Al Hydroxide Research Articles

Surface Stoichiometry and Roughness of a Degraded A380 Alloy after Casting, Technical Cleaning and Packaging.

The surface stoichiometry of the degraded surface of a commercial Al–Si casting was investigated. The die-cast component was previously stored in a sealed plastic envelope. After that, surface stains in the form of white layers were observed. X-ray photoelectron spectroscopy (XPS) was used to study these layers. For comparison, a seemingly unaffected area as well as a freshly cut surface of the casting were also analysed. In order to additionally assess the surface condition, surface roughnesses were measured. Based on the binding energies (BEs) of the Al and O in the XPS spectra, and the stoichiometric results, it was concluded that the surface layers of the degraded and undegraded samples consist mostly of aluminium oxide and aluminium hydroxide. Furthermore, sodium phosphate from the leftover detergent and silicon oxide were detected in both analysed areas. Analyses of the Al KLL Auger transition were used to corroborate this. The relative shares of Al oxide vs. hydroxide based on the elemental concentrations were determined. The chemical compositions and chemical states of the elements in the top layers were thus obtained. The combination of surface-sensitive analytical techniques was found to be a suitable tool for the ex-post identification of the source of defects.

Exploration Implications of Multiple Formation Environments of Advanced Argillic Minerals

Abstract Advanced argillic minerals, as defined, include alunite and anhydrite, aluminosilicates (kaolinite, halloysite, dickite, pyrophyllite, andalusite, zunyite, and topaz), and diaspore. One or more of these minerals form in five distinctly different geologic environments of hydrolytic alteration, with pH 4–5 to <1, most at depths <500 m. (1) Where an intrusion-related hydrothermal system, typical of that associated with porphyry Cu ± Au deposits, evolves to white-mica stability, continued ascent and cooling of the white-mica–stable liquid results in pyrophyllite (± diaspore) becoming stable near the base of the lithocap. (2) A well-understood hypogene environment of formation is vapor condensation near volcanic vents, where magmatic SO2 and HCl condense into local groundwater to produce H2SO4 and HCl-rich solutions with a pH of 1–1.5. Close to isochemical dissolution of the host rock occurs because of the high solubility of Al and Fe hydroxides at pH <2, except for the SiO2 component, which remains as a siliceous residue because of the relatively low solubility of SiO2. This residual quartz, commonly with a vuggy texture, is largely barren of metals because of the low metal content in high-temperature but low-pressure volcanic vapor. Rock dissolution causes the pH of the acidic solution to increase, such that alunite and kaolinite (or dickite or pyrophyllite at higher temperatures) become stable, forming a halo to the residual quartz. This initially barren residual quartz, which forms a lithocap horizon where permeable lithologic units are intersected by the feeder structure, may become mineralized if a subsequent white-mica–stable liquid ascends to this level and precipitates copper and gold. (3) Boiling of a hydrothermal liquid generates vapor with CO2 and H2S. Where the vapor condenses above the water table, atmospheric O2 in the vadose (unsaturated) zone causes oxidation of H2S to sulfuric acid, forming a steam-heated acid-sulfate solution with pH of 2–3. In this environment, kaolinite and alunite form in horizons above the water table at <100°C. Silica derived within the vadose zone will precipitate as amorphous silica at the water table, as the condensate follows the hydraulic gradient, causing opal replacement above and at the aquifer. (4) By contrast, where condensation of this vapor occurs below the water table, the CO2 in solution forms carbonic acid (H2CO3), leading to a pH of 4–5. This marginal carapace of condensate, with temperatures up to 150°–170°C, commonly acts as a diluent of the ascending parental NaCl liquid. This steam-heated liquid forms intermediate argillic alteration of clays, kaolinite, and Fe-Mn carbonates; this kaolinite, which can be present at depths of several hundreds of meters, can potentially be mistaken as having been caused by a steam-heated acid-sulfate or supergene overprint. (5) The final setting is supergene, caused by posthydrothermal weathering and oxidation of mainly pyrite, locally creating pH <1 liquid because of high concentrations of H2SO4 within the vadose zone and forming kaolinite, alunite, and Fe oxyhydroxides. This genetic framework of formation environments of advanced (and intermediate) argillic alteration provides the basis to interpret alteration mineralogy, in combination with alteration textures and morphology plus zonation, including the overprint of one alteration style on another. This framework can be used to help focus exploration for and assessment of hydrothermal ore deposits, including epithermal, porphyry, and volcanic-hosted massive sulfide.

