Due to the wide range of uses of water-soluble polymers in commercial products, water contamination by polymers has become a serious environmental concern. Adsorption onto an acidic clay, obtained from Tsunagi mine, Niigata, Japan, of water-soluble polymers from aqueous solutions was investigated as a means of purifying water. Poly(vinylpyrrolidone) (PVP) was used as a sample polymer in an attempt to find optimal conditions for extracting the greatest proportion of polymer from the aqueous solution. The adsorption isotherms at lower equilibrium concentrations were of type L, indicating a strong affinity between the acidic clay and PVP. A larger amount of PVP was adsorbed when a higher-molecularweight PVP (comparison between MWs of 160,000 and 10,000) was used. From the Langmuir equation, the adsorption capacity was calculated as 0.029 g/g clay for the adsorption of poly(vinylpyrrolidone) from an aqueous solution. The adsorption of PVP from a NaCl solution (simulated sea water) was also possible though the amount of adsorption was slightly less than from an aqueous solution. A polymer removal efficiency of >90% was achieved when 200 mg of the acidic clay was added to 50 mL of 0.001 wt.% PVP aqueous solution. The acidic clay was also used for adsorption of poly(ethylene glycol), poly(vinyl alcohol), and polyacrylamide from aqueous solutions.

This paper considers variable annuity (VA) contracts embedded with guaranteed minimum accumulation benefit (GMAB) riders when policyholder’s proceeds are taxed upon early surrender or maturity. These contracts promise the return of the premium paid by the policyholder, or a higher rolled-up value, at the end of the investment period. A partial differential equation valuation framework which exploits the numerical method of lines is used to determine fair fees that render the policyholder and insurer breakeven. Two taxation regimes are considered: one where capital gains are allowed to offset losses and a second where gains do not offset losses. Most insurance providers highlight the tax-deferred features of VA contracts. We show that the regime under which the insured is taxed significantly impacts prices. If losses are allowed to offset gains then this enhances the market, increasing the policyholder’s willingness to participate in the market compared to the case when losses are not allowed to offset gains. With fair fees from the policyholder’s perspective, we show that the net profit is generally positive for insurance companies offering the contract as a naked option without any hedge. We also show how investment policy, as reflected in the Sharpe ratio, impacts and interacts with policyholder persistency.

The order-disorder behavior of the isomorphous cation substitution of the octahedral sheet of phyllosilicates was investigated by Monte Carlo simulations based only on atomistic models in some three-species systems Al/Fe/Mg including a wide range of different octahedral compositions that can be relevant to clay compositions found in nature, especially for smectites and illites. In many cases, phase transitions do not occur, in that long-range order is not attained, but most systems exhibit short-range order at low temperature. The ordering of the octahedral cations is highly dependent on the cation composition. Variations in the tetrahedral charge (smectite vs. illite) produce slight differences in the cation distribution and the short-range and long-range order of octahedral cations do not change drastically. The average size of Fe clusters and the long-range order of Fe are not larger in illites than in smectites as previous reports concluded, but the proportion of Fe3+ cations non-clustered is higher in smectites than in illites. This behavior supports the experimental behavior of the Fe effect on the Al-NMR signal, which is lower in illites than in smectites.

Methoxykaolinite is a very popular organo-modified kaolinite. Even though it has a number of interesting properties, this nanohybrid material is still underused in terms of practical applications. In the present study, methoxykaolinite was synthesized and used for the first time as an electrode modifier for Pb(II) determination in various aqueous media. X-ray powder diffractometry (XRD), 13C nuclear magnetic resonance (NMR), and Fourier-transform infrared (FTIR) spectroscopy were used as characterization tools to confirm the presence of grafted methoxy groups in the interlayer space of kaolinite. The electrochemical characterization of methoxykaolinite using the cationic probe Ru(NH3)63+ showed that the modified clay presents favorable interactions with cationic compounds. A methoxykaolinite-modified electrode was applied successfully to the quantification of Pb(II) in aqueous solution. At optimized experimental conditions, the calibration curve in the concentration range 0.025–0.3 μM showed excellent linearity (R2 > 0.99), a sensitivity of 3.36 μA μM–1, and a detection limit of 5.6 nM. This detection limit was 10 times lower than the minimum concentration of Pb(II) authorized in drinking water. The sensor was used also for the determination of Pb(II) in tap, river, and well water samples with only minor loss of sensitivity and recoveries (90±5% to 110±4%). Thanks to the excellent biocompatibility of kaolinite, the sensor was applied for Pb(II) detection in human urine. Recovery in the range 98±8% to 103±6% was obtained when three freshly collected urine samples were spiked with known amounts of Pb(II). These results showed the interesting potential of methoxykaolinite as an electrode modifier for trace-level detection of cations, even in biological samples.

