Weathering of clay minerals induced by fluoride-containing solutions from phosphogypsum by-product

1995 ◽  
Vol 75 (2) ◽  
pp. 219-226 ◽  
Author(s):  
J. M. Arocena ◽  
M. J. Dudas ◽  
L. Poulsen ◽  
P. M. Rutherford
Keyword(s):  
Surface Area ◽  
Pore Space ◽  
Clay Fraction ◽  
Calcareous Soils ◽  
Phosphate Fertilizer ◽  
Exchange Capacity ◽  
Process Water ◽  
Clay Liners ◽  
Mineral Stability ◽  
Geochemical Reactions

The production of phosphate fertilizer from phosphate rock results in the formation of phosphogypsum (PG) and HF. Soluble F− ends up in process water and in the pore space of the PG by-product. This study determined changes in the amount, properties and mineral composition of soil clay upon reaction with acidic PG solutions. Calcareous and non calcareous soils were reacted with PG leachates (PG-L, 30 mg F− L−1) and process water (PG-PW, 6070 mg F− L−1) using a sequential batch equilibration method. Phosphogypsum-L did not alter the clay fraction as much as PG-PW, which dissolved as much as two-thirds of the clay fraction. Phosphogypsum-PW reduced surface area of clay fractions from about 500 to 150 m2 g−1; Cation exchange capacity CEC was decreased from about 60 to 17 cmolc kg−1 clay. Reduction in surface area and CEC in PG-PW treated soil corresponded to near complete dissolution of smectite and a negative enrichment of mica. Kaolinite in coarse clay of the PG-PW treatment was reduced to 20% of the control and was completely destroyed in fine clay fractions. Amorphous silica was produced from the F−-induced dissolution of clay. The results indicate there is likely to be considerable alteration of minerals in subsoils beneath PG waste repositories and of clay liners used at some storage facilities. Key words: Clay liners, landfills, dissolution, waste management, leachates, geochemical reactions, mineral stability

scholarly journals A rainfall simulation study of erosion of some calcareous soils

2013 ◽  
Vol 3 (3) ◽  
pp. 179-183 ◽  
Keyword(s):  
Calcium Carbonate ◽  
Cation Exchange Capacity ◽  
Soil Loss ◽  
Clay Fraction ◽  
Calcareous Soils ◽  
Exchange Capacity ◽  
Rainfall Simulation ◽  
Runoff And Soil Loss ◽  
Raindrop Impact ◽  
Rain Simulator

In order to study the erodibility characteristics of some calcareous soils from Central Greece, the instability of aggregates of 2.0-4.7 mm in water was studied. Soil loss experiments were also conducted in the laboratory using a rain simulator where soil loss was measured and the soils’ attitude was studied under the conditions of simulated rainfall. It was found that the instability of aggregates is negatively correlated with cation exchange capacity and the total specific surface of soils. Also the calcium carbonate content affects positively the aggregates instability. The process which seems to control dominantly the time that runoff occurs and the runoff and soil loss quantity, is the creation of surface seals with raindrop impact due to large calcium carbonate quantities that are met in the clay fraction.

Probabilistic Estimation of Specific Surface Area and Cation Exchange Capacity: A Global Multivariate Distribution

2020 ◽  
Author(s):  
Atma Sharma ◽  
Budhaditya Hazra ◽  
Giovanni Spagnoli ◽  
Sreedeep Sekharan
Keyword(s):  
Specific Surface ◽  
Cation Exchange ◽  
Surface Area ◽  
Specific Surface Area ◽  
Cation Exchange Capacity ◽  
Probabilistic Approach ◽  
Clay Fraction ◽  
Exchange Capacity ◽  
Liquid Limit ◽  
Vine Copula

