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EN
The mechanism of SO2 absorption in seawater is investigated, and the experiment was carried out accordingly. Emphasis is on applications of seawater scrubbing of ship’s power plant exhaust gas containing SO2. The formulated model is used to predict the influence of various parameters on both pH of tailwater and seawater desulfurization capability, e.g., the partial pressure of SO2, the partial pressure of CO2, tailwater temperature, pH and alkalinity of seawater. Experiment results indicated that the seawater desulfurization capacity increases with both increasing partial pressure of SO2, pH and alkalinity and decreasing partial pressure of CO2 and temperature. The study shows the desulfurization capacity of seawater with 3.5% salinity is approximately twice that of freshwater. Different scenarios in which the required absorbent supply rate for a given SO2 removal efficiency are studied. It is observed a 97% removal efficiency, corresponding to meeting the SOx limits in the SOx emission control areas (SECA) while operating on a heavy fuel oil containing sulfur 3.5 wt. %, requires a minimum water supply rate of 0.0407–0.0683 m3/kWh, depending mainly on the water composition in terms of alkalinity and salinity. Such data are important in assessing the operation cost of the water scrubbing system.
EN
Hulls of ships are often made of steel, which are produced under the supervision of classification societies. Usually, the hull steel of ordinary strength category A is used for the ship's shell (the yield strength is 235 MPa and the impact strength 27 J at 20ºC). Vessels sail in sea areas with various levels of salinity and thus with different corrosiveness. The average salinity of the seas is taken as 3.5% content of sodium chloride. This article presents the results of corrosion tests of S235 JRG1 steel in an aqueous solution in which the mass fraction of sodium chloride was: 0.7%, 1.4%, 2.2%, 2.8%, 3.5% and 4.2%. Corrosion tests were performed using the potentiodynamic method. As parameters characterizing the corrosion properties of the tested steel, the corrosion current density and corrosion potential were assumed. Statistically significant influence of seawater salinity on the corrosion properties of hull structural steel of ordinary strength of category A was found. The highest value of the corrosion current density was observed in the solution containing 3.5% NaCl mass fraction was observed. In seawater with a sodium chloride content in the range of 0.7 to 3.5%, an increase in the value of the corrosion current density was observed, along with the increasing share of NaCl. In seawater with higher salinity, the corrosion rate was reduced. The corrosion potential of S235JRG1 steel decreases with the NaCl content in the corrosive solution. The susceptibility of this material to corrosion in seawater increased.
EN
Due to the paramagnetic properties and the ability to passivation, for the production of hulls of some vessels (mainly warships), corrosion-resistant (stainless) steels with austenitic structure are used. This article describes the influence of seawater salinity on selected corrosion properties of high-alloy steel X5CrNi 18-10 (304). The average salinity of the seas is taken as 3.5% content of sodium chloride. Corrosion rate of the tested material was evaluated in an aqueous solution of sodium chloride was evaluated. The NaCl concentration in corrosive solutions was 0.7%, 1.4%, 2.1%, 2.8%, 3.5%, 4.2%. Corrosion tests were performed using the potentiodynamic method. The range of electrochemical potential changes was Ecorr ±150 mV. Corrosion rate was assessed on the basis of corrosion current density measurements. Corrosion potential values against the saturated calomel electrode were also determined. Based on the obtained measurement results and non-parametric significance tests carried out, a significant influence of seawater salinity on the value of corrosion current density and corrosion potential was found. The highest value of corrosion current density (jcorr), and thus the highest corrosion rate, was recorded for 3.5% NaCl solution. In the concentration range from 0.7 to 3.5% NaCl in solution, the corrosion rate of austenitic steel increases. A further increase in salinity of electrolyte results in the inhibition of corrosion rate of steel. There is almost a full negative, linear correlation between the proportion of sodium chloride in the corrosive solution and the value of corrosion potential. Along with the rise in the salinity of seawater, increase the electrochemical activity, and thus the corrosion susceptibility, thus the corrosion susceptibility, of the austenitic steel X5CrNi 18-10 was observed.
