Environmental applications of inorganic-organic clays for recalcitrant organic pollutants removal: Bisphenol A

Bisphenol-A (BPA) adsorption onto inorganic-organic clays (IOCs) was investigated. For this purpose, IOCs synthesised using octadecyltrimethylammonium bromide (ODTMA, organic modifier) and hydroxy aluminium (Al13, inorganic modifier) were used. Three intercalation methods were employed with varying ODTMA concentration in the synthesis of IOCs. Molecular interactions of clay surfaces with ODTMA and Al13 and their arrangements within the interlayers were determined using Fourier transform infrared spectroscopy (FTIR). Surface area and porous structure of IOCs were determined by applying Brunauer, Emmett, and Teller (BET) method to N2 adsorption-desorption isotherms. Surface area decreased upon ODTMA intercalation while it increased with Al13 pillaring. As a result, BET specific surface area of IOCs was considerably higher than those of organoclays. Initial concentration of BPA, contact time and adsorbent dose significantly affected BPA adsorption into IOCs. Pseudo-second order kinetics model is the best fit for BPA adsorption into IOCs. Both Langmuir and Freundlich adsorption isotherms were applicable for BPA adsorption (R2 > 0.91) for IOCs. Langmuir maximum adsorption capacity for IOCs was as high as 109.89 mg g‒1 and it was closely related to the loaded ODTMA amount into the clay. Hydrophobic interactions between long alkyl chains of ODTMA and BPA are responsible for BPA adsorption into IOCs.

A numerical study of the effect of loading conditions on tubular hydroforming

In this work, the mechanics of tubular hydroforming under various types of loading conditions is investigated. The main objective is to contrast the effects of prescribing fluid pressure or volume flow rate, in conjunction with axial displacement, on the stress and strain histories experienced by the tube and the process of bulging. To this end, axisymmetric finite element simulations of free hydroforming (without external die contact) of aluminium alloy tubes are carried out. Hill’s normally anisotropic yield theory along with material properties determined in a previous experimental study [A. Kulkarni, P. Biswas, R. Narasimhan, A. Luo, T. Stoughton, R. Mishra, A.K. Sachdev, An experimental and numerical study of necking initiation in aluminium alloy tubes during hydroforming, Int. J. Mech. Sci. 46 (2004) 1727–1746] are employed in the computations. It is found that while prescribed fluid pressure leads to highly non-proportional strain paths, specified fluid volume flow rate may result in almost proportional ones for the predominant portion of loading. The peak pressure increases with axial compression for the former, while the reverse trend applies under the latter. The implication of these results on failure by localized necking of the tube wall is addressed in a subsequent investigation.

CAE-based prediction of projectile residual velocity for impact on single and multi-layered metallic armour plates

The present, paper deals with the CAE-based study Of impact of jacketed projectiles on single- and multi-layered metal armour plates using LS-DYNA. The validation of finite element modelling procedure is mainly based on the mesh convergence study using both shell and solid elements for representing single-layered mild steel target plates. It, is shown that the proper choice of mesh density and the strain rate-dependent material properties are essential for all accurate prediction of projectile residual velocity. The modelling requirements are initially arrived at by correlating against test residual velocities for single-layered mild steel plates of different depths at impact velocities in the ran.-c of approximately 800-870 m/s. The efficacy of correlation is adjudged, in terms of a 'correlation index', defined in the paper: for which values close to unity are desirable. The experience gained for single-layered plates is next; used in simulating projectile impacts on multi-layered mild steel target plates and once again a high degree of correlation with experimental residual velocities is observed. The study is repeated for single- and multi-layered aluminium target plates with a similar level of success in test residual velocity prediction. TO the authors' best knowledge, the present comprehensive study shows in particular for the first time that, with a. proper modelling approach, LS-DYNA can be used with a great degree of confidence in designing perforation-resistant single and multi-layered metallic armour plates.

