2022 - Repozytorium publikacji - Politechnika Gdańska

Pokaż publikacje z roku

Publikacje z roku 2022

Pokaż wszystkie

Study of the Layer-Type BST Thin Film with X-ray Diffraction and X-ray Photoelectron Spectroscopy
- Agata Lisińska-Czekaj
- Dionizy Czekaj
2022 Pełny tekst Materials
In the present paper, results of X-ray photoelectron studies of electroceramic thin films of barium strontium titanate, Ba1xSrxTiO3 (BST), composition deposited on stainless-steel substrates are presented. The thin films were prepared by the sol-gel method. A spin-coating deposition of BST layers with different chemical compositions was utilized so the layer-type structure of (0-2) connectivity was formed. After the deposition, the thin-film samples were heated in air atmosphere at temperature T = 700 C for 1 h. The surfaces of BST thin films subjected to thermal treatment were studied by X-ray diffraction. X-ray diffraction measurements confirmed the perovskite-type phase for all grown thin-film samples. The oxidation states of the elements were examined by the X-ray photoelectron spectroscopy method. X-ray photoelectron spectroscopy survey spectra as well as high-resolution spectra (photo-peaks) of the main metallic elements, such as Ti, Ba, and Sr, were compared for the layer-type structures, differing in the deposition sequence of the barium strontium titanate layers constituting the BST thin film.
Study of the Resistance to Influence of Aggressive Liquids on Concrete with Lightweight Aggregate
- Marzena Kurpińska
- Elżbieta Haustein
- Filip Kurpiński
2022 Pełny tekst
The corrosion of the structure of concrete caused by the aggressive external environment is one of the main problems that can reduce the durability of buildings. The paper analyzes the influence of the type of component on selected properties of lightweight concrete (LWC) exposed to aggressive liquids. When lightweight concrete containing porous aggregates is used, the influence of an aggressive environment may be of particular importance. The monograph presents the results of tests of four light concretes with different water-cement ratios and different compositions, which were exposed to aggressive liquids. The concrete mixes were prepared with a granulated expanded glass aggregate (GEGA) and granulated sintered ash aggregate (GAA) with a mineral additive silica fly ash. LWC specimens were curing in laboratory for one year and then subjected to aggressive liquids for 60 days. The types of environments were: strong acid—HCl, 1% and 2% concentration, weak acid—CH3COOH, 1% and 2% concentration, and an aqueous salt solution of Na2SO4, 1% and 2% concentration. Then, the structure was analyzed and the influence of aggressive liquids on the compressive strength of the LWC was examined. Moreover, the change in weight of lightweight concrete samples after corrosion was determined. The obtained test results indicate that the test method can be used for the accelerated estimation of the influence of aggressive liquids on the LWC. LWC with GEGA and GAA aggregates show high resistance to aggressive liquids. Moreover, the research results indicate that the most aggressive solution was HCl solution, while Na2SO4 turned out to be the least aggressive. The higher the concentration of the destructive factor, the faster the corrosion progressed. Concretes containing aggregates made of foamed glass and sintered fly ash are suitable for use both in traditional construction and in facilities exposed to an aggressive environment.
Study on AR Application Efficiency of Selected iOS and Android OS Mobile Devices
- Monika Zamłyńska
- Adrian Lasota
- Grzegorz Debita
- Przemysław Falkowski-Gilski
2022
Currently, the number of scenarios for using AR (Augmented Reality) tools grows every year. Yet, there are still some open performance issues associated with this technology, related with the efficiency of the mobile device itself, including build-in components or the operation system. The purpose of this study was to investigate available augmented reality engines for mobile platforms. First, a review of current graphics and AR engines was conducted, based on which measurement aspects were selected taking into consideration the device performance. Next, we have performed a series of research studies, including different 3-dimensional AR modes and scenarios, both with and without a tag. The research was carried out using 4 mobile devices, with 3 of them running Android OS and 1 powered by iOS (with 2 different AR libraries). The performed tests and obtained results can aid any interested individual when choosing the right mobile device, as well as configuring the AR environment, for various UX (User Experiences).
