This blog post is a placeholder for collecting links to interesting research papers, background reading, etc. - on the topic of graphene filters for saltwater desalination.
Suggested Background Reading:
"Scientists at Monash University have developed a graphene-based filter that can desalinate ocean water instantly using minimal energy."
"The filter is just a few atoms thick, made from graphene oxide with nanoscopic pores that allow water molecules through while blocking salt and other impurities. Unlike traditional desalination, which uses energy-intensive reverse osmosis, this filter works passively under low pressure—making it ideal for remote or disaster-stricken regions."
"Its efficiency could help solve water scarcity for millions. Tests show it can purify seawater faster and more effectively than any existing system, without relying on heavy infrastructure"
New Monash-designed water filter removes stubborn ‘forever chemicals’
"The research team designed a beta-cyclodextrin (βCD) modified graphene
oxide (GO-βCD) membrane with nanoscale channels that selectively retain
PFAS while allowing water to pass through."
"In tests, the Monash membrane significantly outperformed traditional
polyamide membranes, which typically remove only about 35 per cent of
short-chain PFAS. The team also confirmed that the membrane creates an
energetic barrier that prevents PFAS movement, effectively blocking
contamination."
"Study first author and Monash PhD candidate, Eubert Mahofa, highlighted the significance of this breakthrough in PFAS filtration: 'PFAS
are difficult to manage because they dissolve easily in water and can
spread far from their original source, making contamination challenging
to contain and remediate. Removing small PFAS molecules from water has
been a major hurdle for existing filters,'"
Paper:
Manipulating Intrapore Energy Barriers in Graphene Oxide Nanochannels for Targeted Removal of Short-Chain PFAS
"Removal of per- and polyfluoroalkyl substances (PFAS) from water has
become a research topic of interest in recent times. However, it is very
challenging to remove short-chain (<C8) PFAS from water
sources using traditional means, especially in mixtures. Herein, a
β-cyclodextrin (βCD)-modified graphene oxide (GO-βCD) membrane is
designed with asymmetrically sized nanochannels that exhibit strong
affinitive binding interactions with PFAS. PFAS transport is
significantly hindered within the GO-βCD lamella due to interactions
with the strategically embedded βCD sites and complementary molecular
dynamics simulations reveal that short-chain PFAS exhibit ∼20% stronger
binding affinity to βCD compared to that of alternative structures of
cyclodextrins. The GO-βCD membrane demonstrates remarkable simultaneous
retention of over 90% from a mixture of perfluorobutanoic acid (PFBA),
perfluoropentanoic acid (PFPeA), perfluorohexanoic acid (PFHxA), and
perfluorooctanoic acid (PFOA) while achieving a permeance of 21.7 ± 2 L m–2 h–1 bar–1
and upconcentrating the feed by ∼300%. The performance of GO-βCD was
compared to that of polyamide membranes, which exhibit a significant
decline in capacity to retain short-chain PFAS (∼35% for PFBA). In
combining permeation experiments and molecular dynamics simulations with
the transition state theory model, it was demonstrated that the energy
barrier for transport of PFAS is greater within the GO-βCD laminar
architecture compared to that of GO-αCD and pristine GO. These modified
membranes have strategically embedded sites capable of hindering PFAS
transport and provide an approach for removing broad-spectrum PFAS under
realistic conditions, over long-term operation (24 h), and at
concentrations relevant to surface and ground waters."
Other Suggested Papers:
Advanced Thermal Optimization of Solar Stills Using Encapsulated Phase Change Materials and Graphene Oxide Nanoparticles for Enhanced Energy Efficiency
"Solar desalination is a widely employed system that harnesses solar
energy to produce drinking water. The key advantages of solar stills
include that the generation of freshwater is a renewable energy-based,
eco-friendly, and cost-effective process. This sustainable approach
addresses the critical need for clean water while minimizing ecological
impact and offering economic benefits. In the solar still system, the
configuration of the absorber plays a crucial role, as an ineffective
absorber can lead to lower thermal performance and reduced water
productivity. This investigation focuses on an absorber design that
incorporates a tube container containing Phase Change Material (PCM) of
paraffin wax. The encapsulation of PCM within the still enhances heat
transfer and provides heat energy, especially during radiation
fluctuations. Moreover, the thermal properties of the PCM were improved
by introducing graphene oxide nanoparticles dispersed within. Three
different concentrations of graphene oxide (0.3 wt%, 0.6 wt%, and
0.9 wt%) were investigated. It was explored that paraffin with 0.9 wt%
graphene oxide nanoparticle demonstrates superior thermal performance
compared to paraffin alone. Significantly, at a concentration of
0.9 wt%, the paraffin/graphene oxide nanoparticles showed increased
water productivity, temperature, and still thermal efficiency by around
33.9%, 41.2%, and 68.7%, respectively."
