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The biogeochemical cycling of arsenic (As) and antimony (Sb) is coupled with sulfur (S). Biogenic sulfide from microbial sulfate reduction under anaerobic conditions may enhance the release of coexisting As and Sb through the formation of labile thioarsenate (AsV-S) and thioantimonate (SbV-S). To understand the competition between As and Sb for thiolation and its effect on their mobility, we investigated the speciation and fate of As and Sb in the presence of indigenous microbiota in sediments during multiple oxic-anoxic cycles. Sediments with Sb contents at low (L-Sb, 570 mg/kg Sb, 50 mg/kg As), medium (M-Sb, 2,560 mg/kg Sb, 90 mg/kg As) and high (H-Sb, 10,090 mg/kg Sb, 190 mg/kg As) levels were collected in the Xikuangshan mining area, the largest Sb mine in the world. Our aqueous speciation analysis indicated that As was released under anoxic conditions whereas Sb was mobilized during oxic cycles in all samples. The As release was not driven by the transformation of Fe-bearing phases, but by biogenic sulfide through the formation of soluble AsV-S. AsV-S was the primary soluble species under anoxic conditions as evidenced by its high percentage, up to 80% in L- and M-Sb sediments, and 60% in H-Sb sediment. AsV-S was formed prior to SbV-S in L- and M-Sb sediments and even suppressed SbV-S formation in H-Sb sediment, indicating that limited biogenic sulfide preferentially bound with As rather than Sb. The Sb mobility was not associated with sulfide, but mainly regulated by its redox transformation between mobile antimonate and immobile antimonite. X-ray absorption near edge structure (XANES) spectra of Sb, As and S showed that no As or Sb sulfide precipitation was formed during the incubation. The Fe K-edge XANES analysis suggested the minor transformation of Fe-bearing phases between goethite (32 ± 8%), hematite (24 ± 7%) and magnetite (25 ± 4%), resulting in a limited effect of Fe cycling on As mobility. The results of our study signify the competition of As and Sb in thiolation and improve our understanding of the contrasting behaviors of As and Sb during oxic-anoxic cycles.

Calcium dynamics in the developing pollen of Chinese fir (Cunninghamia lanceolata) were investigated using an antimonate calcium precipitation method. After microspores were released from the tetra...

Reaction of the tungsto-antimonate [Sb 8 W 36 O 132 ] 24-polyoxometalate with late trivalent lanthanide cations (from Gd to Lu) gives rise to the formation of eight isostructural molecular compounds [{Sb 3 ( 3-O) 2 Ln(H 2 O)Ln(H 2 O) 2 (SbW 10 O 37)(SbW 8 O 31)} 2 ] 22-(Ln = Gd III (1), Tb III (2), Dy III (3), Ho III (4), Er III (5), Tm III (6), Yb III (7), Lu III (8)). All compounds were characterized by routine solid-state techniques (IR spectroscopy, TGA, single crystal X-ray diffraction) and, by SAXS measurements in aqueous solutions to assess their stabilities. Luminescent properties of compounds 5 and 7 were also studied.

Iron (Fe) oxides are important host phases for antimony (Sb), a toxic metalloid of environmental concern. In wetland soils and sediments, poorly ordered Fe oxides such as ferrihydrite may undergo reductive dissolution and mineralogical transformation upon reaction with dissolved sulfide (S(-II)). The consequences of these processes for the mobility of associated Sb have not been investigated to date. Here, we allowed Sb(V)-bearing ferrihydrite (molar ratio of Fe:Sb = 400) to react with varying S(-II) concentrations (Fe(III):S(-II) = 0.2, 0.5, and 1) at pH 6 and 8 over 32 days. Changes in speciation and concentration of Fe, S and Sb in the aqueous, colloidal and solid phase were examined through a combination of aqueous-phase analyses, X-ray diffraction and synchrotron X-ray absorption spectroscopy. Addition of S(-II) caused rapid reduction of Fe(III), thereby producing elemental S and Fe(II). X-ray diffractometry and Fe K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy revealed that S(-II) addition resulted in the precipitation of Fe(II) sulfides (mackinawite (FeS) and pyrite (FeS2)) and formation of secondary Fe(III) oxides (goethite (FeOOH) and hematite (Fe2O3)). The formation of mackinawite and pyrite was further confirmed by S K-edge X-ray absorption near-edge structure (XANES) spectroscopy, and was found to occur to the greatest extent in the high-sulfide treatments. The initial reductive dissolution of ferrihydrite was paralleled by a fast increase in dissolved Sb concentrations, with ∼25% of total Sb being released in the high-sulfide treatments. The Sb release was followed by Sb immobilization within ∼1–7 days. Since ion-chromatography ICP-MS revealed antimonate (Sb(OH)6-) as the primary Sb aqueous phase species throughout the experiment, with only negligible concentrations of antimonite (Sb(OH)3) and only very minor amounts ( 3 kDa) size fraction at pH 8 under medium and high S(-II) conditions, while no colloidal Sb was found in other treatments. Together, these results show that Fe oxide sulfidization can have opposing effects on Sb mobility. On the one hand, the initial sulfide-promoted Fe oxide dissolution triggers Sb release into the aqueous phase. On the other hand, Sb can subsequently be immobilized via sorption to secondary Fe oxides and newly-formed Fe sulfides during the later stages of sulfidization. Sulfidization reactions, and the complex opposing impacts on Sb mobility, should therefore be considered for the risk assessment and derivation of adequate management strategies at Sb-impacted sites which experience sulfidic conditions.

The features of the formation of compounds based on silver antimonate obtained in the AgNO3–Sb2O3–MoO3 system by the solid-phase reaction were investigated. For a synthesis temperature of 1023 K, a homogeneous concentration region of the Ag2−xSb2−xMoxO6 solid solution with a structure of the defective pyrochlore type in the range of 0.0 ≤ x ≤ 2.0 was detected. The Rietveld method, within the constraints of the Fd-3m space group, was used to refinement of X-ray diffraction data, specify the structural parameters of powders, and the correlation of structural disorder with their electrically conductive properties. Relative density and average particle size for ceramic samples sintered at 1223 K were determined using scanning electron microscopy.