Combined Use of Calciprill and Sodium Silicate Improves Chemical Properties of Low-pH Soil

The highly weathered, acidic tropical soils are generally less fertile because of their low pH, high exchangeable acidity, and Al, Fe, and Mn saturations. Using soil amendments to solve the aforementioned problems is essential. To this end, Calciprill and sodium silicate are worth considering because of their high neutralizing value and dissolution to suppress exchangeable acidity and Al, Fe, and Mn hydrolysis, while at the same time increasing soil pH to improve the availability of inorganic N, available P, exchangeable base cations, and Effective Cation Exchange Capacity (ECEC). An incubation study was conducted to determine the right combination of Calciprill and sodium silicate to reduce exchangeable acidity and Al and Fe hydrolysis to improve inorganic N, available P, exchangeable base cations availability, and ECEC. Bekenu series (Typic Paleudults) was incubated with a combined use of Calciprill at 80%, 90%, and 100% Ca saturations and sodium silicate at 90, 105, 120, 135, and 150 kg ha−1 for 40, 80, and 120 days, respectively. The laboratory incubation study was carried out using a Completely Randomized Design (CRD) with triplicates to determine the aforementioned treatment effects of the combined use of Calciprill and sodium silicate on soil pH, exchangeable, Al, inorganic N, available P, electrical conductivity, exchangeable cations (K, Ca, Mg, Na, Fe, and Mn), and ECEC using standard procedures. Soils with both amendments significantly increased soil inorganic N, available P, electrical conductivity, exchangeable base cations (K, Ca, Mg, and Na), and ECEC. This was because the amendments increased soil pH by suppressing exchangeable acidity. Moreover, they transformed Al, Fe, and Mn ions into insoluble compounds such as Al and Fe hydroxides and Mn oxides because of their high inherent exchangeable cations, especially Ca and Na. This suggests that the combined use of Calciprill and sodium silicate can enhance soil productivity. The most suitable combination is 7.80 g Calciprill and 9.26 g sodium silicate (C3S5) per one kilogram soil. Additionally, the findings provide fundamental information for future greenhouse and field trials to determine the effects of the suitable combination of the amendments uncovered by this present study on soil health and crop productivity.

Solution 31P NMR Investigation of Inositol Hexakisphosphate Surface Complexes at the Amorphous Aluminum Oxyhydroxide-Water Interface.

Phytate (myo-inositol hexakisphosphate, myo-IHP) is one of the most common organic phosphorus (P) species in soils and sediments which can be mineralized to increase the concentration of dissolved phosphate in pore water. Because of its six phosphate functional groups, functional group-specific adsorption mechanisms in reactive soil minerals become important in predicting solubility. In this study, solution 31P NMR was used to elucidate the functional group-specific adsorption mechanisms of myo-IHP at the amorphous Al hydroxide (AAH)-water interface at pH 6.5 in conjunction with batch adsorption experiments and Zetasizer measurements. The adsorption maximum of myo-IHP with AAH was ∼312.50 mmol kg-1, and the charge reversal effects in IHP-reacted AAH particles suggested the presence of inner-sphere surface species. The upfield shifts of various phosphate groups in the NMR spectra further supported the formation of inner-sphere IHP complexes at the AAH-water interface. When the initial myo-IHP/AAH (mol kg-1) was decreased from 2.5 to 1.25-1.67, P1,3 and P4,6 functional groups were coordinated in addition to P2; P5 became reactive with the ratio being decreased to <0.84, P5. This multifunctional group coordination increased aggregate size. The study showed that the availability of surface sites of adsorbents influenced the functional group-specific myo-IHP adsorption.

