Modeling Arsenate Competitive Adsorption on Kaolinite, Montmorillonite and Illite

Manning, Bruce A.; Goldberg, Sabine

doi:10.1346/ccmn.1996.0440504

Cited by 260 publications

(145 citation statements)

References 40 publications

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“…Indeed, higher kaolinite content than for the other two soil clay fractions (Table 1) was found in this soil. The contribution of the typically lower SSA of kaolinite than montmorillonite and illite (Manning and Goldberg, 1996) was also detected in the lowest SSA of the Rollesbroich WDC sample compared with the other soil samples (Table 6). In the Rollesbroich WDC sample, the introduction of the kaolinite particle structure of lower aspect ratios (Wilkinson and Lead, 2007) possibly creates large pores in the compact arrangement of dominant illite thin platelets of higher aspect ratios (ratio of platelet diameter to thickness) in the WDC microstructure.…”

Section: Contribution Of Metal Oxide Nanoparticles To the Colloidal Pmentioning

confidence: 90%

Effect of metal oxide on surface area and pore size of water-dispersible colloids from three German silt loam topsoils

et al. 2014

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Abstract:The surface area and pore structure of easily dispersed soil particles < 2 µm in size (water-dispersible colloids, WDCs) are important for carbon sequestration and transport in soil. Two processes are essential for the terrestrial carbon cycling. In this work, we determine the effects of dithionite-citrate-bicarbonate (DCB) extractable metal oxides, and oxalate extractable metal oxides on the specific surface area (SSA) and pore structure of WDCs from silt loam topsoils of three TERENO test sites with a similar clay content (20%) in Germany (arable (Selhausen), grassland (Rollesbroich) and forest (Wuestebach) soils). The N 2 gasadsorption (−196°C), small-angle X-ray scattering (SAXS), dynamic light scattering (DLS) and microelectrophoretic (ME) methods were used and compared. Results show that 1) the SSA of the WDCs from Selhausen, Rollesbroich, and Wuestebach decreased more after DCB treatment (27%, 35%, and 44%) than after oxalate treatment (5%, 14%, and 22%). DCB removed metal oxide nanoparticles from WDCs were found to have diameters (d p ) ranging from 4 nm to 8 nm and the surface loading ratios on the surface of aluminosilicate residues in WDCs were estimated to be 11% to 22% for three soils where the highest value was found in the acidic forest soil. 2) Pore sizes in the mesopore range (2 nm to 50 nm) were analyzed in the WDC fractions. The results were discussed in terms of accessible open pores for the pristine WDCs and WDC samples from which metal oxide nanoparticles and organic carbon (OC) had been removed. The lower average pore radius (R p ) measured by the N 2 gasadsorption method based on the total volume (V t ) to SSA ratio variations in WDCs without metal oxides compared to WDC with metal oxides indicated a contraction of the porous structure of WDCs due to the presence of metal oxide nanoparticles. The pore size distribution (PSD) analysis showed a sensitive contribution of metal oxide nanoparticles in the low range of pore sizes (< 25 nm) of WDCs. In SAXS measurements, higher surface fractal dimensions (D s ) were observed in WDCs before the metal oxides removal, which supports a roughness increase of the interfaces in the presence of nanoparticles. The colloidal characterization of WDCs by the DLS and ME methods shows, at a µm scale, the role of positively charged metal oxide nanoparticles in forming WDCs with a more compact structure by decreasing the particle size (d z ) and the negative zeta potential (ζ).3) The comparison of R p , k, d z and d p results between different soils also indicates the dependence on the clay mineralogy of WDCs so that the heterocoagulation between kaolinite and illite (clay minerals of different aspect ratios) increases the size of soil mesopores (Rollesbroich). In conclusion, the results of this study clearly show that the combination of the N 2 gas-adsorption, SAXS, DLS and ME methods allows the characterization of soil porosity in the nanometer range where metal oxide nanoparticles contribute to a more compact structure of WDC.

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Section: Contribution Of Metal Oxide Nanoparticles To the Colloidal Pmentioning

confidence: 90%

Effect of metal oxide on surface area and pore size of water-dispersible colloids from three German silt loam topsoils

et al. 2014

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“…3), favouring desorption from mineral surfaces including illite, which comprised 30 % of the crystalline mineralogical fraction (Fig. 2c) (Manning, 1996).…”