Qian Daosun (1887–1966) was imprisoned for collaborating with the Provisional Government in North China under Japanese occupation, and to this day he is labelled as hanjian (traitor). Yet, Qian was first and foremost a cultural literatus, librarian, and an exceptional translator with an in-depth understanding of Japanese culture and languages. This article examines the crucial role that Japan and the Japanese language played for Chinese cultural literati in their quest to save China. It also brings to the forefront the dilemmas and agonizing choices Qian faced in his attempt to promote Sino-Japanese cultural exchange in the midst of war, in particular as a librarian. Wartime libraries are highly contested sites of selection, destruction, censorship, preservation, confiscation, and knowledge production. An added layer of complexity was Japan’s cultural policy in China that promoted Japanese-language collections and governed libraries such as the Beijing1 Modern Science Library where Qian worked. What exacerbated Qian’s dilemmas was his upbringing, which led him to form close personal connections with like-minded Japanese literati. Lastly, this article revisits the hanjian label by comparing Qian’s fate to that of other librarians and returned students of Japan, such as May Fourth writer Lu Xun and patriotic bibliophile Zheng Zhenduo. By deliberately examining May Fourth writers alongside hanjian and Japanese intermediaries, the intention is to dismount arbitrary labels and divisions that have set them apart and against each other in the resistance versus collaboration dichotomy.

The loading of various phosphates on the surfaces of nanoparticles of allophane (1–2SiO2·Al2O3·5–6H2O) was investigated. The allophane used was a high-silica type with a Si/Al ratio of 0.85. The phosphate-sorption isotherm was measured using (NH4)2HPO4 solution, which showed the highest phosphate sorption of the seven phosphates examined. This sorption isotherm was in better agreement with the Langmuir equation than the Freundlich equation. The resulting maximum sorption capacity was 4.87 mmol/g and the Langmuir constant was 0.0033 L/mmol. The sorption energy (ΔG) calculated from the Langmuir constant was −2.96 kJ/mol. The amount of loaded phosphate varied greatly according to the phosphate used, being greater for orthophosphates than for polyphosphates. The amount of loaded phosphate also depended on the cation present, in the order Ca-Na-NH4-phosphate. The Si/Al ratios of the samples were decreased by orthophosphate loading due to the partial replacement of SiO4 by PO4 tetrahedra, but this effect was offset by the partial dissolution of the allophane by polyphosphate loading. The 29Si magic angle spinning nuclear magnetic resonance (MAS NMR) spectra of all the phosphateloaded samples showed an increase of a peak at −90 ppm (the Q1–Q3 polymerized tetrahedral unit) and the decrease of a peak at −78 ppm peak (the Qo monomeric tetrahedral unit). The 31P MAS NMR spectra showed peaks at ~−10 ppm, assigned to Q2 units corresponding to polymerized tetrahedra which consisted of loaded PO4 together with Si(Al)O4. The structure changes produced in allophane by phosphate loading are discussed in light of these data.

Soil–alkali interaction leads to abnormal soil behavior due to significant changes in mineralogy and morphology. The effect of alkali on the swelling behavior of natural clays has been explored in recent years, but the swelling behavior of alkali-transformed clay minerals is still unclear. The objective of the current study was to investigate the effect of alkali concentration on swelling characteristics of natural and alkali-transformed kaolinitic clays. The study was complemented further with micro-level investigations. Red earth and kaolin, which are regarded as non-swelling kaolinitic clays, were utilized. The results showed that alkalis induced greater swelling in natural clays than in alkali-transformed clays. The results revealed further that alkali-transformed clays exhibited decreases in swelling when exposed to increased alkali concentrations. Moreover, the degree of transformation played an important role in the swelling behavior of alkali-transformed kaolinitic clays when inundated with water and with various alkali concentrations. These variations may be attributed to the different extents of mineralogical and microstructural changes caused by alkali treatment.

