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In recent years, electro-membranes have garnered attention for their potential to address the limitations of conventional membranes, such as low permeability, poor selectivity, and fouling. Notably, electrospun electrochemical membranes have emerged as promising solutions, offering increased surface area and uniform porosity, leading to enhanced permeability and pollutant rejection in water treatment applications. This comprehensive review systematically analyzes the preparation methods of frequently employed electrochemical membranes, focusing on their characterizations, processes, and essential parameters. Surface modification techniques, nanomaterial integration, and material selection are pivotal aspects explored in this review. Various fabrication methods, including dip coating, sintering, sol-gel, and integrated approaches, are examined in detail, emphasizing their roles in enhancing membrane functionality. The integration of nanomaterials into mixed matrix electrochemical membranes presents opportunities to develop highly efficient composite membranes. Furthermore, this review analyzes into the fabrication processes of both polymeric and ceramic electrochemical membranes, highlighting the need for scaling up production processes and testing these membranes in real-world scenarios to validate their performance. Advancements in electro-membrane technology have facilitated the development of composite membranes that are not only affordable and scalable but also possess tunable physicochemical properties, promising significant advancements in water treatment methodologies.

Wetting of metal surfaces plays an important role in fuel cells, corrosion science, and heat-transfer devices. It has been recently stipulated that Cu surface is hydrophobic. In order to address this issue we use high purity (1 1 1) Cu prepared without oxygen, and resistant to oxidation. Using the modern Fringe Projection Phase-Shifting method of surface roughness determination, together with a new cell allowing the vacuum and thermal desorption of samples, we define the relation between the copper surface roughness and water contact angle (WCA). Next by a simple extrapolation, we determine the WCA for the perfectly smooth copper surface (WCA = 34°). Additionally, the kinetics of airborne hydrocarbons adsorption on copper was measured. It is shown for the first time that the presence of surface hydrocarbons strongly affects not only WCA, but also water droplet evaporation and the temperature of water droplet freezing. The different behavior and features of the surfaces were observed once the atmosphere of the experiment was changed from argon to air. The evaporation results are well described by the theoretical framework proposed by Semenov, and the freezing process by the dynamic growth angle model.

Highly effective, hybrid separation materials for water purification were generated following a bioinspired system available in nature. The desert beetle was the inspiration for the generation of separation materials. Using the hydrophobic poly(vinylidene fluoride) (PVDF) membrane as the basis, the membrane was first activated and then furnished with silane-based linkers, and the covalent anchoring of chitosan was successfully accomplished. The obtained surface architecture was a copy of the desert beetle’s armor possessing a hydrophobic matrix with hydrophilic domains. The modification was done in the presence or the lack of catalyst (N,N-diisopropylethylamine) that made it possible to tune easily wettability, roughness, and material as well as adhesive features. The membrane morphology and surface chemistry were studied by applying a series of analytical techniques. As a result of chitosan attachment, substantial improvement in transport and separation was reported. Pristine PVDF was characterized by a water flux of 5.28 kg m–2h–1and an activation energy of 48.16 kJ mol–1. The water flux and activation energy for a hybrid membrane with chitosan were equal to 15.55 kg m–2h–1and 33.98 kJ mol–1, respectively. The hybrid materials possessed enhanced stability and water resistance that were maintained after 10 cycles of membrane distillation tests.

The work contains results related to the application of membrane separation processes (i.e., membrane distillation and microfiltration) in dairy products processing. The performance of titania ceramic membranes (pristine as well as hydrophobized) was studied in the microfiltration process of whey and lactose solutions. On the other hand, polymeric porous hydrophobic membranes, (polypropylene—PP and polytetrafluoroethylene—PTFE) were tested in the air-gap membrane distillation (AGMD) process in contact with whey and lactose solutions. The extended material and physiochemical characterization (including fouling issues) of membrane materials before and after the separation process was performed. Transport of lactose solution across the membranes was characterized by higher effectiveness comparing with whey solution. Lactose played an important role and reduced the interactions with membrane material. Lactose solution possessed lower adhesion ability than whey what influenced the fouling and reduction of permeate flux. Membrane distillation was found to be a process that generates high-quality water with retention > 99% while simultaneously concentrating whey or lactose solutions. Microfiltration process was characterized by a rejection of lactose in the range of 80–90% for pristine ceramic membrane and hydrophobized one, respectively. The tendency to fouling in the case of AGMD process was associated with the higher contribution of polar part (29%) of the surface free energy SFE for PTFE membrane. The lowest value of normalized flux decline was observed for PP membrane, and that was correlated with the smallest contribution of polar interaction in SFE, the lowest value of roughness (RSM), contact angle (CA), and contact angle hysteresis (HCA), determined for the membrane after its utilization in the separation process.

