Content Of Clay Particles Research Articles

Study on Dispersive Influencing Factors of Dispersive Soil in Western Jilin Based on Grey Correlation Degree Method

The study on dispersion mechanism of dispersive soil has attracted attention in water conservancy project. In order to investigate the main dispersive influencing factors of soil, grey correlation degree method was used to analysis the relation between dispersion degree and exchanging sodium percentage, clay particles content, organic matter, PH, specific surface area, structure damage rate, cation exchange capacity. The results show that the cation exchange capacity and exchangeable sodiuma do the best contribution to the dispersion of soil, and the specific surface area and the structure damage rate influenced the dispersion slightly.

Trend Effect and an Isotropy of Soil Particle Composition in the Chengdu Plain

This paper studies the spatial variation characteristics of soil particle composition on both sides of Qingbaijiang River (Chengdu Xin Du District of Sichuan province) by using the geostatistical component of ArcGIS and GS software. The results have shown that the trends of sand contents in the east-west direction and the north-south direction were first order and second order, respectively. And the trends of both silt particle and clay particle contents were first order in the east-west direction, and second order in the north-south direction. The anisotropy semi variance models of sand particle content showed that the ranges in the long axis direction were 718.77 m and 677.01 m and the ranges in the short axis direction were 273.78 m and 276.63 m with first order and second order. The results showed that the difference between the ranges in the short axis direction and the ranges in long axis direction changed little, while the anisotropy semi variance model had longer ranges than the isotropy model with the trend parameters of first order. From the error analysis and the result that reflect regional and local trend, it indicated that Kriging interpolation method considering the study about soil particle composition along Qingbaijiang River with the second order trend effect was the best, comparing the contour maps of sand particle content under different trend effects and anisotropy parameters.

Dispersion and reaggregation of nanoparticles in the polypropylene copolymer foamed by supercritical carbon dioxide

For the preparation of nanocomposites, we conducted environmentally benign foaming processing on polypropylene (PP) copolymer/clay nanocomposites via a batch process in an autoclave. We investigated the dispersion and the exfoliation of the nanoclay particles. Full exfoliation was achieved by the foamability of the matrix PP copolymer using supercritical carbon dioxide (sc CO2) and subcritical carbon dioxide (sub CO2). More and smaller cells were observed when the clay was blended as heterogeneous nuclei and sc CO2 was used. Small angle X-ray scattering showed that highly dispersed states (exfoliation) of the clay particles were obtained by the foaming process. Since the clay particles provided more nucleating sites for the foaming of the polymer, a well dispersed (or fully exfoliated) nanocomposite exhibited a higher cell density and a smaller cell size at the same clay particle concentration. Expansion of the adsorbed CO2 facilitated the exfoliation of the clay platelets; thus, sc CO2 at lower temperature was more efficient for uniform foaming-cell production. Fully dispersed clay platelets were, however, re-aggregated when subjected to a further melting processing. The reprocessed nanocomposites still had some exfoliated platelets as well as some aggregated intercalates. The dual role of the nanoclay particles as foaming nucleus and a crystallization nucleus was confirmed by cell growth observation and nonisothermal crystallization kinetics analysis. A low foaming temperature and a high saturation pressure were more favorable for obtaining a uniform foam. The PP copolymer was found to be foamed more easily than polypropylene. A small amount of other olefin moieties in the backbone of the polymer facilitated better foamability than the neat polypropylene.