Polycarboxylate superplasticizer (PCE) is a widely used water-reducing agent that can reduce significantly the water demand of concrete, which reduces the porosity and enhances the strength and durability of the concrete. (The PCE consists of a single backbone with many long PEO side chains.) Generally, aggregate occupies >70 wt.% of concrete; clay minerals are ubiquitous in nature and are difficult to avoid in mined aggregates. Clay minerals in aggregate often render the PCE ineffective and give rise to rapid loss of the fluidity of the concrete; this phenomenon is referred to as ‘poor clay tolerance of PCE.’ Though the poor clay tolerance of PCE is known widely, the relationship between the clay tolerance and the molecular structure of the PCE, in particular the effect of the side-chain structures, on clay tolerance is not understood completely. The objective of the present study was to determine the effect of different grafting densities of polyethylene oxide (PEO) side chains on the clay tolerance of PCE. The raw materials included mainly PCE, which was synthesized using acrylic acid and isopentenol polyoxyethylene ether, and a natural montmorillonite (Mnt), one of the most common clay minerals. The loss of fluidity of the cement paste was tested to assess the clay tolerance; total organic carbon was used to measure the amount of PCE adsorbed; X-ray diffraction, transmission electron microscopy, Fourier-transform infrared spectroscopy, and thermogravimetric analysis were used to investigate the microstructure of the intercalated Mnt. The results showed that preventing the superficially adsorbed PCE from being intercalated into Mnt was of great importance in terms of the improvement in clay tolerance of PCE, which increased with greater grafting density of PEO in the side chain of the PCE. The results also suggested the possibility that polymers which intercalate preferentially into the Mnt could improve significantly the clay tolerance of the PCE system.

Fe(II)–Fe(III) green rust identified in soil as a natural mineral is responsible for the blue-green color of gley horizons, and exerts the main control on Fe dynamics. A previous EXAFS study of the structure of the mineral confirmed that the mineral belongs to the group of green rusts (GR), but showed that there is a partial substitution of Fe(II) by Mg(II), which leads to the general formula of the mineral: ${[{\text{Fe}}_{1-x}^{2+}{\text{Fe}}_x^{3+}{\text{Mg}}_y{(\text{OH})}_{2+2y}]}^{x+}{[x{\text{OH}}^{-}\cdot m{\text{H}}_2\text{O}]}^{x-}$${[{\rm{Fe}}_{1 - x}^{2 + }{\rm{Fe}}_x^{3 + }{\rm{M}}{{\rm{g}}_y}{({\rm{OH}})_{2 + 2y}}]^{x + }}{[x{\rm{O}}{{\rm{H}}^ - } \cdot m{{\rm{H}}_2}{\rm{O}}]^{x - }}$. The regular binary solid-solution model proposed previously must be extended to ternary, with provision for incorporation of Mg in the mineral. Assuming ideal substitution between Mg(II) and Fe(II), the chemical potential of any Fe(II)-Fe(III)-Mg(II) hydroxy-hydroxide is obtained as: $\text{μ}=X_1{\text{μ}}_{\text{1}}^{\text{o}}+X_2{\text{μ}}_{\text{2}}^{\text{o}}+X_3{\text{μ}}_{\text{3}}^{\text{o}}+\text{R}T[X_1\text{ln}{X}_1+X_2\text{ln}{X}_2+X_3\text{ln}{X}_3]+A_{12}{X}_2(1-X_2)$${\rm{\mu }} = {X_1}{\rm{\mu }}_{\rm{1}}^{\rm{o}} + {X_2}{\rm{\mu }}_{\rm{2}}^{\rm{o}} + {X_3}{\rm{\mu }}_{\rm{3}}^{\rm{o}} + {\rm{R}}T[{X_1}{\rm{ln}}{X_1} + {X_2}{\rm{ln}}{X_2} + {X_3}{\rm{ln}}{X_3}] + {A_{12}}{X_2}(1 - {X_2})$. All experimental data show that the mole ratio X2 = Fe(III)/[Fetotal + Mg] is constrained (1) structurally and (2) geochemically. Structurally, Fe(III) ions cannot neighbor each other, which leads to the inequality $X_2\alpha \raisebox{1ex}{$1$}\!\left/ \!\raisebox{-1ex}{$3$}\right..$${X_2}\leqslant {\raise0.5ex\hbox{$\scriptstyle 1$}\kern-0.1em/\kern-0.15em\lower0.25ex\hbox{$\scriptstyle 3$}}.$ Geochemically, Fe(III) cannot be too remote from each other for GR to form as Fe(OH)2 and Mg(OH)2 are very soluble, so $X_2\alpha \raisebox{1ex}{$1$}\!\left/ \!\raisebox{-1ex}{$4$}\right.$${X_2}\geqslant {\raise0.5ex\hbox{$\scriptstyle 1$}\kern-0.1em/\kern-0.15em\lower0.25ex\hbox{$\scriptstyle 4$}}$. A linear relationship is obtained between the Gibbs free energy of formation of GR, normalized to one Fe atom, and the electronegativity ϰ of the interlayer anion, as: μo/n = −76.887ϰ — 491.5206 (r2 = 0.9985, N = 4), from which the chemical potential of the mineral fougerite μ is obtained in the limiting case X3 = 0, and knowing ${\text{μ}}_{\text{1}}^{\text{o}}=-489.8$${\rm{\mu }}_{\rm{1}}^{\rm{o}} = - 489.8$ kJmol−1 for Fe(OH)2, and ${\text{μ}}_{\text{3}}^{\text{o}}=-832.16$${\rm{\mu }}_{\rm{3}}^{\rm{o}} = - 832.16$ kJmol−1 for Mg(OH)2, the two unknown thermodynamic parameters of the solid-solution model are determined as

