Absence Of Carbon Research Articles

Investigating mechanochemical behavior of Cr2O3–B2O3–Mg–C quaternary system

Fundamental aspects of reaction behavior and formation path in the Cr2O3–B2O3–Mg–C quaternary system have been studied to synthesize chromium boride–chromium carbide nanocomposite. In order to find the influence of simultaneous presence of magnesium and carbon on final products, various powder mixtures were chosen according to following reaction: B2O3+Cr2O3+(9− x) Mg+x C. The value of x varied from 0 to 4. In the absence of carbon (x=0), CrB2 was synthesize through mechanically induced self-propagating reaction (MSR). In the presence of 8molMg and 1mol C (x=1), the dominant boride phase was CrB while no chromium carbide was detected. By increasing C content (x=2), the magnesiothermic reduction occurred in MSR mode; whereas, the synthesis of Cr3C2 initiated after combustion reaction and completed gradually during milling for 6h. Further increase in C amount (x=3) resulted in formation of Mg3(BO3)2 as unwanted phases as well as CrB and Cr3C2. In the presence of 6molMg and 4mol (x=4), no mechanical reaction was observed even after 8h of milling. Optimum value of x for the formation of CrB–Cr3C2 nanocomposite was 2. Based on the morphological evolutions, it is evident that the mechanosynthesized powder is made up of nanometric particles.

Sb-AlC 0.75 -C composite anodes for high-performance sodium-ion batteries

Abstract Antimony (Sb) nanoparticles dispersed in a hybrid matrix consisting of aluminum (Al) and carbon, AlC 0.75 -C were synthesized via one-step high-energy mechanical milling (HEMM) process and assessed as potential anode materials for use in sodium-ion batteries. The introduction of carbon during HEMM led to the formation of individual Sb nanoparticles dispersed in the AlC 0.75 -C matrix; in the absence of carbon during HEMM, an AlSb alloy was formed. The Sb-AlC 0.75 -C composite anodes demonstrated better cycling performance as well as higher rate capability compared to an AlSb anode; these improved properties could be due to the well-developed Sb phase, which acts as an electrochemically active nanocrystalline material in the AlC 0.75 /carbon conductive matrix. Furthermore, when fluoroethylene carbonate (FEC) was added to the electrolyte, the sodium-ion cells exhibited the best electrochemical performances, corresponding to a capacity retention of 83% at 100 cycles at 100 mA g −1 and a high rate capacity retention of 58% at 5000 mA g −1 . In addition, the as-prepared Sb-AlC 0.75 -C composite has a high tap density; thus, its volumetric capacity was approximately three times that of carbon.

Terrestrial arthropods from the Late Pleistocene of Jamaica - systematics, palaeoecology and taphonomy: supplement

The Red Hills Road Cave, Jamaica, is the most important site for terrestrial arthropods in the post-Miocene of the Greater Antilles. Its fauna includes millipedes, isopods, crabs and insects, in addition to land snails and vertebrates. Arthropods are preserved in three dimensions and delicate structures such as limbs can be recognized. This unusual preservation was favoured by acidic groundwater rich in dissolved calcium carbonate; periods of high rainfall during which the bottle-shaped cave was filled with water; and any arthropod washed in would have drowned. The absence of spiders, centipedes and most insects is due to the absence of carbonate in their exoskeletons. Millipedes and isopods possess a potential for preservation by carbonate mineralization that does not occur in other groups; they secrete calcium carbonate in the exoskeleton which hardens the cuticle and is water permeable, bringing about mineral replacement of the original structures. Within the cave, fossil millipede taxa include Rhinocricus sp. or spp., Chondrotropis sp., Caraibodesmus verrucosus (Pocock) and Cyclodesmus sp. cf. C. porcellanus Pocock. The isopod fauna includes Pseudarmadillo sp., Venezillo boonae Van Name, and Philoscia spp. 1 and 2. Crab claws belong to Sesarma sp. cf. S. cookei Hartnoll. Millipedes and isopods are particularly complete, representing drowned individuals fossilized soon after death; land crabs occur as fingers and rare chelae, suggesting that they may be exuviae. Only the most robust parts of insects have been discovered, but are particularly rare, consisting of three taxa of fly puparia and one possible beetle elytra. Copyright © 2012 John Wiley & Sons, Ltd.

