Wyniki wyszukiwania dla: ENVIRONMENTAL DEGRADATION
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Degradation of polyurethanes in sea water
PublikacjaOceniono degradowalność różnych poliuretanów w wodzie morskiej Bałtyku. Porównano te dane z wynikami stopnia degradacji poliuretanów w wodzie morskiej z dodatkiem azydku sosowego. Ocenę stopnia degradacji przeprowadzano na podstawie pomiarów zmian masy, właściwości mechanicznych i morfologii przed i po procesie degradacji. Wykazano, że różna podatność na degradację poliuretanów w wodzie morskiej związana jest z ich odmiennym stopniem...
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Reactive extrusion of biodegradable aliphatic polyesters in the presence of free-radical-initiators: A review
PublikacjaNowadays, growing attention is being paid to the environment and sustainability, what fully justified research works focused on modification of biodegradable polymers and their composites. In this field of research reactive extrusion seems to be the most promising approach, which fits well to sustainable development strategy. In In the present work, the in-situ modification of biodegradable aliphatic polyesters and the compatibilization...
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Spatial variability of the hydrochemistry of shallow groundwaters and surface waters of the Rensdyrbekken: A case study of a permafrost catchment in Bellsund (SW Spitsbergen, Svalbard)
PublikacjaProgressive climate change may have unpredictable consequences for the Arctic environment. Permafrost catchments off the west coast of Svalbard, described as “thin” and “warm,” are particularly sensitive to climate change. The interdisciplinary research on the hydrochemical response of surface and underground water functioning within a small permafrost catchment area focused on the determination of the impact of meteorological...
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Oxygen concentration regulated the efficient liquefaction of vulcanized natural rubber
PublikacjaOxidative liquefaction represents a promising avenue for the homogeneous and high-value utilization of waste tire rubber. Given that truck tires predominantly comprise natural rubber (NR), this study investigated the efficient liquefaction of vulcanized NR regulated by oxygen concentration. Remarkably, the liquefaction of vulcanized NR was realized with an oxygen concentration of 75 % at 200 °C within 3 min. FTIR spectroscopy showed...
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Assessment of the devulcanization process of EPDM waste from roofing systems by combined thermomechanical/microwave procedures
PublikacjaEthylene-propylene-diene rubber (EPDM) is a elastomer widely used in common industrial applications. EPDM can be shaped into sheets and employed as isolating material for roofing systems. In this study, scraps of EPDM from commercial, industrial and residential roofing systems were treated by combined thermo-mechanical and microwave devulcanization processes including peroxide of benzoyl (BPO). The devulcanized EPDM (Dev-EPDM)...
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Reemission of inorganic pollution from permafrost? A freshwater hydrochemistry study in the lower Kolyma basin (North-East Siberia)
PublikacjaPermafrost regions are under particular pressure from climate change resulting in widespread landscape changes, which impact also freshwater chemistry. We investi- gated a snapshot of hydrochemistry in various freshwater environments in the lower Kolyma river basin (North-East Siberia, continuous permafrost zone) to explore the mobility of metals, metalloids and non-metals resulting from permafrost thaw. Partic- ular attention...
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Processing, physico-mechanical and thermal properties of reclaimed GTR and NBR/reclaimed GTR blends as function of various additives
PublikacjaIn this work, ground tire rubber (GTR) was mechano-chemically reclaimed in the presence of bitumen and various additives. During studies three types of processing and curing additives: (i) peptizer P300; (ii) vulcanization accelerator tetramethylthiuram disulfide (TMTD) and (iii) organic peroxide di(2-tert-butyl-peroxyisopropyl)benzene (BIB1) were applied to enhance reclaiming of GTR. Reclaiming process was evaluated by oscillating...
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The influence of amorphous macrodiol, diisocyanate type and l-ascorbic acid modifier on chemical structure, morphology and degradation behavior of polyurethanes for tissue scaffolds fabrication
PublikacjaStudies described in this work were related to the bulk synthesis and characterization of polyurethanes (PURs) obtained with the use of cyclic 4,4′-methylene bis(cyclohexyl isocyanate) (HMDI) or linear 1,6-hexamethylene diisocyanate (HDI), amorphous α,ω-dihydroxy(ethylene-butylene adipate) macrodiol (PEBA), 1,4-butandiol (BDO) chain extender and dibutyltin dilaurate (DBTDL) catalyst. Obtained PURs were modified with l-ascorbic...
