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The development of eco‐friendly, high‐efficiency polyoxometalates (POMs) catalysts is vital for advancing catalytic oxidation and electrochemical detection in environmental protection. Herein, a POM‐based CuII‐containing complex with the molecular formula [H(4‐AP)]8[Cu2(H2O)4(P2Mo5O23)2]·8H2O (1) (4‐AP = 4‐aminopyridine) is synthesized using the hydrothermal method, and the crystal structure is determined by single X‐ray diffraction (SXRD), infrared (IR) spectroscopy, and powder X‐ray diffraction (PXRD). Structurally, complex 1 exhibits a one dimension (1D) chain arrangement, composed of CuII ions and Strandberg‐type (P2Mo5O23)6− anionic clusters. These 1D chains are further interconnected through [H(4‐AP)]+ ligands, resulting in the formation of a two dimension (2D) supramolecular network. Complex 1 serves as an outstanding heterogeneous catalyst for the oxidation of methyl phenyl sulfide (MPS), demonstrating a remarkable conversion rate of 99% for MPS and a selectivity of 98% toward methyl phenyl sulfoxide (MPSO). In addition to its catalytic capabilities, complex 1 is also employed in the electrochemical detection of FeIII and CrVI ions, with low limits of detection (LODs) at 4.92 µm for FeIII and 7.82 µM for CrVI. [ABSTRACT FROM AUTHOR]

To design and synthesize high‐nucleated titanium‐oxo clusters rationally based on molecular building blocks with potential coordination ability is still a great challenge. In this work, a family of titanium‐oxo clusters, including Ti2, Ti6, Ti12, and Ti20 clusters, have been assembled from large‐size ligand embonic acid‐modified {Ti2} molecular building blocks under solvothermal conditions. By modulating auxiliary linkers and solvent types, the {Ti2} building blocks exhibit varying degrees of polymerization to form high‐nuclear titanium‐oxo clusters. Notably, Ti20 with high nucleation, as the decamer containing {Ti2} building blocks, can act as a stable and heterogeneous catalyst to efficiently catalyze the oxidation of sulfides to sulfones and sulfoxides when using H2O2 as the green oxidant. This study provides a new approach for the design and synthesis of highly nucleated and homometallic TOCs based on {Ti2} units. [ABSTRACT FROM AUTHOR]

Chemical fixation of carbon dioxide (CO2) is an energy-saving method for alleviating the greenhouse gas emissions, whereas it persists a challenge posed by the demand for efficient catalysts. Herein, four unprecedented examples of tetradecanuclear vanadium clusters, namely, [(C2H8N2)6(CH3O)8(CH3OH)2VIV10VV4O26] (V14−1), [(C3H10N2)6(CH3O)8(CH3OH)2VIV10VV4O26](V14−2), [(C6H14N2)6(CH3O)8(CH3OH)2VIV10VV4O26]·5H2O (V14−3) and [(C4H12N2O)4(C4H11N2O)2(CH3O)2VIV10VV4O28]·6H2O (V14−4), have been triumphantly designed and constructed under solvothermal conditions. Among them, compounds V14−1–4 are the first cases of tetradecanuclear vanadium clusters without the introduction of inorganic acid radical ions. Two main units [VIV10VV4O26]8+ and [VIV10VV4O28]4+ represent brand-new configurations of tetradecanuclear vanadium clusters. Given the fact that the presence of VIV/VV can potentially facilitate electron transfer and consequently expedite catalytic reactions, we explored the catalytic activities of these compounds. Remarkably, V14−1 was further used as a heterogeneous catalyst in the CO2 fixation into cyclic carbonates under milder conditions (60 °C, 0.5 MPa) and exhibited higher catalytic activity. Also, the experimental results indicated that V14−1 could efficiently catalyze the sulfoxidation, which could fully convert most sulfides within 40 min at room temperature. Moreover, as a stable heterogeneous catalyst employed in CO2 fixation with epoxides and oxidation of sulfides, V14−1 could be consecutively used multiple cycles without losing its catalytic activity. [ABSTRACT FROM AUTHOR]

Blue light-mediated oxidation of sulfides to sulfoxides with O 2 over TzTz-TA advances in a selective and prompt manner. [Display omitted] Recently, triazine-based two dimensional (2D) porous materials have received increasing attention in photocatalysis. Herein, CTF-1, a covalent triazine framework, was adopted as the blueprint for designing a 2D bespoke photocatalyst. The thiazolo[5,4- d ]thiazole (TzTz) linkage was inserted into the framework of CTF-1, affording TzTz-TA, which belongs to conjugated microporous polymers (CMPs). Rather than the direct insertion via the challenging C H activation, TzTz-TA was assembled from 2,4,6-tris(4-formylphenyl)-1,3,5-triazine and dithiooxamide, in which TzTz was formed in situ by a process of catalyst-free solvothermal condensation. Both CTF-1 and TzTz-TA had similar energy gaps (E g), photocurrents, and charge carrier lifetimes, in line with the similar molecular underpinnings. However, the reduction potential of TzTz-TA is less negative than that of CTF-1 due to the insertion of TzTz linkage, in a more appropriate position for activating O 2 to superoxide (O 2 •–). In return, blue light-mediated oxidation of sulfides to sulfoxides with O 2 over TzTz-TA was accomplished with significantly superior conversions to those over CTF-1. Intriguingly, extensive sulfides could be oxidized to corresponding sulfoxides with outstanding recycling stability of TzTz-TA. Notably, attendance of an induction period was observed during TzTz-TA photocatalysis. This work highlights the vast potential of designing triazine-based porous materials to meet the tailor-made demands, such as the oxidative transformation of organic molecules with O 2. [ABSTRACT FROM AUTHOR]