Influence of spontaneous decomposition on the electrochemical formic acid oxidation on a nanostructured palladium electrode

The formic acid electrooxidation reaction was studied in a flow cell in 1M HCOOH–0.5M H2SO4 solution on a palladium film electrode. The evaluation of the open circuit potential (OCP) decay demonstrated that the spontaneous dehydrogenation of formic acid is quickly verified, leading to hydrogen adsorption and absorption. Moreover, the absence of carbon containing adsorbed species was verified by the application of voltammetric stripping after OCP and chronoamperometry. The results obtained demonstrate that the electrocatalytic oxidation of formic acid on Pd takes place through the spontaneous HCOOH dissociative adsorption with CO2 evolution and the adsorbed hydrogen electrooxidation.

The Inhibitive Effect of Carbon Containing Corrosion Products Inside Corrosion Pits on the Repassivation of Carbon Steels

The effect of carbon containing corrosion products within corrosion pits on the repassivation of pits has been studied on 20# and 45# carbon steels in sodium chloride and sodium hydroxide / nitrate / nitrite solutions. Anodic polarisation tests have been carried out in an attempt to cause pitting corrosion and then measure the repassivation potential. The presence of corrosion products within pits has been demonstrated via EDX. Pits in 0.1 M NaNO2 solutions with different concentrations of NaCl (20 mM, 40 mM, 0.1 M and 0.2 M) have been found to repassivate at different potentials. The repassivation potential of 45# carbon steel is lower than that of 20# when carbon containing corrosion products are detected within corrosion pits, but the difference is negligible when the products are not detected. The presence and absence of carbon containing corrosion products is found to depend on the concentration of chloride. The difference on the repassivation potentials has been ascribed to the inhibitive effect of corrosion products on metal ion diffusion, which may maintain aggressive solution within pits and inhibit repassivation at a low dissolution rate. It has also been found that pits cannot repassivate in NaOH and NaCl solutions, while pitting corrosion cannot take place in NaNO3 and NaCl solutions.

Sorption of trivalent lanthanides and actinides onto montmorillonite: Macroscopic, thermodynamic and structural evidence for ternary hydroxo and carbonato surface complexes on multiple sorption sites

The credibility of long-term safety assessments of radioactive waste repositories may be greatly enhanced by a molecular level understanding of the sorption processes onto individual minerals present in the near- and far-fields. In this study we couple macroscopic sorption experiments to surface complexation modelling and spectroscopic investigations, including extended X-ray absorption fine structure (EXAFS) and time-resolved laser fluorescence spectroscopies (TRLFS), to elucidate the uptake mechanism of trivalent lanthanides and actinides (Ln/AnIII) by montmorillonite in the absence and presence of dissolved carbonate. Based on the experimental sorption isotherms for the carbonate-free system, the previously developed 2 site protolysis non electrostatic surface complexation and cation exchange (2SPNE SC/CE) model needed to be complemented with an additional surface complexation reaction onto weak sites. The fitting of sorption isotherms in the presence of carbonate required refinement of the previously published model by reducing the strong site capacity and by adding the formation of Ln/AnIII-carbonato complexes both on strong and weak sites. EXAFS spectra of selected Am samples and TRLFS spectra of selected Cm samples corroborate the model assumptions by showing the existence of different surface complexation sites and evidencing the formation of Ln/AnIII carbonate surface complexes. In the absence of carbonate and at low loadings, Ln/AnIII form strong inner-sphere complexes through binding to three Al(O,OH)6 octahedra, most likely by occupying vacant sites in the octahedral layers of montmorillonite, which are exposed on {010} and {110} edge faces. At higher loadings, Ln/AnIII binds to only one Al octahedron, forming a weaker, edge-sharing surface complex. In the presence of carbonate, we identified a ternary mono- or dicarbonato Ln/AnIII complex binding directly to one Al(O,OH)6 octahedron, revealing that type-A ternary complexes form with the one or two carbonate groups pointing away from the surface into the solution phase. Within the spectroscopically observable concentration range these complexes could only be identified on the weak sites, in line with the small strong site capacity suggested by the refined sorption model. When the solubility of carbonates was exceeded, formation of an Am carbonate hydroxide could be identified. The excellent agreement between the thermodynamic model parameters obtained by fitting the macroscopic data, and the spectroscopically identified mechanisms, demonstrates the mature state of the 2SPNE SC/CE model for predicting and quantifying the retention of Ln/AnIII elements by montmorillonite-rich clay rocks.