Formation of ω-Al7Cu2Fe phase during laser processing of quasicrystal-forming Al-Cu-Fe alloy

The formation of an ω-Al7Cu2Fe phase during laser cladding of quasicrystal-forming Al65Cu23.3Fe11.7 alloy on a pure aluminium substrate is reported. This phase is found to nucleate at the periphery of primary icosahedral-phase particles. A large number of ω-phase particles form an envelope around the icosahedral phase. On the outer side, they form an interface with an agr-Al solid solution. Detailed transmission electron microscopic observations show that the ω phase exhibits an orientation relationship with the icosahedral phase. Analysis of experimental results suggests that the ω phase forms by precipitation on an icosahedral phase by heterogeneous nucleation and grows into the aluminium-rich melt until supersaturation is exhausted. The microstructural observations are explained in terms of available models of phase transformations.

Effect of process parameters on transport phenomena during solidification in the presence of electromagnetic stirring

In the present work, a numerical study is performed to predict the effect of process parameters on transport phenomena during solidification of aluminium alloy A356 in the presence of electromagnetic stirring. A set of single-phase governing equations of mass, momentum, energy and species conservation is used to represent the solidification process and the associated fluid flow, heat and mass transfer. In the model, the electromagnetic forces are incorporated using an analytical solution of Maxwell equation in the momentum conservation equations and the slurry rheology during solidification is represented using an experimentally determined variable viscosity function. Finally, the set of governing equations is solved for various process conditions using a pressure based finite volume technique, along with an enthalpy based phase change algorithm. In present work, the effect of stirring intensity and cooling rate are considered. It is found that increasing stirring intensity results in increase of slurry velocity and corresponding increase in the fraction of solid in the slurry. In addition, the increasing stirring intensity results uniform distribution of species and fraction of solid in the slurry. It is also found from the simulation that the distribution of solid fraction and species is dependent on cooling rate conditions. At low cooling rate, the fragmentation of dendrites from the solid/liquid interface is more.

Determination of the orthotropic plate parameters of stiffened plates and grillages in free vibration

It is well known that the analysis of vibration of orthogonally stiffened rectangular plates and grillages may be simplified by replacing the actual structure by an orthotropic plate. This needs a suitable determination of the four elastic rigidity constants Dx, Dy, Dxy, D1 and the mass {Mathematical expression} of the orthotropic plate. A method is developed here for determining these parameters in terms of the sectional properties of the original plate-stiffener combination or the system of interconnected beams. Results of experimental work conducted on aluminium plates agree well with the results of the theory developed here.

Synthetic investigations in the sesamin group - Part I. Synthesis of samin, a degradation product of sesamolin

Ethylα-bromovinylacetate (VII) was condensed with the sodio derivative of ethyl piperonoylacetate (VIII) to give diethylα-vinyl-α′-piperonoylsuccinate (IX). The latter on reduction with lithium aluminium hydride furnished the triol (X), which underwent smooth cyclisation with 1% ethanolic hydrogen chloride to 2-(3′, -methylenedioxyphenyl)-hydroxymethyl-4-vinyltetrahydrofuran (XIa). The structure of XIa was established by Oppenauer oxidation to an aldehyde. Ozonolysis of XIa afforded samin (I).

Growth of ionization currents in dry air at high values of E/N

Uniform field steady-state ionization currents were measured in dry air as a function of N at constant E/N (E is the electric field strength and N the gas number density) and constant electrode separation d for 14·13 × 10-16 less-than-or-eq, slant E/N less-than-or-eq, slant 282·5 × 10-16 V cm2. Uniform field sparking potentials were also measured for Nd range 1·24 × 1016 less-than-or-eq, slant Nd less-than-or-eq, slant 245 × 1016 cm-2. The ratio of the Townsend primary ionization coefficient α to N, α/N, was found to depend on E/N only. The secondary coefficients were also evaluated for aluminium and gold-plated electrodes for the above range of E/N. Measurements of the sparking potentials showed that Paschen's law is not obeyed in air at values of Nd near and below the Paschen minimum.