EN
The marine environment plays a major socio-economic role in the Agadir region (south-west Morocco). This area, which hosts important fishery resources, is currently not spared from the pollutants produced in the course of agricultural, domestic, industrial and tourist development. The aim of this study is to assess the impact of the Taghazout bay tourist resort on the bacteriological and physicochemical quality of the coastal waters of Taghazout. The seawater samples were collected between March 2016 and March 2018 at three sampling sites (S1, S2 and S3) in order to monitor the concentrations of fecal coliforms (FC), fecal streptococci (FS) and total germs (TG). The results of physicochemical parameters show seasonal fluctuations influenced by climatic factors. The spatio-temporal monitoring of the bacteriological parameters shows that the average total germ count is 127.05 CFU/100 ml, 39.61 CFU/100 ml for fecal coliforms and 15.21 CFU/100 ml for fecal streptococci. The values of FC80, FC95 and FS90 do not exceed the guide values of the Moroccan standards. This classifies the Taghazout beach in category A (good quality of bathing water). The monitoring analysis recorded by the Pearson correlation test between the environmental parameters and the level of fecal bacteria showed that there was a significant positive correlation between the FC concentrations and rainfall; the FS concentrations showed significant positive correlations with all the environmental parameters while the TG concentrations indicate no correlation with them. The fecal contamination parameters should be routinely monitored for improving the environmental conditions of coastal cities. This must be the case for the Taghazout coastline where a regular monitoring program must be established to evaluate the impact of the new tourist resort “Taghazout bay” on the environmental quality of this ecosystem.
EN
The SOx emissions of the marine engine are regulated by international maritime conventions. In this paper, the effect of various parameters, including SO2 partial pressure, liquid to gas ratio (L/G), alkalinity and pH, was investigated by seawater scrubbing experiment in a turbulent contact absorber (TCA) and a spray absorber (SA) on a laboratory scale. The experimental data showed that the desulfurization efficiency of TCA was mainly dependent on the value of L/G and irrelevant to the changing way of L/G; the appropriate L/G of TCA was 2.3 dm3/m3 and pH of effluent water was 2.4–2.8 at the L/G of 1.1–2.8 dm3/m3. Comparatively, the desulfurization efficiency of increasing liquid flow rate was better than that of decreasing gas flow rate in the SA experiment. At the gas velocity of 1.58 m/s and L/G of 2.3 dm3/m3, the desulfurization efficiencies and drop pressures of TCA and SA were 75.9% and 42.4%, 690 and 260 Pa, respectively. The results indicate that TCA chosen as an absorber is likely to be a competitive desulfurization technique for controlling marine diesel emission.
EN
Due to the fact that marine environment contamination by oil substances are not uncommon, it is necessary to improve the ability of determine their origin. Therefore, research on the possibility of recognizing the type of oil using its individual characteristic manifested in the processes of fluorescence excitation has been undertaken. Oil pollutants present in seawater mainly coming from ship drives, tankers, pipelines or sea bottom seeps, moreover oil leaks from offshore extraction equipment also are possible. For this reason, the crude oil extracted from the Baltic Sea deposit in the Polish Maritime Areas has been chosen for tests. Fluorescence properties of water containing small amounts of oil (concentrations from 5.59 to 55.4 ppm) in the form of oil-in-water emulsion were tested. Individual samples were assigned matrices of fluorescent values for different wavelengths, while excited by monochromatic light also for different wavelengths. The obtained matrices were visualized as a contour maps and 3D charts. For considered concentrations of crude oil dispersed in water, the wavelength-independent fluorescence maximum was determined. Obtained result indicates that in the studied wavelength range, the total fluorescence intensity is proportional to the oil concentration only for the lowest oil concentrations. The analysis of the objective parameter of the difference between the shapes of spectra indicates the similarity of the spectral shape for the lowest oil concentrations. These results are the methodological suggestion, that for the purpose of identifying the type of oil dispersed in water, spectra should be determined for sequences of different dilutions, until the excitation-emission spectra shapes become independent from the oil concentration.