Predicting the film and lens water volume between soil particles using particle size distribution data

Summary We develop four conceptual approaches to quantify the volume of water lenses between soil particles (ei) and adsorbed water films (δi) coating soil particles based on soil Particle Size Distribution (PSD) data. Method 1 is based on expression of the ei as matric suction independent pendular rings and method 2 is based on expression of the ei as function of matric suction. Methods 3 and 4 are based on the coupling of δi estimated with van der Waals and electrostatic forces, with ei estimated with methods 1 and 2 respectively. We show that the filling angle of the lens water is independent of surface tension but increases with the porosity. The four methods are applied to predict effects of ei and δi on Soil Moisture Characteristics (SMC) in eighty soil samples selected from UNSODA database. The total component of the ei in soil water content ranged from 0.0111 (L3 L−3) to 0.1604 (L3 L−3), with the average of 0.0703 (L3 L−3) for method 1 and from 0.0082 (L3 L−3) to 0.0523 (L3 L−3), with the average of 0.0237 (L3 L−3) for method 2. The component of δi is less than 0.0121 of each pore water content. Results showed that for methods 1 and 2, the component of the ei in the soil water content was partially relevant for the prediction of SMC, especially in dry range. Moreover, the accuracy of the method 1 was slightly greater than that of the method 2. We attribute the methods error to the roughness of soil particles, high surface energy content of clay particles and, to the simplified pore geometric concepts that does not effectively reflect the pore geometry. We conclude that the main advantage of the present approaches is developing two different methods for estimation of the volume of the lens water by using only the PSD data and bulk density which are measured easily.

Leaching of Contamination from Stabilization/Solidification Remediated Soils of Different Texture

Abstract Development of soil and groundwater remediation technologies is a matter of great importance to eliminate historically and currently contaminated sites. Stabilization/solidification (S/S) refers to binding of waste contaminants to a more chemically stable form and thus diminishing leaching of contamination. It can be performed using cement with or without additives in order to stabilize and solidify soil with the contamination in matrix. A series of experiments were done to determine leaching properties of spiked soils of different texture bound with cement. Results of experiments showed, that soil texture (content of sand, silt and clay particles) affects the leaching of heavy metals from stabilized soils.

Evaluation of trace element contamination changes in soils using a new normalization factor: Application to the Guadiamar soils (SW Spain) affected by a mine spill in 1998

In 1998, the Aznalcóllar mining accident (SW Spain) released about 2millionm3 of pyrite sludge and 4millionm3 of acidic water flooding more than 4000ha of Agrio and Guadiamar riverbanks. After cleaning operations and amendment applications, a residual pollution remained in soils. To follow the evolution of the contamination, a sampling survey was carried out every two years (from 1999 to 2007) in 10 parcels of 1ha (45 samples) that remained highly contaminated. The general characterization of soils showed two different zones: the northern being more acidic and with lower retention capacity of trace elements than the southern. Remediation actions increased the pH (particularly in the northern part), but they caused the loss of the soil cover, decreasing the phyllosilicate and clay particle contents. Chemical analyses of trace elements revealed a high heterogeneity of the contamination, even in the same sampling hectare. The variation of trace element means with time showed a general decreasing trend for very mobile elements (Cd and Zn), but the results for more immobile elements (As, Cu and Pb) remained unclear. Calculation of the enrichment factor based on a geogenic element (Al) showed the level of contamination, but this index was not useful to study the evolution with time. In order to reduce the variability of the results and study the mobilization of trace elements a contamination normalized factor was proposed. The elements were normalized to Sb, a characteristic and conservative element of the pyrite sludge. The results showed that Pb was immobile, but 40% of initial As has been mobilized during the study period. This index suggests that the main source of As and Pb was the pyrite sludge. Other sources such as the bedrock are quite important in the total concentration of Fe and Co, and acidic water could have been a source for Cd, Cu and Zn. The contamination normalized factor reduced the variability of the results and was useful to study the evolution of trace element contamination. Its application to other sites contaminated by mining or industrial spills could be possible when geochemical data of the pollutants exists.