Section: Sequential Chemical Extractions and Solid-phase P Partitioningmentioning

confidence: 99%

Sediment phosphorus speciation and mobility under dynamic redox conditions

Parsons¹,

Rezanezhad²,

O’Connell³

et al. 2017

Biogeosciences

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Abstract. Anthropogenic nutrient enrichment has caused phosphorus (P) accumulation in many freshwater sediments, raising concerns that internal loading from legacy P may delay the recovery of aquatic ecosystems suffering from eutrophication. Benthic recycling of P strongly depends on the redox regime within surficial sediment. In many shallow environments, redox conditions tend to be highly dynamic as a result of, among others, bioturbation by macrofauna, root activity, sediment resuspension and seasonal variations in bottom-water oxygen (O 2 ) concentrations. To gain insight into the mobility and biogeochemistry of P under fluctuating redox conditions, a suspension of sediment from a hypereutrophic freshwater marsh was exposed to alternating 7-day periods of purging with air and nitrogen gas (N 2 ), for a total duration of 74 days, in a bioreactor system. We present comprehensive data time series of bulk aqueous-and solidphase chemistry, solid-phase phosphorus speciation and hydrolytic enzyme activities demonstrating the mass balanced redistribution of P in sediment during redox cycling. Aqueous phosphate concentrations remained low (∼ 2.5 µM) under oxic conditions due to sorption to iron(III) oxyhydroxides. During anoxic periods, once nitrate was depleted, the reductive dissolution of iron(III) oxyhydroxides released P. However, only 4.5 % of the released P accumulated in solution while the rest was redistributed between the MgCl 2 and NaHCO 3 extractable fractions of the solid phase. Thus, under the short redox fluctuations imposed in the experiments, P remobilization to the aqueous phase remained relatively limited. Orthophosphate predominated at all times during the experiment in both the solid and aqueous phase. Combined P monoesters and diesters accounted for between 9 and 16 % of sediment particulate P. Phosphatase activities up to 2.4 mmol h −1 kg −1 indicated the potential for rapid mineralization of organic P (P o ), in particular during periods of aeration when the activity of phosphomonoesterases was 37 % higher than under N 2 sparging. The results emphasize that the magnitude and timing of internal P loading during periods of anoxia are dependent on both P redistribution within sediments and bottom-water nitrate concentrations.

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“…By contrast, Devau et al (2011) hypothesized that the "negative" pH dependence at low pH was due to the intrinsic PO 4 -P sorption properties of the illite edge sites they believed were important for PO 4 -P sorption in these soils. Earlier work by Edzwald et al (1976) and Manning and Goldberg (1996) showed that illite displays a marked P sorption maximum at around pH 6. Weng et al (2011) attributed their results to synergistic effects of Ca 2+ adsorption to oxides and showed that a surface complexation model would predict a minimum in P solubility near pH 7 under the conditions of their study (these authors used 0.01 M CaCl 2 background electrolyte, which might have affected the results and interpretations).…”

mentioning

confidence: 96%

The pH dependence of phosphate sorption and desorption in Swedish agricultural soils

2012

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A number of previous studies have reported the existence of a minimum in phosphate solubility between pH 5.5 and 7 in non-calcareous soils. Different hypotheses have been forwarded to explain this phenomenon. In this study, ten soil samples with varying textures and phosphorus status were subjected to batch experiments in which dissolved phosphate was measured as a function of pH and phosphate load. Soil samples with more than 20 % clay all had a minimum phosphate solubility between pH 6 and 7, whereas for samples with < 10 % clay, no such minimum was observed. Further experiments involving additions of phosphate and arsenate showed an increasing adsorption of these anions with decreasing pH also below pH 6 in clay soils, suggesting that the pH dependence on adsorption and desorption in short-term experiments was not the same. Kinetic experiments showed that the increased phosphate desorption at lower pH values in noncalcareous clay soils was a quick process, which is consistent with adsorption/desorption being the most important mechanism governing the retention and release of inorganic P.Moreover, by comparing extraction results with batch experiment results for samples from a long-term fertility experiment, it was concluded that more than 60 % of the accumulated phosphate was occluded, i.e. not reactive within six days. Additional evidence for an important role of occluded phosphate comes from an analysis of the Freundlich sorption isotherms for the studied soils. It is hypothesized that interlayered hydroxy-Al and hydroxy-Fe polymers in clay minerals may be important for P dynamics in clay soils by trapping some of the P in an occluded form. The results also suggest that improved knowledge on the speciation and dynamics of phosphorus in soils is required for consistent mechanistically based modelling of phosphate sorption/desorption reactions.

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Modeling Arsenate Competitive Adsorption on Kaolinite, Montmorillonite and Illite

Cited by 260 publications

References 40 publications

Effect of metal oxide on surface area and pore size of water-dispersible colloids from three German silt loam topsoils

Effect of metal oxide on surface area and pore size of water-dispersible colloids from three German silt loam topsoils

Sediment phosphorus speciation and mobility under dynamic redox conditions

The pH dependence of phosphate sorption and desorption in Swedish agricultural soils

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