatment processes, are discussed. Extensive background and examples are provided to help the reader understand the fundamental connections between the fabrication methods, membrane functionality, and membrane efficiency for different water treatment processes

Simultaneous Improvement of Antimicrobial, Antifouling, and Transport Properties of Forward Osmosis Membranes with Immobilized Highly-Compatible Polyrhodanine Nanoparticles

This work shows that incorporating highly compatible polyrhodanine nanoparticles (PRh-NPs) into a polyamide (PA) active layer allows for fabricating forward osmosis (FO) thin-film composite (TFC)-PRh membranes that have simultaneously improved antimicrobial, antifouling, and transport properties. To the best of our knowledge, this is the first reported study of its kind to this date. The presence of the PRh-NPs on the surface of the TFC-PRh membranes active layers is evaluated using FT-IR spectroscopy, SEM, and XPS. The microscopic interactions and their impact on the compatibility of the PRh-NPs with the PA chains were studied using molecular dynamics simulations. When tested in forward osmosis, the TFC-PRh-0.01 membrane (with 0.01 wt % PRh) shows significantly improved permeability and selectivity because of the small size and the high compatibility of the PRh-NPs with PA chains. For example, the TFC-PRh-0.01 membrane exhibits a FO water flux of 41 l/(m²·h), higher than a water flux of 34 l/(m²·h) for the pristine TFC membrane, when 1.5 molar NaCl was used as draw solution in the active-layer feed-solution mode. Moreover, the reverse solute flux of the TFC-PRh-0.01 membrane decreases to about 115 mmol/(m²·h) representing a 52% improvement in the reverse solute flux of this membrane in comparison to the pristine TFC membrane. The surfaces of the TFC-PRh membranes were found to be smoother and more hydrophilic than those of the pristine TFC membrane, providing improved antifouling properties confirmed by a flux decline of about 38% for the TFC-PRh-0.01 membranes against a flux decline of about 50% for the pristine TFC membrane when evaluated with a sodium alginate solution. The antimicrobial traits of the TFC-PRh-0.01 membrane evaluated using colony-forming units and fluorescence imaging indicate that the PRh-NPs hinder cell deposition on the TFC-PRh-0.01 membrane surface effectively, limiting biofilm formation