Browsing by Author "Narayan, Shankar"

Now showing 1 - 4 of 4

Access status: Open Access ,
Multifunctional piezoelectric yarns and meshes for efficient fog water collection, energy harvesting, and sensing
(2024) Parisi, Gregory; Szewczyk, Piotr K.; Narayan, Shankar; Ura, Daniel Paweł; Knapczyk-Korczak, Joanna; Stachewicz, Urszula
Wydział Inżynierii Metali i Informatyki Przemysłowej
Given global water scarcity and the quest for sustainable energy, there's a pressing need for integrated approaches addressing water-energy interdependence worldwide. A practical approach for this challenge involves the implementation of fog water collectors. Herein, a polyvinylidene fluoride (PVDF) multifunctional device capable of harvesting water and electricity from wind is developed and tested, collecting up to 365 mg cm−2 h−1 of fog water. Due to the piezoelectric nature of electrospun PVDF, these yarns and meshes not only serve as piezoelectric sensors, enabling the detection of incoming fog flow and determination of its speed and, bust also harvest electricity by charging a capacitor, making it a green and renewable power source. In this study, promising insights are offered into developing efficient fog water collection methods and utilizing piezoelectric fiber-based yarns and meshes for multifunctional applications in sustainable water management, energy harvesting, and sensing in a single device.
Access status: Open Access ,
Photoresponsive Electrospun Fiber Meshes with Switchable Wettability for Effective Fog Water Harvesting in Variable Humidity Conditions
(2023) Parisi, Gregory; Szewczyk, Piotr K.; Narayan, Shankar; Stachewicz, Urszula
Wydział Inżynierii Metali i Informatyki Przemysłowej
The global water supply worsens yearly with climate change; therefore, the need for sustainable water resources is growing. One of them is fog water collectors with variable surface wettability, with multifunctional designs for utilization worldwide and to address regions with low humidity levels. Therefore, we created fiber meshes with a photoresponsive switchable surface. This study uses electrospun polyvinylidene fluoride (PVDF) meshes, whose wettability is controlled by adding $TiO_{2}$. The fog water collection performance is studied at high and low humidity levels. With $TiO_{2}-PVDF$, the electrospun mesh can be converted from hydrophobic to hydrophilic under UV irradiation and transformed back to a hydrophobic state with heat treatment. The switchable meshes were found to be more effective at water collection after UV irradiation at lower fog rates of 200 $mL·h^{–1}$. The ability to switch between hydrophobic and hydrophilic properties as needed is highly desired in fog collection applications using electrospun meshes, as it can improve overall efficiency after UV irradiation.
Access status: Open Access ,
Thermoresponsive nanofiber yarns for water harvesting enhanced by harp system
(2024) Parisi, Gregory; Szewczyk, Piotr K.; Narayan, Shankar; Stachewicz, Urszula
WIMiIP
The escalating global water crisis necessitates innovative approaches to developing sustainable water resources. Fog water collectors with variable surface wettability offer controlled fog harvesting in water-scarce regions. This study develops thermoresponsive fog collecting materials by electrospinning poly(N-isopropylacrylamide)-polyvinylidene fluoride (PNIPAm-PVDF) into yarns that are transformed into harp-like structures for enhanced water harvesting rate. Both meshes and harps using electrospun membranes exhibit the remarkable ability to transition between hydrophilic and hydrophobic wetting states at temperatures below the lower critical solution temperature (LCST). Hydrophilic and hydrophobic surfaces play distinct roles in fog water collection. Hydrophilic surfaces have a high affinity for water and enables droplet capture. Hydrophobic surfaces help the removal of aggregated water droplet and fog water collection. The highest water collection rate obtained with the electrospun PNIPAm-PVDF harp was 1415 ± 7.0 mg·cm−2 h−1. The water harvesting system based on the electrospun PNIPAm-PVDF harps exhibits a 485 % increase in water collection compared to the standard meshes made from the same material, emphasizing their potential for significantly improving the overall rate in fog water harvesting applications.
Access status: Open Access ,
Wettability gradient of photoresponsive electrospun yarns for harp-based fog water harvesting
(2024) Parisi, Gregory; Szewczyk, Piotr K.; Narayan, Shankar; Stachewicz, Urszula
WIMiIP
Fog water harvesting offers a solution to water scarcity. Here, we introduce a method to enhance fog water harvesting systems utilizing electrospun yarns featuring a wettability gradient. These yarns, made from polyvinylidene fluoride (PVDF) and titanium dioxide (TiO2), gain photoinduced hydrophilicity under UV light due to TiO2 photocatalytic properties, allowing dynamic shifts from hydrophobic to hydrophilic states. Experiments show that an alternating PVDF-TiO2 harp with a wettability gradient surpasses purely hydrophobic or hydrophilic versions in fog collection. The strategic mix of hydrophobic and hydrophilic sections enhances droplet movement and water capture, achieving a 16% increase in collection rate up to 400 mg cm−2 h−1. This approach introduces a novel method for creating wettability gradients in electrospun yarns via UV irradiation and represents a significant advancement in adaptable fog water harvesting systems.