The research of tungsten-antimony crystalline acid (TACA) structural transformations in the condition of ion-exchange and thermolysis of its substituted M+, H+-forms (M+ – Li, Na, K, Ag) were conducted. The data of thermogravimetric and qualitative X-ray phase analyses made it possible to conclude that the thermolysis of TACA and its derivatives proceeds in a wide temperature range from 300 to 1150 K being accompanied by the removal of crystalline water molecules with the formation of phases mixture containing complex antimony oxides of the ( -,  - Sb2O4) modification and WO3. It was shown that compounds based on hydrated forms of monovalent metal antimonates-tungstates are stable up to 1023 K with a pyrochlore-type structure. For pyrochlore-like phases, a monotonic dependence of unit cell parameter a on ion-exchange degree α and the ionic radius of metals r was revealed indicating the formation of solid solutions Мх(Н3О)1–хWSbO6 nН2О (M+ – Li, Na, K, Ag; 0.0≤х

Refereed/Peer-reviewed The removal of antimonate (Sb(V)) species from wastewaters has become a growing concern due to their known genotoxicity and carcinogenicity. In this paper, a hybrid ZIF-8@FeNPs material was synthesized from Zeolite Imidazole Framework-8 (ZIF-8) and zero-valent iron nanoparticles (nZVI) and subsequently used to remove Sb(V) from aqueous solution. Characterization indicated that ZIF-8@FeNPs were successfully synthesized and that the valence state of Sb(V) did not change during the removal process, where adsorption of Sb(V) was facilitated by the high specific surface area and porosity of the hybrid. Advanced characterization also showed that Zn-OH and iron oxides were adsorbed on the material after complexation with Sb(V). Kinetic, isothermal, and thermodynamic modeling indicated that the adsorption process followed pseudo-second-order kinetics, via multilayer adsorption which was spontaneous and endothermic. y ZIF-8@FeNPs. A Sb(V) removal mechanism based on adsorption was proposed. In mining wastewater containing 1.121 mg·L−1 Sb(V), 89.7 % could be removed by the material. During repeated reuse of ZIF-8@FeNPs for the removal of 1 mg·L−1 Sb(V) through four successive cycles, the removal efficiency was still relatively high (39.1 %) after the fourth cycle indicating good potential for practical applications. In addition, ZIF-8@FeNPs also exhibited magnetic properties, which demonstrated that Sb(V) could be easily recovered from wastewater post removal by ZIF-8@FeNPs.

Metallic anions including antimonate (SbV), arsenate (AsV), chromate (CrVI), molybdate (MoVI), selenate (SeVI), tungstate (WV) and vanadate (VV) are important pollutants in the terrestrial environment due to their impacts on human and ecological health. It is essential that appropriate assays are used for derivation of toxicity models and guidance values, and to assess potential impacts on a site-specific basis. Root elongation is a simple and quick method for assessment of metal toxicity, yet there has been little to no validation. This study outlines results demonstrating low sensitivity of metallic anions in the often used 4-d root elongation test relative to 28-day nutrient culture assays. Therefore, root elongation assays may not be suitable for AsV, CrVI, MoVI, SbV, SeVI, and WV toxicity studies based on estimated toxicity parameters given the sensitivity of longer test assays. Only vanadate showed equivalent toxicity in the 4 d and 28 d assays. These results have significant implications for development of toxicity models and derivation of safe soil guidance values involving metallic anions.

The development of inexpensive and abundant catalysts with high activity, selectivity, and stability for the oxygen reduction reaction (ORR) is imperative for the widespread implementation of fuel cell devices. Herein, we present a combined theoretical-experimental approach to discover and design first-row transition metal antimonates as promising electrocatalytic materials for the ORR. Theoretically, we identify first-row transition metal antimonates – MSb2O6, where M = Mn, Fe, Co, and Ni – as non-precious metal catalysts with promising oxygen binding energetics, conductivity, thermodynamic phase stability and aqueous stability. Among the considered antimonates, MnSb2O6 shows the highest theoretical ORR activity based on the 4e− ORR kinetic volcano. Experimentally, nanoparticulate transition metal antimonate catalysts are found to have a minimum of a 2.5-fold enhancement in intrinsic mass activity (on transition metal mass basis) relative to the corresponding transition metal oxide at 0.7 V vs RHE in 0.1 M KOH. MnSb2O6 is the most active catalyst under these conditions, with a 3.5-fold enhancement on a per Mn mass activity basis and 25-fold enhancement on a surface area basis over its antimony-free counterpart. Electrocatalytic and material stability are demonstrated over a 5 h chronopotentiometry experiment in the stability window identified by Pourbaix analysis. This study further highlights the stable and electrically conductive antimonate structure as a promising framework to tune the activity and selectivity of non-precious metal oxide active sites for ORR catalysis.

The environmental mobility and bioavailability of antimony (Sb) are strongly influenced by sorption to Fe(III) oxide minerals, such as goethite (αFeOOH). Exposure to aqueous Fe(II), as occurs, for ...

Oxyanions are ubiquitous in soils, organisms and the environment. Due to their unique chemical structure, oxyanions can be easily transferred into other systems. Carbonate (CO32−), nitrate (NO3−), phosphate (PO43−), silicate (SiO42−) and sulfate (SO42−) are the major oxyanions in organisms and the soil environment, whereas arsenate (AsO43−), antimonate (SbO43−), borate (BO33−), selenate (SeO42−), and tellurate (TeO42−) are generally reported as toxic chemicals found at trace levels. Excessive oxyanions leached from soils into water have caused severe environmental problems. Here, we review the factors affecting the structural configuration of oxyanions and organic acids adsorbed on iron oxides and hydroxides. The configuration of oxyanions on iron (hydr)oxides is controlled by surface loading, pH, sample phase, competing ions and organic acids. Under conditions of low surface loading and low pH at the interface in the absence of competing ions, oxyanions with high affinity possibly form a complex with higher denticity. But an increase in pH decreases the number of sorption sites; thus, a transition from a tri- or bidentate complex to monodentate and outer-sphere complexes occurs.

