Ag/TiO<Subscript>2</Subscript>/EP: a low-cost and floating plasmonic photocatalyst for degrading furfural under visible light irradiation

A low-cost visible light-driven silver/titanium oxide/expanded perlite (Ag/TiO₂/EP) as a floating plasmonic photocatalyst is fabricated by a simple hydrolysis method. Photocatalytic properties of Ag/TiO₂/EP have been studied by scanning electron microscope, X-ray diffraction, UV–Vis (DRS), EDAX, FTIR, chemiluminescence, photoluminescence and X-ray photoelectron spectroscopy methods. The photocatalytic activity of resulting Ag/TiO₂/EP with different Ag contents (3 and 5%) was evaluated by its ability to degrade furfural solution under visible light irradiation. The Ag/TiO₂/EP exhibits wide absorption in the visible light region and shows visible light-driven photocatalytic activities in furfural degradation compared with TiO₂/EP photocatalyst. The Ag/TiO₂/EP (5%) was the best concentration of photocatalyst dosage with almost 80% furfural degradation under visible light. The antibacterial character of Ag/TiO₂/EP with different Ag contents has been tested against Escherichia Coli under visible light. The photocatalytic activity of Ag/TiO₂/EP can be attributed to the plasmonic effect of silver in the separation of photoinduced electrons and holes in resulting photocatalyst. The Ag/TiO₂/EP (5%) as a floating photocatalyst combined with its ability to absorb visible light makes it of significant interest for the purification of industrial wastewater.     

Catalytic nonthermal plasma reactor for the abatement of low concentrations of benzene

Oxidative decomposition of dilute benzene in air was carried out in a dielectric barrier discharge reactor with inner metal fiber electrode that was later modified with transition metal oxides. Typical results indicated the best performance of the designed reactor for the removal of dilute benzene, where conventional techniques may not be efficient. The introduction of transition metal oxides in the discharge zone increased the conversion of benzene and shifted the product distribution to total oxidation. The performance of the reactor was further improved on humidification of air stream. The better performance of MnO_x/SMF over CoO_x and SMF may be due to in situ decomposition of ozone that may lead to the formation of strong oxidant atomic oxygen, whereas the best performance with TiO₂/MnO_x/SMF may be assigned due to the synergy between ozone decomposition on MnO_x surface and photocatalytic action on TiO₂.     

Sorption of uranyl and arsenate on SiO2, Al2O3, TiO2 and FeOOH

Migration of uranium and arsenic in aquatic environments is often controlled by sorption on minerals present along the water flow path. To investigate the sorption behaviour, batch experiments were conducted for uranium and arsenic as single components and also solutions containing both uranium and arsenic in the presence of SiO₂, Al₂O₃, TiO₂ and FeOOH at a pH ranging from 3 to 9. In solutions containing only U(VI) or As(V) with the minerals, the sorption of U(VI) was low at acidic pH range and increases with increasing pH, whereas As(V) showed opposite sorption behaviour to Al₂O₃, TiO₂ and FeOOH from acidic pH range to alkaline condition. For the As(V)–SiO₂ system, the sorption was low for almost all pH. Sorption of U(VI) and As(V) on SiO₂ and FeOOH is almost similar in solutions containing either U(VI) or As(V) separately, or both together. In the U(VI)–As(V)–Al₂O₃ system, a significant retardation in uranyl sorption and an enhancement in arsenate sorption on Al₂O₃ were observed for a wide range of pH. The sorption behaviour of U(VI) and As(V) was changed when Al₂O₃ was replaced by TiO₂, where an increase in sorption was observed for both elements. The sorption behaviour of uranyl and arsenate in the U(VI)–As(V)–TiO₂ system gives evidence for the formation of uranyl–arsenate complexes. The change in sorption retardation/enhancement of U(VI) and As(V) could be explained by the formation of uranyl–arsenate complexes or due to the competitive sorption between uranyl and arsenate species.     