Emerging membrane technologies for sustainable water treatment: a review on recent advance
"The growing scarcity of freshwater resources, coupled
with industrial pollution, necessitates the development of efficient and
sustainable water treatment technologies. Membrane-based desalination
and heavy metal removal processes are at the forefront of these
technologies, providing efficient and reliable solutions to meet the
growing demand for clean water. This study provides a comprehensive
review on recent advancements in desalination technologies, focusing on
emerging materials that have significantly influenced desalination and
heavy metal removal performances. A meticulous screening of recent
review papers on both along with experimental studies published within
the last year is provided, thereby offering an updated perspective on
the ongoing experiments dedicated to water treatment using membranes.
Notably, this review considers various membrane types, including
nanocomposites, biomimetic, thin-film composites, hybrids, and membranes
associated with forward osmosis. Results indicate that nanocomposite
membranes, thin-film composite membranes, and forward osmosis membranes
are widely used for desalination and heavy metal removal compared to
hybrid and biomimetic membranes. This widespread utilization can be
attributed to their well-established fabrication techniques, robust
mechanical properties, high removal%, and better scalability for
industrial applications. In contrast, while hybrid and biomimetic
membranes are promising, they are still under development and facing
challenges pertaining to material synthesis, cost, and integration into
existing systems."
Interfacial Engineering of Sulfonated Polyethersulfone/ZIF-8 Forward Osmosis Membranes: Applying Sulfonation and Interlayers for Enhanced Desalination Performance
"This study explores the strategic synthesis of sulfonated
polyethersulfone (SPES) with tunable sulfonation degrees to engineer
selective interfacial layers (SLs) for thin-film composite (TFC) forward
osmosis (FO) membranes. To overcome the persistent trade-off between
water permeability and salt rejection in conventional TFC membranes,
this work introduces an interlayer engineering strategy utilizing
zeolitic imidazolate framework-8 nanoparticles (ZIF-8 NPs). Unlike
traditional approaches that focus solely on membrane surface
modification, the integration of ZIF-8 as a nanostructured interlayer
addresses interfacial defects and enhances solute screening by
leveraging its molecular sieving capabilities and hydrophilicity through
the Janus membrane effect. SPES-based membranes exhibited a notable
enhancement for water flux from 15.23 to 32.12 L/m2 h
compared to neat polyethersulfone (PES) SLs. Simultaneously, the salt
rejection effectively reached 93.9% for SPES/ZIF-8/PA(#2). XRD and FTIR
analyses confirmed the crystallinity and chemical integrity of ZIF-8
NPs, while FESEM revealed their uniform dispersion across the SL
surface. Notably, the sulfonation process not only enhanced surface
porosity but also created a chemically reactive interface for ZIF-8
anchoring, a dual-functionality rarely achieved in prior studies. The
findings offer a scalable framework for designing high-performance TFC
membranes with hierarchically engineered interfaces, paving the way for
next-generation desalination and resource recovery systems."
Surface Roughness Engineering for High-Salt-Tolerant Solar Evaporator with Enhanced Efficiency in Sustainable Desalination
"The accumulation of dense crystal layers on solar evaporators
compromises performances by reducing light absorption efficiency and
obstructing water transport channels, ultimately diminishing evaporation
rate. To mitigate this issue, spatially separated crystallization sites
can be engineered on the evaporator surface to disrupt salt adhesion
and prevent dense layers formation. In this study, we developed a 3D
column-shaped wood evaporator (KAC-DW) by coating delignified wood (DW)
with KOH-activated carbon (KAC). The KAC coating creates microstructured
surface featuring abundant protrusions (~144 mm−2, each 20 μm in
height), which effectively inhibit salt crystal adhesion. Under 1 kW m−2
solar radiation with a 15 wt% NaCl solution, the KAC-DW evaporator
achieved an impressive water evaporation rate of 8.18 kg m−2 h−1 over 96
h (0 m s−1 wind speed)—more than double the performance of uncoated DW
(3.91 kg m−2 h−1). This enhancement stems from two key mechanisms: (1)
the KAC protrusions prevent dense crystal layer formation, preserving
open surface channels for evaporation, and (2) they promote the growth
of loose salt crystals, thereby expanding the effective evaporation area
and further boosting the evaporation rate."