In the present study, a dioxomolybdenum(VI) complex chelated with the ONO tridentate Schiff base ligand supported on chloromethylated polystyrene [MoO2L@CMP] was synthesized and characterized by various spectroscopic techniques like FT-IR, UV-Vis, DRS, SEM and EDAX. Then, its application was investigated in the oxidation of various alkyl and aryl sulfides using hydrogen peroxide in ethanol under reflux conditions. The supported catalyst could readily be recovered from the reaction mixture and reused several times with no considerable increase in its catalytic activity. [ABSTRACT FROM AUTHOR]

[Display omitted] Phosphomolybdate-containing compounds, as emblematic representatives of polyoxometalate-based functional materials, have garnered significant interest in recent years owing to their unique multi functionality properties in various fields. A multifunctional nickel-containing phosphomolybdate compound (H 3 DETA) 4 {Ni[Mo 6 O 12 (PO 4) 2 (OH) 3 (HPO 4) 2 ] 2 }·3H 2 O (1) (DETA = diethylenetriamine) was synthesized under hydrothermal conditions and characterized for its unique multifunctionality. The three-dimensional (3D) supramolecular networks of compound 1 is composed of {Ni[P 4 Mo 6 VO 31 ] 2 }22− polyanions and protonated organic cations (DETA) interacting by hydrogen bonds, exhibit excellent catalytic and electrochemical properties. Compound 1 serves as an efficient heterogeneous catalyst for the catalytic oxidation of sulfides to their corresponding sulfoxides, achieving a 99 % yield in 90 min. Simultaneously, compound 1 functions as electrocatalytic sensor for the electrochemical detection of Cr(VI), ascorbic acid (AA), and Fe(III), demonstrating excellent catalytic efficiency. [ABSTRACT FROM AUTHOR]

The 2D covalent organic frameworks (COFs) offer many 2D planes which are suitable for π–π stacking interactions with other conjugated molecules. To improve the photocatalytic performance of COFs, the synthesis of a pyrene‐tethered 2,2,6,6‐tetramethylpiperidinyl‐N‐oxyl (TEMPO) derivative cocatalyst is hereby described. The pyrene end of the cocatalyst is intercalated in between the layers of the 2D sp2 carbon‐conjugated porphyrin covalent organic framework (Por‐sp2c‐COF) via π–π stacking interactions evidenced by theoretical and experimental studies. The immobilization of pyrene‐tethered TEMPO significantly enhances both the efficiency of photoinduced hole transfer and the stability of Por‐sp2c‐COF for the selective aerobic oxidation of a series of sulfides to sulfoxides under the irradiation of 623 nm red LEDs. This work highlights the merit of π–π stacking as a facile and efficient approach of immobilizing hole transfer cocatalysts without disrupting the physiochemical properties of the 2D COF photocatalyst. [ABSTRACT FROM AUTHOR]

Due to the importance of sulfide removal from wastewater and waste streams, in this study, eight cost-effective electrocatalysts were designed and prepared by electrochemical technique and their performance was evaluated in the presence of a high concentration of sodium sulfide. According to the results, among the prepared electrocatalysts, CuNiDH-NP@G electrode (modified graphite with nitroprusside (vasodilator drug) and CuNi-double hydroxide) had the highest efficiency in sulfide electro-oxidation. Then, to improve the performance of the CuNiDH-NP@G electrode its structure was optimized and investigated by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), and energy-dispersive Xray spectroscopy (EDS). Based on the results of electrochemical analyzes, in the presence of sulfide the process is controlled by diffusion. The diffusion coefficient, heterogeneous electron transfer rate constant and electron transfer coefficient for sulfide electrochemical oxidation were determined 2.85 x 10-5 cm²/s, 3.126 cm.s-1 and 0. 72 respectively. The use of non_noble metals as the electrocatalyst for sulfide electro-oxidation, the very easy, affordable, and fast preparation of the introduced electrode and high performance of it demonstrate important items for the use of this procedure and electrode in the subsequent investigation of a different material. [ABSTRACT FROM AUTHOR]

Main observation and conclusion: The development of bifunctional catalysts has drawn much attention in realizing efficient and feasible catalytic systems to meet the diverse demand of potential industrial applications. Design of stable and powerful bifunctional catalysts for various catalysis systems is highly desirable yet largely unmet. Here, three kinds of decavanadate‐based transition metal hybrids (DTMH) (i.e., Co‐DTMH, Ni‐DTMH and Ag‐DTMH) have been successfully synthesized through a pH tuning strategy and further characterized. Specifically, the rare MO5N six‐coordinated transition metal coordination modes have been detected in Co‐DTMH and Ni‐DTMH, while Ag atoms in Ag‐DTMH exhibited three‐ and five‐coordinated geometries with the tuning of specially selected imidazole ligands. Thus‐obtained clusters can serve as powerful bifunctional catalysts for both sulfide oxidation and C—C bond construction. Remarkably, Ag‐DTMH demonstrated excellent heterogeneous bifunctional catalytic properties in the selective oxidation of sulfides and construction of C—C bond (yields up to 99%), which enable successful recycling for three cycles with remained catalytic activities and structure stability. The newly designed decavanadate‐based transition metal hybrids with bifunctional property hold high promise in the practical applications like continuous catalysis or flow bed reactions. [ABSTRACT FROM AUTHOR]

