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Fadila Darragi - One of the best experts on this subject based on the ideXlab platform.
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anionic rr120 dye adsorption onto raw clay surface properties and adsorption mechanism
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2012Co-Authors: Emna Errais, Ruben Ocampo, Raymonde Baltenweckguyot, Mourad Elhabiri, Joëlle Duplay, Mohamed Khodja, Fadila DarragiAbstract:Abstract Clay minerals are efficient adsorbent for dyes due to their colloidal properties. A Tunisian raw clay (Fouchana) composed of different species of clay minerals (kaolinite, smectite and minor illite) has shown efficiency for removal of anionic dye Reactive Red 120 (RR120) from aqueous solutions. In order to provide a better understanding of the role played by the different clay species in Fouchana, as well as the nature of the adsorption processes which are involved, a comparative study was conducted using standard clays, namely kaolinite KGa-2, smectite SWy-1 and illite IMt-2. Batch adsorption experiments were performed at ambient temperature and pH of the dye solutions. Acido-basic properties of the solid surfaces, electrophoretic mobility of particles, cation exchange capacity, amount of Exchangeable cations and specific surface were investigated. Principal component analysis was used to highlight the influence of the physicochemical characteristics of the clay minerals in the adsorption behavior. The results show that for the conditions set in this study, kaolinite in the Fouchana raw clay plays a major role in anionic dye adsorption, mainly due to its acidic surface sites, but also to Exchangeable Aluminum (III) cations acting as bridges between the clay mineral and the dye molecules. Smectite and illite most likely play a secondary role by adsorption on Exchangeable calcium (II) and dissociated Al (III) OH groups.
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Anionic RR120 dye adsorption onto raw clay: Surface properties and adsorption mechanism
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2012Co-Authors: Ruben Ocampo-torres, Emna Errais, Ruben Ocampo, Mourad Elhabiri, Joëlle Duplay, Mohamed Khodja, Raymonde Baltenweck-guyot, Fadila DarragiAbstract:Clay minerals are efficient adsorbent for dyes due to their colloidal properties. A Tunisian raw clay (Fouchana) composed of different species of clay minerals (kaolinite, smectite and minor illite) has shown efficiency for removal of anionic dye Reactive Red 120 (RR120) from aqueous solutions. In order to provide a better understanding of the role played by the different clay species in Fouchana, as well as the nature of the adsorption processes which are involved, a comparative study was conducted using standard clays, namely kaolinite KGa-2, smectite SWy-1 and illite IMt-2. Batch adsorption experiments were performed at ambient temperature and pH of the dye solutions. Acido-basic properties of the solid surfaces, electrophoretic mobility of particles, cation exchange capacity, amount of Exchangeable cations and specific surface were investigated. Principal component analysis was used to highlight the influence of the physicochemical characteristics of the clay minerals in the adsorption behavior. The results show that for the conditions set in this study, kaolinite in the Fouchana raw clay plays a major role in anionic dye adsorption, mainly due to its acidic surface sites, but also to Exchangeable Aluminum (III) cations acting as bridges between the clay mineral and the dye molecules. Smectite and illite most likely play a secondary role by adsorption on Exchangeable calcium (II) and dissociated Al (III)-OH groups. (C) 2012 Elsevier B.V. All rights reserved.
Shuangcheng Xiao - One of the best experts on this subject based on the ideXlab platform.
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effect of low molecular weight organic anions on Exchangeable Aluminum capacity of variable charge soils
Journal of Colloid and Interface Science, 2005Co-Authors: Shuangcheng XiaoAbstract:Low-molecular-weight (LMW) organic acids exist widely in soils and have been implicated in many soil processes, such as nutrient availability, translocation of metals, fate of heavy metals, and mineral weathering. In this paper, the effect of the LMW organic anions on the Exchangeable Aluminum of two variable-charge soils was examined. The results showed that the organic anions induced an increase or a decrease in the Exchangeable Al, and the extent and direction of the effect depended on the nature of organic anions, surface chemical properties of soils, and pH. For example, at pH 4.5, the quantity of Exchangeable Al of Oxisol in the control system was 2.65 mmol kg −1 , whereas the values in the citrate, oxalate, malonate, malate, tartarate, salicylate, and lactate systems increased by 3.25, 1.93, 1.95, 1.82, 1.28, 0.88, and 0.45 times, respectively. In contrast, the quantity of the Exchangeable Al of Ultisol at pH 4.5 in the oxalate and the citrate systems decreased by 8.8 and 19.6%, respectively. The increase in the Exchangeable Al was caused mainly by the increase in negative surface charge of the soils due to the specific adsorption of organic anions. The ability of organic anions at low concentrations to increase Exchangeable Al for Oxisol followed the order citrate > oxalate and malonate > malate > tartarate > salicylate > maleate > lactate. This order is consistent with that of the effect of the adsorption of anions on the increase in the negative surface charge and/or the decrease in the positive surface charge of the soil. On the other hand, the organic anions could depress the Exchangeable Al through the formation of soluble Al–organic anion complexes under certain conditions. The anions with small stability constants of Al–organic anion complexes, such as lactate, caused an increase in Exchangeable Al with the change in surface charge of the soils, while those with large stability constants, such as citrate and oxalate, caused an increase in the Exchangeable Al at low concentration and a decrease at high concentration.