The pyroantimonate pigments Naples yellow and lead tin antimonate yellow are recognized as some of the most stable synthetic yellow pigments in the history of art. However, this exceptional lightfa...

In this paper, the synthesis, characterization and sensing applications (in terms of liquefied petroleum gas and carbon dioxide gas) of copper antimonate (CuSb2O6) nano-polygons have been reported. The sensing surface was decorated with nano-polygons on a porous network. Structural characterization revealed the crystalline nature of CuSb2O6 with a crystallite size of 21 nm. The optical properties (UV-visible absorption and Fourier transform infrared absorption) of the annealed and as-synthesized CuSb2O6 were also studied. Further, an effort was made towards the development of an LPG sensor using the CuSb2O6 films that are characterized by high sensitivity, high stability, short response and recovery times, and most importantly, room-temperature (27 °C) operation. Examination of the gas sensing properties showed that the CuSb2O6 nano-polygons exhibited better response towards liquefied petroleum gas adsorption than carbon dioxide. The possible surface-sensing mechanism of the decorated surface on exposure to the target gas has also been discussed. The gas-sensing properties demonstrated that the CuSb2O6 nano-polygons are promising candidates for high-performance LPG sensors that operate at room temperature.

Trirutile zinc antimonate (ZnSb2O6) nano-cubes/cuboids have been fabricated by a sol–gel spin-coating method using polyethylene glycol (PEG) as the structure-directing agent. The fabricated films were characterized for surface morphology, along with structural, FT-IR and thermal analysis. The crystallite size of ZnSb2O6 is found to be 35 nm. The fabricated films have been tested for the detection of liquefied petroleum gas (LPG) and carbon dioxide (CO2) gas leakage at room temperature (27 °C). They exhibit fairly high sensitivity (1.73), low response and recovery times (∼41 and 95 s, respectively), and good reproducibility and stability (99.2%) at room temperature for the detection of LPG leakage. Based on these observations, the fabricated film has the potential to be used as a LPG sensor at room temperature.

Pyrite/hematite bi-mineral (FeS2/α-Fe2O3) was obtained by thermal modification of pyrite. FeS2/α-Fe2O3 was investigated and developed as a promising adsorbent for antimonate [Sb(V)] removal. The influence of initial concentration, temperature, initial pH, contact time, and coexisting anions on Sb(V) adsorption performance of FeS2/α-Fe2O3 was investigated. FeS2/α-Fe2O3 exhibited good adsorption performance and excellent removal efficiency. The results of the Langmuir isotherm model indicated that FeS2/α-Fe2O3 had a large adsorption capacity (347.2 mg/g) for Sb(V) removal from water. High removal efficiency by FeS2/α-Fe2O3 was achieved over a broad pH range (2.5–10.7). The coexisting anions had little influence on Sb(V) adsorption by FeS2/α-Fe2O3. The pseudo-second-order and Dubinin–Radushkevich model analyses (E = 12.62 kJ/mol) suggested that FeS2/α-Fe2O3’s Sb(V) removal process was chemisorption. The negative Gibbs free energy change and endothermic enthalpy change of 5.00 kJ/mol indicated that Sb(V) adso...

Zinc antimonate (ZnSb2O6/ZSO) has gained attention as a promising nanostructure because of its distorted Sb–O polyhedra in their structure, superior electrical conductivity and thermal stability. This review focuses on the most important properties of ZnSb2O6 and their applications till date. The review begins with representation of crystal structure, electronic structure and density of states of ZnSb2O6 and it continues with the representation of most important properties such as thermal, electrical, optical and carrier density to understand the electrical conductivity, Seebeck coefficient, thermal stability and band gap. Finally, the discussion is intended on the various applications of ZnSb2O6 to understand the key outcomes. In particular, energy harvesting and storage devices, including lithium-ion batteries (LIBs), supercapacitors (SCs), and solar cells, take part in a crucial role in day-today life owing to the likelihood of replacing conformist energy from fossil fuels. However, proposing an electrode material with efficiency and cost-effectiveness is crucial. This can prevail by implementing ZnSb2O6 as an electrode material and additionally in this review, this material is highlighted in sensing and catalytic applications in an extensive intellect. Finally, the futuristic outlooks are featured based on the latest advances and important findings. Hence, this review proposes that ZnSb2O6 nanostructures can be a crucial material for various environmental and energy-based multifunctional applications.

The anaerobic antimonate [Sb(V)] reduction with a solid-state electrode serving as the sole electron donor was demonstrated by employing a bioelectrochemical system. The highest Sb(V) reduction efficiency was observed at the biocathode potential of −0.7 V versus standard hydrogen electrode using a cathode potential range from −0.5 V to −1.1 V. The scanning electron microscopy and energy dispersive X-ray spectroscopy indicated that both amorphous and crystallized Sb2O3 were formed as products of Sb(V) reduction. The irreversible recovery of bioelectrochemical Sb(V), when the cathode potential deviated from the optimal potential, was explained through the alteration in microbial communities, which was further elucidated by the next-generation sequencing of 16S rRNA gene amplicons. Chryseobacterium koreense and Stenotrophomonas nitritireducens were the dominant species of microbial consortia at Sb(V)-reducing biocathodes. This study revealed a novel option for bioremediation of Sb at underground contaminated sites, where the delivery of organic electron donors is limited or ineffective.