A direct selective approach to the oxidation of sulfides to sulfoxides and sulfones with H2O2 in moderate to good yields is developed. The reaction proceeds in the presence of 2 mol % of VO(acac)2 at room temperature. All sulfoxides and sulfones were detected by gas chromatography, and the molecular structures of 2-methylbenzyl 4-methylphenyl sulfone, 4-methylbenzyl 4-methylphenyl sulfone, 2-bromobenzyl 4-methylphenyl sulfone, and 4-tert-butylbenzyl benzyl sulfone were determined by single crystal X-ray crystallography. [ABSTRACT FROM AUTHOR]

A molybdenum(VI) Schiff base complex as an efficient and highly heterogeneous catalyst was developed by immobilization of a molybdenum complex on the surface of modified Fe3O4 magnetite nanoparticles. The obtained nanoparticles were employed as catalysts for the selective oxidation of sulfides to corresponding sulfoxides using urea hydrogen peroxide as the oxidant. Furthermore, the obtained catalysts showed not only high catalytic activity in oxidation reactions but also high degree of chemical stability in various organic solvents. This nanocatalyst can be easily recovered from the reaction system by using an external magnet and reused several times with high yields. The complete characterization of catalysts was carried out by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM) and FT-IR techniques.

Nickel‐anchored curcumin‐functionalized boehmite nanoparticles (BNPs@Cur‐Ni) as a robust and versatile nanocatalyst was synthesized and well‐characterized by using Fourier transform infrared (FT‐IR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X‐ray (EDX), X‐ray mapping, thermogravimetric analysis (TGA), differential thermal analysis (DTA), Brunauer–Emmett–Teller (BET), X‐ray diffraction (XRD), and inductively coupled plasma optical emission spectroscopy (ICP‐OES). The synthesis of 5‐substituted 1H‐tetrazoles and the oxidation of sulfides were conducted by BNPs@Cur‐Ni with excellent turnover number (TON) and turnover frequency (TOF) outcomes. Also, the catalyst was reused for several sequential runs without Ni leaching or decreasing in reaction yield. Utilizing the curcumin and boehmite with a natural source as well as poly(ethylene glycol) (PEG) as a solvent in this simple protocol can be based on green chemistry rules. [ABSTRACT FROM AUTHOR]

Sponge-like inorganic-organic nanohybrid consisting of sandwich-type polyoxometalate of [P2W18Ce3(H2O)2O71]12− (P2W18Ce3) and dopamine (DA) was fabricated by a simple procedure. The DA/P2W18Ce3 sponge-like nanohybrid is turned into a nanoflower by calcination at 300 °C. The results showed a structure rearrangement of sandwich-type polyoxometalate to the Keggin-type polyoxometalate along with this morphology change. The nanomaterials were fully characterized by scanning electron microscopy (FE-SEM), energy dispersive X-ray analysis (EDX), thermogravimetric analysis (TGA), Fourier transform infrared (FT-IR) spectroscopy, texture analysis (BET), and X-ray powder diffraction (XPRD). The DA/P2W18Ce3 sponge-like nanohybrid and the Keggin nanoflower showed efficiency toward degradation of methylene blue (MB) and rhodamine B (RhB). Moreover, the catalytic activity of the Keggin nanoflower was examined in the oxidation of sulfides to sulfones with H2O2 as oxidant in water at room temperature. The catalyst was reused at least four times without loss of its catalytic activity. [ABSTRACT FROM AUTHOR]

Novel N -bromo nano vanadium oxo Pyridiniumporphyrazine-based molten salt catalyst ([VO(TPPABr)]CBr 3) was designed, synthesized and used for the chemo and homoselective oxidation sulfides and benzylic alcohols. The present study describes the design and synthesis of novel nano N -bromo porphyrazin (N -bromo tetra-2,3-pyridiniumporphyrazinato oxo-vanadium tribromomethanide [VO(TPPABr)] CBr 3) as an efficient, recyclable and thermal stable heterogeneous catalyst for chemo and homoselective oxidation of sulfides to sulfoxides and benzyl alcohols to benzaldehydes. This ecofriendly heterogeneous catalyst was fully characterized by FT-IR spectra, UV–Vis spectra, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and thermal gravimetric analysis (TGA), energy-dispersive X-ray spectroscopy (EDX) and elemental analysis (CHN). The synthesized catalyst exhibited a high-performance and considerable reusability. [ABSTRACT FROM AUTHOR]

Nitrogen-rich hierarchical porous carbon nanofibers (N-PCNFs) with highly efficient catalytic activity for the oxidation of hydrogen sulfide (H 2 S) at low temperature has been constructed through a modified electrospinning technology, using polyacrylonitrile (PAN) and zeolitic imidazolate framework (ZIF-8) as both carbon and nitrogen precursors. The specific surface area, doped nitrogen content and the ratio of micropores to mesopores of N-PCNFs can be readily adjusted by tuning the mass ratio of ZIF-8/PAN, the carbonization temperature combined with chemical activation treatment. After impregnated by sodium carbonate, the as-made N-PCNF catalysts exhibit an ultrahigh activity and superior sulfur capacity (the breakthrough sulfur capacity is up to 3.57 g H 2 S/g cat.) for the transformation of H 2 S into elemental sulfur at room temperature. The enhanced performance of N-PCNF catalysts for the selective oxidation of H 2 S has been demonstrated synergistically deriving from the nitrogen doping and the abundant micropores and mesopores in the one-dimension structural nanocarbons. The rational approach would make a great implication for the design of carbon nanocomposites for the efficient conversion of H 2 S. Unlabelled Image • Nitrogen-enriched hierarchical porous carbon nanofibers (N-PCNFs) were prepared by MOF-mediated electrospinning strategy. • N-PCNFs impregnated by Na 2 CO 3 show ultrahigh catalytic activities for the selective oxidation of H 2 S at room temperature. • The synergisitic effect between high nitrogen-doping level and hierarchical porous 1D structures has been demonstrated. [ABSTRACT FROM AUTHOR]