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Fully bio-based poly(propylene succinate) synthesis and investigation of thermal degradation kinetics with released gases analysis
PublikacjaOne of the most important information about polyesters is their thermal stability and phase transition tem- peratures. These characteristics give information about the promising behavior of the polyester during proces- sing. In this work, linear bio-based polyester polyols were prepared with the use of succinic acid and 1.3- propanediol (both with natural origin). As a polycondensation catalyst was used tetraisopropyl orthotitanate...
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Rheological properties, oxidative and thermal stability, and potential application of biopolyols prepared via two-step process from crude glycerol
PublikacjaIn this work, previously synthesized biopolyols were analyzed in terms of their rheological and thermal properties, very important from the technological point of view. For better evaluation of performed synthesis, the influence of its time and temperature on the properties of biopolyols was determined. In the end, obtained materials were used to prepare rigid polyurethane-polyisocyanurate (PUR-PIR) foams, to evaluate their potential...
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Kinetics study of the fully bio-based poly(propylene succinate) synthesis. Functional group approach
PublikacjaCurrently, the increasing importance of the bio-based chemical compounds development is visible in the polymer chemistry, chemical engineering and materials science. It is well-known that the various purity level and different contaminants characterize petrochemical-based compounds compared to their biobased counterparts. Therefore, it is necessary to find out the contaminants impact on the bio-based monomers synthesis. One of...
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Thermal degradation of polylactic acid (PLA)/polyhydroxybutyrate (PHB) blends: A systematic review
PublikacjaPolylactic acid (PLA) and polyhydroxybutyrate (PHB) are two biopolyesters obtained from renewable resources like corn or sugar under bacterial fermentation. PLA is the most widely used biopolymer in diverse applications. Addition of PHB to PLA can improves the crystallinity of PLA, and thereby its mechanical strength. However, both PLA and PHB suffer from poor thermal stability, which limits their potential industrial application....
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Investigating the combined impact of plasticizer and shear force on the efficiency of low temperature reclaiming of ground tire rubber (GTR)
PublikacjaIn the present work, ground tire rubber (GTR) was mechano-chemically reclaimed at ambient temperature using two-roll mills. Road bitumen and styrene-butadiene-styrene (SBS)-modified bitumen at variable content (in range: 2.5–20 phr) were applied as reactive plasticizers to enhance reclaiming of GTR. For better understanding the plasticizing effect of bitumen on the quality of obtained reclaimed rubber, mechano-chemically reclaimed...
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Characterization of volatile compounds, structural, thermal and physico-mechanical properties of cross-linked polyethylene foams degraded thermo-mechanically at variable times
PublikacjaWaste cross-linked polyethylene foam (wXLPE) was thermo-mechanically degraded at variable time using internal batch mixer. The progress of wXLPE degradation has been investigated by using a simultaneous thermogravimetric/differential scanning calorimetry analyzer coupled with Fourier transform infrared spectroscopy, swelling measurements, tensile tests and scanning electron microscopy. Volatile organic compounds generated during...
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Evaluation of structural change during fast transformation process of cross-linked NR into liquid NR by light pyrolysis
PublikacjaThe presence of cross-linked networks in rubber creates a tremendous problem for recycling and reusing of waste rubber. Fast transformation of cross-linked natural rubber (NR) into liquid natural rubber was carried out by light pyrolysis in temperature range from 240 to 300 °C in variable time (in range: 1–30 min). The transformation efficiency was evaluated by measuring the sol fraction and the cross-link density of the gel fraction....
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Local impedance spectra of organic coatings
PublikacjaPublikacja przedstawia nowe podejście do lokalnych spektroskopowych pomiarów impedancyjnych powłok organicznych, oparte o mikroskop sił atomowych pracujący w trybie kontaktowym. Pomiędzy nieporuszającą się igłę mikroskopu i podłoże metalowe pokryte powłoką epoksydową przyłożono serię sinusoidalnych napięciowych sygnałów pobudzenia w zadanym zakresie częstotliwości. W ten sposób zarejestrowano lokalne widma w trybie "frequency by...