Comparative study on the photodegradation of Indigo Caramine dye using commercial TiO<Subscript>2</Subscript> and natural rutile

The photocatalytic degradation of Indigo Caramine dye using commercial TiO₂ and fine grained natural rutile has been carried out. The commercial TiO₂ and natural rutile were characterized using powder X- ray diffraction (XRD) and Fourier transformed infra red spectroscopy (FTIR). The study on the photodegradation of Indigo Caramine dye using commercial TiO₂ and natural rutile were investigated both under Solar and UV irradiation. The degradation of Indigo Caramine dye was checked by the following parameters like Chemical Oxygen Demand (COD), %T, irradiation time and duration. In both cases using commercial TiO₂ and natural rutile, the COD of the dye solution was reduced from 288 mg/L to less than 20 mg/L, and similarly the %T was increased from 76% to 97% and the percentage decomposition upto 97% within the irradiation duration of 3.5 hrs. The preliminary results obtained on the photodegradation of Indigo Caramine dye are highly encouraging and further work is being carried out for the use of the natural rutile or anatase sources for the other organic decomposition and treatment of industrial effluents.     

Enhancing splitting tensile strength of biocarbonated reactive magnesia-based sand using polypropylene fiber reinforcement

This short communication investigates the involvement of polypropylene fibers in the biocarbonated reactive magnesia cement mixes to improve the splitting tensile strength of sand for soil improvement. By varying the RMC content (5 and 10% by weight of sand) and fiber content (0, 0.5, and 1% by weight of sand), a suitable mix design was determined. The test results showed that the peak tensile strength of biocarbonated RMC-based sand samples with an optimum fiber content of 1% could improve by more than 4 times compared to the biocarbonated sand without fiber reinforcement. This was attributed to the generation of hydrated magnesium carbonates with the microbially induced CO₂/carbonate process, bonding the fiber–matrix and eliminating the brittleness, consequently enhancing the tensile ductility of biocarbonated sand.

     

Photocatalytic ozonation of 2, 4-dichlorophenoxyacetic acid in water with a new TiO2 fiber

More effective techniques are required to mineralize the increasing number of recalcitrant organic contaminants at low concentrations in the water environment using advanced oxidation process. Though relatively new, photocatalytic ozonation (O₃/UV/TiO₂) is considered superior to ozonation (O₃) and photocatalysis (UV/TiO₂), due to synergistic effects and use of immobilized TiO₂ photocatalysts is a milestone in advance oxidation process. This article aimed to elucidate 2, 4-dichlorophenoxyacetic acid (2, 4-D) mineralization characteristics in low aqueous solutions by O₃/UV/TiO₂ using the world’s first high-strength TiO₂ fiber catalyst in laboratory experiments. 2, 4-D degradation and TOC removal in O₃, UV/TiO₂ and O₃/UV/TiO₂ followed pseudo-first order reaction kinetic. The removal rates for 2, 4-D and TOC in O₃/UV/TiO₂ were respectively about 1.5 and 2.4-fold larger than the summation of the corresponding values in O₃ and UV/TiO₂. The O₃/UV/TiO₂ process was characterized by short-lived few aromatic intermediates, faster degradations of aliphatic intermediates and dechlorination as a major step in 2, 4-D mineralization. The significantly enhanced 2, 4-D mineralization in the process was attributed to increased ozone decomposition and reduced electron-hole recombination on TiO₂ surface resulting to a large number of OH generation. The O₃/UV/TiO₂ process with the TiO₂ fiber catalyst was very promising with respect to the major challenges being faced in AOP involving TiO₂, namely separation of powder catalyst in suspension and reduced efficiency of immobilized catalysts (e.g. TiO₂ film/fiber).     

Magnetic,chemical and x-ray studies of magnetites from Tamil Nadu,India

Natural intensity, susceptibility, and Koenigsberger ratio were determined and studies of Rayleigh loops, and high field hysteresis, and variation of susceptibility with temperature from ?196° C to Curie temperature were made on a number of magnetite-quartzite and pyroxene, granulite samples from Tamil Nadu. FeO, Fe₂O₃, and TiO₂ proportions were estimated and cell dimensions were determined. From the magnetic studies it is inferred that in general the samples contain predominantly multidomain grains. In a few cases single-domain particles are detected, while in a few other samples a mixture of superparamagnetic particles and single domain states could be inferred. The relative remanence ratio is found to increase with coercive force. The ferromagnetic mineral in magnetite-quartzites is pure magnetite with a little alteration to hematite while in pyroxene granulites it is a titaniferous magnetite with a small percentage of TiO₂. It is probable that the cell dimensions are dependent on oxidation in magnetites, and on the content of TiO₂ in titaniferous magnetites.     

