Inorganic Clay Minerals Research Articles

EXPLORING THE WETTABILITY CHARACTERISTICS OF ARGILLACEOUS SILTSTONE WITH IMBIBITION AND NMR TECHNIQUE FOR MARINE RESERVOIR EXPLOITATION

The argillaceous siltstone reservoirs in South China Sea involves a wide variety of fossil resources, such as gas hydrate, marine oil, natural gas, and other mineral resources. The argillaceous siltstone with mixed wettability characteristics is easily dispersed in water, and it is difficult to study the wettability of argillaceous siltstone based on water imbibition technique. In this work, an innovative method is proposed to demonstrate the mixed wettability based on imbibition and nuclear magnetic resonance (NMR) technique. The contact angle results show that the affinity of argillaceous siltstone for oil is stronger than that for water. However, the imbibition volume of water is much larger than that of oil. The oil imbibition curve is linear, while water imbibition curve has a two-stage feature. This difference can be explained by the expansion of clay, where more water wet surfaces are exposed to the liquid, leading to changes in wettability. In addition, the coexistence of organic matter and inorganic clay minerals results in a mixed wetting characteristic. Based on NMR technology, a micro wettability index is proposed to quantitatively characterize the micro wettability heterogeneity. The micro water (or oil) wettability index of micropores (0.01-10 ms) is approximately equal to 0.5, indicating the mixed wettability. The micro water wettability index of mesopores (10-500 ms) is approximately equal to 1.0, indicating strong water wettability. These pores or cracks may be induced by clay minerals expansion. The micro oil wettability index of macropores (> 500 ms) is approximately equal to 1.0, indicating strong oil wettability, which is resulted from significant accumulation of organic debris enrichment. It is of great significance to improve the exploration and exploitation efficiency of mineral resources in the South China Sea.

Antibacterial and Biocompatible Polyethylene Composites with Hybrid Clay Nanofillers.

Low-density polyethylene is one of the basic polymers used in medicine for a variety of purposes; so, the relevant improvements in functional properties are discussed here, making it safer to use as devices or implants during surgery or injury. The objective of the laboratory-prepared material was to study the antimicrobial and biocompatible properties of low-density polyethylene composites with 3 wt. % hybrid nanoclay filler. We found that the antimicrobial activity was mainly related to the filler, i.e., the hybrid type, where inorganic clay minerals, vermiculite or montmorillonite, were intercalated with organic chlorhexidine diacetate and subsequently decorated with Ca-deficient hydroxyapatite. After fusion of the hybrid nanofiller with polyethylene, intense exfoliation of the clay layers occurred. This phenomenon was confirmed by the analysis of the X-ray diffraction patterns of the composite, where the original basal peak of the clays decreased or completely disappeared, and the optimal distribution of the filler was observed using the transmission mode of light microscopy. Functional property testing showed that the composites have good antibacterial activity against Staphylococcus aureus, and the biocompatibility prediction demonstrated the formation of Ca- and P-containing particles through an in vitro experiment, thus applicable for medical use.

Chlorella sorokiniana FK-montmorillonite interaction enhanced remediation of heavy metals in tailings

Non-ferrous metal mining activities are known to cause ecological irreversible damage in the tailings and surrounding areas as well as heavy metal (HM) contamination. The enhancement of Chlorella-montmorillonite interaction on the remediation of HM contaminated tailings was verified from the lab to the tailings in Daye City, Hubei Province, China. The results showed a positive correlation between the quantity of montmorillonite and the transformation of Pb and Cu into residual and carbonate-binding states, which resulted in a considerable decrease in the leaching ratio. The buildup of tailings fertility throughout this process benefited from montmorillonite's ability to buffer environmental changes and store water. This further offers a required environmental foundation for the rebuilding of microbial community and the growth of herbaceous plants. The structural equation model demonstrated that the interaction between Chlorella and montmorillonite directly affected the stability of HM, and that this interaction also had an impact on the accumulation of organic carbon, total nitrogen, and available phosphorus, which improved the immobilization of Pb, Cu, Cd, and Zn. This work made the first attempt to apply Chlorella-montmorillonite composite to in-situ tailings remediation, and proposed that the combination of inorganic clay minerals and organic microorganisms was an eco-friendly, long-lasting, and efficient method for immobilizing multiple-HMs in mining areas.