EN
Using the pad welding technique it is possible to regenerate machine parts or improve surface properties such as abrasion, corrosion and aging resistance. To ensure optimum processing conditions and economic efforts should be made, while providing a high deposition efficiency for the small amount of metal in the pad weld substrate. The pad welding process for the test subject should be carried out by preheating to evaporate the moisture and reduce the porosity of the weld. This treatment is required depending on the carbon equivalent. The article presents the results of corrosion tests of multi-groove pads made with the MIG method on a steel substrate. The samples were made of C45E steel. The additional material was a wire made of stainless steel with the factory name CASTOMAG 4554S. The results of previously performed tests allowed determining the optimal process parameters at which we obtain the smallest share of the base material in the padding. Steel samples were prepared and preheated to 300ºC. The hardfacing process was carried out with constant parameters, i.e. current intensity, arc voltage, surfacing speed). Two protective gases were used to apply the additional material: CO2 and argon. The samples were subjected to corrosion tests in two environments (3.5% sodium chloride solution and 0.001 sulfuric acid solution). The assessment of corrosive properties was made on the basis of constant current measurements (potentiodynamic method). The influence of shielding gas on corrosion properties was demonstrated based on the tests.
EN
A number of flotation plants around the world have increased the use of seawater due to limited sources of fresh water. The aim of this research work is to study the role that Mg2+ and Ca2+ ions play in the interactions between kaolinite and chalcopyrite in seawater. In order to achieve this objective, the effect of kaolinite on flotation of chalcopyrite is studied over the pH range from 8 to 11, when flotation is carried out in seawater and in a 0.01M NaCl solution. The influence of calcium, magnesium, sodium, and potassium ions on the extent of depression by kaolinite is evaluated. The micro-flotation results indicate that chalcopyrite is depressed by kaolinite in both 0.01 NaCl solution and seawater. In the 0.01 NaCl solution, the depressing effect of kaolinite decreases as the pH increases from 8 to 11. However, the results obtained using seawater show that the depressing effect of kaolinite is similar to what is observed in a 0.01 NaCl solution only at pH values below 9, but above this pH kaolinite significantly affects the recovery of chalcopyrite. The results from experiments with using solutions containing individual cations show that the depressing action of kaolinite in the presence of Mg2+ and Ca2+ is more obvious at pH values of 9 and 10, respectively, which correlates with the pH values at which the first hydroxy-complexes of these divalent cations start forming. This seems to indicate that depressing effect of kaolinite on chalcopyrite in seawater may be related to formation of hydrolyzed species of calcium and magnesium. These species can induce heterocoagulation between kaolinite and chalcopyrite. The trends observed in the micro-flotation experiments are in good agreement with the results of the induction time measurements and slime coating tests.
EN
The objective of the article is to present one of the most significant factors affecting electrochemical removal of chloride ions from concrete. Based on the literature findings, tests were carried out on specimens containing chloride admixtures introduced to the cement grout, on elements subjected to chloride penetration from the solution in laboratory conditions and on fragments of constructions penetrated by chlorides as a result of a long-term exposure to seawater.
PL
Proces wymuszonej osmozy (FO), nazywany też osmozą, inżynieryjną osmozą lub manipulowaną osmozą, jest membranowym procesem osmotycznym. Wykorzystuje on ciśnienie osmotyczne silnie stężonego roztworu odbierającego, jako siłę napędową, powodującą transport wody przez zwartą membranę polimerową ze strumienia zasilającego do odbierającego. W zależności od składu roztworu zasilającego i przeznaczenia uzyskanego produktu, etap ten może być jedynym wymaganym procesem. Jednakże w większości przypadków pełny układ, wykorzystujący proces wymuszonej osmozy, zawiera kolejny etap, polegający na regeneracji roztworu odbierającego i uzyskaniu czystej wody. Przewaga procesu wymuszonej osmozy nad klasycznymi technikami odsalania polega na mniejszej intensywności blokowania membran, mniejszym zużyciu energii, większej skuteczności retencji soli oraz większym strumieniu wody. Wymuszona osmoza jest coraz częściej stosowana jako proces separacyjny w oczyszczaniu ścieków, produkcji żywności i odsalaniu wód morskich lub słonawych.
