The General Synod of the Scottish Episcopal Church (SEC) met from 7 to 9 June 2023. The meeting was held in hybrid format, with most members attending in person and a small number online.

Interstratified serpentine-smectite was found in the fine-grained fraction of altered metasomatic contact biotite-schists developed between serpentinite and granite-type rocks (Lower Silesia ophiolite sequence, Poland). Ni-rich serpentine-smectite is R0-interstratified lizardite (0.80)-stevensite (0.15)-vermiculite-like (0.05), with a coherent scattering domain (csd) of 5 layers (mean value). The Mg-rich variety of serpentine-smectite is R1 lizardite (0.80)-stevensite (0.20) with a csd size of 7 layers (mean value). A transmission electron microscope study revealed complex layer relationships, with zones composed of various serpentine-smectite packets having lizardite/smectite ratios of 3:1, 2:1, 1:1, 4:1 and scarce serpentine segregations. In both cases, the serpentine-smectites appear to be late products of alteration of the parent biotite-schist.

Experimental and calculated positions and intensities of reflections of the ethylene glycol-saturated, heated (250°C, thermal stage), and air-dried samples are in good agreement. Calculated X-ray diffraction patterns for interstratified glycolated and anhydrous serpentine-smectite are included in the Appendix.

Many soils in southern Switzerland have a black color, contain a large amount of soil organic matter (SOM) and seem to have some andic properties although they did not develop on volcanic parent material. We investigated three typical ‘black’ soils to determine the mechanisms of (clay) mineral formation and transformation. We measured total element pools as well as the dithionite-, pyrophosphate-and oxalate-extractable fractions (Fe, Al, Si). The clay fraction (<2 µm) was analyzed using X-ray diffraction and FTIR spectroscopy. Iron speciation in the solid phase was determined by Mössbauer spectroscopy. With increasing weathering conditions, the plagioclase (albite) content decreases, trioctahedral species in the clay fraction such as biotite, chlorite or trioctahedral vermiculite either decompose or transform into a dioctahedral mineral such as dioctahedral vermiculite or hydroxy interlayered smectite (HIS). Typical weathering products were hydroxy interlayered vermiculite (HIV), HIS, interstratified minerals and kaolinite. The oxidation of Fe(II) into Fe(III) was evident and contributes to the transformation of trioctahedral mineral species into dioctahedral ones. In one soil, a large part of the Fe (up to 41%) was found in the form of Fe oxides. In the surface horizon, the poorly crystalline mineral ferrihydrite was dominant, while in the subsoil goethite prevailed. Maghemite (or maghemite/hematite mixture) was, furthermore, found in distinct concentrations down to a depth of ∼50 cm. The formation of this mineral requires high temperatures which means that a forest fire can influence soil mineralogy down to a considerable depth. The specific climatic conditions with periods of strong humidity alternating with periods of winter droughts, sporadic fire events and the relatively large content of poorly crystalline fractions of Fe and Al contributed to the stabilization of SOM.

Supercritical carbon dioxide (scCO2) processing has been proven as a method for preparing polymer/montmorillonite (MMT) nanocomposites with improved platelet dispersion. The influence of scCO2 processing on the shape and size of the MMT tactoid/platelet, which is of great importance to the final platelet dispersion in the polymer matrix, is scarcely reported in the literature. In the present study, the pristine MMT was first surface modified with 3-glycidoxypropyltrimethoxysilane (the grafted MMT is labeled as GMMT), and then intercalated using three kinds of intercalating agents, myristyltrimethyl-ammonium bromide (MTAB), tetradecyltrihexylphosphonium chloride (TDTHP), and ethoxyltriphenyl-phosphonium chloride (ETPC), in water or scCO2, to study the effect of intercalating agent type and intercalation method on the morphology and thermal properties of GMMT, as a part of a program devoted to the synthesis of polymer/MMT nanocomposites. The structure of intercalated GMMT was characterized by thermogravimetric analysis, X-ray powder diffraction, and scanning electron microscopy (SEM). The optimum intercalation conditions in scCO2 were established by trying a range of reaction times and pressures. The structures of intercalated GMMT obtained under optimum scCO2 conditions and water were compared. The basal spacing of GMMT intercalated in scCO2 was almost the same as that in water, and both were obviously larger than that of GMMT. The GMMT exhibited a compact spherical morphology (examined using SEM), and the surface structures (including surface morphology, surface roughness, and surface compactness) of samples intercalated in water became ‘less compact’ and the degree of the ‘compactness’ of samples intercalated in scCO2 decreased further. Whether in water or scCO2, samples intercalated with TDTHP exhibited a larger basal spacing and the extent of disorder increased compared to that for samples intercalated with MTAB. The pristine MMT was also intercalated for comparison and silane grafting was proven to contribute to the increased basal spacing and ‘less compact’ surface structure.

