Influence of polysaccharides on kaolinite structure and properties in la kaolinite–water system

1990 ◽  
Vol 27 (6) ◽  
pp. 774-788 ◽  
Author(s):  
Raymond N. Yong ◽  
Diana Mourato
Keyword(s):  
Zeta Potential ◽  
Soil Structure ◽  
Water System ◽  
Aggregate Size ◽  
Transport Processes ◽  
Structure And Properties ◽  
Soil Permeability ◽  
Bingham Yield Stress ◽  
Potential Conditions ◽  
Soil Organics

The influence of soil organics on the development of soil structure and behaviour of soils is the motivation for this study. Xanthan and dextran, two soil polysaccharides, were examined in relation to their influence on the development of the structure of kaolinite–polysaccharide systems and also on resultant physicochemical properties. The kaolinite–polysaccharide soils were formed in suspensions under anaerobic and low redox potential conditions to simulate environmental conditions that exist in subsurface soils. Information on the rheology of the kaolinite–polysaccharide system, zeta potential, aggregate size, settling properties, and specific surface area were obtained. Both polysaccharides were shown to develop aggregate groups (floes) which participated to a greater or lesser extent in the overall rheological properties of the kaolinite–polysaccharide complexes. The ability of the polysaccharides to develop flocs is seen as a factor to be considered in studies of soil permeability and transport processes in soil. Together with information from infrared spectroscopy and scanning electron microscopy, and in combination with the results obtained from the physicochemical tests, models of interaction between kaolinite and both polysaccharides are proposed. Key words: soil organics, polysaccharides, kaolinite, rheology, floes, xanthan, dextran, soil structure, zeta potential, kaolinite–polysaccharide system, differential viscosity, Bingham yield stress.

Study on Relationship between Structure and Properties of Polycarboxylate Superplasticizer

2012 ◽  
Vol 487 ◽  
pp. 43-47
Author(s):  
Sheng Hua Lv ◽  
Di Li ◽  
Qiang Cao
Keyword(s):  
Acrylic Acid ◽  
Zeta Potential ◽  
Ethyl Ester ◽  
Functional Groups ◽  
Cement Paste ◽  
Ethyl Acrylate ◽  
Structure And Properties ◽  
Polycarboxylate Superplasticizer ◽  
Carboxylic Groups

A polycarboxylate superplasticizer (PCs) was synthesized by copolymerization of allyl polyoxyethylene ethers (APE), acrylic acid (AA), sodium methylallyl Sulfonate (SMAS) and ethyl acrylate (EA). The effect of functional groups and branch chain on PCs properties was investigated by the test of fluidity of cement paste, retardation performance and Zeta potential of cement particles. The results showed that carboxylic groups and ethyl ester groups can improve water reducing ratio and fluidity of cement paste, and the sulfonic groups has an important contributiion to retardation performance of PCs.

scholarly journals Pore system changes of damaged Brazilian oxisols and nitosols induced by wet-dry cycles as seen in 2-D micromorphologic image analysis

2009 ◽  
Vol 81 (1) ◽  
pp. 151-161 ◽  
Author(s):  
Luiz F. Pires ◽  
Klaus Reichardt ◽  
Miguel Cooper ◽  
Fabio A.M. Cássaro ◽  
Nivea M.P. Dias ◽  
...  
Keyword(s):  
Image Analysis ◽  
Size Distribution ◽  
Soil Structure ◽  
Tropical Soils ◽  
Transport Processes ◽  
Structure Characterization ◽  
Control Treatment ◽  
Simple Method ◽  
Wetting And Drying ◽  
Essential Information