Removal of Mn via coprecipitation and sorption by Fe(II), Fe(III), and Al in mine drainage

In mine drainage, Fe and Mn are the two most abundant elements exceeding the discharge criteria. Although Mn removal generally requires a pH exceeding 9.5–10.0, its coprecipitation and sorption by Fe and/or Al can significantly reduce the required pH. In this study, Mn removal efficiencies, mechanisms, and required pH were investigated by experiments involving varying concentrations of Mn, Fe, and Al at different pH, and X-ray photoelectron spectroscopy (XPS) analyses. At pH > 7.9, precipitation as Mn (hydr)oxides was the principal Mn removal process, as indicated by the Mn removal plots, geochemical modeling, and XPS results. The precipitation was highly promoted by the heterogeneous oxidation of Fe and Al hydroxides. Coprecipitation-sorption experiments showed 65–80% lower Mn concentrations than those of sorption experiments at similar dosages and pH near 7.5. Fe(III) exhibited higher coprecipitation efficiency than Fe(II), possibly due to the prior oxidation of Fe(II). Fe(III) also displayed a coprecipitation-sorption efficiency five times more than Al. To decrease the Mn concentrations from 17–25 mg L−1 to <2 mg L−1 by coprecipitation-sorption, Fe(III)/Mn and Fe(II)/Mn ratios of ∼10 and ∼20, respectively, at pH 9.0 were required. Similarly, an Al/Mn ratio of ∼7 at pH 9.0 was required to reduce the Mn concentration to <5 mg L−1. Furthermore, the required Fe/Mn ratio decreased significantly when the initial Mn concentration decreased to 8–11 mg L−1. Utilizing the deduced relationships, required pH for Mn removal could be estimated and the design of Mn treatment facilities can be more efficient.

Enhanced arsenic removal from water by mechanochemical synthesis of Ca–Al–Fe ternary composites

To date, there have been many studies on arsenic removal by the multi-metal Fe/Al oxide compound adsorbents. The various precious metal oxides were usually incorporated to enhance the removal efficiency while increasing the cost of the complex adsorbents remarkably. In this work, the traditional method of adding rare or precious metal oxides was abandoned, high efficiency and low-cost Ca–Al–Fe ternary composite was synthesized through mechanochemical processing and low temperature calcination for the efficient removal of As(III). The SEM-EDS, BET, XPS and TG-DSC were employed to characterize the Ca–Al–Fe ternary composite before and after As(III) adsorption. Moreover, the As(III) removal mechanism and the composition and physical properties of the Ca–Al–Fe ternary composite were also studied. The kinetics study fitted the pseudo-second-order model, and the adsorption isotherm followed the Freundlich model, of which the maximum adsorption capacity up to 56.86 mg/g. The Ca–Al–Fe ternary composite is of high activity and amorphous type, which can be attributed to the Al(III) and freshly generated Fe(III) to generate Fe–Al hydroxide enhancing the high adsorption capacity. The excellent As(III) removal efficiency and reusability of the Ca–Al–Fe ternary composite suggested its vast application prospects as a competitive candidate for As(III) pollution remediation in water.

Layered Double Mg–Al Hydroxides to Dephosphate Municipal Effluents

Layered Double Mg–Al Hydroxides to Dephosphate Municipal Effluents

Liquid metal derived MOF functionalized nanoarrays with ultra-wideband electromagnetic absorption

Low melting point liquid metal alloys are progressively utilized in different research fields due to their unique physicochemical properties. Among them, EGaIn is liquid at room temperature with an excellent solubility for reactive metal atoms such as Al. Combined with their characteristic flexible surface, large area and atomically flat interfaces, a library of two-dimensional materials can be generated. Liquid metal synthesis routes provide a highly reproducible thickness of nanosheets with fast, simple, scalable, inexpensive, high yield and non-toxic methods, especially for Al oxides and hydroxides. At the same time, Al-based heterojunction structure also shows a good application prospect in the field of electromagnetic wave absorption, therefore, the use of liquid metal synthesis methods to find the synthesis methods of Al-based layered double hydroxide (LDH) and its derivatives remains to be explored. In this work, EGaIn was used as an aluminum reservoir to prepare LDH and metal organic framework (MOFs) nano-arrays. The prepared CoAl-LDH@ZIF 67 can be transformed into CoAl-LDO@Co-C in the subsequent annealing process performed under nitrogen environments. Interestingly, a series of samples with different morphologies can be obtained by changing the synthesis parameters. The excellent electromagnetic wave interactions are fully characterized. It has an effective absorption bandwidth of 8.48 GHz at 2.6 mm. The findings demonstrated in this work pave the way for the application of lightwave and ductile complex nanoarrays obtained from liquid metals.