In this study, we investigated the Sb(V) adsorption on ferrihydrite (Fh) at different pH values, in the presence and absence of common competing anions in soil such as phosphate (P(V)) and arsenate (As(V)). Batch adsorption experiments, carried out at pH 4.5, 6.0, and 7.0, showed a greater affinity of Fh towards P(V) and As(V) with respect to Sb(V), especially at higher pH values, while the opposite was true at acidic pH. The capacity of Fh to accumulate greater amounts of phosphate and arsenate in the 6.0–7.0 pH range was mainly linked to the different acid properties of P(V), As(V), and Sb(V) oxyanions. The Sb(V) adsorption on Fh was highly pH-dependent and followed the following order: pH 4.5 (0.957 mmol·g−1 Fh) > pH 6.0 (0.701 mmol·g−1 Fh) > pH 7.0 (0.583 mmol·g−1 Fh). Desorption of antimonate from Sb(V)-saturated Fh, treated with citric and malic acid solutions, was ~equal to 55, 68, and 76% of that sorbed at pH 4.5, 6.0, and 7.0, respectively, while phosphate, arsenate, and sulfate were able to release significantly lower Sb(V) amounts. The FT-IR spectra revealed substantial absorbance shifts related to the surface hydroxyl groups of Fh, which were attributed to the formation of Fe-O-Sb(V) bonds and supported the formation of inner-sphere bonding between Sb(V) and Fh.

Root plaques and cell wall components play important roles in regulating the uptake of heavy metals in rice plants. Proper doses of selenium (Se) can reduce heavy metal uptake in plants. Whether Se can influence both the formation of root plaques and the contents of root cell wall components to affect heavy metal uptake in plants is unknown. A hydroponic culture system was set up using rice plants (Yangdao No.6) to mainly investigate the roles of root plaques and cell wall components in regulating the uptake of antimony (Sb) and Se in rice plants subjected to Se and different speciation of antimony [antimonite (Sb(III)) and antimonate (Sb(V))]. Se alone or plus different speciation of Sb showed a negative effect on plant growth. Addition of Se did not counteract the toxic effect of inhibiting rice plant growth exerted by Sb, despite the addition of Se to the solution containing 20 mg L−1 Sb(III) or Sb(V) significantly reduced Sb concentration in the roots. Addition of Se stimulated the formation of Mn plaque and addition of 5 mg L−1 Sb(III) or Sb(V) increased the formation of Fe plaque. When compared to the 20 mg L−1 Sb(III) treatment, the addition of 0.8 mg L−1 Se significantly increased the Fe plaque, but did not result in more accumulation of Sb on the root plaques. Other levels of Se did not show positive effects on the formation of Fe plaque on the roots of this rice plant when exposed to Sb(III) or Sb(V). In many cases, the single addition of Se, Sb(III) or Sb(V), especially for Se, can significantly increase the production of pectin, hemicelluloses and lignin. Additional Se helped rice plants exposed to Sb(III) or Sb(V) generate more pectin, hemicelluloses and lignin, especially when exposed to Sb(V). In summary, we speculate that Se inhibits, in most cases, the uptake of Sb in rice plants by affecting the root cell components rather than the formation of root plaques.

The biogeochemical cycling of antimony (Sb) is often coupled with sulfur and sulfate-reducing bacteria (SRB). The biogenic sulfide is usually assumed to facilitate Sb immobilization via Sb2S3 precipitation. Here, on the contrary, we discovered that SRB mobilize adsorbed Sb(V). When SbV(OH)6–-bearing goethite was incubated anaerobically with Desulfovibrio vulgaris DP4, an elevated level of antimony was released due to the formation of thioantimonate, which is the dominant Sb species in solution. Our Fourier transform ion cyclotron resonance mass spectrometry analysis revealed multiple six- or five-coordinate thioantimonate intermediates, suggesting stepwise ligand exchange of hydroxyl groups on SbV(OH)6– by biogenic sulfide. Direct H2S elimination reactions resulted in four-coordinate thioantimonate species as the stable end product, which was confirmed by our density functional theory calculations. The thiolation of antimonate is pH-dependent and occurs in neutral environments. The thiolation changed Sb(V...

© 2019 Elsevier Ltd The role of organic matter (OM) in antimonate (further denoted as Sb(OH) 6 ) mobility in soil is unclear. The objective of this study was to evaluate Sb(OH) 6 –OM interaction. Antimonate solid:liquid distribution coefficients (K D ) were measured at low Sb concentrations in soil samples with a natural gradient in soil organic carbon (OC) that were collected from different depths of up to 3 m in two excavated soil profiles and in a subset of four soil samples with experimentally increased OM concentration from addition of Suwannee River OM. The K D values were related to soil properties by multiple linear regression and described with the CD–MUSIC model of ferrihydrite. The K D values ranged from 12 to 2800 L kg −1 and decreased strongly with increasing OC concentrations, when normalized to the amount of iron (Fe) and aluminium (Al) in acid oxalate extracts (r = −0.69; p < 0.0001). Experimentally increasing OC by ∼1.5 g kg −1 increased soluble Sb and decreased Sb(OH) 6 K D values by up to a factor of 8. The multiple regression model reveals that sorption of Sb(OH) 6 to Fe and Al hydroxides decreases with increasing pH and increasing dissolved organic carbon concentration. This effect could be explained with geochemical modelling by the competitive and electrostatic effects of adsorbed humic substances on Sb(OH) 6 surface complexation to the reactive surface sites of the Fe and Al hydroxides. Finally, both models could predict the in situ pore water Sb concentrations of unspiked samples, with a RMSE of 0.35 for the regression model and 0.43 for the geochemical model on the log 10 Sb concentrations. For these predictions, the 0.1 M Na 2 HPO 4 –extractable Sb concentration was measured and used to estimate the reversibly sorbed Sb pool. This study shows that increasing soil OM increases Sb(OH) 6 mobility at low soil Sb concentration, likely due to competitive sorption on Fe and Al hydroxides and a process based, geochemical model was calibrated to describe Sb(OH) 6 mobility in soil. ispartof: APPLIED GEOCHEMISTRY vol:104 pages:1-45 status: Published online