Specific surface area (SSA) and cation exchange capacity (CEC) are two fundamental clay properties. However, the determination of CEC and SSA is challenging due to inherent uncertainties and difficulty in experimental measurement. Popular approach is to employ transformation models for its estimation. However, most of the existing models were developed on limited sample sizes, and quantification of uncertainty associated with the estimate is not possible. Therefore this study proposes a multivariate probabilistic approach for estimation of CEC and SSA. First, a five-dimensional database (278×5) for parameters liquid limit (LL), plasticity index (PI), clay fraction (CF), CEC and SSA (labelled as CLAY/C-S/5/278) is developed. Thereafter, multivariate distribution for the five parameters in the database is constructed using vine copula approach. Implementation of the proposed approach is demonstrated by updating prior/unconditional probability density function (PDFs) of CEC and SSA given single/ multiple clay parameters using Bayes’ rule. The posterior/conditional PDFs of CEC and SSA are also summarized as practitioner friendly analytical expressions. Two geotechnical application examples are also shown. In the proposed approach, CEC and SSA are characterized by their complete joint distribution, and is, therefore, superior to the popular deterministic transformation approach in literature.

scholarly journals SURFACE AREA AND EXCHANGE CAPACITY OF CLAY IN RELATION TO THE MINERALOGICAL COMPOSITION OF GLEYSOLIC SOILS

1979 ◽  
Vol 59 (4) ◽  
pp. 341-347 ◽  
Author(s):  
C. R. DE KIMPE ◽  
M. R. LAVERDIERE ◽  
Y. A. MARTEL
Keyword(s):  
Surface Area ◽  
Cation Exchange Capacity ◽  
Clay Fraction ◽  
Mineralogical Composition ◽  
Total Surface Area ◽  
Exchange Capacity ◽  
Soil Profiles ◽  
Experimental Measurements ◽  
The Difference ◽  
Good Agreement

A study was made to determine to what extent the mineralogical composition of the clay fraction can be related to the total surface area (So) as well as the cation exchange capacity (CEC) values of Gleysolic soils. Eleven soil profiles were sampled in the regions of Montreal, Quebec and Lake St-Jean. Mineralogical composition, surface area and exchange capacity of the clay fraction, and surface area and exchange capacity of the soils were determined. Results showed good agreement between the experimental measurements of surface area and exchange capacity and the calculated figures obtained by using mineralogical composition and theoretical values of So and CEC of each mineral. The variations in the mineralogical composition of the clay fraction were related to the difference in the degree of evolution of the soils in the three regions.

scholarly journals Application of sorption tests to estimate selected properties of alluvial soils in Żuławy Elbląskie

2011 ◽  
Vol 15 (1) ◽  
pp. 167-177
Author(s):  
Andrzej Olchawa ◽  
Jerzy Terlikowski
Keyword(s):  
Specific Surface ◽  
Cation Exchange ◽  
Surface Area ◽  
Specific Surface Area ◽  
Cation Exchange Capacity ◽  
Mineral Soil ◽  
Clay Fraction ◽  
Exchange Capacity ◽  
Alluvial Soils

Application of sorption tests to estimate selected properties of alluvial soils in Żuławy Elbląskie The specific surface area and hence the sorption or desorption moisture at constant water vapour pressure will increase with increasing content of humus and clay fraction in soils. Adopting such an assumption, preliminary experimental studies were performed to assess the possibility of using sorption/desorption tests to determine some features of alluvial soils from Żuławy such as cation exchange capacity CEC and the specific external surface area Se. Results of the sorption tests were compared with the analyses of the same soil properties determined with standard methods to evaluate the usefulness of the former. Preliminary studies showed a high similarity in the determination of CEC and Se with both methods. Confirmed usefulness of sorption/desorption methods for determination of the specific surface area of mineral soil particles and particularly for analyses of cation exchange capacity would bring a significant simplification of studies and a possibility of their dissemination due to the ease of such analyses. Determination of the specific surface area with the sorption and desorption method does not require sophisticated equipment and laborious and costly preliminary procedures. Dissemination of this method and recognition it as a reference one would, however, need further studies on various soil types.

scholarly journals Effect of Low Zeolite Doses on Plants and Soil Physicochemical Properties

