Interaction of monomeric and polymeric species of metal ions with clay surfaces. IV. Mixed system of aluminium(III) and iron(III)

Soil Research ◽  
1979 ◽  
Vol 17 (1) ◽  
pp. 141 ◽  
Author(s):  
P Rengasamy ◽  
JM Oades
Keyword(s):  
Positive Charge ◽  
Mixed System ◽  
Pure Aluminium ◽  
X Rays ◽  
Soil Systems ◽  
Mixed Solutions ◽  
Polymeric Species ◽  
Starting Solutions ◽  
End Members ◽  
Indifferent Electrolyte

Polymerization of aluminium(III) and iron(III), in mixed solutions of the nitrates, by dialysis against distilled water resulted in polycations having higher Fe/(Fe+Al) mole ratios than those of the starting solutions. A maximum of 25 mole per cent aluminium(III) entered probably into the structure of the po1y[Fe(III)-OH] cation. Ferric aquo-ions polymerized quickly and slower polymerization of aluminium(III) led to the exclusion of the monomeric aluminium(III) during hydrolysis. A more complete polymerization of both aluminium(III) and iron(III) in mixed solutions was initiated by adding sodium hydroxide up to a OH/(Fe+Al) mole ratio of 2.5 and then removing the monomers by dialysis. The resultant polycations had Fe/(Fe+Al) mole ratios close to the original solutions. The pH values and positive charge of these products were higher than any obtained with either pure aluminiurn(III) or iron(III) systems, suggesting that these are copolycations of aluminium(III) and iron(III) rather than a mixture of separate aluminium(III) and iron(III) species. The infrared spectra of these copolycations were different from the pure end members, viz. po1y[Fe(III)-OH] and poly[Al(III)-OH] cations prepared under similar conditions, confirming that they were copolymers rather than a physical mixture of individual polymers. The copolycations coagulated by adding an indifferent electrolyte, sodium nitrate, were amorphous to X-rays. Electron micrographs showed that the morphology of particles in these solutions of copolycations became regular hexagons as the aluminium(III) content increased. The pure aluminium(III) sample showed regular hexagonal particles. In general the particle size decreased with increasing aluminium(III) content. The results obtained for critical coagulation concentration and maximum adsorption for sodium-kaolinite were consistent with the earlier reports for pure aluminium(III) or iron(III) system. Both were related to the positive charge on the copolycations. Maximum adsorption of copolycations on sodium-kaolinite caused charge reversal. The pzc of the copolycation treated kaolinites were between 6.40 and 8.65, the PZC increasing with a1uminium(III) content. The significance of the possible existence of copolycations of aluminium(III) and iron(III) in soil systems is discussed.

scholarly journals Separation and Recycling of Concentrated Heavy Metal Wastewater by Tube Membrane Distillation Integrated with Crystallization

Membranes ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 19 ◽  
Author(s):  
Xiang-Yang Lou ◽  
Zheng Xu ◽  
An-Ping Bai ◽  
Montserrat Resina-Gallego ◽  
Zhong-Guang Ji
Keyword(s):  
Heavy Metal ◽  
Membrane Fouling ◽  
Pure Water ◽  
Sharp Decrease ◽  
Membrane Distillation ◽  
Water Yield ◽  
Mixed System ◽  
Mixed Solutions ◽  
Membrane Flux ◽  
Salt Crystals

Tube membrane distillation (MD) integrated with a crystallization method is used in this study for the concurrent productions of pure water and salt crystals from concentrated single and mixed system solutions. The effects of concentrated Zn2+ and Ni2+ on performance in terms of membrane flux, permeate conductivity, crystal recovery rates, and crystal grades are investigated. Preferred crystallization and co-crystallization determinations were performed for mixed solutions. The results revealed that membrane fluxes remained at 2.61 kg·m−2·h−1 and showed a sharp decline until the saturation increased to 1.38. Water yield conductivity was below 10 μs·cm−1. High concentrated zinc and nickel did not have a particular effect on the rejection of the membrane process. For the mixed solutions, membrane flux showed a sharp decrease due to the high saturation, while the conductivity of permeate remained below 10 μs·cm−1 during the whole process. Co-crystallization has been proven to be a better method due to the existence of the SO42− common-ion effect. Membrane fouling studies have suggested that the membrane has excellent resistance to fouling from highly concentrated solutions. The MD integrated with crystallization proves to be a promising technology for treating highly concentrated heavy metal solutions.