Antimony(Sb(III)) contamination in wastewater has raised global concerns due to its high toxicity. The efficiency and mechanisms of Sb(III) adsorptive removal from wastewater with environmentally-friendly biogenic Mn oxide (BMO) materials as adsorbent were investigated, based on kinetic experiments and multispectroscopic analyses. Kinetic experiments showed that after 300 min of reaction, 97.79–100% of Sb(III) and 85.60–92.92% of total Sb were removed, indicating that BMO can quickly and effectively oxidize Sb(III) and sequester Sb(V) from water. The bacterial activity in BMO did not significantly affect Sb(III) removal, but a decrease in the release of Mn(II) into solution may provide new reactive sites for the re-oxidation of Sb(III). X-ray photoelectron spectrometer (XPS) high-resolution analysis suggested that Sb(V) was the only speciation remaining in the solid phase after the reaction of Sb(III) with BMO. X-ray diffraction (XRD) results further showed that the fast oxidation of Sb(III) by BMO led to the production of Mn(II) antimonate (Mn2Sb2O7) precipitates. Successive extraction experiments confirmed that residual fraction (67.49–83.62%) and Mn oxide bound fraction (13.18–29.72%) were the dominant fractions of Sb(III) after 300 min of reaction, which were relatively stable and had low leaching risks. These findings indicated that BMO performed well in removing Sb(III) from wastewater.

The submicro-sized crystalline antimonic acids (C-SbA) with a transitional pyrochlore-type structure were synthesized through a facile thermolysis method and used as a precipitator for efficient removal of bismuth (Bi) ions from strong acid aqueous solution. The compositions, phases, morphologies and dissolution behaviors of C-SbA materials after thermolysis at different temperatures were analyzed and the effects of temperature, initial concentration, and competing ions on the interaction behaviors between C-SbA and Bi(III) were also investigated. The results show that the water-insoluble C-SbA become considerably dissolvable after heating at ∼350 °C due to the introduction of the mixed valence-state (III, V) and plenty of atomic vacancies. The Bi(III) removal capacity is as large as 250 mg g−1 by the C-SbA powders heated at 350 °C in a 2.0 g L−1 of Bi(III) and 2.0 mol L−1 of H2SO4 solution at 60 °C and the removal efficiency of Bi(III) is over 99%. The removal kinetics can be described by the pseudo-second-order kinetic model. It is found that Bi(III) ions are removed via the co-precipitation reaction between Bi(III) and Sb(V) and the formed bismuth antimonate (Bi3SbO7) nanocrystals are readily recovered together with C-SbA powders because they are inclined to nucleate on the surface of C-SbA particles. This study shows the promising prospect for the application of modified C-SbA in eliminating the group V elements in the copper electrolytes.

A novel Ce-doped magnetic biochar was successfully synthesized by chemical co-precipitation (Ce/FeCP-BC) and solvothermal methods (Ce/FeST-BC) for efficient Sb(V) adsorption. The Ce/FeCP-BC exhibited a high adsorption capacity of 25.0 mg/g, which was two times and one order of magnitude higher than that of Ce/FeST-BC and un-doped BC, respectively. The excellent adsorption performance of Ce/FeCP-BC maintained over a wide pH range or in the presence of coexisting anions. The adsorption results indicated that co-precipitation method was superior to solvothermal method and Ce oxide was the main contribution to Sb(V) adsorption enhancement. The combined results of TEM, XRD, FTIR and XPS revealed that Ce atom was successfully doped into the Fe3O4 structure and abundant hydroxyl groups were formed on the surface of Ce/FeCP-BC. The magnetic performance decreased after Ce doping, but Ce/FeCP-BC still showed good separation potential. Based on the results of batch experiments and physiochemical analyses, the underlying mechanisms controlling Sb(V) adsorption on Ce/FeCP-BC involved the inner-sphere surface complexation, hydrogen bonding, electrostatic attraction and ligand exchange. Among them, the ligand exchange and the formation of Ce–O–Sb complex were the main contributions to the significant Sb(V) adsorption increment on Ce/FeCP-BC. All the results implied that Ce/FeCP-BC could be used as a promising adsorbent for antimonate decontamination.

Antimony (Sb) is a priority pollutant in many countries and regions due to its chronic toxicity and potential carcinogenicity. Elevated concentrations of Sb in the environmental originating from mining and other anthropogenic sources are of particular global concern, so the prevention and control of the source of pollution and environment remediation are urgent. It is widely accepted that indigenous microbes play an important role in Sb speciation, mobility, bioavailability, and fate in the natural environment. Especially, antimony-oxidizing bacteria can promote the release of antimony from ore deposits to the wider environment. However, it can also oxidize the more toxic antimonite [Sb(III)] to the less-toxic antimonate [Sb(V)], which is considered as a potentially environmentally friendly and efficient remediation technology for Sb pollution. Therefore, understanding its biological oxidation mechanism has great practical significance to protect environment and human health. This paper reviews studies of the isolation, identification, diversity, Sb(III) resistance mechanisms, Sb(III) oxidation characteristics and mechanism and potential application of Sb-oxidizing bacteria. The aim is to provide a theoretical basis and reference for the diversity and metabolic mechanism of Sb-oxidizing bacteria, the prevention and control of Sb pollution sources, and the application of environment treatment for Sb pollution.

We report here the complete genome sequence of Geobacter sp. strain SVR, isolated from antimony mine soil in Nakase Mine, Hyogo Prefecture, Japan. SVR strains proliferate using antimonate [Sb(V)] as an electron acceptor, providing insights into the antimony reduction mechanism.