X-ray basal reflections of several HDTMA-vermiculites show that when these contain co-adsorbed molecules of HDTMA-Br, their interlayer spacings are ∼29.5 Å. After HDTMA-Br has been leached out with ethanol, spacings decrease to ∼26 Å, but when exposed to toluene vapor the spacings increase to ∼36 Å, and to ∼45 Å in toluene liquid. Transmission X-ray diffraction photographs of HDTMA-vermiculites, both with and without co-adsorbed HDTMA-Br, indicate that they have highly ordered interlayer structures. The structure of HDTMA-Br-free vermiculite flakes is more open with the interlayer cations arranged in a 3a × b superstructure. In the HDTMA-Br containing HDTMA vermiculite flakes, HDTMA-Br molecules occupy interstitial positions between the HDTMA cations. Swelling in toluene vapor does not disorder the 2-dimensional arrangement of interlayer cations, but disorder does occur in toluene liquid. In toluene vapor, the aliphatic chains of the cations remain partially interdigitated, but in toluene liquid the interdigitation disappears. In response to the layer-charge density, the organization of the interlayer HDTMA units is caused by the self-assembly process responsible for hydrocarbon close packing.

Dyes are toxic and considered to be extremely hazardous to natural environments. Hence, adsorbents to remove dyes from contaminated water are needed. To develop adsorbents with a high adsorption capacity for different dyes, easy separation, and low cost, a novel dye adsorbent was prepared by activating fly ash with NaOH. The adsorbent morphology, structure, and specific surface area were characterized using scanning electron microscopy, X-ray powder diffraction, and surface area measurements using N2 adsorption-desorption. The adsorption abilities of the synthesized adsorbents were examined based on methylene blue and acid fuchsin adsorption from water. The capabilities of the adsorbents as a function of adsorbent use, dye type, dye concentration, time, and pH were investigated and compared. The results for methylene blue and acid fuchsin adsorption were modeled using pseudo-second order kinetics and the Langmuir adsorption isotherm, respectively. These modified adsorbents synthesized from fly ash may provide a promising solution to purify dye-contaminated waste water with the advantages of high efficiency and low cost.

