Interaction of monomeric and polymeric species of metal ions with clay surfaces. II. Changes in surface properties of clays after addition of iron(III)

Soil Research ◽  
1977 ◽  
Vol 15 (3) ◽  
pp. 235 ◽  
Author(s):  
P Rengasamy ◽  
JM Oades
Keyword(s):  
Negative Charge ◽  
Point Of Zero Charge ◽  
Ferric Nitrate ◽  
Net Charge ◽  
Clay Particles ◽  
Polymer Bridging ◽  
Ph Values ◽  
Polymeric Species ◽  
Surface Hydroxyls ◽  
Nitrate Solutions

The adsorption of poly [Fe(III)-OH] cation by claysurfaces led to flocculation of clay particles possibly by polymer bridging while the addition of iron(III) from hydrolysed ferric nitrate solutions resulted in flocculation and cementation by precipitated iron(III). Electrokinetically clays with adsorbed iron(III) behaved similarly to amorphous ferric hydroxides with positive mobilities below the point of zero charge (PZC). Polycations reversed the charge on the clay particles at maximum adsorption, which probably represents neutralization of charge due to surface hydroxyls. When hydrolysed ferric nitrate solutions were added to kaolinite and illite charge reversal occurred at pH values below 6. Adsorption of iron(III) resulted in a partial reduction of negative charge in clays. The reduction of negative charge in kaolinite and illite was close to the charge due to surface hydroxyls. The net charge estimated at all pH values corresponded with the electrophoretic mobility in all the iron(III) clay complexes except bentonite with adsorbed polycations.

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.

Clay dispersion as influenced by pH and net particle charge of sodic soils

Soil Research ◽  
1994 ◽  
Vol 32 (6) ◽  
pp. 1243 ◽  
Author(s):  
M Chorom ◽  
P Rengasamy ◽  
RS Murray
Keyword(s):  
Clay Minerals ◽  
Negative Charge ◽  
Soil Aggregates ◽  
Calcareous Soils ◽  
Percentage Increase ◽  
Sodic Soils ◽  
Net Charge ◽  
Clay Particles ◽  
Clay Dispersion ◽  
Soil Clays

The effect of changing pH on the dispersion of clay from sodic soils was investigated in relation to changes in net charge on clay particles. A positive relationship was obtained between pH and the percentage of dispersible clay for each soil clay. The percentage increase in net negative charge was also positively correlated with pH. However, the slopes of these relationships varied between soil clays. In general, the net negative charge was the primary factor in clay dispersion and the pH affected clay dispersion by changing the net charge on clay particles. In comparing the values for pure clay minerals quoted in the literature with soil clays having similar mineralogy, it was found that soil clays had higher flocculation values. This is shown to be due to higher net negative charge on soil clays than the corresponding values for pure clay minerals found in the literature. The effect of soil organic matter in enhancing the net negative charge probably contributes to the higher charge on soil clays. The critical dispersion concentration for clay dispersion from soil aggregates was lower than the flocculation values observed for the separated soil clays. The separated soil clays had high negative charge due to exposure of surfaces which were originally bonded in the aggregates. The dispersive potential of a number of Alfisols, Oxisols, Aridisols (calcareous soils) and Vertisols collected from different parts of Australia was highly correlated with soil pH. The relationship with CEC was poor because CEC was estimated at a pH different to the natural pH of the soil. This study has brought out the importance of pH in the management of dispersive soils.

scholarly journals Physicochemical Properties and Surface Charge Characteristics of Arid Soils in Southeastern Iran

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
A. H. Moghimi ◽  
J. Hamdan ◽  
J. Shamshuddin ◽  
A. W. Samsuri ◽  
A. Abtahi
Keyword(s):  
Physicochemical Properties ◽  
Surface Charge ◽  
Negative Charge ◽  
Clay Content ◽  
Significant Negative Correlation ◽  
Point Of Zero Charge ◽  
Net Charge ◽  
Excess Negative Charge ◽  
The Common ◽  
The Arid Regions

The majority of previous studies on surface charge characteristics were done on tropical and subtropical soils. Information of such studies in the arid regions is limited. A study was conducted to investigate the relation between soil chemical and mineralogical properties and surface charge characteristics of an arid region in Southeastern Iran. Eight soil pedons, representing the alluvial and the colluvial deposits, were described, and their mineralogical and physicochemical properties were examined. The common clay minerals in the studied area are smectite, palygorskite, kaolinite, chlorite, and illite. The point of zero charge (pH0) values are low (2.85–3.35) in all soils mostly affected by organic carbon (OC) and free iron oxide (Fed).pH0has a significant negative correlation with pH under field conditions (r=−0.45∗,P<0.05). The point of zero net charge (PZNC) levels for all the soils were <2, due to the excess negative charge in these soils. The estimated PZNC values were less thanpH0in all soils because of the high permanent negative charge in these soils. The permanent negative charge (σp) of the soils studied is high and it has a significant positive correlation with pH, CEC, Na, Mg, SAR, clay content, palygorskite, OC, andFed.

scholarly journals Adsorption studies of Mo and Vonto ferrihydrite

2008 ◽  
Vol 72 (1) ◽  
pp. 385-388 ◽  
Author(s):  
L. Brinza ◽  
L. G. Benning ◽  
P. J. Statham
Keyword(s):  
Binary System ◽  
Binding Sites ◽  
Point Of Zero Charge ◽  
High Uptake ◽  
Adsorption Efficiency ◽  
Adsorption Studies ◽  
Ph Values ◽  
Zero Charge ◽  
Kinetics Of

AbstractIn this paper, the kinetics of Mo and V (100 μM) uptake on ferrihydrite (FHY) were evaluated in batch, mono-sorbate systems at pH between 4 and 9, and in bi-sorbate systems in the presence of P (100 μM) at pH 7. In the Mo and V single-sorbate experiments, 100% adsorption was observed at pH values below 6 and 8, respectively. Above the point of zero charge (PZC = 7.97) of FHY, the adsorption efficiency for Mo dropped dramatically (20% at pH 8) while V showed high uptake efficiencies even at pH 9 (60% efficiency). The results from the bi-sorbate experiments (Mo-P and V-P) showed that at pH 7, P out-competed (97%) Mo for binding sites on FHY, while in the V-P binary system only ∼44% of the binding sites are occupied by P with the remaining sites being occupied by V.

