Influence of Electrolyte Concentration, Sodium Adsorption Ratio, and Mechanical Disturbance on Dispersed Clay Particle Size and Critical Flocculation Concentration in Alfisols

2004 ◽  
Vol 35 (9-10) ◽  
pp. 1415-1434 ◽  
Author(s):  
K. P. Panayiotopoulos ◽  
N. Barbayiannis ◽  
K. Papatolios
Keyword(s):  
Particle Size ◽  
Electrolyte Concentration ◽  
Sodium Adsorption Ratio ◽  
Clay Particle ◽  
Mechanical Disturbance ◽  
Critical Flocculation Concentration

Chemical Transformation of Fe, Air & Water to Ammonia: Variation of Reaction Rate with Temperature, Pressure, Alkalinity and Iron

2018 ◽  
Author(s):  
Ping Peng ◽  
Fang-Fang Li ◽  
Xinye Liu ◽  
Jiawen Ren ◽  
jessica stuart ◽  
...  
Keyword(s):  
Particle Size ◽  
Reaction Rate ◽  
Electrolyte Concentration ◽  
Iron Concentration ◽  
Reaction Medium ◽  
Iron Particle ◽  
Intermediate Step ◽  
Ammonia Production ◽  
Pure Nitrogen ◽  
Alkaline Reaction

The rate of ammonia production by the <u>chemical </u>oxidation of iron, N<sub>2</sub>(from air or as pure nitrogen) and water is studied as a function of (1) iron particle size, (2) iron concentration, (3) temperature, (4) pressureand (5) concentration of the alkaline reaction medium. The reaction meduium consists of an aqueous solution of equal molal concentrations of NaOH and KOH (Na<sub>0.5</sub>K<sub>0.5</sub>OH). We had previously reported on the <u>chemical </u>reaction of iron and nitrogen in alkaline medium to ammonia as an intermediate step in the <u>electrochemical </u>synthesis of ammonia by a nano-sized iron oxide electrocatlyst. Here, the intermediate <u>chemical </u>reaction step is exclusively explored. The ammonia production rate increases with temperature (from 20 to 250°C), pressure (from 1 atm to 15 atm of air or N<sub>2</sub>), and exhibits a maximum rate at an electrolyte concentration of 8 molal Na<sub>0,5</sub>K<sub>0,5</sub>OH in a sealed N<sub>2</sub>reactor. 1-3 µm particle size Fe drive the highest observed ammonia production reaction rate. The Fe mass normalized rate of ammonia production increases with decreasing added mass of the Fe reactant reaching a maximum observed rate of 2.2x10<sup>-4</sup>mole of NH<sub>3</sub>h<sup>-1</sup>g<sup>-1</sup>for the reaction of 0.1 g of 1-3 µm Fe in 200°C 8 molal Na<sub>0.5</sub>K<sub>0.5</sub>OH at 15 atm. Under these conditions 5.1 wt% of the iron reacts to form NH<sub>3</sub>via the reaction N<sub>2</sub>+ 2Fe + 3H<sub>2</sub>O ®2NH<sub>3</sub>+ Fe<sub>2</sub>O<sub>3</sub>.

Influence of sodium adsorption ratio on sodium and calcium breakthrough curves and hydraulic conductivity in soil columns

Soil Research ◽  
2007 ◽  
Vol 45 (8) ◽  
pp. 586 ◽  
Author(s):  
Oagile Dikinya ◽  
Christoph Hinz ◽  
Graham Aylmore
Keyword(s):  
Hydraulic Conductivity ◽  
Electrolyte Concentration ◽  
Soil Aggregates ◽  
Breakthrough Curves ◽  
Sodium Adsorption Ratio ◽  
Threshold Concentration ◽  
Critical Threshold ◽  
Soil Columns ◽  
Clay Particles ◽  
The Matrix