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Thermoplastic polyurethanes with glycolysate intermediates from polyurethane waste recycling
PublikacjaThe polyol is a major component in polyurethane formulations and therefore introducing to the formulation recycled polyol (obtained during decomposition process) allows decreasing the usage of pure petrochemical components. In this work, thermoplastic polyurethanes were prepared using various mixtures of a petrochemical macrodiol poly(ethylene-butylene adipate)diol (PEBA) and a recycled glycolysate intermediate, called glycolysate...
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Investigation of volatile low molecular weight compounds formed during continuous reclaiming of ground tire rubber
PublikacjaGround tire rubber was thermo-mechanically reclaimed at different temperature conditions (80, 120, 160 °C) using a co-rotating twin screw extruder. The progress of ground tire rubber reclaiming was evaluated with specific mechanical energy, sol fraction and thermogravimetric analysis. Volatile organic compounds (VOCs) including volatile sulfur compounds (VCSs) released from ground tire rubber and ground tire rubber after reclaiming...
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Wojciech Litwin dr hab. inż.
Osoby1992÷1996 – Studia na Wydziale Mechanicznym Politechniki Gdańskiej1996 – Zatrudniony na Wydziale Oceanotechniki i Okrętownictwa PG2004 – Obrona pracy doktorskiej2014 – obrona rozprawy habilitacyjnej2012 – obejmuje funkcję prodziekan ds. Nauki na Wydziale Oceanotechniki i OkrętownictwaUczestniczył w wielu projektach badawczych oraz pracach zleconych przez przemysł związanych z łożyskowaniem ślizgowym wałów głównych oraz niekonwencjonalnymi...
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Optimization of carbamazepine photodegradation on defective TiO2-based magnetic photocatalyst
PublikacjaIn this work, carbamazepine (CBZ) degradation over defective Fe3O4@SiO2/d-TiO2/Pt photocatalyst was studied. Within the titania structure, Ti vacancies and Pt nanoparticles were introduced to enhance the photocatalyst’s light absorption and influence charge carriers’ mobility. For the carbamazepine degradation, process parameters, e.g., temperature, flux intensity, photocatalyst loading, aeration, pH, and addition of H2O2, were optimized...
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Photocatalytic activity of nitrogen doped TiO2 nanotubes prepared by anodic oxidation: The effect of applied voltage, anodization time and amount of nitrogen dopant
PublikacjaNitrogen doped TiO2 nanotube arrays were prepared by anodizing Ti foils in an organic electrolyte containing specified amounts of urea as nitrogen precursor. The photocatalytic activity of the samples was evaluated by analyzing the degradation kinetics of phenol in water. The influence of tubes’ length, tubes’ surface morphology and amount of nitrogen in the TiO2 lattice on hydroxyl radical formation efficiency, photocatalytic...
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Carbon nitride exfoliation for photocatalysis and photocatalytic ozonation over emerging contaminants abatement
PublikacjaThe production of graphitic carbon nitride was studied with the addition of a following exfoliation step using ultrasounds, at different times. The treatment produced catalysts with much higher surface areas, from 2.18 m2 g 1 with no treatment to 28.34 m2 g 1 after 36 h of exfoliation. During exfoliation, melem was also produced, and may further enhance the photoluminescence and photocatalytic properties. The photocatalytic reaction...
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Modeling and MANOVA studies on toxicity and endocrine potential of packaging materials exposed to different extraction schemes
PublikacjaThe stability of the linings of packaging that is in contact with the goods stored has been of major concern during decades of the development of packaging materials. In this work, an attempt was undertaken to assess the applicability of using two bioassays (Microtox® and XenoScreen YES/YAS) in estimating the stability of packaging (cans, caps, multilayer material) and the impact of their degradation on the toxicity of some simulated media....
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Numerical Modelling of Connections Between Stones in Foundations of Historical Buildings
PublikacjaThe aim of this paper is to analyse the behaviour of old building foundations composed of stones (the main load-bearing elements) and mortar, based on numerical analysis. Some basic aspects of historical foundations are briefly discussed, with an emphasis on their development, techniques, and material. The behaviour of a foundation subjected to the loads transmitted from the upper parts of the structure is described...