1. The fly in the cathedral

2015 ◽  
Author(s):  
Frank Close
Keyword(s):  
Internal Structure ◽  
Nuclear Physics ◽  
Positive Charge ◽  
X Rays ◽  
Ernest Rutherford ◽  
Nuclear Atom ◽  
Positively Charged

‘The fly in the cathedral’ charts the discovery of the nuclear atom and the start of modern atomic and nuclear physics. It began in 1895 with the discovery of X-rays by Wilhelm Roentgen and radioactivity by Henri Becquerel. In 1897, J.J. Thomson discovered the electron and realised they were common to all atoms, which implied that atoms have an internal structure. Negatively-charged electrons are bound to positively-charged entities within the atom, but what carries this positive charge and how is it distributed? It was Ernest Rutherford, in 1911, who announced his solution: all of an atom’s positive charge and most of its mass are contained in a compact nucleus at the centre.

scholarly journals Tensile tests on alloy crystals. Part I.—Solid solution alloys of aluminium and zinc

1927 ◽  
Vol 115 (770) ◽  
pp. 133-147 ◽  
Keyword(s):  
Cross Section ◽  
Tensile Tests ◽  
Pure Metal ◽  
Zinc Alloy ◽  
Pure Aluminium ◽  
X Rays ◽  
Time Of Application ◽  
Test Pieces ◽  
Type Of Fracture ◽  
Made In

In the ‘Proceedings of the Royal Society,’ 1925, some properties of crystals of an aluminium-zinc alloy were described and their method of extension and fracture compared with that of pure aluminium. This alloy contained 18.5 per cent, zinc and was just at the limit of solubility of zinc in aluminium. The crystals broke usually along a plane at, approximately, 45° to the axis and the position of this plane varied with regard to the crystal planes according to the orientation of the particular crystals. This type of fracture was so different to that of the pure metal that it appeared desirable to obtain alloys of intermediate compositions in order to study the effects of increasing amounts of zinc. Further, the small extension before fracture of the alloys containing higher percentages of zinc made it impossible to obtain reliable distortion measurements although measurements of the crystal axes, by means of X-rays, indicated that the distortion was probably of the same nature as aluminium. Through the courtesy of Mr. Murray Morrison, of the British Aluminium Company, a series of alloys were made in the form of 0.5 inch diameter bar. The number of the bar and the corresponding quantity of zinc is given in Table I. The bars will be referred to in future by the numbers in the first column. The bars were cut into lengths, annealed, strained, and further annealed in a way similar to that which had been successful in growing large aluminium crystals. It was found much more difficult to grow crystals right through the cross-section than in aluminium and the results were very variable. This was to be explained partly by the fact that having stretched a bar in the machine the required amount (1 to 2 per cent, on 3 inches), on removing the load there was sometimes as much as 1 per cent, contraction. This applied mostly to alloys containing from 10 per cent, zinc upwards. The bars, therefore, tended to be under strained. If allowance was made for subsequent shrinking by over-stretching, equally variable results were obtained as the bars did not all shrink to the same amount even after carefully regulating the time of application of the load. The alloys as a whole are more sensitive to straining and to heat treatment than the pure metal, and small variations which appeared to make little difference to aluminium doubled or halved the crystal size. An extension of 1 to 2 per cent, was the most successful treatment with a previous and subsequent annealing temperature of 500-550°C. Several crystals occupying the whole cross-section were usually obtained in one bar, and these were cut up and machined into small round test-pieces of 0.25 inches diameter, and of varying lengths according to the lengths of the crystal. The best crystals were put aside for machining square for distortion experiments. These will be described later.

scholarly journals COMMENTS ON THE ELASTIC PROPERTIES IN SOLID SOLUTIONS OF SILVER HALIDES

2012 ◽  
Vol 26 (11) ◽  
pp. 1250066 ◽  
Author(s):  
EFTHIMIOS S. SKORDAS
Keyword(s):  
Solid Solutions ◽  
First Principles ◽  
Mixed System ◽  
Host Crystal ◽  
Silver Halides ◽  
Generalized Gradient ◽  
Generalized Gradient Approximation ◽  
Foreign Molecule ◽  
End Members ◽  
Defect Volume

Recently first principles microscopic calculations, using the generalized gradient approximation, appeared for the solid mixed system AgCl x Br 1-x at various compositions. Here, we suggest a model that can estimate the compressibility of the mixed crystals in terms of the compressibilities of the end members alone. This model makes use of a single parameter, i.e. the compressibility of a defect volume, when considering the volume variation produced by the addition of a "foreign molecule" to a host crystal as a defect volume.

scholarly journals Diffraction of X-rays by crystals at elevated temperatures

1939 ◽  
Vol 172 (948) ◽  
pp. 116-126 ◽  
Keyword(s):  
Single Crystal ◽  
Theoretical Investigation ◽  
Elevated Temperatures ◽  
Chemical Change ◽  
Age Hardening ◽  
Effect Of Temperature ◽  
Pure Aluminium ◽  
X Rays ◽  
X Ray