The paper examines the effects of electrolyte concentration and sodium adsorption ratio (SAR) on the relative saturated hydraulic conductivity (RHC) and the ionic behaviour of calcium (Ca) and sodium (Na) ions in the Na–Ca exchange complex. Batch binary exchange and saturated column transport experiments were carried out to quantify these effects using an agricultural Balkuling soil and a mining residue. Generally, RHC has been found to decrease with time, with increasing SAR, and with decreasing electrolyte concentration. The more rapid decrease in RHC in the mining residue, particularly at the lowest concentration (1 mmol/L), was consistent at all SAR values. The decreases in RHC were likely to be caused by partial blocking of pores by dispersed clay particles, as evidenced by the appearance of suspended clay particles in the effluent during leaching. Significant differences in RHC were observed in the passage of fronts of decreasing electrolyte concentrations for CaCl2 and SAR 15 solutions through the soil columns. These differences were attributable to structural alterations (slaking) of the media and the nature of the particles released and mobilised within the porous structure at any given point in the column. Measurements at the critical threshold concentration and turbidity concentration at SAR 15 revealed structural breakdown of the pore matrix system as evidenced by decreased RHC. The increase in SAR to 15 is initially accompanied by erratic RHC, presumably due to the break up of soil aggregates under the increased swelling forces. The less coherent mining residue soil was substantially more vulnerable to blockage of pores than the Balkuling soil in which clay particles are likely to be more readily mobilised, and hence available to re-deposit and occlude the matrix pores.

Sodic soils - New perspectives

Soil Research ◽  
1993 ◽  
Vol 31 (6) ◽  
pp. 683 ◽  
Author(s):  
ME Sumner
Keyword(s):  
Electrolyte Concentration ◽  
Exchangeable Cation ◽  
Sodic Soils ◽  
The World ◽  
Critical Flocculation Concentration ◽  
Low Levels ◽  
Definition Of ◽  
Physical Degradation ◽  
Soil Behaviour ◽  
Simple Definition

There are large areas of the world where soils are adversely affected by the presence of sodium (Na) as an exchangeable cation. Unlike their saline counterparts which are more extensive, sodic soils have received less attention in the literature. There has been considerable disagreement concerning the definition of sodicity, owing largely to the fact that many experiments used in the development of definitions did not account for the presence of salts in the water used to measure hydraulic properties. These problems are discussed and the conclusion is reached that a single simple definition is no longer possible. This problem is further exacerbated by the fact that many soils which would never have fallen into a previously defined sodic category, do in fact exhibit sodic properties. The major focus of this account of sodicity will therefore be the soils which contain relatively low levels of exchangeable Na. As such soils are widespread in both humid and subhumid areas of the world and are responsible for the production of a large proportion of the world cereal crop, they deserve special attention. Because swelling and dispersion are the primary processes responsible for the degradation of soil physical properties in the presence of Na, an account of clay behaviour in relation to Na and electrolyte concentration is presented before exploring these new realms of sodicity. Pure clay systems are not always suitable for use as models of soil behaviour in terms of dispersion and flocculation. However, as far as swelling is concerned, the correspondence is much better. Nevertheless, the effects of the exchangeable cations on dispersion are predictable albeit usually only qualitatively. This is partly due to the phenomenon of 'demixing' in which the cations are not distributed over all surfaces in the same proportions. The effects of Na and electrolyte concentration in relation to hydraulic conductivity, infiltration, crusting, runoff, erosion and hardsetting are discussed from which it emerges that the effects of Na are manifested in measurable and often sizeable proportions down to very low levels far below those previously used to define sodic soils. The primary processes responsible for physical degradation are swelling at relatively high levels and clay dispersion throughout the range of exchangeable Na percentage (ESP). Provided that the total electrolyte concentration (TEC) is below the critical flocculation concentration (CFC), clays will disperse spontaneously at high ESP values, whereas at lower ESP levels, inputs of energy are required for dispersion. The TEC of the ambient solution, because of its effects in promoting clay flocculation, is crucial in determining soil physical behaviour.

ELECTROPHORESIS OF RESIN EMULSIONS: I. THE EFFECT OF EMULSIFYING AGENTS

1953 ◽  
Vol 31 (3) ◽  
pp. 287-296 ◽  
Author(s):  
L. A. Munro ◽  
F. H. Sexsmith
Keyword(s):  
Particle Size ◽  
Hydrogen Bonding ◽  
Vinyl Acetate ◽  
Electrolyte Concentration ◽  
Chemical Change ◽  
Charged Particles ◽  
Emulsifying Agent ◽  
Glass Cell ◽  
Partial Chemical

A modified Briggs electrophoretic glass cell was used to measure the mobility of over 2500 particles of vinyl acetate latices prepared with different emulsifying agents. Although anionic and cationic agents conferred negative and positive mobilities respectively, nonionic agents invariably resulted in negatively charged particles. This is attributed to partial chemical change to anionic materials or to hydrogen bonding and polarization processes. The nature of the emulsifying agent and electrolyte concentration rather than concentrations of the latex or particle size were the most significant variables affecting the mobility of any latex.

scholarly journals Electrosynthesis of α-Fe2O3 in a Fe(s)|KCl(aq)||H2O(aq)|C(s) System