Olivia L Fraser - One of the best experts on this subject based on the ideXlab platform.
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mineral weathering and podzolization control acid neutralization and streamwater chemistry gradients in upland glaciated catchments northeastern united states
Frontiers in Earth Science, 2019Co-Authors: Scott W Bailey, Kevin J Mcguire, Donald S Ross, Mark B Green, Olivia L FraserAbstract:Headwater streams in the White Mountains, NH, USA have been shown to have downstream gradients of increasing pH and concentrations of base cations coupled with decreasing concentrations of Aluminum. A two-stage acid neutralization model involving shallow soil exchange processes in headwaters coupled with deeper mineral weathering downstream had been proposed to explain these gradients. We conducted synoptic sampling of three headwater catchments in this region that showed variations in this longitudinal pattern, ranging from streams that remain acidic throughout their length to streams with circumneutral pH beginning at their source. To explain these differences, we mapped soils using a hydropedologic approach that emphasizes the influence of groundwater saturation frequency and water table regime on soil formation processes. Stream segments with lower pH and base cation concentrations, coupled with higher concentrations of dissolved organic carbon, Aluminum, and in one case iron, were in subcatchments mapped with shallow to bedrock soils where eluvial soil forming processes dominated. In contrast, stream segments with higher pH and base cation concentrations coupled with low concentrations of dissolved organic carbon and Aluminum were associated with subcatchments with deeper soils where illuvial processes were more dominant. Concentrations of sodium and silicon were relatively uniform across these gradients. Coupled with the higher concentrations of dissolved Aluminum and small pools of Exchangeable Aluminum in the areas of bedrock outcrops and shallow soils, these data suggest that primary mineral dissolution is an important process influencing upper stream reaches. Some stream reaches with obvious groundwater springs show a more abrupt transition suggesting that neutralization along deeper flowpaths may play a role as well. These data suggest a new three stage model of stream chemistry evolution with introduction of organic acids by frequent flushing of organic soils on shallow bedrock along ridge areas, acidic reaches controlled by shallow mineral weathering processes coupled with eluvial soil development, giving way to downstream reaches influenced by illuviation as organometallic complexes precipitate in spodic soil horizons. This new model highlights differences in critical zone evolution along hillslopes in glaciated catchments with implications for understanding gradients in water quality, soil fertility, and response and recovery from disturbances.
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Mineral Weathering and Podzolization Control Acid Neutralization and Streamwater Chemistry Gradients in Upland Glaciated Catchments, Northeastern United States
Frontiers Media S.A., 2019Co-Authors: Scott W Bailey, Kevin J Mcguire, Donald S Ross, Mark B Green, Olivia L FraserAbstract:Headwater streams in the White Mountains, NH, United States have been shown to have downstream gradients of increasing pH and concentrations of base cations coupled with decreasing concentrations of Aluminum. A two-stage acid neutralization model involving shallow soil exchange processes in headwaters coupled with deeper mineral weathering downstream had been proposed to explain these gradients. We conducted synoptic sampling of three headwater catchments in this region that showed variations in this longitudinal pattern, ranging from streams that remain acidic throughout their length to streams with circumneutral pH beginning at their source. To explain these differences, we mapped soils using a hydropedologic approach that emphasizes the influence of groundwater saturation frequency and water table regime on soil formation processes. Stream segments with lower pH and base cation concentrations, coupled with higher concentrations of dissolved organic carbon (DOC), Aluminum, and in one case iron, were in subcatchments mapped with shallow to bedrock soils where eluvial soil forming processes dominated. In contrast, stream segments with higher pH and base cation concentrations coupled with low concentrations of DOC and Aluminum were associated with subcatchments with deeper soils where illuvial processes were more dominant. Concentrations of sodium and silicon were relatively uniform across these gradients. Coupled with the higher concentrations of dissolved Aluminum and small pools of Exchangeable Aluminum in the areas of bedrock outcrops and shallow soils, these data suggest that primary mineral dissolution is an important process influencing upper stream reaches, not just along longer, deeper flowpaths in downslope areas. In contrast, some stream reaches with obvious groundwater springs show a more abrupt transition in pH and base cation concentrations higher along the stream, suggesting that neutralization along deeper flowpaths may play a role in upslope areas as well. These data suggest a new three stage model of stream chemistry evolution. First, organic acids are introduced by frequent flushing of organic soils on shallow bedrock along ridge areas. Second, upper acidic reaches are controlled by mineral dissolution coupled with eluvial soil development. Third, downstream reaches are influenced by illuviation as organometallic complexes precipitate in spodic soil horizons, removing organic acids, and acid-mobile metals from drainage waters. This new model highlights differences in critical zone evolution along hillslopes in glaciated catchments with implications for understanding gradients in water quality, soil fertility, and response and recovery from disturbances
H D Shew - One of the best experts on this subject based on the ideXlab platform.