Selective oxidation of sulfides into sulfoxides or sulfones is an important transformation in organic synthesis. Activated carbon supported Nb-based catalysts were prepared by the impregnation method and then characterized by the XRD, TEM and XPS. The characterization results indicate Nb species is amorphous Nb 2 O 5. The catalysts were applied for the catalytic oxidation of sulfides in aqueous phase with H 2 O 2 as the oxidant. Sulfides could be converted into the corresponding sulfoxides or sulfones with high conversion and selectivity at room temperature. The recycling experiments showed the Nb 2 O 5 /AC catalysts exhibited good reusability. They could be recycled for 10 times without obvious loss of activity and selectivity. Unlabelled Image • AC supported amorphous Nb 2 O 5 catalysts were prepared. • Sulfides could be converted into sulfoxides or sulfones with high conversion and selectivity. • The Nb 2 O 5 /AC catalyst demonstrated excellent recyclability. • The catalytic oxidation of sulfides over Nb 2 O 5 /AC follows a nonradical mechanism. [ABSTRACT FROM AUTHOR]

• Optimal conditions for the maximum nitrate reduction by ADSOB. • Lower Fe2+ addition promoted the denitrification process. • FeS precipitation form dense cellular mineral aggregates at the cell surface. With the short-term exposure to Fe2+, the mechanism of autotrophic denitrification and sulfide oxidation and the correlation between microbial community changes and environmental factors have been explored in the ADSOB process. RSM was used to optimize conditions for the maximum nitrate reduction and sulfide oxidation. About 88% of nitrate could be autotrophically denitrified to nitrogen by utilizing sulfide as the electron donor with the molar ratio C/N of 1.14 and S/N of 0.99 at pH 7.1. Lower Fe2+ additions can reduce TDS inhibition with dissolved sulfide to form FeS precipitates, while high amount of Fe2+ limited the mass transfer of NO 3 − and intermediate products such as S0 may be generated. High-throughput sequencing and RDA analysis revealed the correlation between ferrous iron, environmental factors and microorganisms. Sulfurospirillum , Rhodanobacter , Thauera and Thiobacillus were all slightly promoted at NFL level and inhibited at NFH level. And the narrow angles of the arrows indicated that Thauera , Sulfurospirillum and Thiobacillus were positively correlated with SO 4 2- concentrations, while large angles indicated these bacteria were inversely related with TDS and NO 3 - arrows, which further confirmed that these bacteria played a dominant role in the ADSOB process, and can reduce NO 3 - by the oxidation of TDS. The correlation further indicated that lower Fe2+ additions have a promoting effect, while high concentrations have an inhibiting effect. [ABSTRACT FROM AUTHOR]

Sulfide induced concrete corrosion significantly reduces the service life of the sewer systems. Gaseous hydrogen sulfide (H 2 S) levels are a key factor affecting the corrosion rate and these fluctuate due to the diurnal flow pattern of sewers. Currently, there is little known about how such fluctuations, in particular the periodic deprivation of H 2 S, may affect the corrosion activity. This study investigated the impact of the deprivation of H 2 S on the sulfide uptake rate (SUR) of concrete coupons incubated in laboratory corrosion chambers. After systematic evaluation of the gaseous H 2 S concentration profiles of two sewer systems, two types of profiles, i.e. short- (1 h) and long- (12 h) term deprivation of H 2 S, were applied to the concrete coupons. In comparison to the baseline SUR, exposing the concrete coupon to 0 ppm of H 2 S for 1 h consistently caused a temporary increase of the SUR (i.e. 3.2%–12.5%) following re-supply of H 2 S at baseline levels. With the continuous re-supply of H 2 S, there was gradual and steady decrease of SUR to the level close to the baseline SUR. However, for the case after deprivation of H 2 S for 12 h, the SUR was 5.1% lower than baseline SUR and gradually increased to a level similar to the baseline SUR during the 20–30 min of continuous re-supply of H 2 S. In addition, the simultaneous deprivation of H 2 S and O 2 for 1 h had negligible impact on the SUR. Further analysis suggests that the historically accumulated intermediates of sulfide oxidation could act as electron donors for sulfide oxidizing bacteria (SOB). The replenishment of the intermediates upon the re-supply of H 2 S could play a key role in the increase of SUR after short-term deprivation of H 2 S. However, the activity of SOB could be diminished after long-term deprivation of H 2 S, although the sulfur intermediates still could be available. Estimating the sulfide uptake by concrete using the SUR of the average H 2 S concentration could lead to overestimation of the sulfide uptake. There could be more significant overestimation for the case with longer deprivation of H 2 S. Image 1 • H 2 S deprivation profiles of 2 real sewer systems were analyzed. • SUR increased by 3.2–12.5% after short-term (i.e. 1 h) deprivation of H 2 S. • SUR decreased by 5.1% after long-term (i.e. 12 h) deprivation of H 2 S. • Short-term deprivation of H 2 S and O 2 had negligible impact on SUR. • Overestimation of H 2 S uptake occurred when using SUR of average H 2 S concentration. [ABSTRACT FROM AUTHOR]