Soil pore structure characterization using 2-D image analysis constitutes a simple method to obtain essential information related to soil porosity and pore size distribution (PSD). Such information is important to infer on soil quality, which is related to soil structure and transport processes inside the soil. Most of the time soils are submitted to wetting and drying cycles (W-D), which can cause important changes in soils with damaged structures. This report uses 2-D image analysis to evaluate possible modifications induced by W-D cycles on the structure of damaged soil samples. Samples of three tropical soils (Geric Ferralsol, GF; Eutric Nitosol, EN; and Rhodic Ferralsol, RF) were submitted to three treatments: 0WD, the control treatment in which samples were not submitted to any W-D cycle; 3WD and 9WD with samples submitted to 3 and 9 consecutive W-D cycles, respectively. It was observed that W-D cycles produced significant changes in large irregular pores of the GF and RF soils, and in rounded pores of the EN soil. Nevertheless, important changes in smaller pores (35, 75, and 150 µm) were also observed for all soils. As an overall consideration, it can be said that the use of image analysis helped to explain important changes in soil pore systems (shape, number, and size distribution) as consequence of W-D cycles.

scholarly journals Investigation of Surfactant AOT Mediated Charging of PS Particles Dispersed in Aqueous Solutions

Coatings ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 471 ◽  
Author(s):  
Huiying Cao ◽  
Baichao An ◽  
Yong Wang ◽  
Kun Zhou ◽  
Naiyan Lu
Keyword(s):  
Zeta Potential ◽  
Aqueous Solutions ◽  
Particle Surface ◽  
Water System ◽  
Submicron Particles ◽  
Foam Formation ◽  
Preferential Adsorption ◽  
Aqueous Salt Solutions ◽  
Air Water Interface ◽  
Charging Mechanism

Nano/submicron particles can be activated by surfactants and aggregate at the air-water interface to generate and stabilize foams. Such systems have been applied extensively in the food, medicine, and cosmetic industries. Studying particle charging behavior in a particle/surfactant/water system is a fundamental way to understand the activation of the particle surface. This paper presents an investigation of the charging behavior of polystyrene (PS) particles dispersed in aqueous solutions of the surfactant sodium di-2-ethylhexylsulfosuccinate (AOT). The results showed that zeta potential of PS was related to the AOT concentration with two different concentration regions. Below the critical micelle concentration (CMC), the charging of PS particles was effected by AOT ions; while above the CMC, it came from both AOT ions and AOT micelles. This behavior was different from that observed for PS in aqueous salt solutions. Additionally, the particle concentration and size were found to affect the zeta potential differently in the two AOT concentration regions. By analyzing these results, the charging mechanism of the PS/AOT/water system was revealed to be preferential adsorption. In summary, the study disclosed the internal connection between the PS charging in aqueous AOT solution and the activation of PS particles, as well as their influence to foam formation and stability.

Macropore-matrix mass transfer: reactive solute transport as quantified with Fluorescence imaging

2020 ◽  
Author(s):  
Christoph Haas ◽  
Ruth Ellerbrock ◽  
Horst H. Gerke
Keyword(s):  
Mass Transfer ◽  
Soil Properties ◽  
Fluorescence Imaging ◽  
Mass Exchange ◽  
Soil Structure ◽  
Transport Processes ◽  
Hydraulic Transport ◽  
Soil Matrix ◽  
Adsorption Sites ◽  
Sorption Characteristics

<p>Preferential flow paths in soils play a major role for transport processes of heat, gas, water, and solutes and are important adsorption sites. For mass-exchange processes and water storage in soils, small-scaled soil properties, like the spatial distribution of adsorption sites and their accessibility, and the permeability are crucial. Interfaces between macropores (i.e., earthworm burrows, cracks, and root channels) and the soil matrix control the mass exchange. Water and solute transfer through the interface between bio-pores, aggregate or crack surfaces and the matrix was traced at the scale of small soil blocks (≤45 mm edge length) with Fluorescein (i.e., a reactive, fluorescent dye). The objectives were to visualize and quantify hydraulic transport, and sorption characteristics of earthworm-, root- and shrinkage-induced interfaces. Batch experiments were performed to calibrate the Na-Fluorescein tracer concentration versus fluorescence-intensity relationship and to derive parameters for two kinetic sorption models (i.e., Freundlich vs. Langmuir). Fluorescence imaging in the laboratory of small soil blocks was applied with a self-constructed spraying device, and with the help of the calibration, small-scaled dye-concentration maps were derived. Time- and interface-dependent positions of the wetting fronts in vertical direction were estimated with the help of the cumulative infiltration. Assuming equilibrated conditions between Na-Fluorescein in solution (calculated by multiplying the locale dye-concentration and the local water content) and Na-Fluorescein sorbed to soil, the total mass transfers as a function of macropore-type and spraying time were determined. The results of the mass transfer for water and reactive solutes were characteristic for the soil structure type and depending on the composition of the macropore-matrix interface. Differences were explained by alterations in soil structure and chemical composition of the coatings. Results suggest relations between mass exchange and observable soil properties. This can be helpful for improving the numerical simulation of macropore-matrix mass transfer and inverse simulations of small-scaled hydraulic, transport, and sorption characteristics of macropore walls.</p>