Positional dependence of material flow in friction stir welding: analysis of joint line remnant and its relevance to dissimilar metal welding

Understanding material flow in friction stir welding is important for production of sound dissimilar metal welding that control the intermixing of two alloys being welded and consequent formation of new constituents which influences the weld properties. In the present experimental investigation material flow patterns are visualised using dissimilar and similar aluminium alloys using a simple innovative ,experiment. The experimental results reveal that only a portion of material transported from the leading edge undergoes chaotic flow and the remaining is deposited systematically in the trailing edge of the weld. Using this information it is shown that the formation of a friction stir welding defect, joint line remnant, does not occur only when the weld interface is on the advancing side. The material flow visualisation study has been utilised to analyse the mechanism of weld formation and its usefulness in improving fatigue properties and for dissimilar metal welds.

Studies on friction and transfer layer: role of surface texture

Friction influences the nature of transfer layer formed at the interface between tool and metal during sliding. In the present investigation, experiments were conducted using “Inclined Scratch Tester” to understand the effect of surface texture of hard surfaces on coefficient of friction and transfer layer formation. EN8 steel flats were ground to attain surfaces of different textures with different roughness. Then super purity aluminium pins were scratched against the prepared steel flats. Scanning electron micrographs of the contact surfaces of pins and flats were used to reveal the morphology of transfer layer. It was observed that the coefficient of friction and the formation of transfer layer depend primarily on the texture of hard surfaces, but independent of surface roughness of hard surfaces. It was observed that on surfaces that promote plane strain conditions near the surface, the transfer of material takes place due to the plowing action of the asperities. But, on a surface that promotes plane stress conditions the transfer layer was more due to the adhesion component of friction. It was observed that the adhesion component increases for surfaces that have random texture but was constant for the other surfaces

Rare earth exchanged (Ce3+, La3+ and RE3+) H-Y zeolites as solid acid catalysts for the synthesis of linear alkyl benzenes

Rare earth exchanged H–Y zeolites were prepared by simple ion exchange methods at 353 K and have been characterized using different physicochemical techniques. A strong peak around 58 ppm in the 27Al{1H} MAS NMR spectra of these zeolites suggests a tetrahedral coordination for the framework aluminium. Small peak at or near 0 ppm is due to hexa-coordinated extra-framework aluminium and a shoulder peak near 30 ppm is a penta-coordinated aluminium species; [Al(OH)4]−. The vapor-phase benzene alkylation with 1-decene and 1-dodecene was investigated with these catalytic systems. Under the reaction conditions of 448 K, benzene/olefin molar ratio of 20 and time on stream 3 h, the most efficient catalyst was CeH–Y which showed more than 70% of olefin conversion with 48.5% 2-phenyldecane and 46.8%, 2-phenyldodecane selectivities with 1-decene and 1-dodecene respectively.

Activities, concentration fluctuations and complexing in liquid Ca-Al alloys

Détermination de l'activité du calcium par la méthode d'effusion de Knudsen. Calcul, à partir de la distribution mesurée pour l'aluminium entre l'alliage et du fer pur, de l'activité de l'aluminium dans des alliages riches en calcium. Détermination en combinant les deux méthodes, des activités des deux composants et de l'énergie de Gibbs de mélange pour tout le domaine de composition. Calcul et analyse du facteur de structure concentration-concentration