Cadmium (II) distribution in complex aquatic systems containing ferrihydrite, bacteria and an organic ligand: The effect of bioactivity

The distribution of Cd²⁺ in the presence of phthalic acid (H₂L_p), ferrihydrite and bacteria (Comamonas spp.) was investigated in biologically active systems involving H₂L_p biodegradation. Tests showed that Cd²⁺ sorption onto bacteria, ferrihydrite and bacteria-ferrihydrite mixture increased with pH in all systems, irrespective of H₂L_p degradation or not. The use of bacterial growth medium, Bushnell Hass Broth modified for low phosphate, had negligible effect on Cd sorption. In the presence of ferrihydrite, no difference was observed between Cd²⁺ sorption in the ferrihydrite-live bacteria and in the ferrihydrite-dead bacteria systems as ferrihydrite proved to be the dominant sorption phase. Cadmium sorption to ferrihydrite and to bacterial cells was described using the diffuse layer model and a nonelectrostatic 4-site model, respectively, which were developed for systems lacking H₂L_p degradation. For systems experiencing H₂L_p degradation this modeling approach predicted the general trend of Cd²⁺ sorption-edge shift and gave good fits to the observed sorption data. The results obtained demonstrate that Cd²⁺ sorption in the biologically active system was reasonably estimated by a model developed for biologically inactive systems, although uncertainty exists due to processes involving H₂L_p biodegradation products and changes in the bacterial population.     

Adsorption of molybdenum on to anatase from dilute aqueous solutions

Adsorption of Mo on to hydrous TiO₂ (anatase) particles was investigated. Batch experiments were conducted at 19 and 90 °C over a pH range of 2 to 12 and Mo concentrations ranging from approximately 10⁻⁶ to 10⁻⁴ M. The extent of sorption was strongly dependent on pH and surface loading. Maximum sorption was observed in the acidic pH range at low surface loading. Adsorption behavior was described using the empirical Langmuir adsorption model. A constant capacitance surface complexation model was also used to fit the adsorption isotherms using a ligand exchange reaction for a hydroxyl surface site on anatase. Comparison of experimental data at two different temperatures (19 and 90 °C) indicates that Mo sorption in the acidic pH range decreases with increasing temperature.     

Mineralogy, Chemical Characteristics and Upgrading of Beach Ilmenite of the Top Meter of Black Sand Deposits of the Kafr Al-Sheikh Governorate, Northern Egypt

Egyptian beach ilmenite occurs in a relatively high content in the naturally highly concentrated superficial black sand deposits at specific beach zones in the northern parts of the Nile Delta at Rosetta. Microscopic study shows that the ilmenite occurs as fresh homogeneous black or heterogeneous multicoloured altered grains and exhibits three types (homogeneous, exsolved and altered) of ilmenite varieties. XRD data of ilmenite indicates their association with minor hematite and quartz, whereas leucoxene shows its association with Nb‐rutile, pseudorutile and hematite. Grain size distribution suggests a very fine sand size of >89% and 80% and a fine sand size of 10.5% and 18.3% for fresh and altered ilmenites, respectively. The density of fresh, altered ilmenite and leucoxene concentrates varies from 2.70, 2.50 to 2.40 ton/m³, suggesting a gradual decrease from high grade fresh to leucoxene and consistent with variation in magnetic susceptibility as a consequence of the leaching of iron. Mass magnetic susceptibility reveals 97.6% of ilmenite and 92% of the altered form are obtained at 0.20 and 0.48 ampere. Fresh ilmenite exhibits variable TiO₂ (47.18%) and Fe₂O₃^T (46.10%) with minor MnO, MgO and Cr₂O₃ (1.22, 1.10 and 0.51%). The altered ilmenite is higher in TiO₂ (76.16%) and SiO₂ (4.68%) and lower in Fe₂O₃^T (14.45%), MnO, MgO and Cr₂O₃ (0.39, 0.52 and 0.11%) compared with the fresh form. Three concentrates of ilmenites (G1, G2 and G3) were prepared from crude ore using a Reading cross belt magnetic separator under different conditions, revealing a gradual increase of TiO₂, SiO₂, Al₂O₃ and CaO accompanied by a decrease of Fe₂O₃^T, MgO and Cr₂O₃ with repetition of the separation processes. Several ore dressing techniques were carried out to upgrade the ilmenite concentrate.     