Soil structure dynamics in seedbeds: Effects of soil texture and organic carbon content

2020 ◽  
Author(s):  
Mats Larsbo ◽  
Nargish Parvin ◽  
Maria Sandin
Keyword(s):  
Organic Carbon ◽  
Soil Texture ◽  
Soil Structure ◽  
Clay Content ◽  
Transport Processes ◽  
Image Resolution ◽  
Strong Positive Correlation ◽  
Pressure Potential ◽  
Final State ◽  
Pore Size Distributions

<p>The soil structure near the surface of agricultural soils changes with seasons mainly by land management together with climatic and biological factors. Quantitative analysis of post-tillage changes in soil structure and related hydraulic properties are necessary for evaluating and improving models of soil hydrological and transport processes. The objectives of this study were to quantify changes in soil seedbed structure induced by rainfall and drainage and to estimate the effects of soil texture and SOC on these changes. We collected samples from the harrowed layer of twenty-six fine to coarse textured Swedish mineral soils. Air-dried soil was placed in cylinders (5 cm high, diameter 5 cm) and exposed to simulated rainfall (5 mm h<sup>−1</sup> for 4 h) and drainage (-50 cm pressure potential) cycles in the laboratory. We used X-ray tomography to quantify changes in pore networks in a thin surface layer and in the whole cylinder. Infiltration rates at -5 cm pressure potential were measured using a mini disc tension infiltrometer on replicate air-dried samples and on the samples included in the consolidation experiments at the final state. Total imaged specific pore volumes generally decreased from initial to final state and pore size distributions were shifted towards larger proportions of below image resolution pores (< 80 μm). There was a strong positive correlation between clay content and changes in the specific volume of pores<80 μm. Soils with high clay content and soil organic carbon (SOC) content often have strong aggregates that resist change. Nevertheless, both clay and SOC contents were negatively correlated with the changes in specific imaged pore volume. These results highlight the importance of swelling, which is largely controlled by clay content, for seedbed consolidation. In line with previous studies, when excluding coarse textured soil, the changes in surface porosity were negatively correlated with silt content. Changes in infiltration capacity were not significantly correlated to any basic soil properties. Our results suggest that shrinking-swelling should be a central part in any model for seedbed consolidation.</p>

Tillage-induced changes to soil structure and organic carbon fractions in New Zealand soils

Soil Research ◽  
2001 ◽  
Vol 39 (3) ◽  
pp. 465 ◽  
Author(s):  
T. G. Shepherd ◽  
S. Saggar ◽  
R. H. Newman ◽  
C. W. Ross ◽  
J. L. Dando
Keyword(s):  
Organic Carbon ◽  
Size Distribution ◽  
Soil Structure ◽  
Aggregate Stability ◽  
Aggregate Size ◽  
Aggregate Size Distribution ◽  
Binding Agents ◽  
Rate Of Decline ◽  
Humic Soil