Clay minerals impart important chemical properties to soils, in part, by virtue of changes in the redox state of Fe in their crystal structures. Therefore, measurement of Fe(III)/Fe(II) and partitioning of Fe(II) in different reactive sites in clay minerals (during biological and chemical Fe(III) reduction) is essential to understand their role and their relative reactivity in terms of reduction and immobilization of heavy metal contaminants such as technetium. This study had three objectives: (1) to understand the degree of dissolution of nontronite (Fe-rich smectite) as a result of chemical and biological reduction of Fe(III) in the structure; (2) to quantify partitioning of chemically and biologically produced Fe(II) into different reactive sites in reduced nontronite, including aqueous Fe2+, ammonium chloride-extractable Fe(II) (mainly from the ion-exchangeable sites, denoted as $\text{Fe}{\left(\text{II}\right)}_{{\text{NH}}_4\text{Cl}}$${\rm{Fe}}{\left( {{\rm{II}}} \right)_{{\rm{N}}{{\rm{H}}_4}{\rm{Cl}}}}$), sodium acetate-extractable Fe(II) (mainly from the surface complexation sites, denoted as Fe(II)acetate), and structural Fe(II) (denoted as Fe(II)str); and (3) to evaluate the reactivity of these Fe(II) species in terms of Tc(VII) reduction. Chemical and biological reduction of Fe(III) in nontronite (NAu-2) was performed, and reduced nontronite samples with different extents of Fe(III) reduction (1.2–71%) were prepared. The extent of reductive dissolution was measured as a function of the extent of Fe(III) reduction. Our results demonstrated that chemically and biologically produced Fe(II) in NAu-2 may be accommodated in the NAu-2 structure if the extent of Fe(III) reduction is small (< ∼30%). When the extent of reduction was >∼30%, dissolution of nontronite occurred with a corresponding decrease in crystallinity of residual nontronite. The Fe(II) produced was available for partitioning into four species: ${\text{Fe}}_{\left(\text{ab}\right)}^{2+}$${\rm{Fe}}_{\left( {{\rm{ab}}} \right)}^{2 + }$, Fe(II)acetate, $\text{Fe}{\left(\text{II}\right)}_{{\text{NH}}_4\text{Cl}}$${\rm{Fe}}{\left( {{\rm{II}}} \right)_{{\rm{N}}{{\rm{H}}_4}{\rm{Cl}}}}$, and Fe(II)str. The increase in Fe(II)acetate during the early stages of Fe(III) reduction indicated that the Fe(II) released had the greatest affinity for the surface-complexation sites, but this site had a limited capacity (∼60 µmol of Fe(II)/g of NAu-2). The subsequent increase in $\text{Fe}{\left(\text{II}\right)}_{{\text{NH}}_4\text{Cl}}$${\rm{Fe}}{\left( {{\rm{II}}} \right)_{{\rm{N}}{{\rm{H}}_4}{\rm{Cl}}}}$ indicated that the released Fe(II) partitioned into the exchangeable sites once the amount of Fe at the surface-complexation sites reached half of its maximum site capacity. The fraction of Fe(II)str decreased concomitantly, as a result of Fe(II) release from the NAu-2 structure, from 100% when the extent of Fe(III) reduction was <30% to nearly 65% when the extent of Fe(III) reduction reached 71%. The Fe(II)acetate and Fe(II)str exhibited greater reactivity in terms of Tc(VII) reduction than the $\text{Fe}{\left(\text{II}\right)}_{{\text{NH}}_4\text{Cl}}$${\rm{Fe}}{\left( {{\rm{II}}} \right)_{{\rm{N}}{{\rm{H}}_4}{\rm{Cl}}}}$. Clearly, the surface-complexed and structural Fe(II) are the desirable species when reduced clay minerals are used to reduce and immobilize soluble heavy metals in contaminated groundwater and soils. These results have important implications for understanding microbe—clay mineral interactions and heavy metal immobilization in clay-rich natural environments.

The Assembly met on 20–25 May with the Right Rev'd Sally Foster-Fulton BA BD as Moderator. She is Head of Christian Aid in Scotland and has served as a Parish Minister in the Church of Scotland and in the Presbyterian Church (USA). The Rt Hon Lord Hodge DPSC was re-appointed by His Majesty as Lord High Commissioner to the General Assembly for a second year. The Church has roughly 284,000 members (2021 figures) and around 1,200 charges.

A major problem with polymeric membranes is low hydrophilicity and consequently a tendency to fouling. Preparing composite membranes is one way to improve the properties and performance of the neat membrane. In the present study, the effects of coagulation-bath temperature (CBT) and the hydrophilic nanoclay concentration of montmorillonite (MMT) on the morphology and performance of asymmetric cellulose acetate butyrate (CAB) membranes were investigated. The membranes were prepared via phase inversion induced by immersion precipitation in a water-coagulation bath. The morphology of the membranes prepared was studied by scanning electron microscopy (SEM). The permeation performance of the membranes prepared was studied by experiments using pure water and bovine serum albumin (BSA) solutions as feeds. The results showed that the membrane thickness and pure water flux (PWF) were increased by adding up to 2 wt.% MMT nanoclay to the casting solution. These two parameters decreased with further addition of MMT, however. In addition, the results obtained in the case of filtration of BSA solution indicated that the addition of MMT in the casting solution increased permeate flux and reduced BSA rejection slightly. Furthermore, increasing the MMT nanoclay concentration in the casting solution increased pure water flux recovery and consequently decreased the fouling. Decreasing the CBT in the presence of MMT during membrane preparation resulted in the formation of a more porous structure and consequently increased the flux and simultaneously decreased the BSA rejection.