The microbial reduction of antimonate (Sb(v)) to antimonite (Sb(iii)), which forms insoluble Sb compounds, is a promising approach to remove antimony (Sb) from wastewater. Among the bacterial strains capable of reducing Sb(v) via anaerobic respiration that have been isolated to date, Dechloromonas sp. AR-2 and Propionivibrio sp. AR-3 are promising agents because they can grow aerobically and reduce Sb(v) under both anaerobic and microaerobic conditions. In this study, the effects of temperature, pH, electron donors, and coexisting electron acceptors on Sb(v) reduction and Sb removal by strains AR-2 and AR-3 were investigated to assess the usefulness of the strains in practical Sb treatment scenarios. Efficient Sb(v) reduction and removal by the two strains occurred over a relatively wide temperature range (15–35 °C) and neutral pH (6–7). In contrast, the carbon sources usable by these strains as electron donors for Sb respiration were limited to simple fatty acids such as acetate and lactate. Although strain AR-2 used nitrate and AR-3 used nitrate and arsenate as electron acceptors for anaerobic respiration in addition to Sb(v), the co-presence of other electron acceptors did not inhibit Sb(v) reduction. These results suggest that strains AR-2 and AR-3 can be potentially used in the practical treatment of Sb(v)-containing wastewater.

Proton-exchange membrane water electrolysers provide many advantages for the energy-efficient production of H2, but the current technology relies on high loadings of expensive iridium at the anodes, which are often unstable in operation. To address this, the present work scrutinises the properties of antimony-metal (Co, Mn, Ni, Fe, Ru) oxides synthesised as flat thin films by a solution-based method for the oxygen evolution reaction in 0.5 M H2SO4. Among the non-noble-metal catalysts, only cobalt-antimony and manganese-antimony oxides demonstrate high stability and reasonable activity under ambient conditions, but slowly lose activity at elevated temperatures. The ruthenium-antimony system is highly active, requiring an overpotential of 0.39 ± 0.03 and 0.34 ± 0.01 V to achieve 10 mA cm-2 at 24 ± 2 and 80 °C, respectively, and remaining remarkably stable during one-week tests at 80 °C. The S-number for this catalyst is higher than that for the high-performance benchmark Ir-based systems. Density functional theory analysis and physical characterisation reveal that this high stability is supported by the enhanced hybridisation of the oxygen p- and metal d-orbitals induced by antimony, and can arise from two distinct structural scenarios: either formation of an antimonate phase, or nanoscale intermixing of metal and antimony oxide crystallites.

International audience; This research paper emphasized on application of Judd-Ofelt's (JO) theory for low doped erbium (0.2 mol%) halogeno-antimonate based glasses with molar composition (90 –x) Sb2O3 - x ZnBr2 - 10 NaCl (where x = 10, 20, 30 and 40 mol%). 80 Sb2O3 – 9.8 ZnBr2 - 10 NaCl - 0.2 Er2O3 glass sample has low phonon energy and high refractive index is a potential candidate for luminescence applications. Differential scanning calorimetry (DSC) measurements show good the thermal stability of the prepared glass samples and on the other hand density, expansion coefficient and elastic moduli were reported. Judd-Ofelt's (JO) parameter intensities Ω2 = 3.27 × 10−20 cm2, Ω4 = 1.24 × 10−20 cm2 and Ω6 = 1.88 × 10−20 cm2 were found and these were compared with the literature. Radiative parameters such as spontaneous emission rate, branching ratio and lifetime were calculated. We focused on a high branching ratio radiative transitions 2H11/2 → 4I15/2 (β = 0.94) and 4F9/2 → 4I15/2 (β = 0.901). The overlap between absorption and emission bands is partial and stokes type shifts were presented. The gain curves were determined after calculation of absorption and stimulated emission cross sections. The infrared transmission curve of the glass matrix was marked extrinsic absorption bands SiO and hydroxyl OH possessed high vibration energy played quenching effect for photoluminescence.

A new oxide, sodium-iron antimonate, Na2FeSbO5, was synthesized and structurally characterized, and its static and dynamic magnetic properties were comprehensively studied both experimentally by dc and ac magnetic susceptibility, magnetization, specific heat, electron spin resonance (ESR) and Mössbauer measurements, and theoretically by density functional calculations. The resulting single-crystal structure (a = 15.6991(9) Å b = 5.3323 (4) Å c = 10.8875(6) Å S.G. Pbna) consists of edge-shared SbO6 octahedral chains, which alternate with vertex-linked, magnetically active FeO4 tetrahedral chains. The 57Fe Mössbauer spectra confirmed the presence of high-spin Fe3+ (3d5) ions in a distorted tetrahedral oxygen coordination. The magnetic susceptibility and specific heat data show the absence of a long-range magnetic ordering in Na2FeSbO5 down to 2 K, but ac magnetic susceptibility unambigously demonstrates spin-glass-type behavior with a unique two-step freezing at Tf1 ≈ 80 K and Tf2 ≈ 35 K. Magnetic hyperfine splitting of 57Fe Mössbauer spectra was observed below T∗ ≈ 104 K (Tf1 < T*). The spectra just below T∗ (Tf1 < T < T*) exhibit a relaxation behavior caused by critical spin fluctuations, indicating the existence of short-range correlations. The stochastic model of ionic spin relaxation was used to account for the shape of the Mössbauer spectra below the freezing temperature. A complex slow dynamics is further supported by ESR data revealing two different absorption modes presumably related to ordered and disordered segments of spin chains. The data imply a spin-cluster ground state for Na2FeSbO5. © 2019 American Chemical Society.