Abstract

The geo-psychological separation from the everyday that is embedded in spiritual travel practices, can be seen as a laboratory in which individuals can examine, consider and practice spirituality in a way that is not always available in daily life. This feature of the tourism experience is arguably the reason for the popularity of spiritual tourism experiences among novices to spirituality-driven endeavours, as well as to those who wish to develop and deepen their ongoing transcendent engagement through and during travel. If spirituality is the goal, traveling seems like an ideal setting within which it can be sought and, sometimes, even found. This Special Issue has identified the emergence of a binary between spiritual tourism performance as intrinsically religious and conversely, as secular practice. Considering secular motivations firstly, it is clear that underlying the many specific drivers are deliberations focused on the self with motives like wellness, adventure or recreation predominant. Conversely, religious motivations for spiritual tourism largely leverage links to religion and are centred on specific drivers that are underlined by religious observance, ritualised practice, reaffirmation of identity and cultural performance.

The academic literature on spiritual tourism is often limited to taxonomies of travel, and reasons for spiritually oriented tourism are analysed largely according to their economic, social and historical aspects. Despite the recent growth in interest in spiritually oriented tourism it has become increasingly apparent that to fully understand the practical implication for the field of spiritual tourism, a theoretical discussion on the discursive shift from a ‘religious’ to ‘spiritual’ experience of travel needs to be addressed. Although these concepts have only recently been touched upon in academic travel literature, they have been richly explored in literary travel-focused memoirs.

•Low temperature sol-gel method was developed to functionalize polymeric membranes.•Vacuum, spray and sol gel coating were tested to make photocatalytic HF membranes.•Sol gel coating yielded higher permeability than spray and vacuum coating.•Membranes were carefully characterized to assess coating impact on their properties.•Coated membranes achieved 30–40% degradation of MB and CHD under solar light.

Four main tasks were presented: (i) ceramic membrane functionalization (TiO25 kDa and 300 kDa), (ii) extended material characterization (physicochemistry and tribology) of pristine and modified ceramic samples, (iii) evaluation of chemical and mechanical stability, and finally (iv) assessment of membrane efficiency in vacuum membrane distillation applied for volatile organic compounds (VOCs) removal from water. Highly efficient molecular grafting with four types of perfluoroalkylsilanes and one nonfluorinated agent was developed. Materials with controllable tribological and physicochemical properties were achieved. The most meaningful finding is associated with the applicability of fluorinated and nonfluorinated grafting agents. The results of contact angle, hysteresis of contact angle, sliding angle, and critical surface tension as well as Young’s modulus, nanohardness, and adhesion force for grafting by these two modifiers are comparable. This provides insight into the potential applicability of environmental friendly hydrophobic and superhydrophobic surfaces. The achieved hydrophobic membranes were very effective in the removal of VOCs (butanol, methyl-tert-butyl ether, and ethyl acetate) from binary aqueous solutions in vacuum membrane distillation. The correlation between membrane effectiveness and separated solvent polarity was compared in terms of material properties and resistance to the wetting (kinetics of wetting and in-depth liquid penetration). Material properties were interpreted considering Zisman theory and using Kao diagram. The significant influence of surface chemistry on the membrane performance was noticed (5 kDa, influence of hydrophobic nanolayer and separation controlled by solution-diffusion model; 300 kDa, no impact of surface chemistry and separation controlled by liquid–vapor equilibrium).