Study on some of the strength properties of soft clay stabilized with plastic waste strips
- Worku Firomsa Kabeta
2022 Pełny tekst Archives of Civil Engineering
It is well known that if plastic wastes are not well managed, it has a negative impact on the environment as well as on human health. In this study, recycling plastic waste in form of strips for stabilizing weak subgrade soil is proposed. For this purpose, a weak clay soil sample was mixed with 0.2%, 0.3%, and 0.4% of plastic strips by weight of soil, and the experimental results were compared to the control soil sample with 0% plastic. Laboratory tests on the Standard compaction test, Unconfined compression test (UCS), and California bearing ratio (CBR) were conducted according to the American Society for Testing and Materials (ASTM). The results of the study reveal that there are significant improvements in the strength of weak soil stabilized with plastic waste strips. Accordingly, the Standard Proctor test shows that there is a small increment in the maximum dry density of the soil when it is mixed with plastic strips. The result from the CBR test shows that there is a significant increment of CBR value with the plastic strip content. The unconfined compressive strength test also shows that increasing the percentage of plastic strips from 0 to 0.4% resulted in increased strength of soil by 138% with 2 cm length plastic strips. Therefore, this study recommends the application of plastic strips for improvement of the strength of soft clay for subgrade construction in civil engineering practice as an alternative weak soil stabilization method.
Study on the accuracy of axle load spectra used for pavement design
- Dawid Ryś
- Piotr Burnos
2022 Pełny tekst International Journal of Pavement Engineering
Weigh-in-Motion (WIM) systems are used in order to reduce the number of overloaded vehicles. Data collected from WIM provide characteristics of vehicle axle loads that are crucial for pavement design as well as for the development of pavement distress prediction models. The inaccuracy of WIM data lead to erroneous estimation of traffic loads and in consequence inaccurate prediction of pavement distress process. The objective of the paper is to present a new methodology of heavy traffic axle load spectra (ALS) correction due to weighing errors (systematic and random) that occur in WIM systems. The theoretical solution which is proposed in the paper was validated successfully. The method enables correction of erroneous data to make traffic load statistics used for pavement design more reliable and precise, with no necessity to remove high number of records, as it is used in other methods. The practical meaning of the newly developed method was emphasised by analysis of the effect of relative and random error of WIM data on pavement fatigue life estimation, as well as on the estimated percentage of overloaded vehicles. Mechanistic-empirical approach (M-EPDG) was used for this purpose.
Study on the Positioning Accuracy of the GNSS/INS System Supported by the RTK Receiver for Railway Measurements
- Mariusz Specht
- Cezary Specht
- Andrzej Stateczny
- Paweł Burdziakowski
- Paweł Dąbrowski
- Oktawia Lewicka
2022 Pełny tekst ENERGIES
Currently, the primary method for determining the object coordinates is positioning using Global Navigation Satellite Systems (GNSS) supported by Inertial Navigation Systems (INS). The main goal of this solution is to ensure high positioning availability, particularly when access to satellite signals is limited (in tunnels, areas with densely concentrated buildings and in forest areas). The aim of this article is to determine whether the GNSS/INS system supported by the RTK receiver is suitable for the implementation of selected geodetic and construction tasks in railway engineering, such as determining the place and extent of rail track deformations (1 cm (p = 0.95)), the process of a rapid stocktaking of existing rail tracks (3 cm (p = 0.95)) and for design and construction works (10 cm (p = 0.95)), as well as what the impact of various terrain obstacles have on the obtained positioning accuracy of the tested system. During the research, one INS was used, the Ekinox2-U by the SBG Systems, which was supported by the Real-Time Kinematic (RTK) receiver. GNSS/INS measurements were conducted on three representative sections varying in terms of terrain obstacles that limit the access to satellite signals during mobile railway measurements in Tricity (Poland). The acquired data allowed us to calculate the basic position accuracy measures that are commonly used in navigation and transport applications. On this basis, it was concluded that the Ekinox2-U system can satisfy the positioning accuracy requirements for rapid stocktaking of existing rail tracks (3 cm (p = 0.95)), as well as for design and construction works (10 cm (p = 0.95)). On the other hand, the system cannot be used to determine the place and extent of rail track deformations (1 cm (p = 0.95)).