Dacitic lava recovered from the immediate subsurface of the submarine PACMANUS hydrothermal vent field exhibits variable degrees of hydrothermal alteration resulting from the interaction of the glassy volcanic rocks with mineralizing hydrothermal fluids at relatively low temperatures. Transmission electron microscopic (TEM) investigations revealed that the felsic volcanic glass transformed to nm-thick smectitic flakes of the montmorillonite-beidellite series via a dissolution and reprecipitation mechanism. The process of smectite formation did not proceed through X-ray amorphous or poorly crystalline transitional phases. Alteration of the glass was found to be most pronounced adjacent to perlitic cracks and vesicles that form an interconnected network focusing fluid flow. Glass dissolution adjacent to these fluid pathways resulted in a characteristic alteration texture at the nm scale; the intensely altered groundmass contains round cavities that are partially coated or filled by smectitic flakes. The Mg content of the smectite broadly increases towards the fluid pathways. Smectitic flakes with compositions corresponding to saponite occur in the intensely altered groundmass adjacent to perlitic cracks. In addition, anatase, apatite and rare kaolinite were formed during the alteration of the volcanic glass. Primary minerals including plagioclase show only minor textural evidence of alteration. However, some primary plagioclase laths show X-ray amorphous rims depleted in Na, Ca and Al. The TEM investigations of the dacitic lava samples from the PACMANUS vent field demonstrate that volcanic glass has a higher susceptibility to hydrothermal alteration at low temperatures than most associated primary phases. The findings of the study suggest that the interaction between the volcanic rock and the hydrothermal fluids proceeded under open-system conditions leading to a mobilization of alkali elements and a redistribution of Ti at the nm scale. The Mg required for the formation of trioctahedral smectite was supplied by the hydrothermal fluids.

Studies of the paragenesis of authigenic illite in arkosic sandstones of various regions and ages have revealed that the illitization of kaolinite is an important reaction accounting for the formation of authigenic illite in sandstones during burial diagenesis. The illitization of kaolinite takes place at an intermediate burial depth of 3–4 km, where pressure can reach values of 100 MPa (≈ 1000 bars). The purpose of the present study was to analyze the effect of pressure on the rate of kaolinite illitization in alkaline conditions. Hydrothermal reactions were conducted on KGa-1b kaolinite in KOH solution at 300°C and under pressures of 500, 1000, and 3000 bars for 1 to 24 h. The visual examination of the X-ray diffraction (XRD) patterns indicated a notable influence of pressure on the reaction rate. Molar percentages of muscovite/illite formed at each time interval were calculated from the analysis of two diagnostic XRD peaks, representing the 060 reflections of kaolinite and muscovite/illite. The data were modeled to obtain the initial rate of conversion at each pressure. The results indicated that the initial rate of kaolinite to muscovite/illite conversion is one order of magnitude greater at 3000 bars than at 500 or 1000 bars. Comparison of these data with those in the literature show a faster conversion rate (several orders of magnitude) in an initially high-alkaline solution than in a near-neutral solution.

For more than forty years, The Clay Minerals Society has dispensed a set of source clays which have enabled a large number of researchers to work on similar materials. Many of these source clays remained unchanged over the years but, conversely, other clays have gone out of stock and thus were replaced. This was the fate of montmorillonite STx-1a, which was replaced by STx-1b. Although STx-1a and STx-1b share many basic chemical and mineralogical features, some minor differences exist that can affect behavior. A baseline characterization of the source clay STx-1b, which was the objective of this study, was, therefore, necessary to provide researchers a tool useful not only for new investigation but also to compare new results obtained on STx-1b with literature data on STx-1a. This characterization was gained using traditional and advanced methods that included: 1) chemical composition (major and trace elements); 2) cation exchange capacity determination; 3) thermal analyses coupled with evolved gas mass spectrometry; 4) quantitative mineralogical characterization using powder X-ray diffraction and Rietveld- RIR (Reference Intensity Ratio) refinement; 5) X-ray absorption spectroscopy at the Fe K-edge; 6) diffuse reflectance ultraviolet-visible and infrared spectroscopies; and 7) 29Si, 27Al, and 1H magic-angle spinning nuclear magnetic resonance measurements. According to this multi-analytical approach, the chemical formula for STx-1b is [4](Si7.753Al0.247) [6](Al3.281Mg0.558Fe0.136Ti0.024Mn0.002) [12](Ca0.341Na0.039 K0.061)O20(OH)4.

The competitive adsorption to kaolinite between Cd(II) and four polyaromatic dyes (9-aminoacridine, 3,6-diaminoacridine, azure A and safranin O) was studied in 5 mM KNO3 at 25°C. Under these conditions, Cd adsorbs to the silica face of kaolinite between about pH 4 and 6.5, but at higher pH, adsorbed Cd is progressively relocated to the crystal edges. In the presence of dye, less Cd adsorbed to kaolinite below pH 7. If sufficient dye was added to saturate the kaolinite surface, Cd adsorption was totally suppressed up to ∼pH 6. At higher pH, Cd followed the characteristic pattern for edge adsorption. In separate experiments 9-aminoacridine and azure A displaced pre-adsorbed Cd from kaolinite. The displacement curves were initially linear, with one Cd ion being displaced for every 13 dye molecules adsorbed at pH 5.5, and one Cd ion for every 35 dye molecules at pH 7.5. The interpretation of these results is that the dyes bind to kaolinite much more strongly than Cd(II) does, but only to the silica face.