The functionalization of ceramic materials, metal oxide powders (TiO2and ZrO2), and ceramic membranes (5 kD TiO2and 300 kD TiO2) was performed and thoroughly discussed. The objective of the functionalization was to change the natively hydrophilic character to the hydrophobic. The hydrophilic character of the ceramics generates limitations in wider application of such materials. Material functionalization was performed using perfluoroalkylsilanes and trifunctional(octyl)silanes possessing three different reactive functional groups: −Cl, −OMe, and −OEt. The characterization of functionalized metal oxide powders and ceramic membranes was assessed by a combination of various analytical methods and techniques: NMR, TGA, HR-TEM, FT-IR, SEM-EDX, AFM, and contact goniometry. The impact of molecular structure of grafting agents (type of reactive group), time of functionalization process (5–15 min), and type of membrane morphology on the material, physicochemical, and tribological properties was studied. Effectiveness of hydrophobization was confirmed by HR-TEM technique. The thickness of the attached hydrophobic nanolayer on the surface of ceramics was around 2.2 nm. It was found that the stable hydrophobic surfaces were obtained by functionalization with both fluorinated and nonfluorinated modifiers. The materials modified with perfluoroalkylsilanes (FC6OEt3) and trichloro(octyl)silanes (C6Cl3) during 15 min hydrophobization possess comparable properties: contact angle (CA) equal to 130° and 133°; roughness RMS of 10.2 and 12 nm; adhesive force of 4.1 and 5.7 nN; and Young modulus of 135 and 130 GPa, respectively. The relation between hydrophobicity level and ceramic membrane roughness was discussed applying the Kao diagram concept. 29Si NMR results show that type of modifier has an important influence on grafting efficiency and on the mode of the grafting molecules attachment. In case of grafting with n-octyltrichlorosilane (C6OCl3) and n-octyltrimethoxysilane (C6OMe3), an increase of lateral polymerization across the octylsilane layer was observed.

The combination of microscopic (atomic force microscopy and scanning electron microscopy) and goniometric (static and dynamic measurements) techniques, and surface characterization (surface free energy determination, critical surface tension, liquid entry pressure, hydraulic permeability) was implemented to discuss the influence of perfluoroalkylsilanes structure and grafting time on the physicochemistry of the created hydrophobic surfaces on the titania ceramic membranes of 5 kD and 300 kD. The impact of molecular structure of perfluoroalkylsilanes modifiers (possessing from 6 to 12 carbon atoms in the fluorinated part of the alkyl chain) and the time of the functionalization process in the range of 5 to 35 h was studied. Based on the scanning electron microscopy with energy-dispersive X-ray spectroscopy, it was found that the localization of grafting molecules depends on the membrane pore size (5kD or 300kD). In the case of 5kD titania membranes, modifiers are attached mainly on the surface and only partially inside the membrane pores, whereas, for 300kD membranes, the perfluoroalkylsilanes molecules are present within the whole porous structure of the membranes. The application of 4 various types of PFAS molecules enabled for interesting observations and remarks. It was explained how to obtain ceramic membrane surfaces with controlled material (contact angle, roughness, contact angle hysteresis) and separation properties. Highly hydrophobic surfaces with low values of contact angle hysteresis and low roughness were obtained. These surfaces possessed also low values of critical surface tension, which means that surfaces are highly resistant to wetting. This finding is crucial in membrane applicability in separation processes. The obtained and characterized hydrophobic membranes were subsequently applied in air-gap membrane distillation processes. All membranes were very efficient in MD processes, showing good transport and selective properties (∼99% of NaCl salt rejection). Depending on the membrane pore size and used modifiers, the permeate flux was in the range of 0.5–4.5 kg·m–2·h–1and 0.3–4.2 kg·m–2·h–1for 5 kD and 300 kD membranes, respectively.

The present study investigated the impact of the driving force (Δp) on the transport properties. All the experiments and calculations were performed for air-gap membrane distillation (AGMD). In the course of the experiments, it was found that an identical value of Δpcould be attained by applying different values of feed and permeate temperatures. It was highlighted that constant values of water fluxes could be achieved using the constant driving force created by different temperatures. Moreover, the relation between ${J_{{{\rm{H}}_2}{\rm{O}}}}$and 1/Tfwas shown to be linear only for the ${J_{{{\rm{H}}_2}{\rm{O}}}}$created at ΔT= Tf− Tp> 35 K. This work’s significant finding was to highlight the limitation of the Arrhenius-type equation applied in the activation energy calculations.