2018 ◽  
Vol 21 (4) ◽  
pp. 182-186 ◽  
Author(s):  
Nia Siskawati ◽  
Didik Setiyo Widodo ◽  
Wasino Hadi Rahmanto ◽  
Linda Suyati
Keyword(s):  
Particle Size ◽  
Electrolyte Solution ◽  
Oxidation Reaction ◽  
Electrolyte Concentration ◽  
Salt Bridge ◽  
Anode Chamber ◽  
Fe2o3 Particle ◽  
Electrolysis Method ◽  
Reduction And Oxidation

Research on α-Fe2O3 electrosynthesis has been performed in the system Fe(s)|KCl(aq)||H2O(aq)|C(s). Electrolysis produces a reduction and oxidation reaction so that it requires a proper electrolyte concentration in the process. The purpose of this study was to obtain α-Fe2O3 compounds, determine the products produced by FTIR and XRD, and determine the size of the grains of products with PSA. Electrolysis method of two compartment was used in this research. The cathode and anode compartments was connected with the salt bridge. In anode chamber containing electrolyte solution KCl was varied (0,2 M; 0,3 M; 0,4 M; 0,5 M and 0,6 M) whereas at cathode space there was aquades. Electrolysis was run at 12 V for 8 hours. The electrolysis result was then calcined for two hours at a temperature of 500°C. The resulting product was then characterized by (FTIR, XRD, and PSA). The resulting product is then characterized by (FTIR, XRD, and PSA). The results showed that brown ferrihydrite was obtained in a concentration of 0.2 M; 0.3 M; 0.4 M; 0.5 M and 0.6 M were 21.6 mg; 24.1 mg; 34.5 mg; 39.4 mg and 62.4 mg respectively. Ferrihydrite produced from electrolysis of KCl 0.4 M concentration was dark red The XRD results show the presence of α-Fe2O3 and PSA results show that the α-Fe2O3 particle size is 151.57-171.25 nm.

Chemical Transformation of Fe, Air & Water to Ammonia: Variation of Reaction Rate with Temperature, Pressure, Alkalinity and Iron

2018 ◽  
Author(s):  
Ping Peng ◽  
Fang-Fang Li ◽  
Xinye Liu ◽  
Jiawen Ren ◽  
jessica stuart ◽  
...  
Keyword(s):  
Particle Size ◽  
Reaction Rate ◽  
Electrolyte Concentration ◽  
Iron Concentration ◽  
Reaction Medium ◽  
Iron Particle ◽  
Intermediate Step ◽  
Ammonia Production ◽  
Pure Nitrogen ◽  
Alkaline Reaction

The rate of ammonia production by the <u>chemical </u>oxidation of iron, N<sub>2</sub>(from air or as pure nitrogen) and water is studied as a function of (1) iron particle size, (2) iron concentration, (3) temperature, (4) pressureand (5) concentration of the alkaline reaction medium. The reaction meduium consists of an aqueous solution of equal molal concentrations of NaOH and KOH (Na<sub>0.5</sub>K<sub>0.5</sub>OH). We had previously reported on the <u>chemical </u>reaction of iron and nitrogen in alkaline medium to ammonia as an intermediate step in the <u>electrochemical </u>synthesis of ammonia by a nano-sized iron oxide electrocatlyst. Here, the intermediate <u>chemical </u>reaction step is exclusively explored. The ammonia production rate increases with temperature (from 20 to 250°C), pressure (from 1 atm to 15 atm of air or N<sub>2</sub>), and exhibits a maximum rate at an electrolyte concentration of 8 molal Na<sub>0,5</sub>K<sub>0,5</sub>OH in a sealed N<sub>2</sub>reactor. 1-3 µm particle size Fe drive the highest observed ammonia production reaction rate. The Fe mass normalized rate of ammonia production increases with decreasing added mass of the Fe reactant reaching a maximum observed rate of 2.2x10<sup>-4</sup>mole of NH<sub>3</sub>h<sup>-1</sup>g<sup>-1</sup>for the reaction of 0.1 g of 1-3 µm Fe in 200°C 8 molal Na<sub>0.5</sub>K<sub>0.5</sub>OH at 15 atm. Under these conditions 5.1 wt% of the iron reacts to form NH<sub>3</sub>via the reaction N<sub>2</sub>+ 2Fe + 3H<sub>2</sub>O ®2NH<sub>3</sub>+ Fe<sub>2</sub>O<sub>3</sub>.

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