Influences of Change of Plasma on Strength Property of Eolian Sand

The plasma in the eolian sand, included silt particle and clay particle, change easily and hugely. For studying their influences on the strength property of eolian sand, mixed silt particles and clay particles into eolian sand in different proportions to measure the internal friction angle and cohesion under different forming and testing conditions. The result indicates that: for the same kind of test specimen under different test types, the changes of cohesion and internal friction coefficient are regular. For the same test type, the changes of both cohesion and internal friction coefficient of different test specimens are regular. Generally, when the content of silt particles and clay particles is lower than a certain value, the cohesion and internal friction coefficient increase accordingly and rapidly along with the increase of silt particles and clay particles; after the content of silt particles and clay particles is larger than this value, the cohesion and internal friction coefficient increase slowly or decline along with the increase of silt particles and clay particles. The change range of this value is approximately between 45%～65%, the content of silt particles and clay particles. For the purpose of this test, as to the transition of test specimens from typical sandy soil to fine grained soil caused by the increase of silt particles and clay particles, the change point of strength is at 45％ approximately, which is basically consistent with the compacting test and CBR test, etc.

Predict Model for Water Content of Dredged Sludge under the Aeration-Vacuum Condition

The clogging problem occurs in the dewatering projects of sludge with high water content and high clay particles content can be solved by the aeration-vacuum dewatering method. And the water in the sludge can be separated out quickly. Through the dewatering model test of the sludge with this method, the effects of vacuum degree and aeration rate on the dewatering results are studied. The relationship between the initial and final water content is got under the aeration-vacuum condition. Through the fitting analysis of the dewatering curves, the predict model for water content of dredged sludge is presented. And the effect mechanism of the vacuum degree and aeration rate are analyzed.

Predict Model for Water Content of Dredged Sludge under the Aeration-Vacuum Condition

The clogging problem occurs in the dewatering projects of sludge with high water content and high clay particles content can be solved by the aeration-vacuum dewatering method. And the water in the sludge can be separated out quickly. Through the dewatering model test of the sludge with this method, the effects of vacuum degree and aeration rate on the dewatering results are studied. The relationship between the initial and final water content is got under the aeration-vacuum condition. Through the fitting analysis of the dewatering curves, the predict model for water content of dredged sludge is presented. And the effect mechanism of the vacuum degree and aeration rate are analyzed.

Study on Scouring Stability of Powder Sand Embankment Slope with Cover Layer

Abstract. The content of clay particles in powder sand is low, with small cohesion. Embankment erosion by water will lead to instability, to make a cover layer with clay. In order to resolve the erosion of powder sand embankment slopes affected by the rain, tested the powder sand and the cover layer soil, and conducted a survey of slope erosion situation in the embankment, divided the types of erosion. On this basis, base on the energy method, analysis the slope erosion by the impact of slope gradient, slope shape, the density and width of cover layer soil, rainfall intensity, conclude some applicable scouring protective measures for conditions of slope. The results provide a reference for the design of powder sand slope protective technology.

Dependence of Heavy Soil Transport Function on Soil Profile Depth

Dependence of Heavy Soil Transport Function on Soil Profile DepthThe aim of this work was to quantify the effect of soil profile depth on the transport function of heavy soils. Treatments were carried out between 2006 and 2009 in Milhostov. Two variants were examined : the (conventional soil tillage and long-time no-tilled variant). Soil samples were taken in spring and autumn from soil profile depth of 0.00-0.60 m from each 0.10 m. For further evaluation the average values were used. Particle size composition, bulk density, total porosity and maximum capillary capacity were determined. Content of clay particles in soil profile was in interval 59.64-68.53% and such soils are characterised in the range from clay-loamy soil to clayey soil. The bulk density increased with the depth of soil profile and its values reached 1 184-1 646 kg m-3. The total porosity was in range 37.68-55.17% and it decreased with the depth of soil profile. The values of maximum capillary capacity were characterised for heavy soils with high content of clay particles. The depth had statistically significant effect on all observed parameters. In average, on both variants the bulk density was higher than 1 400 kg m-3, the total porosity was lower than 47% and the content of clay was higher than 30%, pointing to the possibility of soil compaction, which will result in reduced transport function of heavy soils.