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Screen-printed Sn-doped TiO2 nanoparticles for photocatalytic dye removal from wastewater: A technological perspective
PublikacjaTiO2 is widely used as a photocatalyst with a wide band gap, which limited its application. Ion doping and formulating a high-quality screen-printing paste enhance its features. However, the printability of objects for advanced application seems essential nowadays. In this research, the Sn-doped TiO2 nanoparticles were prepared through a sol-gel method followed by calcination at various temperatures of 450 °C, 550 °C, 650 °C, 750...
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The ILs-assisted electrochemical synthesis of TiO2 nanotubes: The effect of ionic liquids on morphology and photoactivity
PublikacjaFacile and environmentally benign one-step titanium anodization method for TiO2 nanotubes (NTs) formation in a presence of ionic liquids (ILs) was proposed. Influence of the IL structure and its content in ethylene glycol electrolyte on morphology, surface properties and photoactivity of the TiO2 NTs was investigated. Possible interactions between IL and TiO2 NTs as well as the mechanism of NTs formation during anodic oxidation...
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The influence of humic substances in treated sewage on the quality of surface waters
PublikacjaAt present the evaluation of WWTP effectiveness is based upon organic matter and nutrients removal. Recently it was found out that sewage treatment leads to formation of resistant to biochemical degradation organic compounds, similar to humic acids. The humic acids formed during sewage treatment process play diversified functions when discharged to surface waters - for instance they can act as carriers of hydrophobic organic pollutants...
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Effects of beach wrack on the fate of mercury at the land-sea interface – A preliminary study
PublikacjaSince the 1970s, the amount of aquatic plants and algae debris, called beach wrack (BW), has increased along the shores of industrialised regions. The strong ability of primary producers to accumulate pollutants can potentially result in their deposition on the beach along with the BW. Despite that, the fate and impact of such pollutants on sandy beach ecosystems have not been investigated so far. This study examines the fate...
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Exploring synergistic effects in physical-chemical activation of Acorus calamus for water treatment solutions
PublikacjaThe research proposed a novel method of obtaining sorption material from readily available Acorus calamus bio- mass through a combination of physical and chemical activation processes. The material with the highest specific surface area (1652 m2 g−1) was obtained by physical activation with CO2, followed by chemical activation with KOH. Reversing the order of activation methods resulted in a lower specific surface area (1014 m2...
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Rare earth ions doped K 2 Ta 2 O 6 photocatalysts with enhanced UV–vis light activity
PublikacjaNew rare earth-doped K2Ta2O6 photocatalysts were successfully synthesized by hydrothermal method. The effect of dopant type (Y,Yb,Ho,Pr,Er) and amount of rare earth precursor (2,4,8 and 10 mol%) on the physicochemical and photocatalytic properties of RE-K2Ta2O6 have been investigated. All as-prepared materials were characterized by UV–vis diffuse reflectance spectroscopy, Brunauer-Emmett-Teller specific surface area measurement,...
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Visible-light-driven lanthanide-organic-frameworks modified TiO2 photocatalysts utilizing up-conversion effect
PublikacjaHighly efficient and quite stable composite with core-shell-like architecture reported herein, responds to the challenge of sunlight-driven photocatalysts. The Ln(ndc)/TiO2 photocatalytic system comprises active lanthanide-carboxylate coordination networks (Nd, Er, Ho, and Tm as metal ions, and 2,6-naphthalene dicar-boxylic acid as the organic linker) and inert titanium dioxide and allow to convert incompatible visible radiation...
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The effect of Ag, Au, Pt, and Pd on the surface properties, photocatalytic activity and toxicity of multicomponent TiO2-based nanomaterials
PublikacjaMulticomponent TiO2-based nanomaterials (MC-NMs) show better physicochemical properties than their individual components or bulk materials. However, the same unique properties that offer innovative applications might also pose unknown risks to human health and the environment. In this context, TiO2- based nanomaterials with a mixture of noble metal precursors (Ag, Au, Pt, and Pd) for large-scale technological applications in air...
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A novel (Ti/Ce)UiO-X MOFs@TiO2 heterojunction for enhanced photocatalytic performance: Boosting via Ce4+/Ce3+ and Ti4+/Ti3+ redox mediators
PublikacjaTitanium-substituted cerium-oxo-based UiO MOFs with terephthalate linkers modified by various groups (–Br, –NH2, –NO2) or their derivatives (N-heterocyclic or biphenyl groups) were combined with titanium dioxide in a multistep route to obtain a core-shell-like architecture. DFT simulations showed that Ce- and bimetallic Ti/Ce- MOFs exhibited different charge compensation. Extended characterization revealed the formation of heterojunctions between...