${\text{μ}}_{\text{2}}^{\text{o}}=+119.18{\text{kJmol}}^{-1}$${\rm{\mu }}_{\rm{2}}^{\rm{o}} = + 119.18\;{\rm{kJmo}}{{\rm{l}}^{ - 1}}$ for Fe(OH)3 (virtual), and A12 = −1456.28 kJmol−1 (non-ideality parameter). From Mössbauer in situ measurements and our model, the chemical composition of the GR mineral is constrained into a narrow range and the soil solutions-mineral equilibria computed. Soil solutions appear to be largely overstaurated with respect to the two forms observed.

Leaching experiments with metallic uranium-aluminum research-reactor fuel elements in repository-relevant MgCl2-rich salt brine (brine 2) were performed. A Mg-Al layered double hydroxide (LDH) with chloride as the interlayer anion was identified as a crystalline secondary-phase component. In the present study, the incorporation of Cd into the structure of the Mg-Al-Cl LDH was investigated. Synthesis by a coprecipitation method was performed and the Mg-Cd-Al-Cl LDH obtained was characterized. The sorption behavior of selenium on the LDH was investigated in water, clay pore-water (Mont-Terri-type), and brine 2. Using a LDH concentration of 10 g/L, the sorption kinetics were rapid and equilibrium was reached within 12 h. The sorption of selenium decreased with increasing amount of chloride anions in the solutions. The chloride anions acted as competing anions for the sorption of selenium. The effect of pH on selenium sorption was investigated and a large buffer capacity of the LDH was observed. For the range of selenium concentration used, linear sorption isotherms were obtained which obeyed the Freundlich and Dubinin-Radushkevich models. From these, the energies of selenium sorption were calculated to be in the range of ion-exchange processes.

Kaolinite is a clay mineral with diverse environmental, industrial, and agricultural applications. The influence of the crystallographic properties of kaolinite, e.g. structural disorder, on these applications is of great interest. Qualitative and quantitative analyses of kaolinite structural disordering over the last 70 years have revealed three main sources of layer-stacking disordering: (1) enantiomorphic stacking; (2) dickite-like stacking; and (3) random shift of layers. What influence do these stacking disorders have on the reactivity of kaolinite? The objective of the present study was to investigate the influence of stacking disorder on the intercalation and dissolution of kaolinite layers. To minimize the effect of particle size on reactivity, the 1–2 μm fractions of five geologic kaolinites were used. The 1–2 μm fractions varied in the degree of structural disorder. The kaolinites were: (1) intercalated with saturated CH3COOK solution at room temperature to examine the effect of stacking disorder on intercalation; and (2) dissolved in 4 M NaOH at 80°C to examine the effect of stacking disorder on kaolinite stability in alkaline solution. Samples with a low degree of stacking disorder intercalated twice as much and dissolved >1.5 times as much as the most disordered sample. The infrared spectrum of the undissolved kaolinite residue in 4 M NaOH showed relative intensities of OH-stretching bands characteristic of a kaolinite-dickite mixture. The binding strength (i.e. resistance to intercalation) of the undissolved residue by NaOH was high; the residue could not be intercalated by CH3COOK. Differences in the average interlayer binding strength were attributed to the greater proportions of dickite-like sequences in highly disordered kaolinite compared to ordered kaolinite specimens. These results suggested that the binding strength of kaolinite layers is proportional to the degree of stacking disorder. Dickite-like sequences, a type of stacking defect, contributed to the lower reactivity of highly disordered kaolinite.