EN
Forward osmosis (FO), also known as osmosis, engineered osmosis or manipulated osmosis, is an osmotically driven membrane process. FO utilizes osmotic pressure of a highly concentrated draw solution as a driving force to transfer water from a feed solution to the draw solution through a dense polymeric membrane. Depending on the concentration of solutes in the feed and the intended use of the product, this stage may be the only process required. In most cases however, a complete FO system utilizing the forward osmosis contains a subsequent step for the draw solute regeneration to finally produce a clean water. Potential advantages of FO over classical desalination processes include its low fouling intensity, low energy consumption, higher salt rejection and higher water flux. It attracts growing attention as separation process in wastewater treatment, food processing, and seawater/brackish water desalination.
EN
The paper presents the study about impregnability of various loose materials dedicated as the fillers of oil absorbent socks and booms. Purpose of the survey was finding the material, which is characterized with the smallest hygroscopicity and the highest absorptivity towards typical fuels used in the marine techniques. The cause of take up the topic is the fact, that the contamination of sea areas with petroleum substances are unfortunately very often, are dangerous for natural environment and first of all are so hard to remove from the sea surface. The natural, mineral and synthetic sorbents were studied under laboratory conditions. Samples of the ten kinds of sorbent, each of 2 grams, were treated with the same amount of the diesel fuel, heavy fuel oil and the sea water also, each time in the same period-time (5 minutes). In order to determine the reliability of the results the authors carried out the test fivefold for the one of searched sorbents (recognized as the most hydrophobic-oleophilic substance). The results are presented in graphical form, based on which we are able to select sorbent that fulfils the greatest extent of required expectations. The results of performed tests show that the method that was described in the paper could be used to test the suitability of various materials for the production of devices for collecting the oil film from the surface of the water.
EN
The paper presents petroleum concentration in coastal waters of Gdańsk Bay, which was measured in 2006 – 2012. The oil concentration ranges from below the detection limit, i.e. 1 μg kg–1 to almost 120 μg kg–1. The concentration does not usually exceed 60 μg kg–1 and its average value is 11.7 μg kg–1. The presence of petroleum in coastal water is characterized by seasonality, with the lowest values in summer and the highest in winter. The conducted research showed that the coastal zone is not the source of petroleum contamination of the sea. The main reason for the presence of petroleum in the coastal water is the migration of polluted water within the bay. The inflow of pollutants from the mainland is yet another source of the contamination in the sea.
EN
The natural seawater contains both dissolved and suspended organic substances originating from natural sources and human activities – like the marine transport fleet among other. To specify the type and quantity of vitally valid as well as dangerous for properly functioning marine ecosystems substances complicated and sophisticated chemical instrumentation and methodologies must be used. Only a small number of seawater components it is possible easily to determine their concentrations – for example, the salt content is determined directly in the bulk of water through simultaneous measurement of electrolytic conductivity and temperature of water. It is worth to search similarly quick method for oil substances directly in the seawater. Taking into account seawater organic pollutants originating from natural sources inter alia crude oils, the presence of refinery petroleum substances due to their fluorescence in ultra-violet light can be determined based on fluorescence spectroscopy. The aim of this paper is to search fluorescence features of oil substances dissolved in natural seawater based on excitation-emission spectroscopy. In the paper fresh and oily contaminated seawater taken from the coastal area of the Baltic Sea were used. As an oil pollution ‘Petro-baltic’ oil were applied. The natural seawater, at first was laboratory exposed to low extremely amount of oil and then it was examined by fluorescence under UV light. The seawater from vicinity of Gdynia (Poland) were tested as fresh and after artificially contaminated by different amount of oil (from 0.5 to 500 ppm). Spectrofluorometer Hitachi F-7000 FL was applied to measure excitation-emission spectra (EEMs). Low amounts of oil (up to several ppm) cause increasing of main peak in excitation-emission spectra (EEMs). Addition of larger amounts of oil results in appearance new peaks, which originate from fluorescence of soluble fractions of oil artificially added to examined water. These specific features of oil describe the spectroscopic signatures of oil, which is the basis to development operational method of the source of oil pollution identification.