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The effect of calcination temperature on structure and photocatalytic properties of Au/Pd nanoparticles supported on TiO2
PublikacjaBimetallic nanoparticles, composed of two different metal elements, can exhibit peculiar electronic, optical, and catalytic or photocatalytic properties that are absent in the corresponding monometallic nanoparticles. We show the effect of calcination temperature (from 350 to 700°C) on the structure and the photocatalytic properties of Au/Pd-modified TiO2. The composition of the bimetallic Au/Pd nanoparticles in relation to their...
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Visible light activity of rare earth metal doped (Er3+, Yb3+ or Er3+/Yb3+) titania photocatalysts
PublikacjaA series of Er3+-TiO2, Yb3+-TiO2 and Er3+/Yb3+-TiO2 photocatalysts were obtained via sol-gel method, using rare earth metal (RE) precursor ranging from 0.25 to 10 mol%. The experiments demonstrated that phenol in aqueous solutions was successfully degraded under visible light (> 450 nm) using RE3+-TiO2. The as-prepared samples were characterized by X-ray diffraction (XRD), X-ray photoelectron emission spectroscopy (XPS), UV-Vis...
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The effect of gold shape and size on the properties and visiblelight-induced photoactivity of Au-TiO2
PublikacjatIn the present investigation, TiO2modified with a different geometry and size of gold particles, suchas nanospheres (NSPs), nanostars (NSTs) and nanorods (NRs), were prepared by the immobilizationmethod. The effect of the gold shape, size and TiO2matrix type (TiO2microspheres or rutile TIO-6 TiO2)were systematically investigated. The obtained photocatalysts were thoroughly characterized by UV–visdiffuse-reflectance spectroscopy...
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Assessment of toxic and endocrine potential of substances migrating from selected toys and baby products
PublikacjaAnalysis of literature data shows that there is limited information about the harmful biological effects of mixture of compounds from the EDC group that are released from the surface of toys and objects intended for children and infants. One of the tools that can be used to obtain such information is appropriate bioanalytical tests. The aim of this research involved determining whether tests that use living organisms as an active...
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The ILs-assisted solvothermal synthesis of TiO2 spheres: the effect of ionic liquids on morphology and photoactivity of TiO2
PublikacjaEffect of the ionic liquid (IL) structure (chain length in the imidazolium cation) on morphology and photoactivity of TiO2 particles has been systematically investigated. The TiO2 microspheres have been successfully synthesized via facile solvothermal method assisted by ionic liquids, such as 1-butyl-3-methylimidazolium chloride [BMIM][Cl] and 1-decyl-3-methylimidazolium chloride [DMIM][Cl] using tetra-tert-butyl orthotitanate...
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Zintegrowane sterowanie systemami zaopatrzenia w wodę pitną
PublikacjaOptymalne ekonomicznie zaspokojenie w miastach bieżącego zapotrzebowania na wodę pitną tak, aby spełnione były wymagania jakości dostaw oraz jakości samej wody jest złożonym zadaniem. Zarówno aspekty aplikacyjne jak i teoretyczne tego problemu są przedmiotem intensywnych prac prowadzanych w sektorach naukowych i przemysłowych na całym świecie. Prace te finansowane są przez przemysł, komitety naukowe oraz Programy Ramowe Unii Europejskiej....
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Jacek Namieśnik prof. dr hab. inż.
OsobyUrodził się 10 grudnia 1949 r. w Mogilnie, zmarł 14 kwietnia 2019 r. w Gdańsku – polski chemik, profesor nauk chemicznych, specjalizujący się w chemii analitycznej i środowiskowej. Rektor Politechniki Gdańskiej w latach 2016–2019. Studia wyższe ukończył w 1972 r. na Wydziale Chemicznym Politechniki Gdańskiej, uzyskując tytuł magistra inżyniera chemika. W 1972 r. rozpoczął pracę na Politechnice Gdańskiej, gdzie w 1978 r. obronił...