Modifying water sorption properties with polymer additives for atmospheric water harvesting applications

Metal- and halide-free, solid-state polymeric water vapor sorbents for efficient water-sorption-driven cooling and atmospheric water harvesting

“…For practical air-conditioning applications, the PAETA-X hydrogel has the potential to be used in sorption beds by coating to the surface of the heat exchanger or integrating into porous silica gel, expanded graphite, metallic foam, and activated carbon fiber to form composite sorbents, which can be achieved through grafting, coating, or composite methods. 45,[61][62][63][68][69][70] Atmospheric water harvesting application A typical AWH test involves water sorption and desorption processes where water vapor sorption occurs at night-time while solar-assisted desorption, condensation, and thus water production occur during the daytime. Carbon nanotubes (CNTs) were introduced into PAETA-Ac hydrogel as the photothermal component.…”

An overview of solid and liquid materials for adsorption-based atmospheric water harvesting

“…Similarly, silica gel-LiCl was modified with polyvinylpyrrolidone (PVP) to create a sorbent with high water-holding and water harvesting capacity. 116 The prototype built for silica gel-LiCl-PVP provided about 0.43 g water /g sorbent .…”

“…Comparison of water production capacity by composite adsorbents. CaCl 2 + MCM-41, 107 CaCl 2 + saw wood + Vermiculite, 98 ALiCa30, 104 PAM + CNT + CaCl 2 , 105 LiCl + MgSO 4 + ACF, 109 AS5Li30, 111 ACF30, 100 SC30, 100 graphene nanocomposite foam, 117 birnessite, 118 silica gel-LiCl-PVP, 116 binary/FCNT, 114 and CaCl 2 @Fe-Fc-HCPs. 115 …”

Polymeric Hydrogels—A Promising Platform in Enhancing Water Security for a Sustainable Future

“…Based on these requirements, and as will be described in the following sections in detail, hydrogels can be excellent moisture sorbents due to their: i) strong affinity to water which enables significant moisture capture capacity and water storage capability due to their network swelling, [24,94,97] ii) direct recovery of liquid water via incorporation of stimuli-responsive polymers, [22,23] and iii) low enthalpy of vaporization which facilitates desorption of sorbed water molecules via solar evaporation. [21,24] Furthermore, the presence of a large amount of pores within the hydrogels can also increase the water vapor sorption rate via i) their high affinity to water, [359] ii) the unhindered vapor transport via interconnected pathways, [359] and iii) the capillary condensation effect. [360,361] In such porous hydrogels, water vapor initially attaches to the outer surface of the hydrogel followed by their transfer to the inner pores space, and finally they diffuse to the internal porous structure of the hydrogel through capillary channels.…”

“…Hydrogels can also be applied in the form of additives or coatings on sorbents of dessicants to enhance their water vapor sorption capacity, [359] or as coatings on support materials such as cotton and cellulose acetate nanofibers for moisture harvesting. [362][363][364][365][366] Furthermore, stimuli-responsive polymers or compounds such as the PNIPAM and spiropyran were combined with hydrogels in order to demonstrate their ability to reversibly switch from a state of high moisture-capture ability to another that repels the sorbed water by either a temperature change and/or light irradiation.…”