A novel dissimilatory antimonate [Sb(V)]-reducing bacterium, strain SVR, was isolated from soil of a former antimony (Sb) mine. Strain SVR coupled Sb(V) reduction to acetate oxidation with an apparent reduction rate of 2.4 mM d−1. The reduction of Sb(V) was followed by the precipitation and accumulation of white microcrystals in the liquid medium. The precipitates were initially small and amorphous, but they eventually developed to the crystal phase with a length > 50 µm. Strain SVR removed 96% of dissolved Sb as the precipitates. An X-ray diffraction analysis indicated that the microcrystals were the orthorhombic Sb trioxide (Sb2O3), i.e., valentinite. Phylogenetic and physiological analyses revealed that strain SVR is a member of the genus Geobacter. The cell suspension of strain SVR incubated with acetate and Sb(V) at pH 7.0 was able to form valentinite. Interestingly, at pH 8.0, the cell suspension formed another crystalline Sb2O3 with a cubic structure, i.e., senarmontite. Our findings provide direct evidence that Geobacter spp. are involved in Sb(V) reduction in nature. Considering its superior capacity for Sb removal, strain SVR could be used for the recovery of Sb and the individual productions of valentinite and senarmontite from Sb-contaminated wastewater.

Microbial antimonate (Sb(V)) reduction is a promising approach to remove Sb(V) from wastewater. However, current knowledge regarding microbial Sb(V) reduction is limited to strictly anaerobic conditions. This study was the first to isolate three facultative-anaerobic Sb(V)-reducing bacterial strains from the sludge collected from a wastewater treatment facility in an antimony products plant. Two of the isolated strains, designated Dechloromonas sp. AR-2 and Propionivibrio sp. AR-3, were characterized based on their Sb(V)-reducing abilities. When cultivated under anaerobic conditions with Sb(V) and acetate as the electron acceptor and donor, respectively, both strains could efficiently reduce 5.0 mM Sb(V), removing most of it from the water phase within 7 d. Along with Sb(V) reduction by the strains, white precipitates, which were likely amorphous Sb(OH)3 solids, were formed with a minor generation of soluble antimonite. Additionally, respiratory Sb(V) reduction by both strains occurred not only under anaerobic but also microaerobic conditions. It was suggested that Sb(V) reduction and the growth abilities of the strains under microaerobic conditions presented a substantial advantage of the use of strains AR-2 and AR-3 for practical applications to Sb(V)-containing wastewater treatment.

Multinary chalcogenido (semi)metalate salts exhibit finely tunable optical properties based on the combination of metal and chalcogenide ions in their polyanionic substructure. Here, we present the structural expansion of chalcogenido germanate(IV) or stannate(IV) architectures with SbIII, which clearly affects the vibrational and optical absorption properties of the solid compounds. For the synthesis of the title compounds, [K4(H2O)4][Ge4S10] or [K4(H2O)4][SnS4] were reacted with SbCl3 under ionothermal conditions in imidazolium‐based ionic liquids. Salt metathesis at relatively low temperatures (120 °C or 150 °C) enabled the incorporation of (formally) Sb3+ ions into the anionic substructure of the precursors, and their modification to form (Cat)16[Ge2Sb2S7]6[GeS4] (1) and (Cat)6[Sn10O4S20][Sb3S4]2 (2 a and 2 b), wherein Cat=(C4C1C1Im)+ (1 and 2 a) or (C4C1C2Im)+ (2 b). In 1, germanium and antimony atoms are combined to form a rare noradamantane‐type ternary molecular anion, six of which surround an {GeS4} unit in a highly symmetric secondary structure, and finally crystallize in a diamond‐like superstructure. In 2, supertetrahedral oxo‐sulfido stannate clusters are generated, as known from the ionothermal treatment of the stannate precursor alone, yet, linked here into unprecedented one‐dimensional strands with {Sb3S4} units as linkers. We discuss the single‐crystal structures of these uncommon salts of ternary and quaternary chalcogenido (semi)metalate anions, as well as their Raman and UV‐visible spectra., Three sulfido (semi)metalates, (Cat)16[Ge2Sb2S7]6[GeS4] (1) and (Cat)6[Sn10O4S20][Sb3S4]2 (2 a and 2 b), Cat=(C4C1C1Im)+ (1 and 2 a) or (C4C1C2Im)+ (2 b), were obtained by salt metathesis from [K4(H2O)4][Ge4S10] or [K4(H2O)4][SnS4] and SbCl3 in imidazolium‐based ionic liquids at moderate temperatures (120 °C). The incorporation of Sb3+ ions into the (modified) anionic substructures is reflected in the Raman and UV‐visible spectra of the products.

In this study, diatomite coated with Fe-Mn oxides (DFMO) was synthesized through calcination. The adsorption of antimonate (Sb(V)) by DFMO was studied, and environmental factors affecting the adsorption were investigated. The components of DFMO were identified as γ-Fe2O3, γ-MnO2, and SiO2, in the presence of diatomite covered with nanoscale metal oxides. Batch experiments were carried out to evaluate the antimonate adsorption performance in aqueous solution. Results showed that maximum Sb(V) adsorption capacity of DFMO reached 10.7 mg/g at pH 4, corresponding to 22.2 mg/g per unit metal oxides. Antimonate adsorption occurred on heterogenous surface, following the Freundlich and Pseudo-second order model. Overall, antimonate adsorption was favored at acidic condition due to low point of zero charge. However, when treating electroplating wastewater, neutral pH condition exhibited a higher efficiency than acidic pH, because co-existing ions in electroplating wastewater significantly affects antimony adsorption. Further investigation showed that among different potential co-existing ions, fluoride can strongly inhibit the adsorption of antimonate at 5 mg/L under pH 4. Density functional theory (DFT) analysis confirmed that adsorption energy on DFMO follows: HF

Calcium distribution in fertile and sterile anthers of a thermosensitive male-sterile wheat genotype was investigated using an antimonate precipitation method. During fertile anther development, be...