The role of carbon and nitrogen on the H-mode confinement in ASDEX Upgrade with a metal wall

Carbon (CD4) and nitrogen (N2) have been seeded in ASDEX Upgrade (AUG) with a tungsten wall and have both led to a 20–30% confinement improvement. The reference plasma is a standard target plasma with Ip /BT = 1 MA/2.5 T, total input power Ptot ~ 12 MW and normalized pressure of βN ~ 1.8. Carbon and nitrogen are almost perfectly exchangeable for the core, pedestal and divertor plasma in this experiment where impurity concentrations of C and N of 2% are achieved and Zeff only mildly increases from ~1.3 to ~1.7. As the radiation potentials of C and N are similar and peak well below 100 eV, both impurities act as divertor radiators and radiate well outside the pedestal region. The outer divertor is purposely kept in an attached state when C and N are seeded to avoid confinement degradation by detachment. As reported in earlier publications for nitrogen, carbon is also seen to reduce the high field side high density (the so-called HFSHD) in the scrape off layer above the inner divertor strike point by about 50%. This is accompanied by a confinement improvement for both low (δ ~ 0.25) and high (δ ~ 0.4) triangularity configurations for both seeding gases, due to an increase of pedestal temperature and stiff core temperature profiles. The electron density profiles show no apparent change due to the seeding. As an orthogonal effect, increasing the triangularity leads to an additionally increased pedestal density, independent of the impurity seeding. This experiment further closes the gap in understanding the confinement differences observed in carbon and metal wall devices; the absence of carbon can be substituted by nitrogen which leads to a similar confinement benefit. So far, no definite physics explanation for the confinement enhancement has been obtained, but the experimental observations in this paper provide input for further model development.

Solute Segregation During Ferrite Growth: Solute/Interphase and Substitutional/Interstitial Interactions

The segregation of solutes to austenite/ferrite transformation interfaces during decarburization/denitriding of Fe-Mn-C, Fe-Mn-N, and Fe-Si-C ternary alloys was studied by using atom probe tomography. Manganese was found to segregate noticeably to the transformation interface in the presence of carbon, while no segregation could be detected in the presence of nitrogen. This result might indicate that manganese interacts little with the interface itself and that its interaction with the interstitial controls its segregation behavior. In the case of Fe-Si-C, the experiments were complicated by interface motion during quenching. Preliminary results suggest that silicon was depleted at the interface in contrast to the commonly observed segregation behavior of silicon at grain boundaries of ferrite and austenite. This observation could be explained by taking into account the repulsive interaction between silicon and carbon along with the intense segregation of carbon to the interface. This would lead to a net repulsive interaction of silicon with the interface even when considering the intrinsic tendency of silicon to segregate to the boundary in the absence of carbon. The results presented here emphasize the need to account for the interaction of all solutes present at the interface in ferrite growth models.

Effect of CaCO3(S) Nucleation Modes on Algae Removal from Alkaline Water.

The role of calcite heterogeneous nucleation was studied in a particle-coagulation treatment process for removing microalgae from water. Batch experiments were conducted with Scenedesmus sp. and Chlorella sp. in the presence and absence of carbonate and in the presence and absence of magnesium to delineate the role of CaCO3(S) nucleation on microalgae removal. The results indicate that effective algae coagulation (e.g., up to 81% algae removal efficiency) can be achieved via heterogeneous nucleation with CaCO3(S); however, supersaturation ratios between 120 and 200 are required to achieve at least 50% algae removal, depending on ion concentrations. Algae removal was attributed to the adsorption of Ca2+ onto the cell surface, which provides nucleation sites for CaCO3(S) precipitation. Bridging of calcite particles between the algal cells led to rapid aggregation and formation of larger flocs. However, at higher supersaturation conditions, algae removal was diminished due to the dominance of homogeneous nucleation of CaCO3(S). The removal of algae in the presence of Ca2+ and Mg2+ required higher supersaturation values; however, the shift from heteronucleation to homonucleation with increasing supersaturation was still evident. The results suggest that water chemistry, pH, ionic strength, alkalinity, and Ca2+ concentration can be optimized for algae removal via coagulation and sedimentation.

Rapid Mobilization of Noncrystalline U(IV) Coupled with FeS Oxidation.