Synthesis and Characterization of an Novel Intercalated Polyacrylamide/Clay Nanocomposite

Solving the problem of the low temperature and low salt resistances of conventional polyacrylamide and the high cost of functional monomers, and thus, introducing it to the interlayer space provided by a layered structure for polymer modification, is a promising option. In this study, montmorillonite was used as the inorganic clay mineral, and an intercalated polyacrylamide/clay nanocomposite was synthesized via in situ intercalation polymerization. The optimal synthesis conditions were a clay content of 10.7%, preparation temperature of 11 °C, initiator concentration of 2.5 × 10-4 mol/L, and chain extender concentration of 5%. The IR results showed that the polymer was successfully introduced to the nanocomposite. The synthesized intercalated polyacrylamide/clay nanocomposite exhibited a better thickening effect, good viscoelasticity, and better salt resistance and thermal stability than polyacrylamide. In addition, the thickening capacity and thermal stability were superior to the salt-resistant polymer, with a 16.0% higher thickening viscosity and a 15.1% higher viscosity retention rate at 85 °C for 60 d. The intercalated polyacrylamide/clay nanocomposite further expanded the application of polyacrylamide in petroleum exploitation.

Supramolecular coassembly of amino clay and anionic polyacrylamide with enhanced crystallinity and luminescence

In this work, we illustrate the role of amine-grafted inorganic clay minerals as the efficient supramolecular crosslinker for anionic polyacrylamide. Amine-grafted clay was synthesized, which possesses cationic two-dimensional surface to allow intercalation of polymer chains. Hydrogen bonding and electrostatic attraction enable the sufficient complexation between the components to give lamellar packing. The coassembled morphology shows dependence to the concentration and fraction of components. The crystalline architectures emerged at specific situation, which was confirmed by the X-ray diffraction results. Coassembly not only enhanced the ordered molecular arrangements, but also appended enhanced luminescent properties. This work investigates the role of amino clay as supramolecular crosslinker to control the ordered aggregation behavior of polymers, which offers a strategy to fabricate polymer-mineral composite materials.

Insights into shale gas adsorption and an improved method for characterizing adsorption isotherm from molecular perspectives

• The specific multiscale inter-connected pore models of shale are proposed. • The dependences of diverse media properties and pore size on CH 4 adsorption behaviors are clearly examined by GCMC simulations. • An improved method for calibrating isothermal adsorption experimental result is proposed. Gas adsorption behavior in shale complex porous media is of great importance to gas in place (GIP) evaluation and exploration. At present, the mechanism of methane adsorption has not been adequately investigated in multi-size nanoscale space via experimental and simulation methods. In this work, the specific multi-size inter-connected pore models are proposed to study the adsorption isotherm and density profiles based on the veritable pore structure characterizations of shale samples. The grand canonical Monte Carlo (GCMC) simulations are utilized to give insight into methane adsorption behavior in organic matter and inorganic clay minerals with multi-size pores at reservoir conditions. Based on the proposed models, the effects on adsorption behaviors of methane molecules under the simultaneous action of diverse media surfaces and variable pore sizes are carefully examined. In addition, the adsorbent-adsorbate interactions, which involve the cation exchange and the isosteric heat variations with media surfaces, are carefully investigated to reveal complex adsorption behaviors in shale nanopores. Considering the identified factors influencing methane adsorption and the shortcomings of experimental test, an improved method for calibrating the gas adsorption isotherms in shale is proposed from a molecular perspective, which takes into account several factors, including i) the accessible volume of methane molecules, ii) the pore size distribution in shale, and iii) the composition of organic matter and clay minerals. The GCMC simulation results are integrated into the process of calibrating experimental results in a case study with a shale sample from the Longtan Formation in the Sichuan Basin, China. The findings of this study advance the in-depth understanding of gas adsorption mechanisms in complex nanoporous structure and provide a reliable approach to evaluate the GIP in shale.

