The water stability of natural clay aggregates containing polyvinyl alcohol

Soil Research ◽  
1968 ◽  
Vol 6 (1) ◽  
pp. 59 ◽  
Author(s):  
BG Williams ◽  
DJ Greenland ◽  
JP Quirk
Keyword(s):  
Polyvinyl Alcohol ◽  
Soil Aggregates ◽  
Equal Weight ◽  
Dilute Solution ◽  
Natural Clay ◽  
Clay Particles ◽  
Polymer Molecules ◽  
Loam Soil ◽  
Concentrated Solution ◽  
Clay Aggregates

The effect of the adsorption of polyvinyl alcohol (PVA) by natural clay aggregates on their ability to withstand rapid wetting and shaking in water has been determined. It was found for aggregates from the B horizon of the Urrbrae loam soil (60% of < 2 � material and 0.74% of organic carbon) that between 1 and 2% by weight of PVA was sufficient to almost completely prevent breakdown into micro-aggregates. Separation of clay particles from the aggregates by abrasive forces was also largely prevented. Polymer adsorbed slowly from a dilute solution was more effective than an equal weight of polymer adsorbed rapidly from a concentrated solution. Analysis of the rate of breakdown curves enabled the initial breakdown due to rapid wetting, and the subsequent abrasive forces, to be distinguished. The results provide further support for the hypothesis previously advanced that soil aggregates are stabilized by polymer molecules that line the surfaces of the pores, binding together the clay domains which comprise the walls of the larger pores.

Note on the distribution of polymer molecules in dilute solution

1950 ◽  
Vol 5 (3) ◽  
pp. 383-386 ◽  
Author(s):  
Paul M. Doty ◽  
Robert F. Steiner
Keyword(s):  
Dilute Solution ◽  
Polymer Molecules

Acetylene reduction by non-symbiotic bacteria in artificial soil aggregates amended with glucose

1974 ◽  
Vol 20 (6) ◽  
pp. 877-881 ◽  
Author(s):  
C. I. Mayfield ◽  
R. L. Aldworth
Keyword(s):  
Sandy Loam ◽  
Soil Aggregates ◽  
Peripheral Zone ◽  
Sandy Loam Soil ◽  
Artificial Soil ◽  
Clay Loam ◽  
Sandy Clay Loam ◽  
Sandy Clay ◽  
Loam Soil ◽  
Soil Activity

The C2H2-reduction assay was used to study the activity of non-symbiotic N2-fixing bacteria in glucose-amended artificial soil aggregates prepared from a sandy clay loam and a sandy loam soil. Anaerobic incubation under nitrogen resulted in significantly higher rates and greater total quantities of C2H2 reduction than did incubation in air. In the sandy clay loam soil activity under both incubation conditions was due to anaerobic N2-fixing bacteria, whereas in the sandy loam soil aerobic N2-fixing bacteria also proliferated in the aggregates. Direct observation of sectioned aggregates by fluorescence microscopy showed that peripheral zone 1 mm thick sup ported the growth of aerobic microorganisms. The anaerobic microsites in the interior of the aggregates were well protected since disruption procedures involving vigorous shaking with aerated water were required to allow O2 to penetrate and inhibit the anaerobic activity.

Strength and Permeability of Bentonite-Assisted Biocemented Coarse Sand

2020 ◽  
Author(s):  
Guoliang Ma ◽  
Xiang He ◽  
Xiang Jiang ◽  
Hanlong Liu ◽  
Jian Chu ◽  
...  
Keyword(s):  
Unconfined Compressive Strength ◽  
Volume Fraction ◽  
Coarse Sand ◽  
Effective Concentration ◽  
Carbonate Precipitation ◽  
Natural Clay ◽  
High Concentration ◽  
Strength Enhancement ◽  
Microbially Induced Carbonate Precipitation ◽  
Clay Aggregates

To effectively stabilize coarse sand, bentonite was introduced in microbially induced carbonate precipitation (MICP) grouting. Varying concentrations (0 g/L, 20 g/L, 40 g/L and 80 g/L) of bentonite were added to bacterial suspensions (BSs), which were magnetically stirred to form bacterial-bentonite suspensions (BBSs). Then, coarse sand specimens were treated with BBSs and cementation solutions (CSs) to different cementation levels. The results showed that the addition of bentonite could increase the volume fractions of the precipitates consisting of calcium carbonate (CaCO3) and bentonite. The permeability decreased exponentially as the volume fraction of precipitates increased. As the active precipitates increased when a lower concentration (e.g., 20 g/L) of bentonite was added to the MICP grouting, the unconfined compressive strength (UCS) was substantially improved. However, detrimental effects were observed for specimens treated with a high concentration of bentonite. These results indicate that the effective concentration of natural clay aggregates used in MICP grouting was different for different engineering applications, e.g., seepage control and strength enhancement. The current work provides an encouraging method of improving the MICP technique.

The Association of Polymer Molecules in Dilute Solution.

1947 ◽  
Vol 51 (1) ◽  
pp. 32-57 ◽  
Author(s):  
Paul Doty ◽  
Herman Wagner ◽  
Seymour Singer
Keyword(s):  
Dilute Solution ◽  
Polymer Molecules

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.