The reactivity of disordered, noncrystalline U(IV) species remains poorly characterized despite their prevalence in biostimulated sediments. Because of the lack of crystalline structure, noncrystalline U(IV) may be susceptible to oxidative mobilization under oxic conditions. The present study investigated the mechanism and rate of oxidation of biogenic noncrystalline U(IV) by dissolved oxygen (DO) in the presence of mackinawite (FeS). Previously recognized as an effective reductant and oxygen scavenger, nanoparticulate FeS was evaluated for its role in influencing U release in a flow-through system as a function of pH and carbonate concentration. The results demonstrated that noncrystalline U(IV) was more susceptible to oxidation than uraninite (UO2) in the presence of dissolved carbonate. A rapid release of U occurred immediately after FeS addition without exhibiting a temporary inhibition stage, as was observed during the oxidation of UO2, although FeS still kept DO levels low. X-ray photoelectron spectroscopy (XPS) characterized a transient surface Fe(III) species during the initial FeS oxidation, which was likely responsible for oxidizing noncrystalline U(IV) in addition to oxygen. In the absence of carbonate, however, the release of dissolved U was significantly hindered as a result of U adsorption by FeS oxidation products. This study illustrates the strong interactions between iron sulfide and U(IV) species during redox transformation and implies the lability of biogenic noncrystalline U(IV) species in the subsurface environment when subjected to redox cycling events.

The Effect of Carbonate and pH on Hydrogen Oxidation and Oxygen Reduction on Pt-Based Electrocatalysts in Alkaline Media

We investigated the performance of several carbon-supported RuxPty electrocatalysts for their alkaline hydrogen oxidation and oxygen reduction performance in the presence of carbonate and compared their performance with monometallic, carbon-supported Pt. Our results indicate a strong dependence of HOR upon pH for the monometallic Pt catalysts (22 mV/pH) and a weak dependence upon pH for the Ru-containing electrocatalysts (3.7, 2.5, and 4.7 mV/pH on Ru0.2Pt0.8, Ru0.4Pt0.6, and Ru0.8Pt0.2, respectively). These results are consistent with our previous findings that illustrate a change in rds from electron transfer (on monometallic Pt) to dissociative hydrogen adsorption (on RuxPty catalysts). Analysis of the kinetic currents to determine the rate-determining step via Tafel slope analysis provides additional data supporting this conclusion. There is no difference in the performance at comparable pH values in the presence or absence of carbonate on monometallic Pt indicating that water/hydroxide is the primary proton acceptor for alkaline HOR in 0.1 M KOH aqueous electrolyte. Finally, we observe no pH or carbonate dependence for the ORR on monometallic Pt.

The Effect of Carbonate and pH on Hydrogen Oxidation and Oxygen Reduction on Pt-Based Electrocatalysts in Alkaline Media

We investigated the performance of several carbon-supported RuxPty electrocatalysts for their alkaline hydrogen oxidation and oxygen reduction performance in the presence of carbonate and compared their performance with monometallic, carbon-supported Pt. Our results indicate a strong dependence of HOR upon pH for the monometallic Pt catalysts (22 mV/pH) and a weak dependence upon pH for the Ru-containing electrocatalysts (3.7, 2.5, and 4.7 mV/pH on Ru0.2Pt0.8, Ru0.4Pt0.6, and Ru0.8Pt0.2, respectively). These results are consistent with our previous findings that illustrate a change in rds from electron transfer (on monometallic Pt) to dissociative hydrogen adsorption (on RuxPty catalysts). Analysis of the kinetic currents to determine the rate-determining step via Tafel slope analysis provides additional data supporting this conclusion. There is no difference in the performance at comparable pH values in the presence or absence of carbonate on monometallic Pt indicating that water/hydroxide is the primary proton acceptor for alkaline HOR. Finally, we observe no pH or carbonate dependence for the ORR on monometallic Pt.

Suppressing graphene nucleation during CVD on polycrystalline Cu by controlling the carbon content of the support foils

The oxidative carbon removal from Cu foils was systematically studied together with the resulting suppression of the graphene flake nucleation during subsequent chemical vapor deposition (CVD). The carbon content was determined by segregating bulk dissolved carbon during a special rapid cooling process towards the surface, where it was detected by x-ray photoelectron spectroscopy. After exposure to a standardized hydrogen pretreatment, the Cu foils deliver irregularly distributed CVD grown flakes with diameters of 0.1–20 μm. Such foils still contain 40–240 monolayers of carbon, which could be removed by exposure to an oxygen partial pressure of ∼10−5 mbar diluted in 1 mbar Ar carrier gas. This controlled procedure allowed the quantification of the carbon removal while inducing exclusively reversible restructuring of the Cu foil. Only when lowering the carbon content to values well below 1 monolayer per entire Cu foil, the flake nucleation during CVD drops to values below 1 flake/mm2. We also show that it is the absence of carbon and not the presence of oxygen which accounts for the low flake density and that graphene can be grown with up to mm sized domains. Our data question many proposed explanations why certain growth protocols deliver graphene of comparable high quality.

