8 research outputs found
Clean water recycling through adsorption via heterogeneous nanocomposites: Silver-based metal-organic framework embellished with graphene oxide and MXene
Cationic methylene blue (MB) and anionic orange G (OG) dyes were adsorbed using the first-ever synthesized nanocomposite of MXene-AgMOF. At 200 mg/L and 0.01 g, GO-AgMOF, MXene-AgMOF, and AgMOF were able to adsorb 99.9%, 99.0%, and 98.0% of cationic MB dye, respectively, from water. The nanocomposites were characterized both before and after adsorption using different characterization techniques. These nanocomposites show promise as cationic contaminant adsorbents, with an adsorption capacity of 399.9 mg/g for GO-AgMOF. Also, the enhanced adsorption capacity of AgMOF for anionic and cationic dyes suggests its potential use in environmental remediation when combined with MXene
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鈥搊rganic 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
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/(m<sup>2</sup>路h), higher than a water flux of 34 l/(m<sup>2</sup>路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/(m<sup>2</sup>路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
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
In Situ Ag-MOF Growth on Pre-Grafted Zwitterions Imparts Outstanding Antifouling Properties to Forward Osmosis Membranes
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