The effects of increasing cropping and soil compaction on aggregate stability and dry-sieved aggregate-size distribution, and their relationship to total organic C (TOC) and the major functional groups of soil organic carbon, were investigated on 5 soils of contrasting mineralogy. All soils except the allophanic soil showed a significant decline in aggregate stability under medium- to long-term cropping. Mica-rich, fine-textured mineral and humic soils showed the greatest increase in the mean weight diameter (MWD) of dry aggregates, while the oxide-rich soils, and particularly the allophanic soils, showed only a slight increase in the MWD after long-term cropping. On conversion back to pasture, the aggregate stability of the mica-rich soils increased and the MWD of the aggregate-size distribution decreased, with the humic soil showing the greatest recovery. Aggregate stability and dry aggregate-size distribution patterns show that soil resistance to structural degradation and soil resilience increased from fine-textured to coarse-textured to humic mica-rich soils to oxide-rich soils to allophanic soils. Coarse- and fine-textured mica-rich and oxide-rich soils under pasture contained medium amounts of TOC, hot-water soluble carbohydrate (WSC), and acid hydrolysable carbohydrate (AHC), all of which declined significantly under cropping. The rate of decline varied with soil type in the initial years of cropping, but was similar under medium- and long-term cropping. TOC was high in the humic mica-rich and allophanic soils, and levels did not decline appreciably under medium- and long-term cropping. 13C-nuclear magnetic resonance evidence also indicates that all major functional groups of soil organic carbon declined under cropping, with O-alkyl C and alkyl C showing the fastest and slowest rate of decline, respectively. On conversion back to pasture, both WSC and AHC returned to levels originally present under long-term pasture. TOC recovered to original pasture levels in the humic soil, but recovered only to 60–70% of original levels in the coarse- and fine-textured soils. Aggregate stability was strongly correlated to TOC, WSC, and AHC (P < 0.001), while aggregate-size distribution was moderately correlated to aggregate stability (P < 0.01) and weakly correlated to AHC (P < 0.05). Scanning electron microscopy indicated a loss of the binding agents around aggregates under cropping. The effect of the loss of these binding agents on soil structure was more pronounced in mica-rich soils than in oxide-rich and allophanic soils. The very high aggregate stabilities of the humic soil under pasture was attributed to the presence of a protective water-repellent lattice of long-chain polymethylene compounds around the soil aggregates.

scholarly journals High-frequency monitoring reveals nutrient sources and transport processes in an agriculture-dominated lowland water system

2015 ◽  
Vol 12 (8) ◽  
pp. 8337-8380 ◽  
Author(s):  
B. van der Grift ◽  
H. P. Broers ◽  
W. L. Berendrecht ◽  
J. C. Rozemeijer ◽  
L. A. Osté ◽  
...  
Keyword(s):  
Water Quality ◽  
High Frequency ◽  
Water Discharge ◽  
Water System ◽  
Water Systems ◽  
Transport Processes ◽  
Rainfall Events ◽  
Nutrient Sources ◽  
Pumping Station ◽  
Frequency Monitoring

Abstract. Many agriculture-dominated lowland water systems worldwide suffer from eutrophication caused by high nutrient loads. Insight in the hydrochemical functioning of embanked polder catchments is highly relevant for improving the water quality in such areas. This paper introduces new insights in nutrient sources and transport processes in a low elevated polder in the Netherlands using high-frequency monitoring technology at the outlet, where the water is pumped into a higher situated lake, combined with a low-frequency water quality monitoring program at six locations within the drainage area. Seasonal trends and short scale temporal dynamics in concentrations indicated that the NO3 concentration at the pumping station originated from N-loss from agricultural lands. The NO3 loads appear as losses with drain water discharge after intensive rainfall events during the winter months due to preferential flow through the cracked clay soil. Transfer function-noise modelling of hourly NO3 concentrations reveals that a large part of the dynamics in NO3 concentrations during the winter months can be related to rainfall. The total phosphorus (TP) concentration almost doubled during operation of the pumping station which points to resuspension of particulate P from channel bed sediments induced by changes in water flow due to pumping. Rainfall events that caused peaks in NO3 concentrations did not results in TP concentration peaks. The by rainfall induced and NO3 enriched quick interflow, may also be enriched in TP but this is then buffered in the water system due to sedimentation of particulate P. Increased TP concentrations associated with run-off events is only observed during a rainfall event at the end of a freeze–thaw cycle. All these observations suggest that the P retention potential of polder water systems is highly due to the artificial pumping regime that buffers high flows. As the TP concentration is affected by operation of the pumping station, timing of sampling relative to the operating hours of the pumping station should be accounted for when calculating P export loads, determining trends in water quality or when judging water quality status of polder water systems.