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2617
Author(s):  
Alicja Szatanik-Kloc ◽  
Justyna Szerement ◽  
Agnieszka Adamczuk ◽  
Grzegorz Józefaciuk
Keyword(s):  
Plant Growth ◽  
Physicochemical Properties ◽  
Cation Exchange ◽  
Surface Area ◽  
Cation Exchange Capacity ◽  
N Fertilization ◽  
Exchange Capacity ◽  
First Year ◽  
Soil Physicochemical Properties ◽  
Water Holding

Thousands of tons of zeolitic materials are used yearly as soil conditioners and components of slow-release fertilizers. A positive influence of application of zeolites on plant growth has been frequently observed. Because zeolites have extremely large cation exchange capacity, surface area, porosity and water holding capacity, a paradigm has aroused that increasing plant growth is caused by a long-lasting improvement of soil physicochemical properties by zeolites. In the first year of our field experiment performed on a poor soil with zeolite rates from 1 to 8 t/ha and N fertilization, an increase in spring wheat yield was observed. Any effect on soil cation exchange capacity (CEC), surface area (S), pH-dependent surface charge (Qv), mesoporosity, water holding capacity and plant available water (PAW) was noted. This positive effect of zeolite on plants could be due to extra nutrients supplied by the mineral (primarily potassium—1 ton of the studied zeolite contained around 15 kg of exchangeable potassium). In the second year of the experiment (NPK treatment on previously zeolitized soil), the zeolite presence did not impact plant yield. No long-term effect of the zeolite on plants was observed in the third year after soil zeolitization, when, as in the first year, only N fertilization was applied. That there were no significant changes in the above-mentioned physicochemical properties of the field soil after the addition of zeolite was most likely due to high dilution of the mineral in the soil (8 t/ha zeolite is only ~0.35% of the soil mass in the root zone). To determine how much zeolite is needed to improve soil physicochemical properties, much higher zeolite rates than those applied in the field were studied in the laboratory. The latter studies showed that CEC and S increased proportionally to the zeolite percentage in the soil. The Qv of the zeolite was lower than that of the soil, so a decrease in soil variable charge was observed due to zeolite addition. Surprisingly, a slight increase in PAW, even at the largest zeolite dose (from 9.5% for the control soil to 13% for a mixture of 40 g zeolite and 100 g soil), was observed. It resulted from small alterations of the soil macrostructure: although the input of small zeolite pores was seen in pore size distributions, the larger pores responsible for the storage of PAW were almost not affected by the zeolite addition.

Characteristics of variably saturated granular bentonite after long-term storage at near-field relevant temperatures

Clay Minerals ◽  
2013 ◽  
Vol 48 (2) ◽  
pp. 343-361 ◽  
Author(s):  
M. Valter ◽  
M. Plötze
Keyword(s):  
Physicochemical Properties ◽  
Cation Exchange ◽  
Surface Area ◽  
Cation Exchange Capacity ◽  
Elevated Temperatures ◽  
Near Field ◽  
Exchange Capacity ◽  
Hydraulic Permeability ◽  
Cation Composition ◽  
Retention Capacity

AbstractBentonite is a potential material for use in the engineered barrier of radioactive waste repositories because of its low hydraulic permeability, self-sealing capability and retention capacity. It is expected that bentonite would react at the elevated temperatures accompanying the radioactive decay in the nuclear waste. The presented study was started in order to improve understanding of the coupled influence of temperature and (pore) water on the physicochemical and mineralogical properties of bentonite during thermal treatment under near-field relevant conditions. Granular Na-bentonite MX-80 was differently saturated (Sr = 1–0.05) and stored at different temperatures (50–150°C) in a closed system. Upon dismantling after different periods of time (3 to 18 months), mineralogical characteristics, cation exchange capacity and content of leachable cations, as well as physicochemical properties such as surface area and water adsorption were investigated.The results showed a high mineralogical stability. A slight conversion from the sodium to an earth alkali form of the bentonite was observed. However, considerable changes in the physicochemical properties of the bentonite were observed, particularly by treatment above the critical temperature of 120°C. The cation exchange capacity decreased during heating at 150°C by approximately. 10%. The specific surface area dropped by more than 50%. The water uptake capacity under free swelling conditions showed a slight tendency to lower values especially for samples heated for more than 12 months. The water vapour adsorption ability in contrast drops by 25% already within three months at T = 120°C. These changes are mostly related to the variations in the interlayer cation composition and to smectite aggregation processes. The observed alterations are rather subtle. However, temperatures ⩾ 120°C had a remarkable negative influence on different properties of MX-80.