Fabrication of aluminum beads derived from selectively recovered Al-rich precipitates and their application into defluoridation.

This work introduced a new way of fabricating a granular material with the supply of Al-rich precipitates selectively obtained from acid mine drainage (AMD), and its potential as a promising adsorbent for fluoride (F) was evaluated. Through the selective sequential precipitation (SP) process in the field, Al-rich precipitates with high purity (>81%) were collected at the high recovery rate (>99.8%) as a raw material for adsorbent fabrication. The granular adsorbent (ALB) was synthesized through encapsulation of precipitate powders by chemically inducing polymeric bead formation. The characterization results revealed that ALB possessed a highly porous structure and embedded a large number of nanoparticles of amorphous Al hydroxides inside its framework. Less adsorption of F occurred at an alkaline pH condition due to the competitive effect of hydroxyl ions. The adsorption process can be divided into fast adsorption by the outer surface and slow diffusion in the inner phase. The maximum adsorption capacity of ALB for F was calculated to be 17.7 mg g-1 in the Langmuir isotherm model fitting results. By the repetitive adsorption/desorption and XPS results, it turned out that both chemisorption and physisorption gave a contribution in the removal of F, and the regeneration of adsorbent using NaOH was effective to restore the adsorption capability but accompanied the loss of adsorption sites. As a result, it can be concluded that a granule-type material fabricated using Al-rich precipitates selectively recovered from AMD neutralization can be considered as a promising adsorbent for F removal in aqueous solution.

Operando leaching of pre-incorporated Al and mechanism in transition-metal hybrids on carbon substrates for enhanced charge storage

Operando leaching of pre-incorporated Al and mechanism in transition-metal hybrids on carbon substrates for enhanced charge storage

Rainfall is the major driver of plant Si availability in perudic gibbsitic Andosols

The amount of water available to leach solutes from soil is one of the major features determining mineral weathering, mineral neoformation and soil properties. It affects the fate of dissolved silicon (Si), which may follow four routes: leaching, mineral synthesis, adsorption, uptake by plants forming phytoliths. Here, we quantify the reservoirs of bioavailable Si and phytolithic Si in topsoils (0–20 cm) from wet tropical Andosols along a climosequence where mean annual rainfall (MAR) increases from 2650 to 4400 mm with increasing altitude (65–375 m asl) in Basse-Terre, Guadeloupe. We assessed bioavailable Si through CaCl2 extraction in soil, and foliar analysis in banana plants. We evaluated the pool of phytolithic Si through Na2CO3 extraction and heavy liquid separation. The Na2CO3 extraction was performed on both the bulk soil and oxalate–treated soil (ox-Na2CO3) cleared of its amorphous aluminosilicates. The Andosols have reached an advanced weathering stage. Their secondary products included (Al, Fe)–humus complexes, ferrihydrite, gibbsite, poorly crystalline Al hydroxide, and aluminous allophanic substances. The contents of organic C, metal-humus, ferrihydrite and gibbsite increased in soils in the wettest conditions (>3000 mm) whereas allophane content concomitantly decreased. Silicon leaf content varied little (3.8–5.3 g kg−1), but slightly decreased with increasing MAR (r = −0.48). Bioavailable Si content in soil decreased from 63 to 12 mg kg−1 with increasing MAR (r = −0.92), and was strongly correlated (r = +0.95) to that of phytolithic Si as assessed after ox-Na2CO3 extraction, linked to fresh, labile phytoliths. The Si/Al atomic ratio of the ox-Na2CO3 extract regularly decreased from 1.06 to 0.37 with increasing MAR, hence corroborating strongest desilication in soils in the wettest conditions. In these highly leached, gibbsitic Andosols, rainfall is thus the major driver of plant Si availability.