Study on VR Application Efficiency of Selected Android OS Mobile Devices
- Przemysław Falkowski-Gilski
- Karol Fidurski
2022
Currently, the number of scenarios for using VR (Virtual Reality) technology grows every year. Yet, there are still issues associated with it, related with the performance of the mobile device itself. The aim of this work is to perform an analysis of the effectiveness of virtual reality applications in case of mobile platforms. We put the main emphasis on examining the performance and efficiency of four different hardware and software platforms, evaluated in a number of research scenarios, related with typical user activities. The performance of various consumer devices running Android OS was assessed using selected benchmark applications. Additionally, a custom-build environments was also created to facilitate further testing, including an enhanced HCI (Human-Computer Interface) linking the mobile device, head-mounted googles, and a powerful desktop PC. The performed tests and obtained results can aid any interested individual when choosing the right mobile device, as well as config uring the VR environment, for various UX (User Experience) purposes.
Subiektywny pomiar jakości programów radiowych strumieniowanych w sieci metodą crowdsourcingu
- Przemysław Falkowski-Gilski
2022 Przegląd Telekomunikacyjny + Wiadomości Telekomunikacyjne
Obecnie słuchacze mają dostęp do swoich ulubionych programów i audycji radiowych za pośrednictwem naziemnego standardu analogowego FM (Frequency Modulation) oraz cyfrowego DAB+ (Digital Audio Broadcasting plus). Należy podkreślić, że ten sam materiał nadawany jest jednocześnie w kilku technikach (tzw. simulcast), a znaczna większość rozgłośni udostępnia swoje programy także online. Niniejsza praca przedstawia wyniki badań dotyczących jakości transmisji programów radiowych strumieniowanych w sieci. Kampanię pomiarową przeprowadzono metodą tzw. crowdsourcingu przy udziale 45 słuchaczy.
Successive cytotoxicity control by evolutionary surface decorated electronic push-pull green ZnCr-LDH nanostructures: Drug delivery enlargement for targeted breast cancer chemotherapy
- Mahsa Kiani
- Mojtaba Bagherzadeh
- Yousef Fatahi
- Hossein Daneshgar
- Moein Safarkhani
- Ghazal Salehi
- Pooyan Makvandi
- Mohammad Saeb
- Eder C. Lima
- Navid Rabiee
2022 Pełny tekst OpenNano
The reason for the increasing bioavailability and biocompatibility of the porous nanomaterials in the presence of different (bio)molecules is still unknown. The role of difference functional groups and their interactions with the potential bioavailability and biocompatibility is of great importance. To investigate the potential contribution of the electronic effects (especially on the surface of the porous nanomaterials) on their biomedical behavior, a series of surface-decorated green ZnCr-layered double hydroxide (LDH) porous nanocarriers is developed as a non-viral vector. Different conjugations investigated these porous LDHs for optimizing and minimizing the cytotoxicity for targeted breast cancer therapy. Quick low-temperature synthesized ZnCr-LDH nanocarriers method with enlarged drug delivery windows decorated with leaf extracts and benzamide-like molecules revealed a push-pull electronic synergistic effect on cytotoxicity and enhanced cell viability, biocompatibility, aggregations, and interactions with the cell membranes. The pre-defined model drug, doxorubicin (DOX), unraveled chemotherapy performance in response to MCF-7 cell lines, with ≈ 60% drug payload contributed from functional groups of leaf extracts. Moreover, electron-poor and electron-rich benzamide-like molecules attached to the ZnCr-LDH surface enhanced the relative cell viability up to 29% and 32%, respectively. The in vivo experiments on breast cancer of treated mice (H&E) revealed unaggregated cellular arrays and antibacterial activity against E. coli (gram-negative) and S. aureus (gram-positive) bacteria. Benzamide-like ZnCr-LDH nanocarriers showed a suitable zone of inhibition beyond 10 mm, compared to the standard. Cytotoxicity control achieved herein seems promising for the future ahead of nanomedicine.