Performance evaluation of different chitosan-clay composite materials for efficient harvesting of Chlorella vulgaris and impacts on downstream bioproduct processing and water reusability

As an environmentally friendly bioflocculant, chitosan has a great application potential in the field of microalgae harvesting due to its biocompatibility. In this work, three different inorganic clay minerals (kaolin, montmorillonite, and diatomite) were selected to prepare chitosan-clay composite materials (CTS/KAL, CTS/MML and CTS/DTE) as flocculants to harvest microalgae cells. The harvesting capacities of CTS/KAL, CTS/MML and CTS/DTE were accordingly 97.37%, 97.81% and 98.34% for microalgae cells under the dosage of 60 mg/L, microalgae concentration of 0.923 g/L, settling time of 30 min and pH of 10. CTS/DTE showed excellent harvesting performance for microalgae cells, mainly due to the enhancement of charge neutralization, sweeping and bridging effects. Based on the phenomenological theory, the second-order polynomial model was used to analyze the influences of different external factors on the microalgae harvesting efficiency. A reasonable performance relationship between CTS-clays for harvesting of microalgae cells and external factors was established. The analysis of carbohydrates, proteins, and fatty acids of microalgae biomass collected by CTS/KAL, CTS/MML, CTS/DTE and centrifugation showed that the harvesting of CTS-clay did not influence the properties of biomass. The experimental results of water resource recycling and re-cultivation after microalgae harvesting by CTS/KAL, CTS/MML and CTS/DTE exhibited that the growth rates of 50% circulating medium + 50% fresh BG11 culture medium were accordingly 2.512, 2.466 and 2.572 times higher than those of 100% circulating medium. It is concluded that chitosan-clay composite materials are efficient and environmentally friendly flocculants with a great applicable potential in microalgae harvesting.

Tribological properties of novel palygorskite nanoplatelets used as oil-based lubricant additives

Layered palygorskite (PAL), commonly called attapulgite, is a natural inorganic clay mineral composed of magnesium silicate. In this study, an aqueous miscible organic solvent treatment method is adopted to prepare molybdenum-dotted palygorskite (Amo-PMo) nanoplatelets, which greatly improved the specific surface area of PAL and the dispersion effect in an oil-based lubricant system. Their layered structure and size were confirmed using transmission electron microscopy (TEM) and atomic force microscopy. Following a tribological test lubricated with three additives (PAL, organic molybdenum (SN-Mo), and Amo-PMo), it was found that the sample of 0.5 wt% Amo-PMo exhibited the best tribological properties with a coefficient of friction of 0.09. Moreover, the resulting wear scar diameter and wear volume of the sliding ball surface were 63% and 49.6% of those lubricated with base oil, respectively. Its excellent lubricating performance and self-repairing ability were mainly attributed to the generated MoS2 adsorbed on the contact surfaces during the tribochemical reaction, thereby effectively preventing the direct collision between asperities on sliding solid surfaces. Thus, as-prepared Amo-PMo nanoplatelets show great potential as oil-based lubricant additives, and this study enriches the existing application of PAL in industry.

Functionalization, Uptake and Release Studies of Active Molecules Using Halloysite Nanocontainers

Halloysite nanotubes are inorganic clay minerals of kaolin group. Halloysite possess unique morphology, chemical composition, cation exchange capacity and charge properties making them ideal candidate for various industrial application. In the present study, an attempt was made to functionalize the exterior surface of halloysite nanocontainer. The surface of halloysite nanocontainer was modified using tetrabutylammonium chloride (TBAC). Further an attempt was made to employ these functionalized nanocontainers to uptake and release the active molecule (dye Acid Red1). TBAC-modified nanocontainer indicated higher adsorption capacity of 4.54 mg/g as compared to unmodified nanocontainer (3.08 mg/g). The release behaviour of active molecule from loaded nanocontainers was found with change in pH and temperature. Since the loading characteristics of functionalized nanocontainers were found to be adsorption dependent, parameters such as effect of time, loading, pH, initial concentration were studied for analysing the loading characteristics. The dye release from 0.5 g dye-loaded TBAC-modified nanocontainers at pH 11 and at 32 °C was found to be 92%. Lastly, the release readings were analysed for the best fit (97%) using permeation kinetic model (Peppa’s model).

Organic-inorganic hybrid layer-by-layer electrostatic self-assembled film of cationic dye Methylene Blue and a clay mineral: Spectroscopic and Atomic Force microscopic investigations