During an investigation of age-hardening of an alloy of aluminium with 4% copper, a large number of Laue photographs was taken and attention was directed to certain anomalous streaks on these photographs which altered as the process of hardening took place (Preston 1938). In addition to these streaks, which were associated with the chemical change in the crystal, there were others which did not seem to change with the hardness and which were also present on photographs of aluminium. A further investigation showed that when a single crystal of the alloy or of pure aluminium was photographed at a temperature of about 550° C, the intensity of these streaks was greatly increased. The purpose of the present paper is to give a description of this effect which has now also been observed in crystals of rocksalt, periclase, diamond and zinc. The presence of streaks running through the normal reflexions is a commonplace on Laue photographs; they were observed 25 years ago by Friedrich (1913) in photographs of KCl and NaCl. Ten years later Faxén (1923), in a theoretical investigation of the effect of temperature on the intensity of X-ray reflexion, referred to Friedrich’s observations and suggested that an attempt should be made to correlate these streaks with the temperature of the crystal. So far as I am aware this suggestion has never been carried out. The experiments described below show that Faxén was correct in his surmise that the streaks are connected with the temperature of the crystal.

Interaction of monomeric and polymeric species of metal ions with clay surfaces. III. Aluminium(III) and chromium(III)

Soil Research ◽  
1978 ◽  
Vol 16 (1) ◽  
pp. 53 ◽  
Author(s):  
P Rengasamy ◽  
JM Oades
Keyword(s):  
Molecular Weight ◽  
Metal Ion ◽  
Negative Charge ◽  
Positive Charge ◽  
Gel Filtration ◽  
Charge Reversal ◽  
Original Solution ◽  
Polymeric Species ◽  
Surface Hydroxyls ◽  
Nitrate Solutions

Hydrolysis and polymerization in aluminium nitrate and chromic nitrate solutions with different metal/OH ratios were studied by gel filtration chromatography and ultrafiltration techniques. The characteristics of poly[Al(III)-OH] cations separated by ultrafiltration depended on the molecular weight which was controlled by the OH/Al ratio of the original solution. When the OH/Al ratio was <2.0, the polycations had molecular weight < 50 000, high positive charge and were stable. When the ratio was > 2.0 , the polycations had molecular weight > 100 000, low positive charge and rapidly condensed to gibbsite. Polymerization in chromic nitrate solutions was slow and the separated poly[Cr(III)-OH] cations had low molecular weight (<20000), high positive charge and were stable. The interaction of monomeric and polymeric species of aluminium(III) and chromium(III) with the surfaces of sodium-kaolinite, sodium-bentonite and sodium-illite was studied using hydrolysed nitrate solutions of aluminium and chromium, and separated polycations. The results obtained were consistent with the earlier observations of the iron(III) system, and the behaviour could be explained on the basis of positive charge and probable structure of polycations. The adsorption of aluminium(III) and chromium(III) on clay surfaces from hydrolysed metal ion solutions was related to OH/Al or OH/Cr ratios and pH. The adsorption of polycations was low and related to their positive charge. Maximum adsorption resulted in charge reversal on clays. Addition of the hydrolysed nitrate solutions to clays also caused charge reversal and reduction of negative charge. The adsorption from a mixture of monomers and polymers on bentonite surfaces reduced negative charge markedly due to interlayer formation, while the adsorption of separated polycations in low amounts neutralized the charge on surface hydroxyls and led to the flocculation of clays. The anomalous behaviour of the poly[Al(III)-OH] cations of molecular weight >100 000 could be explained if they consisted of planar sheets, formed from coalesced rings of aluminium octahedra, which crystallized into gibbsite.

Interaction of monomeric and polymeric species of metal ions with clay surfaces. I. Adsorption of iron(III) species

Soil Research ◽  
1977 ◽  
Vol 15 (3) ◽  
pp. 221 ◽  
Author(s):  
P Rengasamy ◽  
JM Oades
Keyword(s):  
Iron Atom ◽  
Positive Charge ◽  
Molecular Size ◽  
Ferric Nitrate ◽  
Distilled Water ◽  
Critical Coagulation Concentration ◽  
Sodium Bentonite ◽  
Polymeric Species ◽  
Surface Hydroxyls ◽  
Nitrate Solutions