Hydrophobic titania ceramic membranes (300 kD) were prepared by grafting of C6F13C2H4Si(OC2H5)3and C12F25C2H4Si(OC2H5)3molecules and thus applied in membrane distillation (MD) process of NaCl solutions. Grafting efficiency and hydrophobicity were evaluated by contact angle measurement, atomic force microscopy, scanning electron microscopy, nitrogen adsorption/desorption, and liquid entry pressure measurement of water. Desalination of NaCl solutions was performed using the modified hydrophobic membranes in air gap MD (AGMD) and direct contact MD (DCMD) processes in various operating conditions. High values of NaCl retention coefficient (>99%) were reached. The permeate fluxes were in the range 231–3692 g·h–1·m–2, depending on applied experimental conditions. AGMD mode appeared to be more efficient showing higher fluxes and selectivity in desalination. Overall mass transfer coefficients (K) for membranes tested in AGMD were constant over the investigated temperature range. However, Kvalues in DCMD increased at elevated temperature. The hydrophobic layer was also stable after 4 years of exposure to open air.

To design new material for blood-related applications one needs to consider various factors such as cytotoxicity, platelet adhesion, or anti-thrombogenic properties. The aim of this work is the design of new, highly effective materials possessing high blood compatibility. To do this, the new composites based on the poly(vinylidene fluoride) (PVDF) support covered with a single-walled carbon nanohorns (CNHs) layer were prepared. The PVDF-CNHs composites were subsequently used for the first time in the hemocompatibility studies. To raise the hemocompatibility a new, never applied before for CNHs, plasma-surface modifications in air, nitrogen and ammonia were implemented. This relatively cheap, facile and easy method allows generating the new hybrid materials with high effectiveness and significant differences in surface properties (water contact angle, surface ζ-potential, and surface functional groups composition). Changing those properties made it possible to select the most promising samples for blood-related applications. This was done in a fully controlled way by applying Taguchi's “orthogonal array” procedure. It is shown for the first time that nitrogen plasma treatment of new surfaces is the best tool for hemocompatibility rise and leads to very low blood platelet adhesion, no cytotoxicity, and excellent performance in thromboelastometry and hemolysis tests. We propose a possible mechanism explaining this behavior. The optimisation results are coherent with biological characterisation and are supported with Hansen Solubility Parameters. New surfaces can find potential applications in cardiological and circulatory system implants as well as other blood-related biomaterials.

The tubular and planar TiO2ceramic membranes were modified by grafting with perfluoroalkylsilanes (PFAS) molecules. Two types of PFAS were used for grafting process: 1H,1H,2H,2H-perfluorooctyltriethoxysilane (C6) and 1H,1H,2H,2H-perfluorotetradecyltriethoxysilane (C12). Studies showed that hydrophilic surface of titania ceramic membranes can be efficiently modified as a results of the proposed grafting method. Grafting efficiency of the tubular membranes was determined by measurement of liquid water entry pressure (LEPw), whereas grafting efficiency of planar membranes was verified by contact angle measurement. The contact angle values of the planar membranes are 130 and 140° for grafting with C6 and C12, respectively. The LEPwof the tubular membranes increased from 2 bar to 10 bar after modification by C12, whereas the LEPwvalues were constant at 2 bar when TiO2membrane was modified by C6 molecules. It was found that water contact angle, LEPw, and water flux in the membrane distillation (MD) process essentially depend on the time of grafting and the type of PFAS used. Retention coefficients for both membranes are very high, close to unity. The results were additionally analyzed using chemometric simplex method, this resulted in determining the optimum time of grafting. For the membrane grafted by C6, the optimum time according to simplex method was equal to 26 h (flux 4055 [g h-1 m-2]), whereas for a membrane grafted by C12 was 17 h (flux 4535 [g h-1 m-2]). The highest fluxes of permeate in MD were observed for the optimum times of grafting.

An essay is presented on nomadic tendencies and wanderlust. The author also discusses the role of technological advancements in transportation and information technology in making travel easier and safe. She also discusses the history of human desire to travel from place to place along with her experience of reading the work of writer Bruce Chatwin.

This paper is the result of a distance learning project held between the above named Universities. The objective of the project (April to July 2006) was to create international students teams that work on a joint research project. The students participated in two seminars in Flensburg and in Nijmegen on the topics innovation, intercultural management and transborder cooperation. Team work was supported by teleconferences and the learning platform MOODLE. This paper deals with the topic of culture in network and gives first insights on challenging aspects in cross-border cooperation. In order to approach the topic empirically, research has been undertaken in a network located between the Czech Republic, Germany and Poland. Challenges and obstacles in this network are shown to find possible approaches to overcome cultural diversity. Information and communication infrastructure has been identified as a main driver of good network performance.