Analysis of a weathered profile on sulfide mineralization at Mugga Mugga, Western Australia

The mineralogy and geochemistry of the massive pyrite-pyrrhotite mineralization, which contains minor magnetite, sphalerite and galena, the weathered profile and surface gossan at Mugga Mugga in Western Australia have been examined. Reactions between amphibolite wall rocks and acid waters from the oxidation of the iron sulfides have resulted in distinct mineralogical zonation of the weathered profile which is further modified near the surface by lateritization. At the base of the weathered zone an opaline chert (Opal-CT) has been precipitated from fluctuations of the water table. A gossanous zone from 25.14–68.80 m with boxworks after massive pyrite is modified by abundant kaolinite, dickite and an alunite-type mineral derived from amphibolite wall rocks, while above 25.14 m both plinthite and mottled clay zones of a laterite profile are evident. Some characteristics of a mature gossan profile – sulfate-phosphate-arsenate near the base, a carbonate zone higher in the profile, and an oxide zone near the surface – overprint the gross zonation.At the interface between sulfide and weathered rock Mg, Ca, K, S, Zn, Cd, Hg, Ba are depleted, As, Sb, Mo, Cr and V contents increase and in the weathered zone, SiO₂, TiO₂, P₂O₅, SO₃, Pb, Zn, Hg, Sb, Co, Ni, W, Ba, Sr and Zr decrease up the profile whilst Al₂O₃, Fe₂O₃, CO₂, Cu and As increase. Of the elements associated with the massive pyrite (Pb, Zn, Cu, Ag, As, Cd, Hg, Sb, Co, Ni) anomalous concentrations of Pb, Cu, Ag, As and Sb occur in the surface gossan despite the possibility of complete leaching by highly acidic solutions. These anomalies are similar to those found in gossans over pyrite mineralization elsewhere in the Yilgarn Block.     

Manufactured metal and metal-oxide nanoparticles: Properties and perturbing mechanisms of their biological activity in ecosystems

The inorganic manufactured nanoparticles as TiO₂, Ag°, the iron oxides and CeO₂ are more and more present in various manufactured products and in the aqueous media (TiO₂). Their dispersion in the ecosystems during their life cycle will be associated with interactions with biota (plants, bacteria, fishes). The present work shows strong relations between particular physical chemical properties of very small nanoparticles (size < 30 nm) and biological activity perturbations. It is shown that Ag° and CeO₂ act at very low concentrations. TiO₂ act via the ROS production due to their photo-reactivity.     

Lithogeochemistry of hypogene, supergene and leached cap samples, berg porphyry copper deposit, British Columbia

In this paper we examine the influence of the development of supergene oxide and sulphide zones on the original hypogene geochemical patterns at the Berg deposit, British Columbia.The deposit, in the alpine zone of the Tahtsa Range, was logged (GEOLOG) and sampled in fourteen diamond drill holes along a N—S section and from outcrop where possible. Anomalous populations of major and trace elements were defined using log probability graphs and a sequential extraction (10% hydrochloric acid— ammonium oxalate — potassium chlorate/hydrochloric acid — nitric/perchloric acids) was used to study the distribution of elements between carbonate, oxide, sulphide and silicate phases.Core logs and assays show that primary ore minerals (chalcopyrite—molybdenite) extend from the outer part of the porphyry intrusion into the surrounding hornfels where the best grades of copper are found close to the intrusive contact. Maximum copper grades, however, result from development of a supergene enrichment blanket. Within the hypogene zone, principal lithogeochemical patterns reflect the differences in composition of the hornfels, originally intermediate to basic volcanics, and the intrusion, as well as the introduction of F and trace metals (Cu, Mo, Pb, Zn and Ag). Distribution of Ag is broadly comparable to that of Cu and Mo whereas anomalous Pb and Zn are present as peripheral haloes around the potential ore zones.Emergence of strongly acidic ground water and precipitation of iron oxides, indicate that leaching processes are active. Furthermore, although primary sulphides, associated with both their oxidation products and secondary sulphides, can still be found in surface samples, sequential extractions on drill core clearly indicate vertical redistribution of copper between oxide, carbonate and sulphide phases. Using ratios of metal concentrations to TiO₂, the surface concentrations of trace metals can be compared with those at depth and the relative amount of enrichment or depletion can be quantified. In highly leached sites the absolute concentrations of Cu, Mn and Zn are low which is reflected in TiO₂ ratios of <1. However, Mo, Pb and Ag are enriched at the same sites (TiO₂ ratios >1). In areas where physical erosion exceeds leaching (topographic lows) primary sulphides co-exist with secondary sulphide and oxide minerals. Here Cu, Mo, Pb, Zn, Mn and Ag are enriched. Fluorine is relatively unaffected by the leaching process. It would appear signature for a cale alkaline Cu and Mo porphyry deposit in an area where outcrop was intensely leached.     