Efficient removal of arsenite by a composite of amino modified silica supported MnO2/Fe–Al hydroxide (SNMFA) prepared from biotite

Developing materials from natural minerals to efficiently remove arsenite (As(Ⅲ)) from solution is vital important for resources comprehensive utilization and environment protection. In this study, biotite containing minerals was used to prepare a novel composite of amino modified silica supported MnO2/Fe–Al hydroxide (SNMFA composite), which was then applied to remove arsenite. Scanning electron microscope (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) results indicated that many amorphous MnO2 and Fe–Al hydroxide nano sheets were loaded on the surface of layered silica structure. Batch experiments showed that this composite could efficiently remove As(Ⅲ) from aqueous solution, and the maximal removal capacity was identified as 46.11 mg/g. As(Ⅲ) adsorption behaviours of SNMFA composite were confirmed by the pseudo-second-order kinetic model and Langmuir model, indicating that As(Ⅲ) adsorption on its surface was monolayer adsorption. The adsorption process was a pH and temperature dependent process, and increasing pH and temperature have facilitated the removal of As(Ⅲ). Thermodynamic analysis showed that As(Ⅲ) adsorption process was a spontaneous endothermic reaction. The As(Ⅲ) removal was mainly relied on the stable inner-sphere coordination model, and the corresponding mechanisms were involved in chelation, precipitation, oxidation-adsorption and electrostatic interaction.

Impact of freeze-thaw cycles on organic carbon and metals in waters of permafrost peatlands

Despite the importance of soil and surface waters freezing in permafrost landscapes, the behaviour of dissolved organic carbon (DOC), nutrients and metals during periodic freeze-thaw cycles (FTC) remains poorly known. The on-going climate warming is likely to increase the frequency of FTC in continental aquatic settings, which could modify the chemical composition of waters. In this study, we conducted 9 repetitive cycles of overnight freezing (−20 °C) and 5 h thawing (4 °C) in the laboratory using representative 0.22 μm-filtered waters from NE European permafrost peatland: leachates of vegetation and soil, and natural surface waters (depression, thermokarst lake and river). Only minor (<5%–15%) changes of DOC concentrations, SUVA254 and molecular weight were observed in all leachates and the depression water. In contrast, several trace elements (Fe, Al, P, Mn, As, and REE) exhibited sizable variations during FTC (>10%). The leachates and the depression water were enriched in trace elements, whereas the thermokarst lake and the river demonstrated a decrease in concentration of Fe (−39 and −94%, respectively), Al (−9 and −85%), and Mn (−10 and −79%) during FTC. Overall, the observations demonstrated an increase in aliphatic low molecular weight organic matter (OM), and the precipitation of Fe, Al hydroxides and organo-mineral particles. Therefore, enhanced of frequency of FTC can favour the release of metals and toxicants from acidic OM-rich surface waters and maintain stable OM-metals-colloids in large lakes and rivers, thus regulating aquatic transport of DOC and metals from soils to the Arctic Ocean.

Valleriite, a Natural Two-Dimensional Composite: X-ray Absorption, Photoelectron, and Mössbauer Spectroscopy, and Magnetic Characterization.

Valleriite is of interest as a mineral source of basic and precious metals and as an unusual material composed of two-dimensional (2D) Fe–Cu sulfide and magnesium hydroxide layers, whose characteristics are still very poorly understood. Here, the mineral samples of two types with about 50% of valleriites from Noril’sk ore provenance, Russia, were examined using Cu K- and Fe K-edge X-ray absorption fine structure (XAFS) spectroscopy, X-ray photoelectron spectroscopy (XPS), 57Fe Mössbauer spectroscopy, and magnetic measurements. The Cu K X-ray absorption near-edge structures (XANES) spectra resemble those of chalcopyrite, however, with a higher electron density at Cu+ centers and essentially differ from those of bornite Cu5FeS4; the Fe K-edge was less informative because of accompanying oxidized Fe-containing phases. The post-edge XANES and extended XAFS (EXAFS) analysis reveal differences in the bond lengths, e.g., additional metal–metal distances in valleriites as compared with chalcopyrite. The XPS spectra confirmed the Cu+ and Fe3+ state in the sulfide sheets and suggest that they are in electron equilibrium with (Mg, Al) hydroxide layers. Mössbauer spectra measured at room temperature comprise central doublets of paramagnetic Fe3+, which decreased at 78 K and almost disappeared at 4.2 K, producing a series of hyperfine Zeeman sextets due to internal magnetic fields arising in valleriites. Magnetic measurements do not reveal antiferromagnetic transitions known for bornite. The specific structure and properties of valleriite are discussed in particular as a platform for composites of the 2D transition metal sulfide and hydroxide (mono)layers stacked by the electrical charges, promising for a variety of applications.