Influences of Change of Plasma on CBR of Eolian Sand

The plasma in the eolian sand, included silt particle and clay particle, change easily and hugely. For studying their influences on the strength property of eolian sand, mixed silt particles and clay particles in different proportion into the eolian sand to carry out CBR test. The test result indicates that, along with the increase of silt particle and clay particle content the CBR value also increases within a certain range, which indicates the increase of silt particle and clay particle content can firstly improve the gradation of eolian sand; after the gradation is improved can obtain large compaction dry density, and at the same time also can enhance the earth strength, included the CBR value. The range of silt particle and clay particle content made the CBR value increase is also very large: ≤40% when formed under dry state, and ≤45% when formed under optimum or saturated water content; if the water content in forming could be retained at all times, the former could be ≤55% and the latter still ≤45%. The mechanism analysis further indicates that, when there were no excessive silt particles and clay particles, in the large range of silt particles and clay particles changing from small to large, the engineering nature of eolian sand will be improved due to the improvement of gradation, which is advantageous to the extensive application of dry compaction process; but the eolian sand formed by dry compaction is defective on microstructure, and so the requirements for silt particle and clay particle content should be more strict in practical works.

Montmorillonite Functionalized with Pralidoxime As a Material for Chemical Protection against Organophosphorous Compounds

Montmorillonite K-10 functionalized with α-nucleophilic 2-pralidoxime (PAM) and its zwitterionic oximate form (PAMNa) is introduced as a versatile material for chemical protection against organophosphorous (OP) compounds such as pesticides and chemical warfare agents (CWA). Upon inclusion into the montmorillonite interlayer structure, the pyridinium group of PAMNa is strongly physisorbed onto acidic sites of the clay, leading to shrinking of the interplanar distance. Degradation of diethyl parathion by PAMNa-functionalized montmorillonite in aqueous-acetonitrile solutions occurred primarily via hydrolytic conversion of parathion into diethylthio phosphoric acid, with the initial stages of hydrolysis observed to be pseudo-first-order reactions. Hydrolysis catalyzed by the clay intercalated by PAMNa was 10- and 17-fold more rapid than corresponding spontaneous processes measured at 25 and 70 °C, respectively. Hydrolytic degradation of diisopropyl fluorophosphate (DFP), a CWA simulant, was studied on montmorillonite clay functionalized by PAMNa and equilibrated with water vapor at 100% relative humidity by ³¹P high-resolution magic angle spinning NMR and was observed to be rather facile compared with the untreated montmorillonite, which did not show any DFP hydrolysis within 24 h. The incorporation of the functionalized clay particles into elastomeric film of polyisobutylene was shown to be a means to impart DFP-degrading capability to the film, with clay particle content exceeding 18 wt %.

The influence of oil contamination on the geotechnical properties of coastal sediments in the Yellow River Delta, China

The effect of contamination by crude oil has been assessed using samples from hand dug trial pits in the Hai-gang region of the Yellow River Delta. In addition to electrical resistivity and in situ penetration tests, grain size analysis, Atterberg limits, compaction, direct shear test and a micro-structure scan were undertaken. The results show that contamination was in the shape of a plume and non-uniform to a depth of 1 m. The more heavily polluted soil had a higher clay particle content, liquid and plastic limit and compression coefficient. However, no notable correlations were found between oil contamination and shear strength parameters.

10.1007/s11475-008-3009-7

The results of long-term stationary studies on the properties of loamy soils under forest and plowland in the middle taiga subzone were summarized. Spatial and temporal changes in the morphology and physicochemical properties of agrosoddy-podzolic soils as compared to forest ones, the peculiar pedogenesis of the soils in automorphic positions and on the slopes, and the activation of gleying in these soils were discovered. The downward displacement of the eluvial horizon, the shift to a heavier texture of the arable layer due to the soil cultivation, the variation in the content of clay and silty particles in this layer depending on the duration and stability of the freezing periods, and the decrease in the removal of clay and most oxides in the developed soils were revealed. The removal of iron, aluminum, calcium, and magnesium oxides and the profile distribution of clay indicate the intensification of eluviation in the soils of mesodepressions. The long-term use of podzolic soils in agrocenoses resulted in the leveling of the humus reserves in the entire catena.