Impacts of hydrous manganese oxide on the retention and lability of dissolved organic matter

Minerals constitute a primary ecosystem control on organic C decomposition in soils, and therefore on greenhouse gas fluxes to the atmosphere. Secondary minerals, in particular, Fe and Al (oxyhydr)oxides—collectively referred to as “oxides” hereafter—are prominent protectors of organic C against microbial decomposition through sorption and complexation reactions. However, the impacts of Mn oxides on organic C retention and lability in soils are poorly understood. Here we show that hydrous Mn oxide (HMO), a poorly crystalline δ-MnO₂, has a greater maximum sorption capacity for dissolved organic matter (DOM) derived from a deciduous forest composite O_i, O_e, and O_a horizon leachate (“O horizon leachate” hereafter) than does goethite under acidic (pH 5) conditions. Nonetheless, goethite has a stronger sorption capacity for DOM at low initial C:(Mn or Fe) molar ratios compared to HMO, probably due to ligand exchange with carboxylate groups as revealed by attenuated total reflectance-Fourier transform infrared spectroscopy. X-ray photoelectron spectroscopy and scanning transmission X-ray microscopy–near-edge X-ray absorption fine structure spectroscopy coupled with Mn mass balance calculations reveal that DOM sorption onto HMO induces partial Mn reductive dissolution and Mn reduction of the residual HMO. X-ray photoelectron spectroscopy further shows increasing Mn(II) concentrations are correlated with increasing oxidized C (C=O) content (r = 0.78, P < 0.0006) on the DOM–HMO complexes. We posit that DOM is the more probable reductant of HMO, as Mn(II)-induced HMO dissolution does not alter the Mn speciation of the residual HMO at pH 5. At a lower C loading (2 × 10² μg C m^?2), DOM desorption—assessed by 0.1 M NaH₂PO₄ extraction—is lower for HMO than for goethite, whereas the extent of desorption is the same at a higher C loading (4 × 10² μg C m^?2). No significant differences are observed in the impacts of HMO and goethite on the biodegradability of the DOM remaining in solution after DOM sorption reaches steady state. Overall, HMO shows a relatively strong capacity to sorb DOM and resist phosphate-induced desorption, but DOM–HMO complexes may be more vulnerable to reductive dissolution than DOM–goethite complexes.     

The effect of titanium and phosphorus on ferric/ferrous ratio in silicate melts: an experimental study

The effect of TiO₂ and P₂O₅ on the ferric/ferrous ratio in silicate melts was investigated in model silicate melts at air conditions in the temperature range 1,400–1,550 °C at 1-atm total pressure. The base composition of the anorthite–diopside eutectic composition was modified with 10 wt % Fe₂O₃ and variable amounts of TiO₂ (up to 30 wt %) or P₂O₅ (up to 20 wt %). Some compositions also contained higher SiO₂ concentrations to compare the role of SiO₂, TiO₂, and P₂O₅ on the Fe³⁺/Fe²⁺ ratio. The ferric/ferrous ratio in experimental glasses was analyzed using a wet chemical technique with colorimetric detection of ferrous iron. It is shown that at constant temperature, an increase in SiO₂, TiO₂, and P₂O₅ content results in a decrease in the ferric/ferrous ratio. The effects of TiO₂ and SiO₂ on the Fe³⁺/Fe²⁺ ratio was found to be almost identical. In contrast, adding P₂O₅ was found to decrease ferric/ferrous ratio much more effectively than adding silica. The results were compared with the predictions from the published empirical equations forecasting Fe³⁺/Fe²⁺ ratio. It was demonstrated that the effects of TiO₂ are minor but that the effects of P₂O₅ should be included in models to better describe ferric/ferrous ratio in phosphorus-bearing silicate melts. Based on our observations, the determination of the prevailing fO₂ in magmas from the Fe³⁺/Fe²⁺ ratio in natural glasses using empirical equations published so far is discussed critically.     