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soils suppressive to black root rot of burley tobacco caused by thielaviopsis basicola
Phytopathology, 1991Co-Authors: John R Meyer, H D ShewAbstract:Soils suppressive to black root rot were detected in fields in which the pathogen was present but in which little or no disease had developed on susceptible cultivars of burley tobacco. Suppressive soils were characterized by low base saturation, low calcium, Exchangeable Aluminum levels of 1 meq/100 g of soil or higher, and soil pH less than 5. Suppressiveness was confirmed under controlled environmental conditions with fumigated field soils reinfested with Thielaviopsis basicola (...)
Valdomiro Severino De Souza Júnior - One of the best experts on this subject based on the ideXlab platform.
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Genesis and Classification of Nitisols from Volcano-Sedimentary Lithology in Northeastern Brazil
Sociedade Brasileira de Ciência do Solo, 2019Co-Authors: Edivan Uchôa Cavalcanti Da Costa, Jane Kelly Silva Araujo, Laércio Vieira De Melo Wanderley Neves, José Coelho De Araújo Filho, Juliet Emília Santos De Sousa, Marcelo Metri Corrêa, Mateus Rosas Ribeiro Filho, Valdomiro Severino De Souza JúniorAbstract:ABSTRACT On the southern coast of Pernambuco State (PE), Brazil, lithotypes of the Cabo Basin (volcanic and sedimentary rocks), in association with the relief, allow the determination of the dynamics of the formation of Nitossolos Háplicos (Nitisols), including those with high levels of Exchangeable Aluminum. The objective of this study was to evaluate the influence of lithological diversity (basalt and sedimentary siliciclastic rocks) on the morphological, physical, chemical, and mineralogical properties of Nitossolos Háplicos along a slope (P1-summit, P2-backslope, P3-footslope) on the southern coast of PE, in order to consider its genesis and the relation of soil properties to adjacent environments and to evaluate its framing within the Brazilian Soil Classification System (SiBCS). The interaction of lithology/soil permeability and climate indicate significant differences in the mineralogical composition and dynamics of soil chemical elements. The profiles P1 and P2 are subject to monosialitization, ferralitization, and alitization processes. All profiles showed high Fe contents (ferric soils) and clay fractions, consisting primarily of kaolinite, goethite, hematite, and gibbsite, as well as quartz and feldspar in the sand and silt fractions. However, smectite minerals (P3) are probably inherited from the sedimentary source material. In the conglomerate samples, under P3, biotite, muscovite, and plagioclase were identified. Allytic characteristics (P3) are probably associated with the weathering of aluminous smectite minerals. These properties distinguish these soils from adjacent Nitossolos and other Nitossolos in Brazil. For the classification of soils according to SiBCS, considering the high levels of Fe and Al, Nitossolo Háplico distroférrico (P1 and P2) and Nitossolo Háplico alitiférrico (P3) are suggested, and according to the World Reference Base of Soils (WRB), the soils are classified as Ferritic Nitisols
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Genesis and classification of Nitisols from volcano-sedimentary lithology in northeastern Brazil.
'FapUNIFESP (SciELO)', 2019Co-Authors: Edivan Uchôa Cavalcanti Da Costa, José Coelho De Araújo Filho, Araujo J. K. S., Neves L. V. De M. W., J. E. S. De ,souza, CorrÊa M. M., Ribeiro Filho M. R., Valdomiro Severino De Souza JúniorAbstract:On the southern coast of Pernambuco State (PE), Brazil, lithotypes of the Cabo Basin (volcanic and sedimentary rocks), in association with the relief, allow the determination of the dynamics of the formation of Nitossolos Háplicos (Nitisols), including those with high levels of Exchangeable Aluminum. The objective of this study was to evaluate the influence of lithological diversity (basalt and sedimentary siliciclastic rocks) on the morphological, physical, chemical, and mineralogical properties of Nitossolos Háplicos along a slope (P1-summit, P2-backslope, P3-footslope) on the southern coast of PE, in order to consider its genesis and the relation of soil properties to adjacent environments and to evaluate its framing within the Brazilian Soil Classification System (SiBCS). The interaction of lithology/soil permeability and climate indicate significant differences in the mineralogical composition and dynamics of soil chemical elements. The profiles P1 and P2 are subject to monosialitization, ferralitization, and alitization processes. All profiles showed high Fe contents (ferric soils) and clay fractions, consisting primarily of kaolinite, goethite, hematite, and gibbsite, as well as quartz and feldspar in the sand and silt fractions. However, smectite minerals (P3) are probably inherited from the sedimentary source material. In the conglomerate samples, under P3, biotite, muscovite, and plagioclase were identified. Allytic characteristics (P3) are probably associated with the weathering of aluminous smectite minerals. These properties distinguish these soils from adjacent Nitossolos and other Nitossolos in Brazil. For the classification of soils according to SiBCS, considering the high levels of Fe and Al, Nitossolo Háplico distroférrico (P1 and P2) and Nitossolo Háplico alitiférrico (P3) are suggested, and according to the World Reference Base of Soils (WRB), the soils are classified as Ferritic Nitisols.bitstream/item/199267/1/2019-024.pd