Gold is typically extracted from ores using a cyanidation process. However, environmental regulations and low productivity are the main drawbacks of cyanide usage. Alternative technologies for gold extraction are being studied although development of any new technology necessitates additional investments. In South Korea, recovery of gold and silver is performed by the local copper producer by feeding gold concentrate into a smelter. An integrated copper-making process might be an efficient and feasible alternative for the extraction of precious metals without the use of toxic cyanide. Installed exhaust gas cleaning system of copper smelter would minimize the toxic effects of hazardous elements (arsenic, bismuth, antimony, etc.) contained in gold concentrates. A kinetic and thermodynamic understanding of the effects of gold concentrates on copper metallurgy is necessary for the operation. The effects of various parameters on the oxidation kinetics of sulfides were investigated. [ABSTRACT FROM AUTHOR]

The present work reports the preparation of 40MoAl200 and its full characterization using a number of analytical techniques (XRD, TEM, TGA, BET, EDX). Liquid‐assisted ball milling proved to be a key tool to achieve both the best efficiency of 40MoAl200 as a novel Keggin type catalyst in the selective sulfoxidation reaction and also for succeeding in its effective recovery and reuse. In addition, the liquid assisted grinding process was studied in detail evaluating the influence of different parameters such as frequency of rotation (rpm), number and size of the stainless steel balls used and reaction time. The use of aqueous hydrogen peroxide is essential as water proved to exert a crucial role to improve both yields and selectivity towards sulfoxide formation. The procedure was representatively extended to a number of substrates with the possibility to extend the scope of the system to produce sulfoxides in high yields (up to 95 %) and satisfactory selectivities (up to 80 %). The catalyst proved to be recoverable and reusable under the optimized reaction conditions. [ABSTRACT FROM AUTHOR]

Abstract For the first time scandium triflate was supported on modified Fe 3 O 4 magnetic nanoparticles [MNPs-PhSO 3 -Sc(OTf) 2 ] and characterized using scanning electron microscopy (SEM), inductively coupled plasma analysis (ICP), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), energy dispersive X-ray spectroscopy (EDX) and vibrating sample magnetometer (VSM) techniques. The MNPs-PhSO 3 -Sc(OTf) 2 was applied as a magnetically recyclable heterogeneous Lewis acid nanocatalyst for the selective oxidation of a variety of sulfides to sulfoxides using hydrogen peroxide as a green oxidant resulting in 90–98% yields under solvent-free conditions at room temperature. It could also be recovered and reused for at least 15 reaction cycles without considerable loss of activity. Graphical abstract Unlabelled Image Highlights • The first MNPs-PhSO 3 -Sc(OTf) 2 was easily synthesized and characterized. • MNPs-PhSO 3 -Sc(OTf) 2 catalyzed highly efficient chemoselective oxidation of sulfides. • The catalyst allows for greener method while keeping high yields and low times. • The catalyst was reused up to 15 times without significant loss of activity. [ABSTRACT FROM AUTHOR]

Novel chiral imidazolium and pyridinium ionic liquids based on tartaric acid and 2-oxazolidinone were designed. Symmetrical dicationic ionic liquids based on tartaric acid have been synthesized and characterized. These chiral ionic liquids were designed by employing very short and simple methods. Incorporation of alkyl halide over tartaric acid and 2-oxazolidinone is an important step. N-methyl imidazole and pyridine were used for preparation of quaternary salts. These ionic liquids have been evaluated for the asymmetric sulfide oxidation. Chiral ionic liquids based on tartaric acid showed superior chiral inducing property as compare to 2-oxazolidinone based chiral ionic liquids. [ABSTRACT FROM AUTHOR]

Summary: Anoxygenic phototrophic sulfide oxidation by green and purple sulfur bacteria (PSB) plays a key role in sulfide removal from anoxic shallow sediments and stratified waters. Although some PSB can also oxidize sulfide with nitrate and oxygen, little is known about the prevalence of this chemolithotrophic lifestyle in the environment. In this study, we investigated the role of these phototrophs in light‐independent sulfide removal in the chemocline of Lake Cadagno. Our temporally resolved, high‐resolution chemical profiles indicated that dark sulfide oxidation was coupled to high oxygen consumption rates of ~9 μM O2·h−1. Single‐cell analyses of lake water incubated with 13CO2 in the dark revealed that Chromatium okenii was to a large extent responsible for aerobic sulfide oxidation and it accounted for up to 40% of total dark carbon fixation. The genome of Chr. okenii reconstructed from the Lake Cadagno metagenome confirms its capacity for microaerophilic growth and provides further insights into its metabolic capabilities. Moreover, our genomic and single‐cell data indicated that other PSB grow microaerobically in these apparently anoxic waters. Altogether, our observations suggest that aerobic respiration may not only play an underappreciated role in anoxic environments but also that organisms typically considered strict anaerobes may be involved. [ABSTRACT FROM AUTHOR]

The regioselective bromination and iodination of unprotected aromatic primary amines using enclathrated hydrogen peroxide as an oxidant under mild conditions has been developed, in which potassium bromide (KBr) and potassium iodide (KI) were used as brominating and iodinating agents, respectively. The adduct shows not only regioselectivity for para- or ortho-isomers but also a remarkable chemoselectivity for monobromination. Selective oxidation of sulfides to sulfoxides and sulfones has also been studied and good to excellent yields of the desired products were obtained. Acetic acid was found to be the solvent of choice for these reactions. This simple method represents an ecologically benign and alternative pathway for the oxidative halogenation of anilines and the oxidation of sulfides to sulfoxides and sulfones. [ABSTRACT FROM AUTHOR]