Scalable Multifunctional Fabrics with Boosted Intrinsic Photothermal Efficiency for Salt-Resistant Solar-Driven Janus Evaporators
"Global population growth and climate change are causing freshwater
scarcity, which necessitates creative solutions like solar-driven
desalination. This technology's widespread adoption is hampered by cost
and efficiency issues. Intrinsic photothermal conversion efficiency has
gotten less attention than light trapping and thermal management, which
have been the main focuses of efforts to increase photo-to-vapor
efficiencies. Here, a commercial padding and vapor polymerization method
are used to develop scalable nylon fabrics that act as solar absorbers.
This is achieved by anchoring iron catalysts with hydrolyzed
perfluorooctyltriethoxysilane chains, which cause confined
polymerization of pyrrole to generate polypyrrole. By narrowing the
bandgap and generating bioinspired light-trapping nanostructures, this
technique achieves a superior intrinsic photothermal conversion
efficiency of 84.6%, which is 4.94 times higher than that of unconfined
polymerization. These fabrics are used to create a Janus evaporator,
which operates steadily in prolonged seawater testing and shows an
evaporation rate of 3.84 kg m−2 h−1. The low manufacturing cost of ≈28 RMB m−2
emphasizes its scalability and economic potential. This work offers
insights into the design of high-performance, scalable, and
cost-effective solar absorbers by prioritizing increases in light
absorption and intrinsic photothermal conversion efficiencies for
developing solar desalination technology."
Robust Design of Fiber Bundle Reinforced PES Hollow Fiber Loose Nanofiltration Membranes With Long-Term Operation Stability
"Usually, reinforcement is introduced into the membrane matrix to solve
the problem of hollow fiber membranes with poor mechanical properties.
Herein, the fiber bundle reinforced PES hollow fiber loose NF membranes
with GO doping were fabricated by the skin-core fiber spinning
technology and concentric circle method in order to overcome the easily
collapsible hollow fiber membrane at medium and high-pressure operation.
The reinforced structure and content of GO exhibited noticeable effects
on the structure and properties of membranes. On the one hand, the
fiber bundle constructed the excellent mechanical properties of the
membrane (185 MPa) for enhancing the lateral pressure resistance, which
was beneficial for long-term stability. On the other hand, the high
permeation flux and efficient dye desalination property were obtained
due to the doping of GO. For example, the permeation flux of the
obtained PPG-3 membrane was up to 115.6 L m−2 h−1 with the rejection of Congo red (99.8%) and MgCl2
(only 4.0%). Consequently, the GO-doping and fiber bundle reinforced
way could be considered as a synergistic effect to prepare the high
permeation flux and long-term operation stability of the hollow fiber
loose NF membranes, which will be suitable for dye desalination in
textile wastewater treatment."
Janus Membrane for Simultaneous Water Purification and Power Generation
"The intricate water‐energy nexus pinpoints the necessity of
simultaneously managing both resources. The effective interaction
between water movement and porous materials lies at the heart of
membrane processes as well as hydrovoltaic technology. Herein, an
innovative water‐energy cogeneration system combining hydrovoltaic
technology into membrane distillation processes is reported, leveraging
hierarchically porous structures composed of polyaniline (PANI) and
polydopamine (PDA)‐modified carbon nanotubes (CNTs) nanofilaments on a
commercial PVDF substrate. The heat‐conductive CNTs network with the
water‐rich PDA, improves thermal efficiency, enhancing water production
by 17.3% compared to bare PVDF. Synergistically enhanced by efficient
ion transport within the PANI network, electron accumulation along the
PANI‐PDA‐CNTs direction, and the conductive nanobridge effect of CNTs, a
continuous and durable power density of 2.78 µW cm⁻² is achieved in the
commercially available membrane filtration process. This work provides
an accessible approach to concurrently addressing water and energy
challenges."