Geochemical constraints on the middle Triassic Kani Zarrineh karst bauxite deposit, Irano–Himalayan belt, NW Iran: Implications for elemental fractionation and parental affinity

The middle Triassic Kani Zarrineh bauxite deposit, in the Irano–Himalayan belt, located 20 km northwest of Saqqez city in northwestern Iran, occurs in depressions of the early Triassic bedrock carbonates of the Elika Formation. The ores formed during the Carnian Pluvial Event under high atmospheric pCO2 conditions and humid episodes. Powder-XRD analyses revealed that the Kani Zarrineh bauxite is mainly composed of diaspore, hematite, and kaolinite. There is a broad inverse relationship between hematite abundance and diaspore abundance in the profile with a downward increase of hematite and an upward increase of diaspore. Among minor constituents, single crystals rich in high field strength elements, such as florencite, monazite-(Ce), xenotime-(Y), and zircon were detected by SEM-EDS analyses. R-mode factor analysis indicates that most of the variance of the dataset is explained by a factor accounting for the competition between the Al2O3–TiO2–Ga–HFSE pool and the SiO2–Fe2O3–U–first row transition metals pool, and related to the coupled effect of a change of redox conditions and climatic regime. The other two factors are related to the importance of phosphate minerals (e.g., florencite and monazite) in hosting LREE, and to the influence that the chemistry of the soil solutions, especially pH, exerted in promoting the preferential mobility of HREE. Both these factors contribute to explaining LREE/HREE fractionation in the Kani Zarrineh bauxite ores. A negative correlation between the Ce/Ce* and the TOC (r = –0.91) corroborates the fact that bauxitization occurred in an environment characterized by a progressive increase in Eh upward. The coupled Ce/Ce* increase and TOC decrease upward are likely related to soil aeration, a progressive increase in soil temperature, and a reduction in soil moisture. An upward decrease of soil moisture is also consistent with an increase in the abundance of Al hydroxides that require drier conditions than those necessary for the formation of Fe oxyhydroxides. Finally, the evaluation of elemental mobility and results of the R-mode factor analysis indicate that, in addition to Al, high field strength elements Nb and Ta can be used confidently for assessing parental affinity of the Kani Zarrineh bauxite ores. The Al/Ta and Nb/Ta ratios and the Sm/Nd and Eu/Eu* provenance proxies reveal that mafic rocks interbedded in the early Triassic bedrock carbonates of the Elika Formation are likely protoliths of the Kani Zarrineh bauxite ores. This finding is consistent with what is observed for some bauxite deposits from the Mediterranean-type karst bauxite belt, especially from northwestern Iran of different ages that basalt rocks were the parent rock of these deposits.

Laterite as a Potential Seepage Barrier From a Karst-Depression Tailings Impoundment

AbstractIn the absence of the necessary valley topography, karst depressions are sometimes used to construct conventional impoundments in order to contain tailings. Leakage is a primary concern for such impoundments. The purpose of the current study was to determine the characteristics and barrier performance of laterite mantling karst depressions, using, as an example, the Wujiwatang (WJWT) tailings impoundment, located in the Gejiu mining area, southwestern China. The geotechnical-hydrogeological properties, geochemistry, mineral compositions, and particle shapes of the laterite were investigated by geotechnical techniques, chemical analysis, X-ray diffraction (XRD), and scanning electron microscopy (SEM). The results showed that the laterite contained poorly sorted particles that covered a wide spectrum of grain sizes (&lt;5 mm to &lt;50 nm), and was unexpectedly categorized as silty clay or silt with a high liquid limit. The continuous gradation and small D90 value helped the laterite achieve saturated hydraulic conductivities in the range of &lt;10–6 cm/s required for impoundment liners. The laterite beneath the tailings impoundment was finer-grained and had a lower permeability than that of the laterite on the depression walls within the same depression. Geochemically and mineralogically, the laterite was classified as true laterite and its major mineralogical constituents were gibbsite and goethite with chlorite occurring in trace amounts. The laterite was dominated by subspherolitic–spherolitic cohesionless grains (concretions) made up of Al, Fe, Ti, and Mn oxides and hydroxides. The laterite did not have plasticity indices in the clay range. Fortunately, slopewash prior to tailings containment selectively transported the finer oxide concretions to the depression floor, creating a natural low-permeability barrier for the WJWT tailings impoundment. This is undoubtedly important for the planning and design of future karst depression-type tailings impoundments around the world.