The crystal chemistry of Ti-rich trioctahedral micas of plutonic origin, cropping out at Black Hill (South Australia) has been investigated by combining electron microprobe analysis, single crystal X-ray diffraction, Mössbauer spectroscopy and X-ray photoelectron spectroscopy. Chemical analyses have shown the samples taken to be quite homogeneous and Ti-rich (TiO2 ≈ 7 wt.%). Mössbauer investigation yielded Fe2+/Fe3+ ≈ 30. X-ray photoelectron spectroscopy analysis seems to suggest the occurrence of three Ti species: octahedral Tr4+(60%), octahedral Ti3+(26%), and tetrahedral Ti4+(14%). The analyzed sample belongs to the 1M polytype and the relevant crystal data from structure analysis are: a = 5.347(1) Å, b = 9.261(2) Å, c = 10.195(2) Å, β = 100.29°(1). Anisotropic structure refinement was performed in space group C2/m, and converged at R = 2.62, Rw = 2.80. Structural details (the c cell parameter, the off-center shift of the M2 cation towards 04, the bond-length distortions of the cis-M2 octahedron, the interlayer sheet thickness, the projection of K−O4 distance along c*, the difference <K−O>outer-<K−O>inner) support the occurrence of the Ti-oxy substitution (VIR2+ + 2(OH)− ⇌ Ti4+ + 202− + H2) in the sample. Analysis of structural distortions as a function of the Ti content revealed that the positions of the oxygens 03 and 04 are displaced in opposite senses along [100]. This produces an enlargement of the M1 site with respect to the M2 site and a shortening of the interlayer distance. This trend seems to be in common with other Ti-rich 1M micas of plutonic origin.

Chemical denudation and chemical weathering rates vary under climatic, bedrock, biotic, and topographic conditions. Constraints for landscape evolution models must consider changes in these factors on human and geologic time scales. Changes in nutrient dynamics, related to the storage and exchange of K+ in clay minerals as a response to land use change, can affect the rates of chemical weathering and denudation. Incorporation of these changes in landscape evolution models can add insight into how land use changes affect soil thickness and erodibility. In order to assess changes in soil clay mineralogy that result from land-use differences, the present study contrasts the clay mineral assemblages in three proximal sites that were managed differently over nearly the past two centuries where contemporary vegetation was dominated by old hardwood forest, old-field pine, and cultivated biomes. X-ray diffraction (XRD) of the oriented clay fraction using K-, Mg-, and Na-saturation treatments for the air-dried, ethylene glycol (Mg-EG and K-EG) solvated, and heated (100, 350, and 550°C) states were used to characterize the clay mineral assemblages. XRD patterns of degraded biotite (oxidized Fe and expelled charge-compensating interlayer K) exhibited coherent scattering characteristics similar to illite. XRD patterns of the Mg-EG samples were, therefore, accurately modeled using NEWMOD2® software by the use of mineral structure files for discrete illite, vermiculite, kaolinite, mixed-layer kaolinite-smectite, illite-vermiculite, kaolinite-illite, and hydroxy-interlayered vermiculite. The soil and upper saprolite profiles that formed on a Neoproterozoic gneiss in the Calhoun Experimental Forest in South Carolina, USA, revealed a depth-dependence for the deeply weathered kaolinitic to the shallowly weathered illitic/vermiculitic mineral assemblages that varied in the cultivated, pine, and hardwood sites, respectively. An analysis of archived samples that were collected over a five-decade growth period from the pine site suggests that the content of illite-like layers increased at the surface within 8 y. Historical management of the sites has resulted in different states of dynamic equilibrium, whereby deep rooting at the hardwood and pine sites promotes nutrient uplift of K from the weathering of orthoclase and micas. Differences in the denudation rates at the cultivated, pine, and hardwood sites through time were reflected by changes in the soil clay mineralogy. Specifically, an increased abundance of illite-like layers in the surface soils can serve as a reservoir of K+.