Graphical abstract Two symmetrical double-sided Schiff base ligands and their vanadium complexes has been synthesized and fully characterized. The interaction of the two vanadium complexes with bovine serum albumin (BSA) was investigated by spectroscopic techniques. SOD-like activity and ABTS free radical scavenging ability were also studied. The results showed that the microenvironment of BSA can enhance the activity of the complexes. The complexes can catalyze asymmetric catalytic oxidation of Methyl phenyl sulfide. Abstract Two symmetrical double-sided Schiff base ligands, H 4 L1 and H 4 L2, were synthesized by condensation of salicylaldehyde and 2-hydroxy-1-naphthaldehyde with oxalodihydrazine, respectively. The crystal structures of their vanadium complexes were analyzed by single crystal X-ray diffraction. The interaction between the synthesized complexes and BSA was studied by various spectral methods. The binding parameters including quenching constant K SV , binding constant K , and binding mode were obtained using fluorescence quenching method. The study shows that the quenching type was a static quenching process caused by formation of complex. The SOD activities of the complexes were determined by xanthine oxidase-NBT reduction method. The antioxidant capacity of the complexes was determined by the ABTS method. The results indicate that the activity of hybrid protein was more pronounced than that of the corresponding complex. At the same time, the hybrid protein can catalyze asymmetric oxidation of methyl phenyl sulfide. [ABSTRACT FROM AUTHOR]

Abstract Constraining the rate at which sulfide minerals undergo oxidative weathering at low atmospheric O 2 is crucial for understanding the evolution of the Archean and Proterozoic biosphere when O 2 was a trace atmospheric gas. However, recent studies attempting to constrain sulfide oxidation rates, atmospheric O 2 sinks, and trace metal delivery to seawater under Archean conditions are limited by the need to extrapolate from experimental pyrite oxidation kinetics determined at much higher O 2 levels. Extrapolation of those data sets to Archean levels of O 2 (<10−5 present atmospheric level or PAL prior to 2.4 Ga) leads to more than an order of magnitude uncertainty in sulfide mineral oxidation rates, hampering efforts to quantify oxidative weathering under early Earth conditions. To quantify sulfide oxidation kinetics at low p O 2 , we conducted aqueous pyrite and molybdenite oxidation experiments at ∼2–1200 nM dissolved O 2 and pH values 1.83, 5.08, and 8.58. Our experimental approach used LUMOS O 2 sensors to extend the p O 2 range explored by oxidation experiments down to 10−5 PAL p O 2 , the limit of the sensors, which is up to three orders of magnitude lower than the p O 2 range explored in previous work. From these experiments, we use 28 independent rate measurements to derive a new rate law for the oxidation of pyrite as a function of p O 2 : r pyrite = 10 - 8.83 (± 0.27) O 2 0.50 ± 0.04 H + - 0.25 ± 0.02 , Where r pyrite is the rate of oxidation in mol/m2 sec, and the activities of dissolved [O 2 ] and [H+] are in (mol/L). Our results most closely match the previous rate law presented by Williamson and Rimstidt (1994), but indicate a stronger pH dependence than previous studies. We also present the first kinetic rate law for molybdenite oxidation at low O 2 , based on 13 independent rate measurements: r molybdenite = 10 - 8.3 (± 2.3) O 2 0.5 ± 0.3 , Where r molybdenite is the rate of oxidation in mol/m2 sec, and the activity of dissolved [O 2 ] is in (mol/L). We find molybdenite oxidation to be nearly as rapid as pyrite oxidation even at low concentrations of dissolved O 2 (equivalent to <10−5 PAL p O 2), in contrast to previous work which argued for a threshold effect for molybdenite oxidation. Both pyrite and molybdenite oxidation kinetics exhibit a constant half-order dependence on dissolved O 2 down to nanomolar levels of O 2. We show that this behavior is best explained by a reaction mechanism in which O 2 undergoes dissociative adsorption to the sulfide mineral surface. This mechanism helps to resolve major uncertainties regarding the reaction mechanism of O 2 with pyrite and molybdenite mineral surfaces and provides a strong theoretical basis for the robust extrapolation of present results to higher and lower O 2 concentrations. [ABSTRACT FROM AUTHOR]

We present here a new class of niobium oxoclusters that are stabilized effectively by carboxylate ionic liquids. These functionalized ILs are designated as [TBA][LA], [TBA][PA], and [TBA][HPA] in this work, in which TBA represents tetrabutylammonium and LA, PA, and HPA refer to lactate, propionate, 3‐hydroxypropionate anions, respectively. The as‐synthesized Nb oxoclusters have been characterized by use of elemental analysis, NMR, IR, XRD, TGA, HRTEM. It was found that [TBA][LA]‐stabilized Nb oxoclusters (Nb−OC@[TBA][LA]) are uniformly dispersed with an average particle size of 2–3 nm and afforded exceptionally high catalytic activity for the selective oxidation of various thioethers. The turnover number with Nb−OC@[TBA][LA] catalyst was over 56 000 at catalyst loading as low as 0.0033 mol % (1 ppm). Meantime, the catalyst also showed the high activity for the epoxidation of olefins and allylic alcohols by using only 0.065 mol % of catalyst (50 ppm). The characterization of 93Nb NMR spectra revealed that the Nb oxoclusters underwent structural transformation in the presence of H2O2 but regenerated to their initial state at the end of the reaction. In particular, the highly dispersed Nb oxoclusters can absorb a large amount of polar organic solvents and thus were swollen greatly, which exhibited "pseudo" liquid phase behavior, and enabled the substrate molecules to be highly accessible to the catalytic center of Nb oxocluster units. Go oxo! A new class of niobium (Nb) oxocluster has been developed through coordination stabilization with carboxylate ionic liquids (ILs), which are uniformly dispersed with an average particle size of 2–3 nm. These oxoclusters afforded high catalytic activity for the selective oxidation of thioethers and olefins with ultra‐low catalyst loading. Characterization revealed that the Nb oxoclusters underwent structural transformation in the reaction but regenerated to their initial state at the end of reaction (see figure). [ABSTRACT FROM AUTHOR]