Understanding the reactions taking place in the hematite-oxalic acid system is important in order to clean iron oxides from filters and to remove iron from mineral concentrates. Previous studies reported the formation of an unwanted solid phase during this process. The objective of the current work, therefore, was to visualize and rationalize the iron dissolution steps taking place in the hematite–oxalic acid reaction by combining density functional theory (DFT) calculations and experimental data. The results of DFT calculations indicated that a precipitate was formed in this reaction; XRD analysis of the solid phase after the dissolution experiment revealed the formation of humboldtine as the precipitate. The attachment of oxalate on the hematite surface and the reduction of Fe(III) to Fe(II) were key steps for humboldtine formation. Both simulations and the experimental results showed that greater oxalic acid concentrations yielded more precipitate, suggesting a simple and novel route to synthesize humboldtine, a material which is relevant to the demand for clean energy.

Widespread lateritized ultramafic rocks in the southern part of the Muratdağı region of Turkey constitute a significant source of Ni-Cr-bearing ore with economic potential. However, no mineralogical or geochemical characterizations of these important materials have been performed previously. The aim of the present study was to describe the mineralogy, geochemistry, and genesis of Ni-Cr-bearing smectite in garnierite and ferruginous saprolite associated with the lateritized ophiolite-related ultramafic rocks. The lateritic zones are well developed over serpentinized harzburgitic mantle peridotites. The lateritized units and related bedrocks were examined using polarized-light microscopy, X-ray diffraction, scanning and transmission electron microscopies, and chemical and isotopic methods. The garnierite-containing saprolites are enriched in smectite, Fe-(oxyhydr)oxide phases, and opal-CT. Micromorphological images revealed that flaky smectite and, locally, Fe-rich particles, alunite, gypsum, gibbsite, and sulfur crystals developed along the fractures and dissolution voids. The development of saprolite demonstrates chemical weathering. The presence of silicified and Fe-(oxyhydr)oxide phases associated with gypsum, alunite, and local native sulfur in vertical and/or subvertical fractures and fault infillings are indicative of hydrothermal processes along the extensional, tectonically related fault systems. Chemical weathering and hydrothermal processes, which probably started during the Oligocene and Miocene, led to the formation of nontronite, Fe-bearing montmorillonite, and local Fe-rich kaolinite. Nickel and Cr are concentrated significantly in the saprolite zone and are positively correlated with Fe2O3 content, which is controlled by the formation of nontronite, montmorillonite, and Fe-(oxyhydr)oxide phases. Nickel-Cr-bearing nontronite and montmorillonite precipitated from alkaline water as a result of the increasing (Fe2O3+Al2O3+Cr2O5+Ni+Co)/(MgO+SiO2) ratio under the control of both chemical weathering and hydrothermal processes. The Fe and Mg (associated with Ni and Cr) required for the formation of smectite were supplied by solutions from both chemical weathering and hydrothermal alteration of Ni-Cr-bearing olivine and pyroxene in the harzburgitic bedrock; the Al was supplied by schists, granite, and volcanic units.

The state and dynamics of water and cations in pure and mixed Na-Cs-montmorillonite as a function of the interlayer water content were investigated in the present study, using Monte Carlo and classical, molecular-dynamics methods. While highly idealized, the simulations showed that the swelling behavior of hetero-ionic Na-Cs-montmorillonite is comparable to the swelling of a homo-ionic Na- or Cs-montmorillonite. The mixed Na-Cs-montmorillonite is characterized by intermediate interlayer distances compared to homo-ionic Na- and Cs-montmorillonites. Dry, hetero-ionic Na-Cs-montmorillonite is characterized by a symmetric sheet configuration, as is homo-ionic Cs-montmorillonite.

We found that at low degrees of hydration the absolute diffusion coefficient of Cs+ is less than for Na+, whereas at greater hydration states the diffusion coefficient of Cs+ is greaterthan for Na+. An analysis of the relative diffusion coefficients (the ratio between the diffusion coefficient of an ion in the interlayer and its diffusion coefficient in bulk water) revealed that water and Na+ are always less retarded than Cs+. With large interlayer water contents, tetralayer or more, Na+ ions preferentially form outer-sphere complexes. The mobility perpendicular to the clay surface is limited and the diffusion is equivalent to two-dimensional diffusion in bulk water. In contrast, Cs+ ions preferentially form ‘inner-sphere complexes’ at all hydration states and their two-dimensional diffusion coefficient is less than in bulk water.

The question remains unanswered as to why experimentally derived relative diffusion coefficients of Cs+ in the interlayer of clays are about 20 times less than those we obtained by classical molecular dynamics studies.