The metachromic cationic dye Methylene Blue (MB) belongs to the thiazine class of organic dye. This dye cation can interact electrostatically with inorganic clay mineral Montmorillonite (MMT) to form organic-inorganic hybrid layer-by-layer (LbL) self-assembled film onto a poly(allylamine hydrochloride) coated quartz substrate. The degree of dye aggregations in LbL films was found to depend on concentrations of both MMT clay and MB in LbL self-assembled films as evidenced by UV–vis absorption spectroscopic technique. The adsorption of dye molecules to the LbL films was found to a two-step exponential process: first step was very fast and the later process had a much delay period. Also the assembling behavior and organizations of MB molecules in the host clay matrix in LbL films significantly depend on pH of dye solution from which LbL film was fabricated. For MMT/MB mixed solution the π-π* transition of absorption bands of MB shifted to lower wavelength due to the formation of large number of H-aggregates in their mixed aqueous solution. Fourier Transform infrared (in ATR mode) spectroscopic method was employed to explore the electrostatic interaction between clay MMT and MB in LbL films. Atomic Force microscopic image of hybrid LbL films revealed the surface morphology and roughness profile of the organic-inorganic hybrid molecular assemblies onto the solid substrate.

Molecular simulation of displacement of shale gas by carbon dioxide at different geological depths

The rising worldwide energy demand has greatly stimulated the exploitation of shale gas. Meantime, global warming mainly caused by CO2 emission is a significant concern. As a new scenario, injecting CO2 to displace shale gas is proposed to improve the exploitation efficiency of shale gas and reduce the amount of CO2 emission. In this work, we use a grand canonical Monte Carlo simulation to investigate the displacement of shale gas by CO2 and the sequestration of CO2 simultaneously in a modeled shale matrix at different geological depths from 1 to 4km, where the shale is modeled by inorganic clay mineral and organic matter. We find that both the displacement amount of CH4 and the sequestration amount of CO2 increase with the pore size of the shale at a fixed CO2 injection pressure, which suggests that the hydro-fracturing technology would be very beneficial for displacement exploitation of shale gas. Moreover, we also find that the optimum operating condition for CO2 displacing shale gas is at the depth of 1km, which provides a guidance and reference for displacement exploitation of shale gas by CO2.

Removal of polycyclic aromatic hydrocarbons (PAHs) from inorganic clay mineral: Bentonite.

There has been limited study of the removal of polycyclic aromatic hydrocarbons (PAHs) from inorganic clay minerals. Determining the amount of PAH removal is important in predicting their environmental fate. This study was carried out to the degradation and evaporation of PAHs from bentonite, which is an inorganic clay mineral. UV apparatus was designed specifically for the experiments. The impacts of temperature, UV, titanium dioxide (TiO2), and diethylamine (DEA) on PAH removal were determined. After 24h, 75 and 44% of ∑12 PAH in the bentonite were removed with and without UV rays, respectively. DEA was more effective as a photocatalyst than TiO2 during UV application. The ∑12 PAH removal ratio reached 88% with the addition of DEA to the bentonite. It was concluded that PAHs were photodegraded at high ratios when the bentonite samples were exposed to UV radiation in the presence of a photocatalyst. At the end of all the PAH removal applications, higher evaporation ratios were obtained for 3-ring compounds than for heavier ones. More than 60% of the amount of ∑12 PAH evaporated consisted of 3-ring compounds.

Synthesis of Highly Active and Thermally Stable Nanostructured Pt/Clay Materials by Clay-Mediatedin SituReduction

Novel and intriguing one-pot in situ method for the preparation of nanostructured Pt-clay materials under simple conditions is reported. In this synthesis, an inorganic clay mineral such as synthetic hectorite ("Laponite XLG") or natural montmorillonite ("Kunipia F") serves as a mild and effective reducing agent for Pt ions, which is uncommon for such a clay system, and also acts as an outstanding stabilizer for the resulting Pt nanoparticles. In aqueous solution, exfoliated colloidal clay platelets forms complex with Pt ions in the initial stage of mixing. Devoid of any organic dispersants or external reducing agents, subsequently, the Pt nanoparticles (3-6 nm) generated by clay-assisted in situ reduction of Pt ions successfully anchored onto the clay nanoplatelets. The Pt-clay material features a very high surface area (312 m(2) g(-1)) and has excellent catalytic activity, as was kinetically evaluated via the reduction of 4-nitrophenol with NaBH(4). After drying, this remarkably stable nanocomposite is completely redispersible in water and displays extreme thermal stability (up to 500 °C). On the basis of these results, this synthetic strategy is anticipated to be a very simple, economical, and green approach for the synthesis of nanostructured Pt-clay materials.

