Highly Efficient Clean Water Production from Contaminated Air with a Wide Humidity Range

Abstract

contaminated inevitably by the impurities, such as microorganisms, fine particulate matters (PM), and toxic gases like sulfur oxides (SO x ). [11,12] Recently, miscellaneous hygroscopic materials have been explored for moisture capture. For instance, metalorganic frameworks (MOFs) like MOF-801 could harvest 0.25 g g −1 water at a relative humidity (RH) of 20%, and poly(Nisopropyl acrylamide)/sodium alginate (PNIPAAm/Alg) polymer hydrogel demonstrated 0.6 g g −1 water uptake at the RH of 80%, respectively. [13][14][15][16] However, MOF-801 only worked in a narrow RH range (<20% RH) with low water uptake, and the quality of the oozed water from PNI-PAAm/Alg hydrogel was uncertain for the risk of impurities. As a result, it is still a big challenge for harvesting high-quality clean water free of impurities from the air within a full range of humidity.Herein, we demonstrate a highly efficient clean water production system from a contaminated environment with a wide range of humidity based on a rationally designed sodium polyacrylate (PAAS)/graphene framework (PGF). This porous framework with plentiful oxygen functional groups facilitates the sorption of water vapor in humid air and simultaneously grabs the impurities under van der Waals force (Figure 1). Moreover, a high solar-thermal conversion capability of PGF makes water easily desorbed under sun irradiation. [2,17,18] As a result, such a PGF presents the equilibrium water uptake of 0.14 g g −1 at a low RH of 15%, and a superhigh uptake of 5.20 g g −1 at an RH of 100%, exhibiting the excellent water uptake ability in a wide range of humidity. Under solar irradiation of 1 sun (1 kW m −2 ), the sorbed water can be quickly desorbed into vapor within a few minutes to generate clean water free of impurities. Thus, the PGF meets the requirements of efficient moisture capture, impurities filtration, and clean water production from natural air. For practical application, a lab-made prototype of moisture purification and water harvest (MPWH) system is built to collect over 25 L clean water per kilogram of PGF daily from the atmospheric environment. This PGF offers an efficient platform to capture moisture in ordinary and contaminated air for the production of high-quality clean water.The porous PGF is easily prepared through a convenient freeze-drying method (see details in Materials and Methods, Supporting Information). Typically, PAAS is well dispersed in a graphene oxide (GO) dispersion after ultrasonic treatment (Figure 2a). After the freeze-drying (Figure 2b) and reductionThe huge amount of moisture in the air is an unexplored and overlooked water resource in nature, which can be useful to solve the worldwide water shortage. However, direct water condensation from natural or even hazy air is always inefficient and inevitably contaminated by numerous impurities of dust, toxic gas, and microorganisms. In this regard, a drinkable and clean water harvester from complex contaminated air with a wide humidity range based on porous sodium polyacrylate/graphene framework (PGF...

Tillandsia‐Inspired Hygroscopic Photothermal Organogels for Efficient Atmospheric Water Harvesting

“…As one typical example, porous metal‐organic framework (MOF) enables active capturing of atmospheric water vapor at relatively low humidity and then releases water powered by sunlight . Owing to their premature sorption saturation, these MOF sorbents performed a relatively lower hygroscopic capacity under high RHs (>50 % RH) and only worked in a narrow RH range . Also, the highly hydrophilic hydrogel‐based sorbents (mainly aerogel or xerogel) can experience a hygroscopic process via hydrogen bonding and further contain abundant water molecules inside the three‐dimensional (3D) cross‐linked network in the form of swelling .…”

Progress in the Understanding and Applications of the Intrinsic Reactivity of Graphene‐Based Materials

“…Graphene‐based materials, including pristine graphene, graphene oxide (GO), and reduced graphene oxide (rGO), are useful for various applications such as electronic devices and energy storage, [ 1 ] clean water production, [ 2 ] environmental remediation (e.g., adsorption of oil spill), [ 3 ] photo‐ and electrocatalysis for green energy conversion, [ 4 ] composites reinforcement, [ 5 ] antimicrobial uses, [ 6 ] and nanotheranostics. [ 7 ] Some of the applications take advantage of the apparent physical (e.g., conductivity, hydrophobicity, and surface area) and chemical (e.g., functional groups) properties of the materials, while others rely on their reactivity that is dependent not only on their chemical but also on electronic properties (e.g., catalytic applications).…”

Dual-Stage Atmospheric Water Harvesting Device for Scalable Solar-Driven Water Production

“…at low temperatures under natural sunlight ($65 C). 11,16 Novel MOFs, 12,13,[16][17][18][19][20] zeolites, 21 hydrogels, [22][23][24][25] and other materials [26][27][28][29] have been developed and are promising for AWH applications. However, despite materials advancements, daily water productivity of solar-thermal AWH devices remains low due to limitations to heat and mass transport in adsorption processes, various energy losses in the desorption and condensation process, the significant energy requirement for desorption, and the required rejection of the latent heat of condensation ($2,400 kJ/L) in order to condense the water.…”