EN
The significant part of petroleum substances is transferred to the marine environment after technical activities (inevitable exploitive spills, illegal discharges). However a certain part of petroleum in seawater coming from the natural sources. Therefore, to develop the safety of natural marine environment it is necessary to track not only the anthropogenic pollutants but also the natural sources of petroleum. To distinguish both source of oil the fluorescence properties of oil can be used as the tools to oil identification. The aim of the study is to describe the optical properties of crude oil after it contact with aquatic environment based on fluorescence spectroscopy. For the study, crude oil ‘Petrobaltic’ type potentially found in marine environment due to coming from natural source was applied. To dissolve oil, two different solvent – hexane and Baltic seawater form the Gdynia coast were used. To measure the excitation-emission spectra (EEMs) of oil spectrofluorometer Hitachi F-7000 FL was applied. In the paper, we discuss the changes of oil EEMs in two cases for oil dissolved in n-hexane and for oil dissolved in seawater for various oil concentration. Obtained EEMs for oil dissolved in seawater indicate that EEMs spectrum contain the main peak – describing by the wavelength – independent fluorescence maximum, which was detected for oil dissolved in n-hexane (typical for this kind of oil). However, the intensity of oil fluorescence decreases after oil contact with seawater. This approach could allow expanding the description of complex mixtures of oils as a possible tool proposed for identification the type and origin of oil found in marine environment.
EN
A laboratory study was performed to study the effects of various operating factors, viz. adsorbent dose, contact time, solution pH, stirring speed, initial concentration and temperature on the adsorption of triphenyltin chloride (TPT) onto coal fly ash supported nZnO (CFAZ). The adsorption capacity increases with increase in the adsorbent amount, contact time, pH, stirring speed and initial TPT concentration, and decrease with increase in the solution temperature. The adsorption data have been analyzed by Langmuir, Freundlich, Temkin and Dubinin-Radushkevich (D-R) adsorption models to determine the mechanistic parameters associated with the adsorption process while the kinetic data were analyzed by pseudo first-order, pseudo second-order, Elovich, fractional power and intraparticle diffusivity kinetic models. The thermodynamic parameters of the process were also determined. The results of this study show that 0.5 g of CFAZ was able to remove up to 99.60% of TPT from contaminated natural seawater at 60 min contact time, stirring speed of 200 rpm and at a pH of 8. It was also found that the equilibrium and kinetic data fitted better to Freundlich and pseudo second-order models, respectively. It can therefore be concluded that CFAZ can be effectively used for shipyard process wastewater treatment.
16
Content available Improved oil production by membranes
EN
The objective of this presentation is to show connections of activities leading to improved oil recovery (IOR) when prospecting for oil and gas. Increased wettability of injected water into the reservoirs is caused by specific ions. Technical limitations for production of designer water from seawater by membrane separation are high-lighted. Desirable characteristics of designer water are low NaCl concentrations and high divalent ion concentrations for improving wettability of Crude Oil, Brine and Rock (CBR). Experimental setup incorporated nanofiltration (NF) membranes for ion separation. Retentate from NF contains the main constituents of Designer Water. A property of NF is to retain divalent ions. Performance of the membranes was evaluated in terms of flux and rejection under varying feed compositions, pressures and recovery rates. The research comprised a technical-economical study for salt separation. Results were evaluated in terms of desalination efficiencies and energy requirements. A sensitivity test, spiking Na2SO4 in the feed seawater, showed a decrease in retention of Cl with increasing SO42- concentrations. A reduced permeate flux resulted, however, with increasing Na2SO4 concentrations.
EN
The main problem in the flotation of Cu-Mo sulfide ores in seawater is poor floatability of molybdenite at pH>9.5. Froth stability plays a very important role in determining concentrate grade and recovery in flotation operations and in this paper both floatability and frothability have been tested. The frothability have been studied by measuring froth equilibrium layer thickness in a modified laboratory flotation cell. Two chemical aspects of seawater need to be considered: the content of NaCl (around 87% of salinity), and the concentration of secondary ions (around 13%) (sulfate, magnesium, calcium, bicarbonate ions, etc.). Seawater, NaCl solutions, and seawater’s ions were found to depress frothability. The effect of pH on frothability over the pH range from 9.5 to 11, which is very strong in freshwater, becomes negligible in seawater and the tested electrolyte solutions. The analysis of the relationship between the mechanisms of molybdenite depression and the loss of frothability in seawater implies that the effects of the studied ions on molybdenite floatability and on pulp frothability are different. While depression of molybdenite floatability could be tracked down to magnesium hydroxide precipitation as a main culprit, the depression of frothability is a much more complicated issue.