Clay/Epoxy Nanocomposites

Nanocomposites are a novel class of composite materials where one of the constituents has dimensions in the range between 1 and 100 nm. Recent and ongoing research on polymer/inorganic nanocomposites has shown dramatic enhancements in stiffness, strength and thermal properties over those of polymers, without compromising on density, toughness or processibility. Such improvement in properties has been estimated to correspond to approxi

Scanning study of the optical parameters of sandy soddy-steppe soil samples from the southern Ukraine

It was shown that an office scanner can be used for the acquisition of digital images of soil samples and their analysis using the RGB color system. The content and optical density of the humic acids were the main factors determining the color intensity of sandy soils. With all the other factors being constant, the increase in the content of clay particles resulted in a decrease in the color intensity of the sandy soils, whereas a decrease in the content of the coarse sand increased the color intensity. The content of mobile iron had the least significant effect on the color of the sandy soils.

Soil Organic Carbon and Its Fractions Across Vegetation Types: Effects of Soil Mineral Surface Area and Microaggregates

Abstract Soil organic carbon (SOC) can act as a sink or source of atmospheric carbon dioxide; therefore, it is important to understand the amount and composition of SOC in terrestrial ecosystems, the spatial variation in SOC, and the underlying mechanisms that stabilize SOC. In this study, density fractionation and acid hydrolysis were used to assess the spatial variation in SOC, the heavy fraction of organic carbon (HFOC), and the resistant organic carbon (ROC) in soils of the southern Hulun Buir region, northeastern China, and to identify the major factors that contribute to this variation. The results showed that as the contents of clay and silt particles (0–50 μm) increased, both methylene blue (MB) adsorption by soil minerals and microaggregate contents increased in the 0–20 and 20–40 cm soil layers ( P < 0.05). Although varying with vegetation types, SOC, HFOC, and ROC contents increased significantly with the content of clay and silt particles, MB adsorption by soil minerals, and microaggregate content ( P < 0.05), suggesting that soil texture, the MB adsorption by soil minerals, and microaggregate abundance might be important factors influencing the spatial heterogeneity of carbon contents in soils of the southern Hulun Buir region.

Erosion of Sediment and Organic Carbon from the Kara Sea Coast

We have estimated the erosion of sediment and organic carbon input from the Kara Sea coast based on extensive mapping, geologic and cryolithologic investigations of coastal zone and seafloor sediments, and revision of previously published data. The amount of coastal sediment eroded into the Kara Sea was determined to be approximately 35 million tons. Twenty-seven million tons are attributed to solid material, 7.6 million to thawed ground ice, 0.4 million to organic carbon, and 0.3 million to soluble salts. The estimate of organic carbon input presented herein is 2.5-fold less than previously published elsewhere. The majority of organic carbon in marine clayey deposits was found to be present in an adsorbed form. Its quantity corresponds to the content of clay particles in Pleistocene sediments. Organic carbon content in clay marine sediments remains unchanged during freeze-thaw processes, indicating that this form of carbon is stable unless thermoerosion is taking place.

Erosion of Sediment and Organic Carbon from the Kara Sea Coast

We have estimated the erosion of sediment and organic carbon input from the Kara Sea coast based on extensive mapping, geologic and cryolithologic investigations of coastal zone and seafloor sediments, and revision of previously published data. The amount of coastal sediment eroded into the Kara Sea was determined to be approximately 35 million tons. Twenty-seven million tons are attributed to solid material, 7.6 million to thawed ground ice, 0.4 million to organic carbon, and 0.3 million to soluble salts. The estimate of organic carbon input presented herein is 2.5-fold less than previously published elsewhere. The majority of organic carbon in marine clayey deposits was found to be present in an adsorbed form. Its quantity corresponds to the content of clay particles in Pleistocene sediments. Organic carbon content in clay marine sediments remains unchanged during freeze-thaw processes, indicating that this form of carbon is stable unless thermoerosion is taking place.