ИССЛЕДОВАНИЕ ФОРМ МИГРАЦИИ МЕТАЛЛОВ В РЕКАХ, ПОДВЕРЖЕННЫХ ВЛИЯНИЮ ШАХТНЫХ ВОД КИЗЕЛОВСКОГО УГОЛЬНОГО БАССЕЙНА

Актуальность. Техногенному воздействию кислых шахтных вод подвержены поверхностные водотоки бассейна р. Чусовая – крупнейшего притока р. Кама на территории Пермского края (Россия). Изучение поведения металлов в реках-приемниках шахтных вод обусловлено необходимостью понимания особенностей миграции компонентов в природно-техногенных водах; определения геохимических процессов и механизмов, способствующих выведению токсичных элементов из растворов; и прогнозной оценки вторичного загрязнения за счет растворения образованных соединений при смене физико-химических условий. Результаты, полученные на исследуемом участке, могут отражать особенности геохимического поведения металлов в других загрязненных реках территории Кизеловского угольного бассейна при поступлении в них шахтного дренажа схожего состава. Цель: исследовать формы миграции металлов в водотоках, загрязненных шахтными водами, определить основные вторичные минеральные фазы, способствующие выведению токсичных элементов из раствора, и оценить устойчивость частиц образованных минералов при миграции в речной сети. Объекты: кислотный дренаж из штольни шахты «Таежная» Гремячинского месторождения Кизеловского угольного бассейна, содержащий высокие концентрации сульфатов и тяжелых металлов, и загрязненные шахтными водами реки: Большая Гремячая, Южная Вильва, Усьва и Чусовая. Методы. Физико-химическое моделирование химических форм нахождения металлов в растворе и расчеты степени насыщения выполнялись при помощи программного кода PHREEQC c базой термодинамических данных WATEQ4f. Результаты исследования показали, что в шахтных водах и загрязненных речных водах с рН 2,9–3,4 металлы (Al, Fe, Mn, Zn, Ni, Pb, Cd, Li) находятся как в форме свободных ионов, так и в виде сульфатных комплексов. В реке Юж. Вильва, ниже участка смешения с загрязненными водами р. Бол. Гремячая и далее по потоку, Fe и Al образуют исключительно гидроксокомплексы. Преобладающей формой миграции Ni и Pb являются карбонатные комплексы. Нахождение металлов Li, Cd, Mn и Zn в реках Юж. Вильва, Усьва и Чусовая преимущественно в виде свободных ионов позволяет предположить, что основным механизмом их осаждения является сорбция на гидроксидах и оксигидроксидах Fe и Al, а также на глинистых минералах. Отрицательные индексы насыщения по отношению к сульфатным минералам, характерным для шахтных вод, показали неустойчивость этих минеральных фаз в нейтральных и слабощелочных водах.

Evaluation Of Using Different Adjuvants Used For Preparation Of Staphylococcus Aureus Mastitis Vaccine On The Immune Response

Staphylococcus aureus (S. aureus) was the most prevalent bacteria recorded from clinical and subclinical mastitis. The main objective of the present work is to prepare and evaluate the effectiveness of locally prepared inactivated S. aureus vaccine using different adjuvants Montanide ISA-206, Montanide ISA-70 and alum hydroxide gel for detection of cellular and humeral immune responses. Seventy dairy heifers in the last trimester of gestation divided into (5) groups. Twenty pregnant cows in three groups (G1, G2, and G3) were inoculated intramuscularly with the prepared vaccines four weeks prior to calving then a booster dose at two weeks pre-expected calving. The animals in remaining groups (G4 and G5) were considered as control and safety test respectively. Serum samples from vaccinated and non-vaccinated cows were collected at the 1st and 2nd immunization then at 0, 1, 2, 3 months and (7, 10, 14) days post calving and vaccination and evaluated immunologically using ELISA and Lymphocyte transformation assay, respectively. The results revealed that a progressive increase of immune response in the vaccinated groups (G1 and G2) than that of the third and control groups. These results could be indicated the safety and effectiveness of the Montanide ISA-206, ISA-70 vaccines than alum adjuvant vaccine that reduce the incidence and severity of clinical cases of mastitis. Hence, further studies should be done to elucidate the possibility of field application.