scholarly journals Soil Erodibility Analysis and Mapping in Gilgel Gibe-I Catchment, Omo-Gibe River Basin, Ethiopia

2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
Gizaw Tesfaye ◽  
Tolesa Ameyu
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Soil Erosion ◽  
Catchment Area ◽  
Soil Structure ◽  
Soil Erodibility ◽  
Soil Permeability ◽  
Fine Grained ◽  
Fine Grained Soil ◽  
Texture Class

The soil erosion factor, erodibility, measures the susceptibility of soil particles to transport and detachment by erosive agents. Soil erosion and sedimentation models use soil properties and erodibility as the main input. However, in developing countries such as Ethiopia, data on soil erosion and soil-related properties are limited. For this reason, different researchers use different data sources that are adopted from a large scale and come with very different results. For this reason, the study was proposed to analyze and map the soil erodibility of the catchment area using primary data. 80 mixed soil samples were taken from the catchment with GPS coordinates and analyzed in the laboratory for soil texture class and soil organic matter. Accordingly, sandy clay loam is a dominant soil texture class covering 65% of the catchment area with 2.46% average soil organic matter, which is high in the mountainous part and lower in the lower valley of the catchment area. Most of the catchment area, which accounts for more than 78% of the area, was dominated by medium- or coarse-grained soil structure, and in the upper parts of the catchment area, 21% of the catchment area was covered with fine-grained soil structure. Similarly, 66% of the catchment area was covered with slow to moderate soil permeability, followed by slow soil permeability covering 21% of the area. Finally, the soil erodibility value of the Gilgel Gibe-I catchment was determined to be 0.046 ton h·MJ−1·mm−1 with a range of 0.032 to 0.063 ton·h·MJ−1·mm−1. In general, soils with slow permeability, high silt content, and medium- to fine-grained soil structures are the most erodible. They are conveniently separate; they tend to crust and form high drainage. Knowing this, the catchment has a moderate soil erodibility value. Thus, the study recommends evidence of land cover and the protection of arable land through suitable soil and water protection measures to improve soil permeability and soil structure.

Persistent improvements in the structure and hydraulic conductivity of a Ferrosol due to liming

Soil Research ◽  
2007 ◽  
Vol 45 (3) ◽  
pp. 218 ◽  
Author(s):  
J. M. Kirkham ◽  
B. A. Rowe ◽  
R. B. Doyle
Keyword(s):  
Hydraulic Conductivity ◽  
Organic Carbon ◽  
Soil Structure ◽  
Aggregate Stability ◽  
Aggregate Size ◽  
Soil Surface ◽  
Penetration Resistance ◽  
Organic C ◽  
Soil Penetration Resistance ◽  
Wet Aggregate Stability

Changes in the soil structure and hydraulic conductivity of an Acidic Red Ferrosol were measured in a long-term (1968–2003) fertiliser experiment on pasture in north-western Tasmania, Australia. Studies were initiated following observations of both softer soil surface and cracking on plots that had received 15 t/ha of ground agricultural limestone. Liming decreased penetration resistance and increased hydraulic conductivity. These structural improvements were associated with increased mean dry aggregate size, a small increase in wet aggregate stability, higher exchangeable calcium levels, and increased plant growth, but a 9% decrease in total soil organic carbon in the surface 50 mm. This decrease in organic carbon was not associated with deterioration in soil structure, as may have been anticipated. This was probably because total organic C was still 82 g/kg on unlimed plots. Decreases in soil penetration resistance due to liming increased the likelihood of pugging from livestock but may improve ease of tillage. This research demonstrates that liming can improve the structure of a well-aggregated Ferrosol as well as its previously reported effects of increasing soil pH and yields of pasture and barley despite decreasing organic C.

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