The effect of over 50 years of liming on soil aluminium forms in a Retisol

2019 ◽  
Vol 157 (1) ◽  
pp. 12-19 ◽  
Author(s):  
Z. Kryzevicius ◽  
D. Karcauskiene ◽  
E. Álvarez-Rodríguez ◽  
A. Zukauskaite ◽  
A. Slepetiene ◽  
...  
Keyword(s):  
Soil Profile ◽  
Soil Acidity ◽  
Solid Phase ◽  
Water Soluble ◽  
Total Water ◽  
Clay Particles ◽  
Ph Values ◽  
Exchangeable Al ◽  
Limed Soil

AbstractThe aim of the current study was to evaluate the effect of long-term (56 years) liming on changes in soil pH and aluminium (Al) forms in the soil profile compared with an unlimed soil in a sandy moraine loam of a Dystric Glossic Retisol. Long-term liming had a significant influence on soil acidity of the whole profile, causing increased pH values in the following horizons to 120 cm depth: the ploughing horizon (Ahp), where humus accumulates; the eluvial horizon (E), from which clay particles are leached; a horizon having retic properties and predominantly coarser-textured albic material (E/B); and a horizon with retic properties and predominantly finer-textured argic material (B/E). In the solid phase, non-crystalline Al in limed soil decreased in the Ahp horizon; meanwhile a decrease in total organically bound Al (Alp) and organo–Al complexes of low to medium stability was detected in the deeper El and ElBt horizons. High-stability Al complexes with organic matter were the predominant form of Alp in the unlimed and limed whole soil profile. The concentration of total water-soluble Al ranged from 0.61 to 0.80 mg/l in the limed soil profile but 0.62–1.15 mg/l in the unlimed soil. The highest concentration of exchangeable Al was determined in the upper horizons of the unlimed soil profile and the concentration decreased significantly in the same horizons of the limed soil profile. Long-term liming promoted changes in Al compounds throughout the soil profile.

Influence of Pulp pH on Flotation of Fluorite and Calcite

2012 ◽  
Vol 616-618 ◽  
pp. 614-618
Author(s):  
Wen Juan Zhao ◽  
Dian Wen Liu ◽  
Hong Shuai Li ◽  
Qi Cheng Feng ◽  
Guo Yin Xu ◽  
...  
Keyword(s):  
Infrared Spectroscopy ◽  
Fatty Acid ◽  
Significant Role ◽  
Ph Value ◽  
Froth Flotation ◽  
Point Of Zero Charge ◽  
Zeta Potentials ◽  
Ph Values ◽  
Zero Charge ◽  
Optimum Ph

Pulp pH value plays a significant role in the froth flotation. Especially in the flotation of fluorite, the performance of flotation will be affected greatly by pulp pH. MO, a new kind of modified fatty acid was used as collector, and H2SO4 and Na2CO3 were used to regulate pulp pH in the experiment. The mechanism of influence of pulp pH on flotation of fluorite and calcite was investigated by such parameters as fluorite recovery, zeta potentials and the infrared spectroscopy about minerals at different pulp pH values. As is shown in the results, the point of zero charge(PZC) of fluorite is pH=9.5 and the PZC of calcite is pH=8.5. The optimum pulp pH of the flotation of fluorite and calcite is determined as 9.5~10 and 8~9 respectively. pH value should be controlled above 9 to depress calcite. Finally, 9.5~10 was determined as the optimum pH to float the fluorite from the calcium-containing fluorite ores.

Using variable charge characteristics to understand the exchangeable cation status of oxic soils

Soil Research ◽  
1984 ◽  
Vol 22 (1) ◽  
pp. 71 ◽  
Author(s):  
GP Gillman
Keyword(s):  
Surface Charge ◽  
Soil Ph ◽  
Negative Charge ◽  
Positive Charge ◽  
Exchangeable Cations ◽  
Point Of Zero Charge ◽  
Exchangeable Cation ◽  
Charge Measurement ◽  
Variable Charge ◽  
Variable Surface

The model of Uehara and Gillman was used to estimate the amounts of permanent surface charge, and variable surface charge at soil pH, in two soils from the high rainfall region of coastal Queensland. For each soil series, samples from virgin rain-forest were compared with soil collected from nearby sugarcane fields. One soil contained relatively large amounts of permanent negative charge (up to 3 m.e. per 100g), and hence was moderately supplied with exchangeable cations, while the other soil was dominated by variable charge components and at soil pH contained sufficient positive charge to reduce exchangeable cations to near zero values, despite the presence of about 1 m.e. per 100 g of permanent negative charge. In the latter the position of soil pH with respect to the point of zero charge is of utmost importance for the development of cation exchange capacity. The effect of adsorbed sulfate on positive charge measurement, and valency of the ion used for negative charge measurement, are briefly discussed.

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