Nickel antimonate (NiSb2O6) was synthesized by a microwave-assisted wet chemical method for its application as a potential gas sensor. The powders calcined at 600 °C were corroborated by X-ray diffraction. The microstructure of the material was analyzed by electron microscopy in its scanning and transmission versions, finding different morphologies. The average size of the nanoparticles was estimated at ~ 14.3 nm. X-ray photoelectron spectroscopy showed that the bond energies for Ni (2p) were of 855.2 and 872.9 eV, for Sb, they were of 530.28 and 539.66 eV, and for O(1s), it overlapped the Sb at 530.28 eV. Photoluminescence and UV–Vis spectroscopy measurements confirmed that the emission energy values were of 2.8 and 1.4 eV. Tests carried out in propane and CO atmospheres indicated that the NiSb2O6 nanoparticles possess good response at several concentrations and temperatures of both gases. According to our results, NiSb2O6 is a strong candidate to be applied as a gas sensor.

Silver antimonate-based compounds, formed at partial substitution of ions of quinquevalent antimony with ions of hexavalent molybdenum, have been synthesized using the method of solid-phase reaction. Specificities of phase formation processes of mixtures with various mole ratios of the initial components of a system containing silver nitrate and oxides of trivalent antimony and hexavalent molybdenum have been studied in a wide temperature range from 300 to 1023 K. Using the thermogravimetric analysis data, optimal temperatures for synthesis of powders have been determined. Using the method of qualitative X-ray phase analysis together with the method of high-temperature X-ray diffraction, compositions of reaction products of solid-phase interaction at open air heating have been determined. For the temperature of 1023 K, a homogenous area of formation of a solid solution of silver antimonat-molibdates with the structure of a defective pyrochlore-type within 0,0 ≤ x ≤ 2,0 concentration interval has been determined. In the frameworks of Fd-3m spatial group, a full-profile analysis (the Rietveld method) has been carried out to specify the crystal structure (coordinates of population of ions by crystallographic positions, elementary cell parameters), and interrelation in compositions of the obtained pyrochlore phases with their structural disorder and ion-conducting properties has been determined. Ceramic properties (relative density and average size of particles) of the samples sintered at the temperature of 1373 K have been studied.

Increasing attention has been focused on antimony (Sb) pollution and remediation in aquatic ecosystems, where efficient removal technologies for Sb compounds, particularly Sb(III) and Sb(V), from environmental water are urgently needed. Thus, herein, a mesoporous material, titanate nanotubes (3 nm, TiO2 NTs) with a large surface area was synthesized and used to remove both Sb(III) and Sb(V) from various natural waters. Furthermore, it was characterized via adsorption isotherm and kinetic experiments, and its mechanisms were investigated using various techniques, including Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and density functional theory (DFT) models. The results show that the maximum amounts of Sb(III) and Sb(V) adsorbed on the TiO2 NTs (250.0 mg g−1 and 56.3 mg g−1) were due to electrostatic interactions and complexation, which were 20- and 7-fold greater than that on TiO2 NPs of 12.0 mg g−1 and 8.6 mg g−1, respectively. The removal efficiencies for the TiO2 NMs using tap water, natural surface water and wastewater were satisfactory, which were nearly 100% for Sb(III) and 100%, 98% and 56%, respectively, for Sb(V) with 5 mg/50 mL TiO2 and spiked with Sb (200 μg L−1). The TiO2 NTs showed excellent reusability with 0.5 mol L−1 sodium hydroxide as a desorbing agent. The FTIR and XPS results suggested that the hydroxyl groups play a significant role in the adsorption processes. Based on DFT calculations, it was found that Sb(III) preferred to form O–Ti bonds, Sb(V) formed O–Ti bonds on the {101} facet of the anatase TiO2 NPs, and Sb(V) preferred to adsorb on the {001} facet. However, for Sb(III), there was no preference between the {101} and {001} facets. This study demonstrates that TiO2 NTs are promising, easily synthesizable and environmentally friendly adsorbents for both Sb(III) and Sb(V), and can be potentially applied in wastewater treatment.

The high recombination efficiency of photogenerated charge carriers is the primary factor suppressing the photocatalytic performance of polymeric carbon nitride (CN). To enhance the charge separation, Sb-doped CN (CN/Sb) was firstly synthesized using antimonate as a doping and oxidizing agent. The N–SbIII bond was fabricated in CN/Sb via a redox process, which works as a charge-capture center, evidenced by experimental and theoretical calculation methods, and leads to a prominent enhancement in the charge separation and transfer performance of CN/Sb. CN/Sb exhibits much higher photocatalytic activity than CN in water splitting and environmental remediation. The visible-light photocatalytic hydrogen evolution rate of CN/Sb can reach ∼1.75 mmol g−1 h−1, which is ∼4.5 times that of CN, with an apparent quantum yield of 6.4% at 420 nm. Reactive oxygen species generation rates of CN/Sb are also much higher than those of CN. This work provides not only a new effective way for CN modification but also a deep insight into the metal-doping structure in the CN framework, which can guide future research on metal-doped CN photocatalysts.

Iron-biochar is an efficient adsorbent for contaminants, whereas the role of prepared temperature on removal of antimony (Sb) is unacquainted. In this study, the iron-biochar composites (FBC) were fabricated by co-pyrolysis at 500°C and 800°C and applied to remove antimonite (Sb(III)) and antimonate (Sb(V)) in aqueous. The results showed Fe3O4 was loaded on biochar prepared at 500°C (FBC500), while FeOOH with zero-valent iron (ZVI) was formed on biochar pyrolyzed at 800°C (FBC800). However, FBC500 showed the maximum absorbance for Sb(V) (30.47 mg/g), and FBC800 had optimal removal efficiency for Sb(III) (52.30 mg/g). The sorption of Sb(III) and Sb(V) on FBC was multilayer heterogeneous chemisorption (complexation and ligand exchange). Sb(III) was oxidized to Sb(V) with less toxicity during the corrosion of ZVI on FBC800, leading to the co-precipitation of Sb2O5. The electrostatic interaction affected the adsorption of Sb(V) on FBC500 and FBC800. The FBC800 showed superior reusability and resistance than FBC500.