High-performance Al separation and Zn recovery from a simulated hazardous sludge

Zn2+ is a heavy metal ion, and hazardous sludge from the electroplating and alloy industry is rich in Zn and impure Al and Ca. Such sludge is commonly recycled by dissolution in strong acid and then selective extraction to recycle Zn2+ by a special extraction reagent. In this process, impurity Al3+ is dissolved and then participates in the extraction of Zn2+, so Al3+ should be removed first. Here, a new strategy was reported for the effective removal of Al3+ and recovery of Zn2+ from a simulated Al/Zn-bearing sludge via an improved acid solution–precipitation route. The sludge was simulated by coagulating Zn-bearing waste water (290 mg/L Zn2+) with 600 mg/L polyaluminium chloride. The sludge was dissolved in sulphuric acid and nitric acid to form an acidic solution with Al3+ and Zn2+ concentrations of 3.2 g/L and 5.7 g/L, respectively. The solution was treated directly by hydrothermal method at 270 °C, in which 55% Al3+ was precipitated as boehmite and Al hydroxide. After the addition of 0.2 mL of ethylene glycol, the removal rate of Al3+ dramatically increased to 99.8%, with Zn2+ loss of 1.5%. The residual Zn2+ was 5620 mg/L in the treated solution and further directly precipitated by adjusting the pH of the solution to pH 7.5 with NaOH. The precipitated Zn2+ was in the form of simonkolleite with ZnO content of 63.1%, with Al content of only 0.8%. In the hydrothermal precipitation, the removal rate of Al3+ increased with the temperature and extension of reaction time. Al3+ was hydrolysed and precipitated as aluminium oxonium sulphate hydroxide and then recrystallised in boehmite form. Then, H+ was generated and consumed in the redox reaction of nitrate and ethylene glycol, accelerating the Al3+ precipitation. This method provides a way to efficiently separate Al3+ from a Zn-bearing solution and can be applied in the recycling of Al/Zn-bearing sludge.

Growth Performance and Clinicopathological Analyses in Lambs Repetitively Inoculated with Aluminum-Hydroxide Containing Vaccines or Aluminum-Hydroxide Only

Simple SummaryAluminum-hydroxide is an effective vaccine adjuvant used in most commercial sheep vaccines. It facilitates the establishment of a robust immune response against the vaccine antigen. During the first decade of the 21st century, repetitive injections with vaccines containing aluminum-based adjuvants were proposed to be linked to a progressive wasting syndrome in sheep. The aim of this work was to analyze several clinicopathological parameters, including growth performance, clinical data, and histopathological observations in lambs intensively injected with aluminum-containing vaccines, aluminum-hydroxide only, or a saline solution as control. Although aluminum-hydroxide was linked to chronic inflammatory reactions at the injection site and the development of behavioral changes in sheep, the results presented here indicate that injected aluminum-hydroxide, either alone or in combination with vaccine antigens, is not enough to induce relevant changes in the parameters studied. Other factors such as sex, breed, age, production system, diet or climate conditions could play a role in the development of the previously described wasting syndrome.Aluminum (Al) hydroxide is an effective adjuvant used in sheep vaccines. However, Al-adjuvants have been implicated as potential contributors to a severe wasting syndrome in sheep—the so-called ovine autoimmune-inflammatory syndrome induced by adjuvants (ASIA syndrome). This work aimed to characterize the effects of the repetitive injection of Al-hydroxide containing products in lambs. Four flocks (Flocks 1–4; n = 21 each) kept under different conditions were studied. Three groups of seven lambs (Vaccine, Adjuvant-only, and Control) were established in each flock. Mild differences in average daily gain and fattening index were observed, indicating a reduced growth performance in Vaccine groups, likely related to short-term episodes of pyrexia and decreased daily intake. Clinical and hematological parameters remained within normal limits. Histology showed no significant differences between groups, although there was a tendency to present a higher frequency of hyperchromatic, shrunken neurons in the lumbar spinal cord in the Adjuvant-only group. Although Al-hydroxide was linked to granulomas at the injection site and behavioral changes in sheep, the results of the present experimental work indicate that injected Al-hydroxide is not enough to fully reproduce the wasting presentation of the ASIA syndrome. Other factors such as sex, breed, age, production system, diet or climate conditions could play a role.