Impact of highly basic solutions on sorption of Cs to subsurface sediments from the Hanford site, USA

The effect of caustic NaNO₃ solutions on the sorption of ¹³⁷Cs to a Hanford site micaceous subsurface sediment was investigated as a function of base exposure time (up to 168 d), temperature (10°C or 50°C), and NaOH concentration (0.1 mol/L to 3 mol/L). At 10°C and 0.1 M NaOH, the slow evolution of [Al]_aq was in stark contrast to the rapid increase and subsequent loss of [Al]_aq observed at 50°C (regardless of base concentration). Exposure to 0.1 M NaOH at 10°C for up to 168 d exhibited little if any measurable effect on sediment mineralogy, Cs⁺ sorption, or Cs⁺ selectivity; sorption was well described with a two-site ion exchange model modified to include enthalpy effects. At 50°C, dissolution of phyllosilicate minerals increased with [OH]. A zeolite (tetranatrolite; Na₂Al₂Si₃O₁₀·2H₂O) precipitated in 0.1 M NaOH after about 7 days, while an unnamed mineral phase (Na₁₄Al₁₂Si₁₃O₅₁·6H₂O) precipitated after 4 and 2 days of exposure to 1 M and 3 M NaOH solutions, respectively. Short-term (16 h) Cs⁺ sorption isotherms (10⁻⁹-10⁻² mol/L) were measured on sediment after exposure to 0.1 M NaOH for 56, 112, and 168 days at 50°C. There was a trend toward slightly lower conditional equilibrium exchange constants (Δlog _Na^CsK_c ∼ 0.25) over the entire range of surface coverage, and a slight loss of high affinity sites (15%) after 168 days of pretreatment with 0.1 M base solution. Cs⁺ sorption to sediment over longer times was also measured at 50°C in the presence of NaOH (0.1 M, 1 M, and 3 M NaOH) at Cs⁺ concentrations selected to probe a range of adsorption densities. Model simulations of Cs⁺ sorption to the sediment in the presence of 0.1 M NaOH for 112 days slightly under-predicted sorption at the lower Cs⁺ adsorption densities. At the higher adsorption densities, model simulations under-predicted sorption by 57%. This under-prediction was surmised to be the result of tetranatrolite precipitation, and subsequent slow Na → Cs exchange. At higher OH concentrations, Cs⁺ sorption in the presence of base for 112 days was unexpectedly equal to, or greater than that expected for pristine sediment. The precipitation of secondary phases, coupled with the fairly unique mica distribution and quantity across all size-fractions in the Hanford sediment, appears to mitigate the impact of base dissolution on Cs⁺ sorption.     

Decolorization of simulated spent reactive dye bath using solar / TiO2 / H2O2

Different parameters were investigated to evaluate their effect on the process removal efficiency of reactive dye from simulated spent reactive dye bath, by solar / TiO₂ / H₂O₂, including H₂O₂ concentration, TiO2 loading and pH. As a result 99% of reactive dye can be removed at a TiO₂ loading of 400mg/l, H₂O₂ concentration of 150 mg/l and of pH: 5.2. The effect of photo-catalytic deactivation of TiO₂ on reactive dye removal was studied for ten number of cycles, and found that the extent of deactivation was high for each consecutive repeated use.     

Supercritical gas sorption on moist coals

The effect of moisture on the CO₂ and CH₄ sorption capacity of three bituminous coals from Australia and China was investigated at 55 °C and at pressures up to 20 MPa. A gravimetric apparatus was used to measure the gas adsorption isotherms of coal with moisture contents ranging from 0 to about 8%. A modified Dubinin–Radushkevich (DR) adsorption model was found to fit the experimental data under all conditions. Moisture adsorption isotherms of these coals were measured at 21 °C. The Guggenheim–Anderson–de Boer (GAB) model was capable of accurately representing the moisture isotherms over the full range of relative pressures.Moist coal had a significantly lower maximum sorption capacity for both CO₂ and CH₄ than dry coal. However, the extent to which the capacity was reduced was dependent upon the rank of the coal. Higher rank coals were less affected by the presence of moisture than low rank coals. All coals exhibited a certain moisture content beyond which further moisture did not affect the sorption capacity. This limiting moisture content was dependent on the rank of the coal and the sorbate gas and, for these coals, corresponded approximately to the equilibrium moisture content that would be attained by exposing the coal to about 40–80% relative humidity. The experimental results indicate that the loss of sorption capacity by the coal in the presence of water can be simply explained by volumetric displacement of the CO₂ and CH₄ by the water. Below the limiting moisture content, the CO₂ sorption capacity reduced by about 7.3 kg t^− 1 for each 1% increase in moisture. For CH₄, sorption capacity was reduced by about 1.8 kg t^− 1 for each 1% increase in moisture.The heat of sorption calculated from the DR model decreased slightly on addition of moisture. One explanation is that water is preferentially attracted to high energy adsorption sites (that have high energy by virtue of their electrostatic nature), expelling CO₂ and CH₄ molecules.     