CO2 Utilization For Mechanochemical Carbonation Of Celestine

Abstract Natural celestine (SrSO4) has been succesfully transformed into strontianite (SrCO3) via fast one-step mechanochemical carbonation utilizing gaseous CO2. The process was realized in the environment enriched with LiOH or NaOH additives. The mixtures were milled in a high-energy planetary ball mill for 40 min. The phases formed during the milling were characterized by different characterization techniques, such as X-ray diffraction (XRD) and infrared spectroscopy (FT-IR). The presence or absence of carbon or sulphur in the products was confirmed by a CHNS analysis.

Effect of carbon on the solubility of nitrogen in slag

Abstract The effect of carbon on nitrogen solubility in slag was investigated for the ternary CaO–MgO–SiO2 and the quaternary Al2O3–CaO–MgO–SiO2 slag systems at 1873 K under controlled oxygen and nitrogen potentials. Gas–slag equilibration experiments were conducted using molybdenum and graphite crucibles. In the absence of carbon, the nitrogen solubility was very low. The presence of carbon greatly increased the nitrogen solubility in slag. The total nitrogen content was found to increase with SiO2 and MgO concentration for the carbon saturated slags. Low levels of cyanide were found by wet chemistry with considerable uncertainty. The results analyzed by different methods ruled out cyanide formation being the main reason for the large increase in nitrogen solubility in the presence of pure carbon.

Bio-statistical evaluation of cultural conditions on industrial textile dye decolourisation using a native bacterium Micrococcus endophyticus (ES37)

An indigenous dye-decolourising bacterium Micrococcus endophyticus (ES37) was isolated from dye contaminated soil and identified by 16S rDNA sequencing. The bacterial strain ES37 exhibited 97.19% of dye removal capacity in Luria-Bertani broth composition within 48 h, while the culture containing yeast extract showed 53.4% decolourisation in 72 h. In the absence of carbon and nitrogen sources, the bacterial strain failed to decolourise the dye, even on extended incubation. The effect of environmental factors on decolourisation was investigated by Plackett–Burman design and the significant parameters were lactose, yeast extract and pH. Optimisation of these factors was done by response surface methodology with central composite design; the decolourisation ranged from 0.43 to 77.49%. The optimised levels of lactose, yeast extract and pH were found to be 0.85% (w/v), 0.71% (w/v) and 7.5%, respectively. Under the optimal conditions, decolourisation of remazol golden yellow by ES37 strain was 81.61%, which was in agreement with the predicted value of 79.99%. These findings revealed the interactions and importance of environmental factors on dye decolourisation using native bacteria and also their standard point for an effective dye removal process.

Solution composition and particle size effects on the dissolution and solubility of a ThO2 microstructural analogue for UO2 matrix of nuclear fuel

Abstract The objective of this study was to investigate the dissolution rate of ThO2 which was synthesised to approximate, as closely as possible, the microstructure of UO2 in a nuclear fuel matrix. The optimal sintering temperature for ThO2 pellets was found to be 1750 ℃, which produced pellets with a microstructure similar to UO2 nuclear fuel pellets, with randomly oriented grains ranging in size from 10 to 30 μm. Dissolution was conducted using ThO2 particles of different size fractions (80 to 160 μm and 2 to 4 mm) in the presence and absence of carbonate, in solutions with pH from 2 to 8 and at 80 ℃. Dissolution rates were calculated from Th released from the solid phase to solution. Particles of ThO2 were also leached with 1 M HNO3 at 80 ℃ in order to investigate the morphological changes at the particle surfaces. The concentration of Th was found to be ≥ 10 –9 mol/L at pH ≤ 4, lower than the theoretical solubility of crystalline ThO2. At higher pH values, from 4 to 8, the measured concentrations (10−10 to 10 –12 mol/L) were between the theoretical solubility of ThO2 and Th(OH)4. Grain boundaries were shown to exert an influence on the dissolution of ThO2 particles. Using high resolution aqueous solution analysis, these data presented here extend the current understanding of Th solubility in solution.