scholarly journals Mineralogical characterization of natural clays from Brazilian Southeast region for industrial applications

Cerâmica ◽  
2017 ◽  
Vol 63 (366) ◽  
pp. 253-262 ◽  
Author(s):  
N. I. Alvarez Acevedo ◽  
M. C. G. Rocha ◽  
L. C. Bertolino
Keyword(s):  
Specific Surface ◽  
Clay Fraction ◽  
Exchange Capacity ◽  
Size Analysis ◽  
Mineralogical Characterization ◽  
Southeast Region ◽  
Pore Size Analysis ◽  
Two Samples ◽  
Natural Clays ◽  
Cationic Exchange

Abstract Characterization studies of clays are often performed to identify possible markets for these materials. Bearing this in mind, two samples of natural clays from the Southeast region of Brazil were studied. Conventional techniques of characterization were used. Granulometric analysis and determination of cationic exchange capacity of these clays were also performed. Nitrogen adsorption-desorption measurements were used to determine the Brunauer-Emmett-Teller specific surface area, and Barrett-Joyner-Halenda and t-plot pore size analysis were carried out. The results obtained were similar for the two clays. Both present high clay fraction (above 80 wt%) composed of illite, kaolinite and quartz minerals. Stratified illite-smectite structures were also observed. Traces of calcite were detected in one of the clay samples, while traces of montmorillonite were observed in the other sample. These results were corroborated by the low cationic exchange capacity values obtained for both clays. These clays showed good adsorptive properties, evidenced by their specific surface areas, with predominantly mesoporous structures and slit-like pores. According to their features, these clays have potential use as adsorbents to replace more expensive materials due to their easy availability and low cost.

Cation exchange capacity of loess and overlying soil in the non-carbonate loess sections, North-Western Croatia

2013 ◽  
Vol 5 (4) ◽  
Author(s):  
Nenad Tomašić ◽  
Štefica Kampić ◽  
Iva Cindrić ◽  
Kristina Pikelj ◽  
Mavro Lučić ◽  
...  
Keyword(s):  
Organic Matter ◽  
Cation Exchange ◽  
Transition Zone ◽  
Cation Exchange Capacity ◽  
Clay Fraction ◽  
Sample Pretreatment ◽  
Loess Soil ◽  
Exchange Capacity ◽  
Oxalate Extraction ◽  
North Western

AbstractThe adsorption properties in terms of cation exchange capacity and their relation to the soil and sediment constituents (clay minerals, Fe-, Mn-, and Al-oxyhydroxides, organic matter) were investigated in loess, soil-loess transition zone, and soil at four loess-soil sections in North-Western Croatia. Cation exchange capacity of the bulk samples, the samples after oxalate extraction of Fe, Mn and Al, and after removal of organic matter, as well as of the separated clay fraction, was determined using copper ethylenediamine. Cation exchange capacity (pH∼7) of the bulk samples ranges from 5 to 12 cmolc/kg in soil, from 7 to 15 cmolc/kg in the soil-loess transition zone, and from 12 to 20 cmolc/kg in loess. Generally, CEC values increase with depth. Oxalate extraction of Fe, Mn, and Al, and removal of organic matter cause a CEC decrease of 3–38% and 8–55%, respectively, proving a considerable influence of these constituents to the bulk CEC values. In the separated clay fraction (<2 μm) CEC values are up to several times higher relative to those in the bulk samples. The measured CEC values of the bulk samples generally correspond to the clay mineral content identified. Also, a slight increase in muscovite/illite content with depth and the vermiculite occurrence in the loess horizon are concomitant with the CEC increase in deeper horizons, irrespective of the sample pretreatment.

Sign in / Sign up

Export Citation Format

Share Document