Nanofiltration membranes with ultra-high negative charge density for enhanced anion sieving and removal of organic micropollutants
"Nanofiltration membranes with high charge density are highly attractive
for selectively removing organic micropollutants and divalent anions
from water environments. Here we constructed polyamide (PA) membranes
with ultra-high negative charge density via a sea-squirt nanofibrillated
cellulose restricted interfacial polymerization process. Sea-squirt
nanofibrillated cellulose, which contains a high content of 7.0%
carboxyl groups and 29.8% hydroxyl groups, effectively fettered
piperazine and regulated the interfacial polymerization reaction
kinetics. As a result, the optimized membrane had an ultra-high zeta
potential of −148 mV at pH 7 and a charge density of −32.6 mC m ⁻² .
This membrane achieved outstanding performance metrics, including a
water permeance of 41.5 l m ⁻² h ⁻¹ bar ⁻¹ , exceptional SO 4 ²⁻ /Cl ⁻
selectivity of 144.5 and greatly increased water/organic micropollutant
selectivity. Molecular dynamics simulations revealed a 73.1% reduction
in the diffusion rate of piperazine due to competitive forces, leading
to a PA surface enriched with -COOH groups. This work provides an
effective strategy for tuning the PA membrane charge density to increase
water purification and wastewater treatment efficiency."
Cyrene-Enabled Green Electrospinning of Nanofibrous Graphene-Based Membranes for Water Desalination via Membrane Distillation
"High-performance and sustainable membranes for water desalination
applications are crucial to address the growing global demand for clean
water. Concurrently, electrospinning has emerged as a versatile
manufacturing method for fabricating nanofibrous membranes for membrane
distillation. However, widespread adoption of electrospinning for
processing water–insoluble polymers, such as fluoropolymers, is hindered
by the reliance on hazardous organic solvents during production.
Moreover, restrictions on industrial solvents are tightening as
environmental regulations demand greener alternatives. This critical
challenge is addressed here by demonstrating, for the first time, the
fabrication of nanofibrous electrospun membranes of PVDF-HFP,
poly(vinylidene fluoride)-co-hexafluoropropylene using a renewable,
environment- and user-friendly solvent system containing Cyrene
(dihydrolevoglucosenone), dimethyl sulfoxide, and dimethyl carbonate.
The same solvent system was further used to produce nanocomposite
graphene oxide (GO) and graphene nanoplatelet (GNP)-containing
nanofibrous electrospun membranes. When tested for water desalination
via membrane distillation, these membranes either outperformed or
matched the performance of those produced with hazardous organic
solvents, achieving salt rejection rates of >99.84% and long-term
stability. The economic viability of the green solvent system was
further validated through Monte Carlo simulations. This work
demonstrates the potential to move fluoropolymer electrospinning from
dimethylformamide-based systems to greener alternatives, enabling the
consistent production of high-quality nanofibrous membranes. These
findings pave the way for more sustainable manufacturing practices in
membrane technology, specifically for water desalination via membrane
distillation."
2D Materials for Potable Water Application: Basic Nanoarchitectonics and Recent Progresses
"Water polluted by toxic chemicals due to waste from chemical/pharmaceuticals and harmful microbes such as E. Coli
bacteria causes several fatal diseases; and therefore, water filtration
is crucial for accessing clean and safe water necessary for good
health. Conventional water filtration technologies include activated
carbon filters, reverse osmosis, and ultrafiltration. However, they face
several challenges, including high energy consumption, fouling, limited
selectivity, inefficiencies in removing certain contaminants,
dimensional control of pores, and structural/chemical changes at higher
thermal conditions and upon prolonged usage of water filter. Recently,
the advent of 2D materials such as graphene, BN, MoS2,
MXenes, and so on opens new avenues for advanced water filtration
systems. This review delves into the nanoarchitectonics of 2D materials
for water filtration applications. The current state of water filtration
technologies is explored, the inherent challenges they face are
outlines, and the unique properties and advantages of 2D materials are
highlighted. Furthermore, the scope of this review is discussed, which
encompasses the synthesis, characterization, and application of various
2D materials in water filtration, providing insights into future
research directions and potential industrial applications."
