“…Furthermore, Wu and group [ 159 ] fabricated an advanced membrane by making a bilateral structure composed of polydopamine (PDA) particles and bacterial nanocellulose together for photothermal membrane distillation with bactericidal capability. The developed membrane ( Figure 12 ) showed a high solar energy-to-collected water efficiency of 68%, permeate flux of 1.0 kg m −2 h −1 under sun irradiation, an improved membrane porosity, and high salt rejection (>99.9%).…”
Membrane-based desalination has proved to be the best solution for solving the water shortage issues globally. Membranes are extremely beneficial in the effective recovery of clean water from contaminated water sources, however, the durability as well as the separation efficiency of the membranes are restricted by the type of membrane materials/additives used in the preparation processes. Nanocellulose is one of the most promising green materials for nanocomposite preparation due to its biodegradability, renewability, abundance, easy modification, and exceptional mechanical properties. This nanocellulose has been used in membrane development for desalination application in the recent past. The study discusses the application of membranes based on different nanocellulose forms such as cellulose nanocrystals, cellulose nanofibrils, and bacterial nanocellulose for water desalination applications such as nanofiltration, reverse osmosis, pervaporation, forward osmosis, and membrane distillation. From the analysis of studies, it was confirmed that the nanocellulose-based membranes are effective in the desalination application. The chemical modification of nanocellulose can definitely improve the surface affinity as well as the reactivity of membranes for the efficient separation of specific contaminants/ions.
“…Furthermore, Wu and group [ 159 ] fabricated an advanced membrane by making a bilateral structure composed of polydopamine (PDA) particles and bacterial nanocellulose together for photothermal membrane distillation with bactericidal capability. The developed membrane ( Figure 12 ) showed a high solar energy-to-collected water efficiency of 68%, permeate flux of 1.0 kg m −2 h −1 under sun irradiation, an improved membrane porosity, and high salt rejection (>99.9%).…”
Membrane-based desalination has proved to be the best solution for solving the water shortage issues globally. Membranes are extremely beneficial in the effective recovery of clean water from contaminated water sources, however, the durability as well as the separation efficiency of the membranes are restricted by the type of membrane materials/additives used in the preparation processes. Nanocellulose is one of the most promising green materials for nanocomposite preparation due to its biodegradability, renewability, abundance, easy modification, and exceptional mechanical properties. This nanocellulose has been used in membrane development for desalination application in the recent past. The study discusses the application of membranes based on different nanocellulose forms such as cellulose nanocrystals, cellulose nanofibrils, and bacterial nanocellulose for water desalination applications such as nanofiltration, reverse osmosis, pervaporation, forward osmosis, and membrane distillation. From the analysis of studies, it was confirmed that the nanocellulose-based membranes are effective in the desalination application. The chemical modification of nanocellulose can definitely improve the surface affinity as well as the reactivity of membranes for the efficient separation of specific contaminants/ions.
“…5c . Overall, PM-PVDF membrane demonstrated many advantages when compared with state-of-the-art PMD membranes 22 , 27 , 28 , 39 – 46 as well as solar-driven interfacial water evaporators (IWE) 1 , 47 – 52 in terms of freshwater production flux and solar-to-vapor efficiency, especially for hypersaline solution treatment. Fig.…”
Section: Resultsmentioning
confidence: 99%
“…An efficient and sustainable strategy to address these challenges in conventional MD and harness the water-energy nexus could be the development of a photothermal MD (PMD) system 12 – 14 , 22 – 24 . The photothermal membrane’s continuous and localized surface self-heating, achieved by harvesting solar energy, could maintain the cross-membrane temperature gradient 25 – 28 . However, it remains a big challenge to construct an ideal PMD membrane that fundamentally possesses the highly desired combination of characteristics, including efficient photothermal effect and durable wetting resistance.…”
Owing to its 100% theoretical salt rejection capability, membrane distillation (MD) has emerged as a promising seawater desalination approach to address freshwater scarcity. Ideal MD requires high vapor permeate flux established by cross-membrane temperature gradient (∆T) and excellent membrane durability. However, it’s difficult to maintain constant ∆T owing to inherent heat loss at feedwater side resulting from continuous water-to-vapor transition and prevent wetting transition-induced membrane fouling and scaling. Here, we develop a Ti3C2Tx MXene-engineered membrane that imparts efficient localized photothermal effect and strong water-repellency, achieving significant boost in freshwater production rate and stability. In addition to photothermal effect that circumvents heat loss, high electrically conductive Ti3C2Tx MXene also allows for self-assembly of uniform hierarchical polymeric nanospheres on its surface via electrostatic spraying, transforming intrinsic hydrophilicity into superhydrophobicity. This interfacial engineering renders energy-efficient and hypersaline-stable photothermal membrane distillation with a high water production rate under one sun irradiation.
“…The ηsys of the interfacial heating MD system was reported as 53.8% under 700 W/m 2 in one of the pioneering studies 24 and 68% under one sun in a more recent study 26 in which polydopamine particles/bacterial nanocellulose layer served as the solar absorber on the feed side of membrane.…”
Globally, hundreds of millions of people still
drink untreated surface water due to the lack of even a basic drinking water
service, and urgently need economical off-grid water treatment devices. A passive, single-stage, permeate-side-heated solar thermal
membrane distillation system is developed for extracting potable water from seawater,
surface water, and municipal wastewater. The carbon black-coated
permeate side of 0.45 µm PVDF membrane absorbs solar radiation and evaporates
the feed water within the pores of the membrane. Under
natural sunlight, the distillate flux was 8.56 kg/(m<sup>2</sup>∙day) at an average
daytime irradiance of 652 W/m<sup>2</sup>, equivalent to the system energy efficiency
of 67.5%, the highest so far for single-stage solar distillation under natural
sunlight. This system removed all the heterotrophic bacteria, 99.9% turbidity, and
99.6% chemical oxygen demand (COD) from wastewater, and reduced electrical
conductivity by 99.9% from seawater, during the first 8 hours of operation
under simulated sunlight (1800 W/m<sup>2</sup>). The operation continued for 32,
18, and 10 days on average for seawater, canal water, and wastewater,
respectively, until the feed water penetrated the membrane. Throughout long-term
experiments, distillate had decreasing flux within 0.98–1.55 kg/(m<sup>2</sup>∙h),
steady pH of 7.2–7.9, steady turbidity of 0.09–0.21 NTU, steady electrical
conductivity within 0.003–0.451 mS/cm, and increasing COD within 1.9–9.2 mg/L regardless
of the type of feed water. Comprehensive water quality tests show that <a>the distillate extracted from all types of feed water meets
U.S. drinking water standards for total coliform, 22 heavy metals and minerals,
7 anions, 5 physical factors, and 50 volatile organic compounds</a>, and will
be safe to drink in real-world applications.
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