SUICIDES FOR ECONOMIC REASONS AS A MEASURE OF THE STATE OF THE ECONOMY: THE CASE OF POLAND
- Jarosław Ziętarski
- Agnieszka Pobłocka
2022 Pełny tekst Współpraca Europejska
Suicides are a phenomenon observed in many countries. The causes of a decision so drastic as far as consequences are concerned include i.a. economic reasons. The question arises whether the changing number of suicides reflects the state of the economy. The direct link between the state of the economy and suicides has not been sufficiently studied so far. The authors of this article attempted to identify the links between selected economic indicators and the number of suicides using statistical and econometric methods. The end result is a description of the connection between indicators determining economic tendencies and suicides for economic reasons. Finding such a connection constitutes an alternative, much cheaper method of assessing the tendencies (climate) of the economy compared to the methods used currently by the Central Statistical Office in Poland or the Ipsos company. In addition, the results of the study allowed to propose an original linear regression model taking into account new variables, compared to the available studies of other authors. The authors' model is an expansion of rather modest scientific discourse on the impact of the economy on the number of suicides. More than 10 years have passed since the beginning of the global financial crisis. In the years 2008–2009, Poland was considered to be 'a green island', i.e. the only country in Europe that did not experience a decline in GDP. The image of this country from the perspective of the consumer looks very different. The increasing number of suicides for economic reasons prompts the analysis of the reasons for this kind of decision. There are relatively few available research papers that would illustrate the link between the state of the economy and the phenomenon of suicides. The authors of this publication, using statistical methods (statistical description and statistical inference), attempted to link the number of suicides for economic reasons to selected economic indicators. The result of the research was the indication of an alternative method for the measurement of selected economic tendency indices of the Polish Central Statistical Office and the Economic Climate Indicator published by Ipsos Polska Sp. z o.o. In addition, a single-equation linear regression model was proposed which not only explains the association of selected indicators describing the condition of an economy with the phenomenon of suicides but can also serve as an early-warning indicator of future suicides
Sulfonamides with hydroxyphenyl moiety: Synthesis, structure, physicochemical properties, and ability to form complexes with Rh(III) ion
- Małgorzata Gawrońska
- Mateusz Kowalik
- Joanna Duch
- Katarzyna Kazimierczuk
- Mariusz Makowski
2022 Pełny tekst POLYHEDRON
Sulfonamides are the first successfully synthesized antimicrobial drugs. The mechanism of sulfonamides’ antimicrobial action involves competitive inhibition of folic acid synthesis and prevention of the growth and reproduction of bacteria. Even though they have been applied in therapy for more than 75 years, sulfonamides are still the drugs of choice for the treatment of various diseases. The aim of this work was to synthesize and characterize two new sulfonamides hydroxyphenyl moiety and investigate their ability to form complexes with Rh(III). The results of recent studies indicate an increased interest in the application of potential platinum-group metal ion complexes as an alternative, promising candidates for anticancer and antimicrobial drugs.
Super tough interpenetrating polymeric network of styrene butadiene rubber‐poly (methyl methacrylate) incorporated with general purpose carbon black ( N660 )
- Jose James
- George Vazhathara Thomas
- Krishanagegham Sidharathan Sisanth
- Hanna Joseph Maria
- Didier Rouxel
- Michał Strankowski
- Nandakumar Kalarikkal
- David Laroze
- Oluwatobi Samuel Oluwafemi
- Tatiana Volova
- Sabu Thomas
2022 JOURNAL OF APPLIED POLYMER SCIENCE
A classic set of polymeric interpenetrating polymeric network (IPN) microcomposites has been fabricated using an elastomer—styrene butadiene rubber [SBR], a thermoplastic poly(methyl methacrylate)-PMMA and with carbon black (CB)-N660 as a filler and reinforcing agent. This synthesized IPN composite can be promisingly employed as a toughened plastic and vibrational damper in a wide service range with excellent thermal stability, optimum storage modulus, and co-continuous morphological pattern. transmission electron microscopy, scanning electron microscopy, atomic force microscopy, and Raman imaging are successfully employed for the morphological characterization. Mechanical, thermal, viscoelastic, and damping features of IPN composites have been carefully studied in detail and compared with parent polymers, corresponding IPN, and composites. The double network formation of filler CB and plastic component PMMA form an intercalated morphological pattern in the SBR matrix with 20 times enhancement in toughness value compared with neat SBR. The fabrication and characterization adopted in this work can definitely act as a platform for the design of new toughened material with excellent performance and cost-effectiveness.