Basalts as probes of planetary interiors: Constraints on the chemistry and mineralogy of their source regions

Basalt magmas, derived by the partial melting of planetary interiors, have compositions that reflect the pre-accretionary history of the material from which the planet formed, the planets, subsequent evolutionary history, the chemistry and mineralogy of the source regions, and the intensive thermodynamic parameters operating at the source and emplacement sites. Studies of basalt suites from the Earth, its Moon, and the eucrite parent body reveal compositional differences intrinsic to their source regions which are, in turn, a characteristic of the planet and its formational and evolutionary history.Major interplanetary differences are observed in iron, , TiO₂, Al₂O₃, Na₂O, Cr, Ni, and in volatile element abundances. The most primitive mare basalts have Mg#s 0.6, on the Earth they are 0.70–0.72 for mid-ocean ridge basalts (MORBs) and up to 0.9 for Archean peridotitic komatiites. Eucrites have Mg#s approaching 0.5 (excepting Binda). These differences reflect inherent differences in of their sources. Striking differences in the TiO₂ abundances of the planetary basalts reflect both inter- and intra-planetary variations in source chemistry. Primitive MORBs and primitive oceanic intraplate tholeiites have a factor of 2–3 difference in TiO₂ at comparable Mg# (0.7–1.2 vs 2–3 wt.% respectively). Three major titania groups are recognized in the mare suite; high TiO₂ (8–13 wt.%), low TiO₂ (2–5 wt.%) and very low TiO₂ (<1 wt.%). The eucrites have TiO₂ contents <1 wt.%.The mare basalts and eucrites have pronounced Na₂O depletion relative to all terrestrial basalts. This is a consequence of the preplanetary accretion loss of volatiles from the material that formed the Moon and the eucrite parent bodies.Mare basalts have consistently lower Al₂O₃ contents than the terrestrial basalts. This may be due either to an inherently lower content of Al₂O₃ in the mare sources or it may reflect Al₂O₃ retention in an aluminous phase.The transition metals are fractionated in all three basalt suites. For terrestrial basalts this may reflect core-separation; however, in the case of the Moon and eucrite parent bodies pre-accretionary separation of metal and silicates is a more reasonable explanation. A pronounced Cr anomaly is observed in terrestrial MORBs but not in the mare basalts. This appears to be related to f_O2 differences in the respective mantles.Overall rare earth element abundances are comparable between all three objects. Mare basalts have a pronounced negative Eu anomaly which is inherited from their source region and is record of plagioclase removal from crystallizing magma ocean early in lunar history (4.4–4.6 Ga). Early separation of plagioclase on the Earth appears to have been a relatively unimportant process.     

Zersetzung von Kalk-Alkali-Gesteinen im rezenten Fumarolengebiet auf Nea Kameni/Santorin/Griechenland

In the present phase of the volcanic activity on Nea Kameni / Santorini / Greece the calc-alkalic volcanic rocks are decomposed by H₂O, CO₂ and SO₂ gases of about 100 °C. Using a method ofGresens (1967) for the determination of gains and losses of compounds five different processes could be distinguished:

1. leaching of compounds
2. enrichment of Ca as gypsum
3. increase of Fe₂O₃ (6%–11%), TiO₂ (0,8%–3%) and Zr
4. enrichment of Al₂O₃ (15%–29%), TiO₂ (0,8%–1,5%) and K
5. increase of Al₂O₃ (15%–26%), Fe₂O₃ (6%–9%), TiO₂ (0,8%–1,3%), Sr, Ba, Pb and Zr

Finally a model for the process of decomposition of calc-alkalic volcanic rocks by sulfuric acid was developed.