Sedimentary and diagenetic processes control the distribution of clay minerals in sedimentary basins, although these processes have seldom been studied continuously in continental sedimentary basins. The Songliao Basin, northeast China, is a large continental, petroleum-bearing basin, and provides a unique study site to understand the sedimentary and diagenetic processes that influence clay assemblages. In this paper, the clay mineralogy of a 2500 m-thick Late Cretaceous (late Turonian to Maastrichtian) terrestrial sedimentary succession (SK-1s and SK-1n cores), retrieved by the International Continental Scientific Drilling Program in the Songliao Basin, was examined. The objective was to determine the diagenetic and paleoenvironmental variations that controlled the formation of clay mineral assemblages, and to determine the thermal and paleoenvironmental evolution of the basin. The results from both cores show that illite is ubiquitous through the succession, smectite is frequently encountered in the upper strata, and ordered mixed-layer illite-smectite (I-S), chlorite, and kaolinite are abundant in the lower strata. Burial diagenesis is the primary control on the observed decrease of smectite and increasing illite, I-S, and chlorite with depth. Observations of clay-mineral diagenesis are used to reconstruct the paleotemperatures and maximum burial depths to which the sediments were subjected. The lowermost sediments could have reached a maximum burial of ~1000 m deeper than today and temperatures ~50°C higher than today in the latest Cretaceous. The transition of smectite to I-S in the SK-1 cores and the inferred paleotemperatures provide new constraints for basin modeling of oil maturation at elevated temperatures in the Songliao Basin. Authigenic kaolinite and smectite are enriched in sandstones with respect to the coeval mudstones from the SK-1n core, as a result of early diagenesis with the participation of primary aluminosilicates and pore fluids. In the upper part of both SK-1 cores, variations in smectite and illite were controlled primarily by paleoenvironmental changes. Increases in smectite and decreases in illite from the late Campanian to Maastrichtian are interpreted as resulting from increasing humidity, a conclusion consistent with previous paleoenvironmental interpretations.

Natural smectites bind aflatoxins from water effectively, but the complex chemical environment in the guts of mammals and other animals can limit binding of aflatoxins. Many efforts have been made to enhance the adsorption capacity and affinity of smectites for aflatoxins in the presence of biological compounds. The main objective of the present study was to modify smectite structures by pillaring and cation exchange to enhance aflatoxin B1 adsorption capacity and selectivity. Smectite was pillared with Al and Al-Fe polycations or saturated with Ca, Mg, Zn, or Li. Structural changes in smectites with or without heat treatment were determined using X-ray diffraction and Fourier-transform infrared spectroscopy. Equilibrium aflatoxin B1 adsorption to the smectites was measured in aqueous solution and in simulated gastric fluid. Pillaring with the polycations expanded smectites in the z-direction to 18.6 Å and the expansion was stable after heating at 500°C. Changes in the Al–OH–Al infrared bands in the stretching region supported the formation of pillared clays. Migration of Mg, Zn, and Li into the octahedral sites of the smectite was observed as Mg and Zn saturation yielded a d spacing of 15 Å at 200°C which collapsed to 9.6 Å at 400°C. The 14.6 Å peak of the Li-saturated smectite collapsed to 9.6 Å at 200°C while the 15 Å Ca-saturated smectite peak was stable up to 400°C. The unheated Al- and AlFe-pillared smectites adsorbed significantly more aflatoxin B1 from an aqueous suspension than did unpillared clay. In both water and simulated gastric fluid, heat treatment decreased aflatoxin B1 adsorption to pillared smectites, but heat treatment increased aflatoxin B1 adsorption to unpillared smectites. Without heat treatment, smectites saturated with divalent cations (Ca, Mg, Zn) adsorbed more aflatoxin B1 from an aqueous suspension than the smectite saturated with a monovalent cation (Li). Ca-saturated smectite showed the greatest aflatoxin B1 adsorption, 114 g kg–1, from aqueous suspension after 400°C heat treatment. The Zn-, Mg-, and Li-saturated smectites showed maximum aflatoxin adsorption of 107, 93, and 90 g kg–1, respectively, after 200°C heat treatment. From simulated gastric fluid with pepsin, the 200°C heated, Zn-saturated smectite had maximum aflatoxin B1 adsorption of 68 g kg–1. Pillared smectites effectively adsorbed aflatoxin B1 from aqueous suspension, but Ca- and Zn-saturated smectites after heat treatment might improve the selectivity of smectites for aflatoxin B1 over pepsin and enhance the efficacy of smectite as a feed additive.