Superconductivity and appearance of negative magnetocaloric effect in Ba1–xKxBiO3 perovskites, doped by Y, La and Pr
- Paweł Pęczkowski
- Maciej Łuszczek
- Elżbieta Szostak
- Naveen Kumar Chogondahalli Muniraju
- Anna Krztoń-Maziopa
- Łukasz Gondek
2022 Pełny tekst ACTA MATERIALIA
Recently, substantial attention is given to the bismuth-based perovskites for variety of electronic applications. The perovskites are used for quantum dots displays (QLED), photovoltaic systems and superconducting (HTS) devices. In this paper comprehensive studies of Ba1–xKxBi1–yREyO3 bismuth perovskites (REBKBO, RE = Y , La or Pr) are reported. Apart from structural anomalous behavior at low temperatures, the electronic properties of the REBKBO can be easily tailored by doping. For instance, critical current den- sities differ by 3 orders of magnitude from 0.07 kA/cm2 (LaBKBO) to 65 kA/cm2 (BKBO). To explain the above behavior, microstructural, magnetic, calorimetric, spectroscopic (FT-IR) studies and ab-initio electronic structure calculations were carried out. The FT-IR shows that the biggest difference in the spectrum compared to the undoped sample was recorded for PrBKBO, due to magnetic contribution of the Pr3+ multiplet. Electronic structure calculations revealed that the BKBO compound shows the highest DOS(EF) compared to the other samples, however, the electronic structure of PrBKBO is very different. The negative magnetocaloric effect observed below 30 K is a highlight of the peculiar properties of that sample. These findings extend possible usage of bismuth-based perovskites towards new applications.
Superhydrophobic sponges based on green deep eutectic solvents for spill oil removal from water
- Patrycja Makoś-Chełstowska
- Edyta Słupek
- Aleksandra Małachowska
2022 Pełny tekst JOURNAL OF HAZARDOUS MATERIALS
The paper described a new method for crude oil-water separation by means of superhydrophobic melamine sponges impregnated by deep eutectic solvents (MS-DES). Due to the numerous potential of two-component DES formation, simple and quick screening of 156 non-ionic deep eutectic solvents using COSMO-RS (Conductor-like Screening Model for Real Solvents) computational model was used. DES which were characterized by high solubility of hydrocarbons and the lowest water solubility were synthesized and embedded on melamine sponges. The new sponges were characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), X-ray diffraction (XRD), and goniometer. Several parameters affecting the crude oil-water separation (i.e. type and amount of DES, density and porosity of sponges, water contact eagle) were thoroughly studied. In order to studies of MS-DES affinity to the selected groups of crude oil i.e. Saturated, Aromatic, Resins, Asphaltenes (SARA) the thin layer liquid chromatography-flame ionization detection (TLC-FID) was used. The obtained results indicate that the melamine sponges impregnated by DES composed of eucalyptol and menthol in 1:5 molar ratio have high real crude oil absorption capacity in the range of 96.1 – 132.2 g/g and slightly depends on crude oil compositions, superhydrophobic properties (water contact angle 152°), low density of 9.23 mg/cm3, high porosity of 99.39%, and excellent reusability which was almost not changing even after 80 cycles. The outcomes indicate that new MS-DES materials could be excellent alternatives as absorbents for the cleanup of crude oil-polluted water.