18
Content available Optical properties of crude oil detected in seawater
EN
The effects of crude oils entering marine environment have been investigated since early 1960s when oil pollution became a subject of global environmental concern. Extraction and transportation of crude oils have been contributing to water pollution especially in closed water basins, such as the Baltic Sea. It was estimated that yearly oil input to the Baltic Sea amounts to 21-70 thousands of tons, which is twice higher than in the North Sea and three times higher than in the North Atlantic. Growing pollution loads into the Baltic Sea created a demand for multifarious studies on the environmental effects of oil products. In this study, we focus on bio-optical and ecological aspects of the presence of crude oil in seawater. Dispersed oil droplets occur in seawater as the result of contaminated river inflows, bilge water discharges and as the consequence of mechanical and chemical dispersion of oil spills. Their optical properties depend on oil type, concentration and size distribution. We present further results obtained from the developed fluorescence-based method for determination of the crude oil concentration in natural Baltic seawater and for evaluation of the oil droplets size by applying vacuum filtering. The results have been measured for the samples collected in Southern Baltic Sea during several ship cruises in 2012. We discuss the application of vacuum filtering in the fluorescence analyses in the context of laboratory, in situ and remote detection of dispersed oil.
EN
Despite of numerous actions undertook by the global and local authorities towards protection of marine environment, oil pollution loads into the Baltic Sea still tend to increase and need to be continuously estimated in order to apply the legal regulations. There is a demand for multifarious studies on the environmental effects of oil products. Dispersed oil droplets occur in seawater as the result of contaminated river inflows, bilge water discharges and as the consequence of mechanical and chemical dispersion of oil spills. Their optical properties depend on oil type, concentration and size distribution. Oil content influences many environmental factors, like water quality and bio-optical parameters (e.g. water-leaving radiance, inherent optical properties, seawater fluorescence). We present a unique study of the collected database of crude oil fluorescence spectra for better understanding the correlations between oil optical properties and its concentration, as well as for evaluation of the oil droplets size by the application of vacuum filtering using three filters of different permeability. Fluorescence spectra have been registered for oil-in-water emulsion samples prepared in the laboratory by mechanical dispersion. We discuss the optical properties of crude oil and the relationships between them in the context of potential remote detection of dispersed oil in seawater.
EN
The main task for natural marine environment protection is to prevent the inflow of various contaminants including oil substances and the real challenge is the ability to rapidly detect these pollutants. Moreover important is to find the source or the maker of the oil spill. In this paper, we consider fundamental physical aspects in the area of possibility of monitoring the natural marine ecosystem based on fluorescence spectroscopy. We utilize the fluorescence ability of numerous oil components – mainly polycyclic hydrocarbons. The paper concerns the spectrofluorimetric characterization of oils have been in use during exploitation of the marine fleet, i.e. lubricate oil, fuels, transformer and hydraulic oils as well as crude oils or their residues. Every kind of oil has a chance to enter the marine environment, especially in a case of ship emergency or after collision with other vessel ore shoreline structure as well as when ship enters the stranding. After discharge of oil, some of oil components are dissolved in the water, bacteria or photochemical reactions, which results in transformation of composition of oil, degrade some. Fluorescence spectrometer Perkin Elmer LS55 was applied to obtain the fluorescence spectra using different excitation wavelength in the range from 240 nm to 500 nm. We discuss the changes of the shapes of excitationemission spectra (EEMs) of various types of oil and the EEMs spectra after contact of oil with seawater as an oil-inwater emulsion, which is the most frequent form of oil in the water column. Significant changes in the shape of spectra and displacement of the peaks are observed.
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