Optimizing Immobilization of Horseradish Peroxidase in the Nano-Scale Porous Structural Inorganic Material

Horseradish peroxidase was immobilized by montmorillonite to construct a nano-scale structural biocatalyst for the stabilization and/or detoxification of phenolic compounds from natural waters. Humic substances extracted from soils were used as a bonding agent, stimulating peptide covalent bonds between enzymes and surface of inorganic clay minerals. Operating conditions including concentrations of enzyme inoculated and duration time and temperature for the immobilization were examined and the optimal condition for maximizing the quantity of enzyme immobilized was found. The results of this study are expected to provide the essential information for the process-efficient and economic enzyme immobilization operations in the environmental engineering as well as for establishing ecological green U-City.

Nanoscale organic/inorganic hybrids based on self-organized dendritic macromolecules on montmorillonites

This article is intended to investigate the aspects regarding the nanoscale organic/inorganic hybrids base on dendritic molecules, and the issues that arises from the use of self-assembly approach upon layered templates for the construction of functional materials. A facile synthesis of polyurea(urethane)/malonamide dendrons (from generation one, G1, to generation three, G3) with phenyl rings (P), decyl groups (D), or azo chromophores (disperse red 1; DR1) in the exterior was developed first. The dendrons consisting of secondary amine functional group in the focal point were successfully introduced into the interlayer space of montmorillonite (MMT) to prepare a series of dendron/MMT nanohybrids that reveal intercalated and exfoliated morphology. We were able to explore the possibility of obtaining the layer spacing up to 126 Å via embedding various dendrons into the silicate interlayers, and to investigate the intercalating effects of different molecular sizes and shapes. These results indicate that organic/inorganic nanohybrids resulting from the association of dendrons and inorganic clay minerals can be contributed by a direct self-assembly of hydrophobic dendrons in the layered confinement. Through embedding the void-rich dendritic molecules into interlayers, these new organic/inorganic layered nanohybrids might possess potential applications for nano-containers, nano-reactors, electro-optical materials, etc.

Development of a polyamide nanocomposite for food industry: Morphological structure, processing, and properties

AbstractIn the last few years, nanocomposites have been a focus of attention for researchers because they frequently exhibit unexpected hybrid properties derived from synergistic reactions between nanoparticles and the polymeric matrix. However, few studies about the dispersion of inorganic clay minerals in polyamide films have been carried out to explain the process of exfoliation. The exfoliation of nanoclays in the polyamide film provides a film with better barrier properties than the intercalation of nanoclays. The present study addresses the analysis of experimental variables (pressure, temperature, processing time, feed position, etc.) involved in the production of a polyamide film with nanoparticles, in order to obtain a film with good exfoliation, barrier and mechanical properties. SEM, TEM and XRD were also evaluated as tools to determine the degree of exfoliation of nanoparticles. The technique used in production of the film, the screw employed and the mixing time were found to be of great importance in obtaining an intercalated or exfoliated final product. The variables involved in obtaining an exfoliated Cloisite 30B/polyamide film by a double screw extruder were optimized, and a film with reduced permeability to oxygen (1,000 times lower than the control film) wasobtained. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers

Inorganic/Organic Hybrid Nanocomposites involving OMMT Clay and Cyanate ester—Siloxane-modified Epoxy Resin: Thermal, Dielectric and Morphological Properties

Inorganic—organic hybrid nanocomposites were prepared by the following steps: (1) homogeneous dispersion of various percentages (1 to 5% w/w) of organically modified montmorollonite clay in epoxy matrix resin; (2) the resulting homogeneous epoxy—clay hybrids were modified with 10 wt.% of hydroxyl-terminated polydiemthyl siloxane (HTPDMS) using γ -aminopropyltriethoxysilane ( γ APS) as coupling agent in the presence of dibutyltindilaurate catalyst; and (3) the siliconized epoxy—clay prepolymers were further modified separately with 10 wt% of three different cyanate ester monomers and cured with diaminodiphenylmethane. The chemical interactions between epoxy, clay, HTPDMS and cyanate ester were confirmed by Fourier transform infrared spectral analysis. The values obtained from differential scanning calorimetry and dynamic mechanical analysis showed that there was a significant loss of glass transition temperatures in the resulting hybrid epoxy nanocomposite systems compared with that of neat epoxy system. The inorganic clay mineral and the formation of thermally stable oxazolidinone structures and siloxane linkages during curing led to significant improvement in the thermal properties of the resulting nanocomposites. A decreasing trend was identified in the resulting nanocomposites from their values of dielectric constant and dielectric loss by the incorporation of clay, HTPDMS and cyanate ester in the epoxy resin. The intercalation/exfoliation structure was studied using X-ray diffraction analysis and the homogeneous/heterogeneous morphology was studied using scanning electron microscopy analysis in the resulting nanocomposites.