The use of oxo vanadium complex with s-propyl-2-aminobenzothioate ligand immobilized onto functionalized magnetic nanoporous MCM-41(Fe3O4@MCM-41@VO-SPATB) as efficient and magnetically recoverable nanocatalyst for oxidation of sulfides into sulfoxides and oxidative coupling of thiols into disulfides using H2O2 as green oxidant is presented. This method provides much improved modification of oxidation reactions in terms of mild reaction conditions, short reaction time and good-to-excellent yields of products. Another important feature of this method is the ability to reuse the magnetite nanocatalyst for several times with no loss of its catalytic activity. [ABSTRACT FROM AUTHOR]

Treatment of manganese(II) acetate tetrahydrate [Mn(CH3COO)2·4H2O] with one equivalent of 2,2′:6′,2′′-terpyridine (terpy) and two equivalents of potassium tetraphenylimido-diphosphinate K[N(Ph2PO)2] in methanol afforded a mononuclear manganese(II) complex, [(terpy)Mn{η1-O-N(Ph2PO)2}2(H2O)] (1), with two terminal [N(Ph2PO)2]– ligands. Interaction of [Mn(CH3COO)2·4H2O] with one equivalent of terpy in the presence of both K[N(Ph2PO)2] and Ph2PO2K in methanol gave a mononuclear manganese(II) complex [(terpy)Mn(η1-O-O2PPh2){N(Ph2PO)2}] (2) with a chelated [N(Ph2PO)2]– ligand. Treatment of manganese(II) dichloride tetrahydrate [MnCl2·4H2O] with three equivalents of K[N(Ph2PO)2] in methanol resulted in isolation of a mononuclear manganese(III) complex [Mn{η1-O-N(Ph2PO)2}-{N(Ph2PO)2}2] (3) with one terminal and two chelated [N(Ph2PO)2]– ligands. Reaction of [Mn(CH3COO)2·4H2O] with one equivalent of 4′-phenyl-[2,2′:6′,2′′]-terpyridine (4-Ph-terpy) and two equivalents of Ph2PO2K in methanol gave [(4-Ph-terpy)Mn(η1-O-O2PPh2)2(H2O)] (4) with a labile water molecule. Complexes 1–4 have been spectroscopically characterized and their structures have been established by single-crystal X-ray diffraction. Catalytic behavior of 1 and 4 for sulfide oxidation was also investigated. [ABSTRACT FROM AUTHOR]

Graphical abstract Manganese(IV) corroles catalyze efficient and selective sulfoxidations with iodobenzene diacetate as the mild oxygen source. The mechanistic studies suggested the different active oxidant forms were involved and significantly affected the catalytic activity. Highlights • Manganese corroles catalyzed efficient sulfoxidations with iodobenzene diacetate. • The reaction conditions, substrate scope and catalyst effects were investigated. • The synthetic utility of this catalytic method was demonstrated. • Kinetic and competition studies were conducted to probe the active oxidants. Abstract Manganese corrole complexes catalyze the efficient oxidation of organic sulfides to sulfoxides with iodobenzene diacetate [PhI(OAc) 2 ] as a mild oxygen source in the presence of small amounts of water. Various substituted thioanisoles can be efficiently oxidized to sulfoxides with quantitative conversions (up to 2500 TONs) and excellent selectivies for sulfoxides. The catalyst effects, including the corrole ligands and oxidation states of the central manganese, were investigated, and showed a significant impact on the catalytic sulfoxidations. The previously known high-valent manganese(V)-oxo corroles were chemically generated and kinetically studied in the oxidation of thioanisole substrates. The competition results suggested the oxidation state of manganese metal is crucial to control the nature of active oxidant forms that significantly affected their catalytic activity. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • New TS-1-derived catalysts were synthesized. • Their catalytic activity towards methyl(phenyl)sulfide S -oxidation was investigated. • Selectivity and progress of reaction have been observed under various conditions. • According to the gathered data a dual catalysis pathway have been proposed. Abstract Titanium-containing zeolite-based catalysts have been synthesized and investigated as catalysts in methyl(phenyl)sulfide oxidation with hydrogen peroxide. A hierarchical TS-1 prepared by the secondary templating and a layered TS-1 without and with silica and silica-titania pillars have been studied. Conventional TS-1 was a benchmarking material. The study focuses on observation of the different catalytic performance with regard to textural properties; presence and volume of mesopores and different diffusion characteristics. Thus, a deficiency and excess of the oxidizing agent were used in the catalysed reactions and the progress of reaction and selectivity to products were studied. All tested catalysts have shown after 240 min almost total conversion of methyl(phenyl)sulfide with different selectivity (substrate/catalyst mass ratio 10). It was observed that the reactants ratio hydrogen peroxide/ methyl(phenyl)sulfide influences the selectivity to sulfoxide or sulfone over a particular catalyst. In the case of hydrogen peroxide deficiency experiments (H 2 O 2 /sulfide = 0.5 mol/mol) the catalysts exhibited different distributions of products. Lamellar catalyst provided 100% selectivity to sulfoxide, the others in range of 90–65% selectivity to sulfoxide; however, the selectivity was independent on the reaction time and substrate conversion. In the case of the excess of the oxidant, except for Ti-pillared TS-1, all the catalysts showed stabile selectivity of 65% towards methyl(phenyl)sulfoxide being independent of the catalyst. The Ti-pillared TS-1 has shown, during the reaction progress, a decrease in the selectivity to sulfoxide from initial 60% to final 20% of sulfoxide at almost total conversion. The only case when higher selectivity to sulfone was achieved was gradual dosing of hydrogen peroxide. [ABSTRACT FROM AUTHOR]