Effect of the method of dispersion on the yield of clay and fine clay

Soil Research ◽  
1982 ◽  
Vol 20 (4) ◽  
pp. 339 ◽  
Author(s):  
DJ Chittleborough
Keyword(s):  
Marked Decrease ◽  
Sandy Loam ◽  
Relative Proportion ◽  
Clay Particles ◽  
Chemical Treatments ◽  
Fine Clay ◽  
Taxonomic Criterion ◽  
Loam Soil ◽  
Effect On Yield ◽  
Dispersing Medium

Because the relative proportion of fine (< 0.2 �m) and coarse clay (2-0.2 �m) is considered an important pedogenetic and taxonomic criterion, the effect on yield of these fractions by different methods of dispersion was investigated for a sandy loam and a clay from the Urrbrae loam. Both soils showed a continued increase in fine clay with time of shaking even after 14 h. This may be a subplasticity effect or due to attrition of coarse clay. Electron micrographs showed that incrustations on coarse clay particles may be a source of fine clay. The amount of total clay from the sandy loam soil continued to rise after 14 h of shaking, but yield from the clay soil was constant after 100 s. Of the chemical treatments only sodium hydroxide had a significant effect. This treatment lead to a marked decrease in the proportion of fine clay. The amount of total and fine clay was unaffected by the 1iquid:solid ratio in the dispersing medium.

scholarly journals Chlorocruorin: A pigment allied to hœmoglobin

1926 ◽  
Vol 99 (696) ◽  
pp. 199-220 ◽  
Keyword(s):  
Blood Plasma ◽  
Visible Spectrum ◽  
Reduced Form ◽  
Dilute Solution ◽  
Green Part ◽  
Concentrated Solution ◽  
Reduced State

The name chlorocruorin was given by Ray Lankester (1867) to a pigment dissolved in the blood plasma of Sabellid, Serpulid and Chlorhæmid polychæte worms. Lankester showed that chlorocruorin is related to hæmoglobin, since he obtained a hæmochromogen from it. The pigment is burgundy-red when in concentrated solution, green when dilute. It will be shown below that while chlorocruorin is constructed on the same plan as hæmoglobin, the differences between the two are very much greater than the differences between specific hæmoglobins. Chlorocruorin exists in an oxidised and a reduced state which are of almost the same colour. The reduced form in dilute solution is a slightly yellower green than the oxidised. The oxidised differs, however, spectroscopically from the reduced form in the same manner as oxyhæmoglobin differs from hæmoglobin. Oxychlorocruorin has two bands in the red-green part of the visible spectrum and reduced chlorocruorin one broader one. These bands are situated to the red of the corresponding hæmoglobin bands. Chlorocruorin like hæmoglobin, can act as a peroxidase (Lankester, 1870).

Development of a Collagen/Clay Nanocomposite Biomaterial

2012 ◽  
Vol 706-709 ◽  
pp. 461-466 ◽  
Author(s):  
Alejandra Reyna-Valencia ◽  
P. Chevallier ◽  
D. Mantovani
Keyword(s):  
Mechanical Properties ◽  
Aqueous Media ◽  
Three Dimensional ◽  
Clay Particles ◽  
Network Characteristics ◽  
Polymer Molecules ◽  
Nanocomposite Hydrogels ◽  
Clay Concentration ◽  
Dimensional Network ◽  
Collagen Hydrogels

Collagen hydrogels are widely used as three-dimensional scaffolds for cells and tissue in culture environments. These materials, which consist of crosslinked biopolymer (protein-based) networks in aqueous media, are particularly suitable for recreating part of the extra-cellular matrix, but their poor mechanical properties represent a major limitation. One strategy to enhance the strength of this kind of hydrogels might be to incorporate clay nanoscopic particles. In fact, it has been observed that the charged surface of clay nanosheets can interact with certain functional groups belonging to polymer molecules, yielding stronger networks. Moreover, clay particles are recognized to be biocompatible. In the present work, the gelation process and the resulting morphological and mechanical properties of collagen/laponite clay nanocomposite hydrogels were invastigated. Upon gelation, the biopolymer molecules assemble into nanoscale fibrils, which bundle into fibers and entangle into a three-dimensional network. The network characteristics depend on tunable parameters such as pH and clay concentration.

The direct observation of polymer molecules and determination of their molecular weight

1964 ◽  
Vol 279 (1376) ◽  
pp. 50-61 ◽  
Keyword(s):  
Molecular Weight ◽  
Direct Observation ◽  
Particle Diameter ◽  
Dilute Solution ◽  
Crystalline Polymers ◽  
Polymer Molecules ◽  
Molecular Weights ◽  
Preferential Evaporation ◽  
Poor Solvent

An experimental investigation of the conditions necessary for the production of compact, single polymer molecules, in a form suitable for direct observation in the electron microscope, is described. Molecules are isolated by dispersing a dilute solution of the polymer as fine droplets on to a suitable substrate: ideally each droplet should contain either one or no polymer molecules. The solution is a mixture of two solvents, a good one and a poor one. Initially the good solvent predominates so that the probability of polymer aggregation is low. Preferential evaporation of the relatively volatile solvent on the substrate itself gives the poor solvent conditions needed for the formation of well-defined molecular spheres. Factors determining the choice of solvent, precipitant, and the composition of the mixture are discussed. There is little difficulty in obtaining single molecules with glassy amorphus polymers; rubbery polymers collapse and spherical molecules are formed only if the entire preparation is carried out at a temperature below that of the glass transition; crystalline polymers are not amenable to this technique. To obtain sufficient contrast the particles have to be shadowed and it is shown that, although certain dimensions are distorted by the metal coating, the shadow length faithfully represents the true particle diameter. Molecular weights, and their distribution, when of the order of a million and above, can readily be accurately determined. Conventional methods are unreliable in this region of high molecular weight.

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