Kosteikkosedimentin fosforivarat ja niiden käyttökelpoisuus kasveille

Maatalouden ympäristötukiohjelmalla pyritään vähentämään maatalouden ravinnekuormitusta, sillä valtaosa fosforin hajakuormituksesta on peräisin maataloudesta. Maataloudesta peräisin olevan fosforin rehevöittävää vaikutusta vesistöissä voidaan pyrkiä vähentämään kosteikoilla, joiden päätarkoituksena on saada valumaveden mukana erodoitunut maa-aines sedimentoitumaan kosteikon pohjalle. Kosteikkojen toimivuudesta ja vesiensuojelun merkityksestä on kuitenkin Suomessa tehdyissä tutkimuksissa saatu ristiriitaisia tuloksia. Tämän työn tavoitteena on selvittää maa-analyysien avulla, mitä valuma-alueelta erodoitunut fosforille tapahtuu kosteikon sedimentissä ja kuinka hyvin sedimentoitunut aines soveltuu kasvualustaksi kasvintuotannossa. Valuma-alueen maanäytteitä ja kosteikon sedimenttinäytteitä vertailemalla havaittiin kosteikossa tapahtuvan erodoituneen maa-aineksen lajittumista. Kosteikosta otetussa sedimenttinäytteessä oli 48 % enemmän savesta kuin valumapellon muokkauskerroksen maanäytteissä. Lisäksi havaittiin, että savespitoisuuden lisääntyminen lisäsi sedimentin reaktiivista pinta-alaa, koska sedimentissä oli 45 % enemmän alumiini- ja rautahydroksideja kuin valuma-alueelta otetuissa maanäytteissä. Hydroksidien runsauden takia fosforin sorptiokapasiteetti oli sedimentissä 52 % suurepi kuin valuma-alueelta otetuissa näytteissä. Sedimenttinäytteiden fosforin sorptiokyllästysaste oli kuitenkin samansuuruinen verrattuna valuma-alueelta otettuihin näytteisiin, sillä hapettuneessa sedimentissä oli 50 % enemmän alumiini- ja rautahydroksidien sitomaa fosforia. Näytteenottohetkellä sedimentti oli pelkistyneessä tilassa, jolloin sen vesiuuttoisen fosforin määrä oli huomattavasti suurempi kuin hapettuneessa sedimentissä. Vastaavasti sedimentin hapettuessa fosforin sorptiokyky kasvoi huomattavasti, sillä pelkistyneestä sedimentistä desorboitui fosforia kosteikon veteen. Tämä havaittiin myös astiakokeessa, sillä sedimentissä kasvanut raiheinä kärsi voimakkaasta fosforin puutoksesta niillä lannoitustasoilla, joilla valuma-alueen maanäytteessä kasvaneella raiheinällä ei silmämääräisesti havaittu esiintyvän puutosoireita. Sedimentin toiselle sadolle annetulla kolminkertaisella fosforin lisälannoituksella saavutettiin samansuuruiset sadon kuiva-ainemäärät, fosforipitoisuudet ja fosforin otot kuin valuma-alueen maanäytteissä kasvaneella ensimmäisellä sadolla oli. Astiakokeen tulosten perusteella pelkistyneessä tilassa ollut sedimentti soveltuu heikosti kasvintuotannon kasvualustaksi suuren fosforisorptiokykynsä ansiosta. Parhaiten sedimentti soveltuisi runsaasti helppoliukoista fosforia sisältäville alueille, kuten karjan jalottelutarhan pohjamateriaaliksi, vähentämään ympäristöön kohdistuvaa fosforikuormitusta.

Analysis of forest soil chemistry and hydrology with a dynamic model ACIDIC.