Sources and biogeochemical cycling of particulate selenium in the San Francisco Bay estuary

As part of a study of estuarine selenium cycling, we measured the concentration, chemical form (speciation), and distribution of particulate selenium under various river flow conditions in the North San Francisco Bay (from the Golden Gate to the Sacramento and San Joaquin Rivers). We also conducted laboratory studies on the accumulation of selenium by phytoplankton, the critical first step in the transformation of dissolved to particulate selenium. Total particulate selenium concentration in the North SF Bay was relatively constant between high and low flow periods, ranging spatially from 0.05 to 0.35 nmol l −1 and comprising between 5 and 12% of the total water column selenium inventory. Mean concentrations were generally highest in the Carquinez Strait–Suisun Bay region (salinity 0–17) and lowest in Central Bay. However, selenium content of suspended particles varied with river flow, with higher content during low flow (9.76 ± 4.17 nmol g −1; mean ± sd; n = 67) compared to high flow (7.10 ± 4.24 nmol g −1; n = 39). Speciation analyses showed that most particulate selenium is organic selenide (45 ± 27%), with a smaller proportion (typically <30%) of adsorbed selenite + selenate and a varying proportion (35 ± 28%) of elemental selenium. Based on the amount of elemental selenium in the seston (total suspended material), we calculate that resuspension of estuarine sediments could contribute 29–100% of particulate selenium in the water column. While selenium content of SF Bay seston (>0.4 μm) is relatively unenriched compared to phytoplankton (13.6–155 nmol g −1 dry weight) on a mass basis, when normalized to carbon or nitrogen, seston contains a similar selenium concentration to SF Bay sediments or phytoplankton cultures. SF Bay seston is thus comprised of selenium-rich phytoplankton and phyto-detritus, but also inorganic clay mineral particles that effectively “dilute” total particulate selenium. Selenium concentrations in algal cultures (11 species) exposed to 90 nmol l −1 selenite show relatively large differences in selenium accumulation, with the diatoms, chlorophytes and cryptophytes generally having lower selenium cell content (3.8 ± 2.7 × 10 −9 nmol selenium cell −1) compared to the dinoflagellates (193 ± 73 × 10 −9 nmol selenium cell −1). Because phytoplankton are such a rich (but variable) source of selenium, their dynamics could have a profound effect on the particulate selenium inventory in the North SF Bay.

Changes in aluminum pools of andisols due to soil acidification

Aluminum concentrations in soil solutions are not only controlled by inorganic clay minerals but also by organically bound aluminum. The objective of this study was to determine which pools contribute to Al dissolution. Soil samples were taken at various distances from tree trunks and at various depths at the Rolling Land Laboratory (RLL), Hachioji, Tokyo. Selective dissolution techniques were used to analyze the changes in pools of solid-phase aluminum. Soil pH values around Hinoki cypresses were in the aluminum buffer range. Exchangeable aluminum contents in soils under Hinoki cypresses were 104 mmolc kg-−1 on the average. This value was similar to that of the cation exchange capacity (CEC) of Andisols at RLL at a soil pH of 4. The relationship between the soil pH and exchangeable, organically bound, and amorphous aluminum pools showed that dissolved aluminum ions in the soil solution were primarily derived from the amorphous Al pool. Dissolved aluminum ions were substituted with base cations of soils, resulting in the increase of the content of exchangeable Al and/or the formation of complexes with organic matter which increased the proportion of organically bound Al pools. Increase in the proportion of organically bound Al pools indicated the importance of complexation with soil organic matter for controlling the aluminum concentration in the soil solution.

Sheets of Alternating Chirality in the Structure of a Novel Iron(III) Complex with a Cyclic Oxamide Ligand

An organic–metalloorganic analogue of the inorganic clay minerals has been obtained from the cyclization of N,N′-bis(ethoxalyl)phenylenediamine in basic medium in the presence of iron(III) ions leading to formation of a cyclic oxamide ligand (L). The combination of intramolecular (covalent) interactions between metal and ligand and intermolecular (noncovalent) ionic interactions creates a novel layered compound with an intriguing crystal structure (shown on the right).