Influence of the background water matrix on the hybrid ceramic MF/O3 system and correlation between pollutants rejection and membrane fouling

AbstractBACKGROUNDThe aim of this work was the investigation of background water matrix impact on the effectiveness of a hybrid process, combining ceramic membrane microfiltration with oxidation processes for the treatment of surface water. The implementation of ozone‐based oxidation during membrane filtration is expected to improve the overall process effectiveness, to enhance the permeate quality and to mitigate membrane fouling.RESULTSThe novel hybrid reactor consisted of a submerged ceramic membrane, while the gas‐containing ozone was introduced with the aid of ceramic gas spargers, producing fine bubbles. Total consumption of ozone during the experiments was achieved. Single ozonation experiments and ozonation in the presence of hydrogen peroxide were performed, as well as single microfiltration (MF). The novelty of this study is connected with the specific investigation of the carbonates and background ions influence on the effectiveness of various membrane hybrid treatment processes; the fouling process and mechanism during the application of membrane filtration was also examined. The connection between permeate quality and the extent of membrane fouling was also discussed.CONCLUSIONSIn the absence of carbonates in the treated water the hybrid processes resulted in a TOC removal up to 75%, while membrane fouling was substantially reduced. © 2015 Society of Chemical Industry

Direct utilization of lignite coal in a Co–CeO2/YSZ/Ag solid oxide fuel cell

The feasibility of employing lignite coal as a fuel in a Direct Carbon Fuel Cell (DCFC) of the type: lignite|Co–CeO2/YSZ/Ag|air is investigated. The impact of several parameters, related to anodic electrode composition (20, 40 and 60 wt.% Co/CeO2), cell temperature (700–800 °C), carrier gas composition (CO2/He mixtures), and total feed flow rate (10–70 cm3/min), was systematically examined. The effect of molten carbonates on DCFC performance was also investigated by employing a eutectic mixture of lithium and potassium carbonates as carbon additives. In the absence of carbonates, the optimum performance (∼10 mW cm−2 at 800 °C), was achieved by employing 20 wt.% Co/CeO2 as anodic electrode and pure CO2 as purging gas. An inferior behavior was demonstrated by utilizing He instead of CO2 atmosphere in anode compartment and by increasing purging gas flow rate. Carbonates infusion into lignite feedstock resulted in a further increase of maximum power density up to 32%. The obtained findings are discussed based also on AC impedance spectroscopy measurements, which revealed the impact of DCFC operating parameters on both ohmic and electrode resistances.

Sorption of Cm(III) and Eu(III) onto clay minerals under saline conditions: Batch adsorption, laser-fluorescence spectroscopy and modeling

The present work reports experimental data for trivalent metal cation (Cm/Eu) sorption onto illite (Illite du Puy) and montmorillonite (Na-SWy-2) in NaCl solutions up to 4.37molal (m) in the absence of carbonate. Batch sorption experiments were carried out for a given ionic strength at fixed metal concentration (mEu=2×10−7m, labeled with 152Eu for γ-counting) and at a constant solid to liquid ratio (S:L=2g/L) for 3<pHm<12 (pHm=−logmH+). The amount of clay sorbed Eu approaches almost 100% (with logKD>5) for pHm>8, irrespective of the NaCl concentration. Variations in Eu uptake are minor at elevated NaCl concentrations. Time-resolved laser fluorescence spectroscopy (TRLFS) studies on Cm sorption covering a wide range of NaCl concentrations reveal nearly identical fluorescence emission spectra after peak deconvolution, i.e. no significant variation of Cm surface speciation with salinity. Beyond the three surface complexes already found in previous studies an additional inner-sphere surface species with a fluorescence peak maximum at higher wavelength (λ∼610nm) could be resolved. This new surface species appears in the high pH range and is assumed to correspond to a clay/curium/silicate complex as already postulated in the literature for kaolinite. The 2 site protolysis non-electrostatic surface complexation and cation exchange sorption model (2SPNE SC/CE) was applied to describe Eu sorption data by involving the Pitzer and SIT (specific ion interaction) formalism in the calculation of the activities of dissolved aqueous species. Good agreement of model and experiment is achieved for sorption data at pHm<6 without the need of adjusting surface complexation constants. For pHm>6 in case of illite and pHm>8 in case of montmorillonite calculated sorption data systematically fall below experimental data with increasing ionic strength. Under those conditions sorption is almost quantitative and deviations must be discussed considering uncertainties of measured Eu concentrations in the range of analytical detection limits.