In this study we analyze how the ion concentrations in forest soil solution are determined by hydrological and biogeochemical processes. A dynamic model ACIDIC was developed, including processes common to dynamic soil acidification models. The model treats up to eight interacting layers and simulates soil hydrology, transpiration, root water and nutrient uptake, cation exchange, dissolution and reactions of Al hydroxides in solution, and the formation of carbonic acid and its dissociation products. It includes also a possibility to a simultaneous use of preferential and matrix flow paths, enabling the throughfall water to enter the deeper soil layers in macropores without first reacting with the upper layers. Three different combinations of routing the throughfall water via macro- and micropores through the soil profile is presented. The large vertical gradient in the observed total charge was simulated succesfully. According to the simulations, gradient is mostly caused by differences in the intensity of water uptake, sulfate adsorption and organic anion retention at the various depths. The temporal variations in Ca and Mg concentrations were simulated fairly well in all soil layers. For H+, Al and K there were much more variation in the observed than in the simulated concentrations. Flow in macropores is a possible explanation for the apparent disequilibrium of the cation exchange for H+ and K, as the solution H+ and K concentrations have great vertical gradients in soil. The amount of exchangeable H+ increased in the O and E horizons and decreased in the Bs1 and Bs2 horizons, the net change in whole soil profile being a decrease. A large part of the decrease of the exchangeable H+ in the illuvial B horizon was caused by sulfate adsorption. The model produces soil water amounts and solution ion concentrations which are comparable to the measured values, and it can be used in both hydrological and chemical studies of soils.

Helsingin Östersundomin pienvesien kartoitus

The area of Östersundom (29,1 square kilometers) was attached to Helsinki in the beginning of the year 2009. Östersundom is formed mostly from the municipality of Sipoo, and partly from the city of Vantaa. Nowadays Östersundom is still quite rural, but city planning has already started, and there are plans to develop Östersundom into a district with 45 000 inhabitants. In this study, the headwaters, streams and small lakes of Östersundom were studied to produce information as a basis for city planning. There are six main streams and five small lakes in Östersundom. The main methodology used in this study was the examination of the physical and the chemical quality of the water. The hygienic quality of the water was also studied. It was also examined whether the waters are in their natural state, or have they been treated and transformed by man. In addition, other factors affecting the waters were examined. Geographical information data was produced as a result of this work. Östersundom is the main area looked at in this study, some factors are examined in the scope of the catchment areas. Water samples were collected in three sampling periods: 31.8 4.9.2009, 3. 4.2.2010, and 10. 14.4.2010. There were 20 sampling points in Östersundom (5 in small lakes, 15 in streams). In the winter sampling period, only six samples were collected, from which one was taken from a small lake. Field measurements associated with water sampling included water temperature, oxygen concentration, pH and electoral conductivity. Water samples were analyzed in the Laboratories of Physical Geography in the University of Helsinki for the following properties: total suspended solids (TSS), total dissolved substances (TDS), organic matter, alkalinity, colour, principal anions and cations and trace elements. Metropolilab analyzed the amount of faecal coliform bacteria in the samples. The waters in Östersundom can be divided to three classes according to water quality and other characteristics: the upper course of the streams, the lower course of the streams and the small lakes. The streams in their upper course are in general acidic, and their acid neutralization capacity is low. The proportion of the organic matter is high. Also the concentrations of aluminium and iron tend to be high. The streams in the lower course have acidity closer to neutral, and the buffering capacity is good. The amounts of TSS and TDS are high, and as a result, the concentrations of many ions and trace elements are high as well. Bacteria were detected at times in the streams of the lower course. Four of the five small lakes in Östersundom are humic and acidic. TSS and TDS concentrations tend to be low, but the proportion of organic matter is often high. There were no bacteria in the small lakes. The fifth small lake (Landbonlampi) differs from the others by its water colour, which is very clear. This lake is very acidic, and its buffering capacity is extremely low. Compared to the headwaters in Finland in general, the concentrations of many ions and trace elements are higher in Östersundom. On the other hand, the characteristics of water were different according to the classification upper course streams, lower course streams, and small lakes. Generally, the best water quality was observed in the stream of Gumbölenpuro and in the lakes Storträsk, Genaträsk, Hältingträsk and Landbonlampi. Several valuable waters in their natural state were discovered from the area. The most representative example is the stream of Östersundominpuro in its lower course, where the stream flows through a broad-leaf forest area. The small lakes of Östersundom, and the biggest stream Krapuoja, with its meandering channel, are also valuable in their natural state.