Uitrafiltration or dialysis against distilled water was used to separate polymerized ferric hydroxy cations from the monomeric cations in hydrolysed solutions of ferric nitrate. Separated poly[Fe(III)-OH] cations were polydispersed and the positive charge was inversely related to molecular size. The separated poly[Fe(III)-OH] cations were found to be stable and did not condense further during a period of 6 months. The association of iron(III) with the surfaces of sodium-kaolinite, sodium-bentonite and sodiumillite was studied using hydrolysed ferric nitrate solutions and separated poly[Fe(III)-OH] cations. As the OH/Fe ratio (and pH) of the ferric nitrate solutions increased, the critical coagulation concentration (CCC) and the maximum adsorption of iron(III) increased. The amount of iron adsorbed in the form of separated po1y[Fe(III)-OH] cations was small and was related to the positive charge per iron atom of the polycations. It is proposed that iron(III) in solutions containing only polycations and solutions containing a mixture of mono- and polycations reacted differently with clay surfaces. A reaction of polycations with the surface hydroxyls leading to chemisorption and irreversible flocculation of clays is proposed.

White-Light Coronal Structures: Streamers and CMEs

1994 ◽  
Vol 144 ◽  
pp. 82
Author(s):  
E. Hildner
Keyword(s):  
Emission Line ◽  
Electron Density ◽  
White Light ◽  
Coronal Mass Ejections ◽  
X Rays ◽  
Solar Cycles ◽  
Temperature Function ◽  
X Ray ◽  
Eclipse Observations ◽  
Coronal Structures

AbstractOver the last twenty years, orbiting coronagraphs have vastly increased the amount of observational material for the whitelight corona. Spanning almost two solar cycles, and augmented by ground-based K-coronameter, emission-line, and eclipse observations, these data allow us to assess,inter alia: the typical and atypical behavior of the corona; how the corona evolves on time scales from minutes to a decade; and (in some respects) the relation between photospheric, coronal, and interplanetary features. This talk will review recent results on these three topics. A remark or two will attempt to relate the whitelight corona between 1.5 and 6 R⊙to the corona seen at lower altitudes in soft X-rays (e.g., with Yohkoh). The whitelight emission depends only on integrated electron density independent of temperature, whereas the soft X-ray emission depends upon the integral of electron density squared times a temperature function. The properties of coronal mass ejections (CMEs) will be reviewed briefly and their relationships to other solar and interplanetary phenomena will be noted.

Emergence of Twisted Magnetic Flux Related Sigmoidal Brightening

2000 ◽  
Vol 179 ◽  
pp. 263-264
Author(s):  
K. Sundara Raman ◽  
K. B. Ramesh ◽  
R. Selvendran ◽  
P. S. M. Aleem ◽  
K. M. Hiremath
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Magnetic Flux ◽  
Ultra Violet ◽  
Active Regions ◽  
Morphological Properties ◽  
Energy Storage And Conversion ◽  
The Sun ◽  
X Rays ◽  
The Magnetic Field

Extended AbstractWe have examined the morphological properties of a sigmoid associated with an SXR (soft X-ray) flare. The sigmoid is cospatial with the EUV (extreme ultra violet) images and in the optical part lies along an S-shaped Hαfilament. The photoheliogram shows flux emergence within an existingδtype sunspot which has caused the rotation of the umbrae giving rise to the sigmoidal brightening.It is now widely accepted that flares derive their energy from the magnetic fields of the active regions and coronal levels are considered to be the flare sites. But still a satisfactory understanding of the flare processes has not been achieved because of the difficulties encountered to predict and estimate the probability of flare eruptions. The convection flows and vortices below the photosphere transport and concentrate magnetic field, which subsequently appear as active regions in the photosphere (Rust &amp; Kumar 1994 and the references therein). Successive emergence of magnetic flux, twist the field, creating flare productive magnetic shear and has been studied by many authors (Sundara Ramanet al.1998 and the references therein). Hence, it is considered that the flare is powered by the energy stored in the twisted magnetic flux tubes (Kurokawa 1996 and the references therein). Rust &amp; Kumar (1996) named the S-shaped bright coronal loops that appear in soft X-rays as ‘Sigmoids’ and concluded that this S-shaped distortion is due to the twist developed in the magnetic field lines. These transient sigmoidal features tell a great deal about unstable coronal magnetic fields, as these regions are more likely to be eruptive (Canfieldet al.1999). As the magnetic fields of the active regions are deep rooted in the Sun, the twist developed in the subphotospheric flux tube penetrates the photosphere and extends in to the corona. Thus, it is essentially favourable for the subphotospheric twist to unwind the twist and transmit it through the photosphere to the corona. Therefore, it becomes essential to make complete observational descriptions of a flare from the magnetic field changes that are taking place in different atmospheric levels of the Sun, to pin down the energy storage and conversion process that trigger the flare phenomena.

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