Superstitions and customs in construction - a contribution to the discussion on the disappearance of this tradition
- Maciej Niedostatkiewicz
2022 Pełny tekst Modern Engineering
Construction is one of the most important, but also the most extensive areas of the economy. That is why we encounter superstitions and customs related to this discipline of the economy quite often:we blew and repeat them, not even knowing what their origin is and what according to old beliefs resulted in their lack of application. This situation applies in practice to all buildings, including residential buildings implemented at different times of time, including today. The aim of the article is to indicate the genesis of selected exaggerations, describe the customs that arose on their basis and present the alleged effects of not cultivating them. Due to the criterion of time in relation to the period of construction of the building, the article discusses superstitions and customs specific to the following stages of the investment: preparatory works and designa, direct implementationand operation and operationand.
Supervised-learning-based development of multi-bit RCS-reduced coding metasurfaces
- Muhammad Abdullah
- Sławomir Kozieł
2022 Pełny tekst IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES
Coding metasurfaces have been introduced as efficient tools allowing meticulous control over the electromagnetic (EM) scattering. One of their relevant application areas is radar cross section (RCS) reduction, which principally relies on the diffusion of impinging EM waves. Despite its significance, careful control of the scattering properties poses a serious challenge at the level of practical realization. This article is concerned with (global) design optimization of coding metasurfaces featuring broadband RCS reduction. We adopt a two-stage optimization procedure involving data-driven supervised-learning, sequential-search strategy, and direct EM-based design closure of the entire metasurface oriented toward maximizing the RCS reduction bandwidth. Our framework is then used to develop a two-bit coding metasurface. To handle the combinatorial explosion at the concurrent meta-atom optimization stage, a sequential-search strategy has been developed that enables global search capability at low computational cost. Finally, EM-based optimization is executed to maximize RCS reduction bandwidth at the level of entire metasurface. The properties of the coding metasurface are demonstrated using monostatic and bistatic RCS performance. The 10-dB RCS reduction can be obtained in the frequency range of 14.8 GHz to 37.2 GHz, in a monostatic configuration. Also, 15-dB RCS reduction can be maintained in the frequency range of 16.7 GHz to 37 GHz. Simulations are validated using physical measurements of the fabricated prototypes. Finally, the performance of the structure is benchmarked against recently reported designs.
Supramolecular deep eutectic solvents and their applications
- Patrycja Janicka
- Massoud Kaykhaii
- Justyna Płotka-Wasylka
- Jacek Gębicki
2022 GREEN CHEMISTRY
In recent years, the growing awareness of the harmfulness of chemicals to the environment has resulted in the development of green and sustainable technologies. The compromise between economy and environmental requirements is based on the development of new efficient and green solutions. Supramolecular deep eutectic solvents (SUPRADESs), a new deep eutectic solvent (DES) subclass characterized by inclusion properties, are a fresh discovery that could have a significant impact on the development of green chemistry. SUPRADESs known in the literature consist of green ingredients, their physicochemical properties are similar to those of conventional DESs, and their supramolecular nature allows for selective binding of numerous chemical compounds – for many applications SUPRADESs show much higher efficiency compared with DESs. Because of the inclusion of cyclodextrins in their structure, these solvents are able to bind to many compounds through the formation of hydrogen bonds (typical of DESs) and at the same time interact with them in a host–guest mechanism. The combination of the environmentally friendly properties of DESs with those of cyclodextrins could be a breakthrough in the context of green chemistry. This review paper summarizes the available knowledge about SUPRADESs – their composition, physicochemical properties, applications and perspectives. SUPRADESs described in the work are fully green, non-toxic, and biodegradable solvents which are capable of efficiently absorbing many substances. So far, few SUPRADESs are known, but some of them are classified as low melting mixtures (LMM). It is very important to systematize the data available on these green solvents and properly classify them. We hope that identifying their potential and green characteristics will support further promising discoveries.
