Browsing by Subject "hydrophobicity"

Now showing 1 - 3 of 3

Access status: Open Access ,
Jak termodynamika i mechanika opisują makroskopową oraz molekularną istotę zwilżalności
(2007) Grodzka, Janina; Pomianowski, Andrzej Aleksander
Recent studies on wetting lead to the two most important conclusions: description (estimation) of wettability needs the knowledge of not only the macroscopic wetting angle but also of the nature of molecular aqueous films that occupy surfaces of all solids; mechanical equilibrium of the wetting process is generally much more rapidly established than the thermodynamic equilibrium of the whole system. In consequence, the macroscopically measured wetting angle is different from the equilibrium angle, when the thermodynamic equilibrium and the formation of the molecular water film on the solid are not attained. Rapidly proceeding investigations of molecular wettability, carried out with the use of AFM (atomic force microscopy), will lead in the near future to unification of the theory and practice of wetting, and in particular will solve the question of the hysteresis of wetting, resulting from changes in the structure of water, directly adjacent to the surfaces of solids.
Access status: Open Access ,
Laboratory experiments for crude oil removal from water surface using hydrophobic nano-silica as sorbent
(2014) Knapik, Ewa; Stopa, Jerzy
Nanomaterials have a great potential for the possible oil spill cleanup due to their unique wettability characteristics and large surface area. This work reports investigations on oil sorption behavior of a commercially available hydrophobic nano-silica when tested with a light paraffinic crude oil and a heavy aromatic crude oil. Sorption experiments were carried out in batch sorption system under static and dynamic conditions. Influence of mass of sorbent, sorption time, temperature and pH value of water on sorption capacity were tested and compared to find an optimal operational conditions for adsorption process. Nanopowder exhibited high selectivity for absorbing oil from water; a removal efficiency found by gravimetric method was high as 96% to 99%. The sorption capacity inereases with the inerease of sorption time and mass of sorbent. Nano-silica powder was found to be effective sorbent material as compared to widely used synthetic fibers.
Access status: Open Access ,
Thermal energy storage performance of liquid polyethylene glycol in core–shell polycarbonate and reduced graphene oxide fibers
(2024) Das, Madhurima; Ura, Daniel P.; Szewczyk, Piotr K.; Berniak, Krzysztof; Knapczyk-Korczak, Joanna; Marzec, Mateusz M.; Pichór, Waldemar; Stachewicz, Urszula
Wydział Inżynierii Metali i Informatyki Przemysłowej
Thermal energy storage is a promising, sustainable solution for challenging energy management issues. We deploy the fabrication of the reduced graphene oxide (rGO)–polycarbonate (PC) as shell and polyethylene glycol (PEG) as core to obtain hydrophobic phase change electrospun core–shell fiber system for low-temperature thermal management application. The encapsulation ratio of PEG is controlled by controlling the core flow rate, and ~ 93% heat energy storage efficacy is apparent for $1.5 mlh^{−1}$ of core flow rate. Moreover, the prepared fiber possesses maximum latent melting and freezing enthalpy of $30.1 ± 3.7$ and $25.6 ± 4.0 Jg^{−1}$, respectively. The transient dynamic temperature vs. time curve of the rGO-loaded phase change fiber demonstrates the delay of fiber surface temperature change compared to pristine fiber. We indeed show that the tunable heat transfer and thermal energy storage efficacy of phase change fiber is achieved via controlled liquid PEG delivery and the addition of rGO in shell architecture. Notably, the effectiveness of unique phase change material (PCM)–based core–shell fibers is concluded from advanced scanning thermal microscopy (SThM) and self-thermoregulation tests.