Surface and Trapping Energies as Predictors for the Photocatalytic Degradation of Aromatic Organic Pollutants
- Szymon Dudziak
- Marta Kowalkińska
- Jakub Karczewski
- Marcin Pisarek
- José D. Gouveia
- José R. B. Gomes
- Anna Zielińska-Jurek
2022 Pełny tekst Journal of Physical Chemistry C
In this study, anatase samples enclosed by the majority of three different crystal facets {0 0 1}, {1 0 0}, and {1 0 1} were successfully synthesized. These materials were further studied toward photocatalytic degradation of phenol and toluene as model organic pollutants in water and gas phases. The obtained results were analyzed concerning their surface structure, reaction type, and surface development. Moreover, the regression model was created to find the correlation between the possible predictors and the photodegradation rate constants (k). From the studied factors, the trapping energy of charge carriers at the surface was found to be the most significant one, exponentially affecting the observed k. This resulted in the overall per-surface activity between the samples being in the order {1 0 1} > {1 0 0} > {0 0 1}. Further introduction of the surface energy (Esurf) to the regression model and the number of possible trapping centers per number of pollutant’s molecules (ntrap·n–1) improved the model accuracy, simultaneously showing the dependence on the reaction type. In the case of phenol photocatalytic degradation, the best accuracy was observed for the model including Esurf ·(ntrap·n–1)1/2 relation, while for the toluene degradation, it included Esurf2 and the S·n–1 ratio, where S is the simple surface area. Concerning different surface features which influence photocatalytic performance and are commonly discussed in the literature, the results presented in this study suggest that trapping is of particular importance.
Surface engineering of graphene oxide membranes for selective separation of perfluorooctanoic acids
- Hasan Khorramdel
- Meysam Omidvar
- Milad Tajaddini
- Yang Huang
- Mohammad Saeb
- Farzad Seidi
- Huining Xiao
2022 JOURNAL OF MEMBRANE SCIENCE
Perfluoroalkyl compounds (PFCs) are environmental toxicants and their widespread detection and accumulation in the environment can be detrimental to the ecosystem. In this study, surface charge of GO membranes was engineered to enhance selectivity of graphene oxide (GO) membranes and for the removal of perfluorooctanoic acid (PFOA ∼400 Da) in real concentration ranges in wastewater streams. The structure and physicochemical properties of the GO and modified GO nanosheets and their corresponding membranes were assessed using several characterization techniques. The modified GO membranes showed a water flux of 83.1 ± 1 L m−2 h−1 together with maximum rejection efficiency of 98.4% for 50 ppm PFOA at pressure of 0.45 MPa, which is the highest value reported to date. Compared to the GO membrane, the modified GO membrane exhibited higher water flux and PFOA rejection efficiency by 300% and 70%, respectively. The high surface charged and electron rich GO nanosheets reduce the interlayer spacing in the modified membrane and simultaneously enhance the surface hydrophilicity which leads to increased PFOA retention and enhanced water permeation. These results point to the potential of the modified GO membranes for wastewater treatment.
Susceptibility to Degradation in Soil of Branched Polyesterurethane Blends with Polylactide and Starch
- Joanna Brzeska
- Grzegorz Jasik
- Wanda Sikorska
- Barbara Mendrek
- Jakub Karczewski
- Marek Kowalczuk
- Maria Rutkowska
2022 Pełny tekst Polymers
A very important method of reducing the amount of polymer waste in the environment is the introduction to the market of polymers susceptible to degradation under the influence of environmental factors. This paper presents the results of testing the susceptibility to degradation in soil of branched polyesterurethane (PUR) based on poly([R,S]-3-hydroxybutyrate) (R,S-PHB), modified with poly([D,L]-lactide) (PLA) and starch (St). Weight losses of samples and changes in surface morphology (SEM, OM and contact angle system) with simultaneously only slight changes in molecular weight (GPC), chemical structure (FTIR and 1HNMR) and thermal properties (DSC) indicate that these materials are subject to enzymatic degradation caused by the presence of microorganisms in the soil. Chemical modification of branched polyesterurethanes with R,S-PHB and their physical blending