Abstract The feasibility of implementing anaerobic ammonium oxidation (anammox) granules to start up high-loading anaerobic sulfide oxidation (ASO) in an upflow anaerobic sludge bed (UASB) reactor was investigated. An innovation method of the reverse start-up of anammox was also validated. Firstly, the reactor was operated to treat sulfide-rich wastewaters into which nitrite was introduced as an electron acceptor. An high-rate performance with sulfide and nitrate removal rates of 105.5 ± 0.11 kg S m−3 d−1 and 28.45 ± 3.40 kg N m−3 d−1, respectively, was accomplished. Sulfurovum were enriched with the increase of the substrate load and then conquered Candidatus Kuenenia to be the predominant bacteria. Excitation-emission matrix (EEM) spectroscopy showed that the intensities of fluorescence decreased and protein-like substrates were the main components associated with the process of start-up. FT-IR analysis found that the main functional groups indicator were O-H groups. Secondly, the reverse start-up of anammox (achieving 90% TN removal) was achieved immediately when the substrate changed. 16S rRNA analysis indicated the successfully enrichment of anammox bacteria (Candidatus Kuenenia). These results suggest that anammox granules can act as inoculum of high-loading ASO process and the reverse start-up provides a new perspective for the fast initiation of anammox process. Graphical abstract Image 1 Highlights • High-loading ASO process was started up by inoculation of anammox sludge. • Microbial community dynamics over different operational periods were revealed. • The reverse start-up of anammox process was quickly achieved. • EEM and FT-IR spectroscopy were employed to characterize changes in EPS. [ABSTRACT FROM AUTHOR]

Abstract Determining the rate at which Acid Mine Drainage (AMD) sulfide oxidation occurs in mining waste products is a central requirement for safe and sustainable long term design of storages, including tails storage facilities, ore stockpiles and waste rock dumps. Inappropriate design can result in AMD acidification, mobilisation of heavy metals and pollution of ground and surface waters. The use of soil gas (oxygen) transport modelling to model AMD based sulfide oxidation and potential acidity loads is widespread, but diffusion coefficients used for modelling are based on existing diffusion coefficient models derived for natural and agricultural soils. Mining wastes are often well sorted due to mineral processing, and differences in soil structure and porosity can impact on diffusion coefficient behaviour compared to natural soils. This study compares a variety of approaches to estimate the diffusion coefficient and compare these results to measured values for comparison and analysis. A diffusion column apparatus is used to compare diffusion coefficient models from the literature with test results from the laboratory in several mining derived AMD materials. The results of the comparison indicate that laboratory testing of diffusion provides more accurate estimation of soil gas diffusion coefficients in mine materials. The use of diffusion coefficient safety factor approaches are explored as possible alternatives, if measurement of mine material matrix soil gas diffusion coefficient is not possible. Highlights • Modelled diffusion coefficient data was compared with measured data for AMD soils. • Mining wastes are strongly sorted in comparison to natural agricultural soils. • Underestimates of diffusion may create AMD treatment problems. • Diffusion coefficient safety factors are recommended if measurement is not possible. • Design of economic < $500 diffusion chamber for mining sector using UPVC. [ABSTRACT FROM AUTHOR]

Abstract Three novel and green nano-scale magnetic solid base catalysts (CoFe 2 O 4 @glycine-M (M = Pr, Tb and Yb)) have been synthesized and characterized by XRD, TGA, VSM, EDX, ICP-OES, SEM and FT-IR spectroscopy. These robust nanohybrid catalysts as efficient and reusable heterogeneous nanocatalyst systems were used for synthesis of 5‐substituted 1H–tetrazoles and sulfoxides in green condition. The present methodology has outstanding advantages such as simplicity of procedure, facile synthesis, high activity, easy isolation of the products and reusability for several consecutive runs without significant loss of their catalytic efficiency. Graphical abstract Image 1 Highlights • Three green and novel catalysts were prepared by simple methods. • Prepared catalysts used as an efficient catalysts for synthesis of 5‐substituted 1H–tetrazoles and oxidation of sulfides. • These catalysts could be recovered easily by magnetic decantation and reused many times without important decrease in efficiency. [ABSTRACT FROM AUTHOR]

Nb‐monosubstituted polyoxotungstates of the Lindqvist and Keggin structures, (Bu4N)3[Nb(O)W5O18] (1) and (Bu4N)4[PW11NbO40] (2), respectively, catalyze oxidation of organic sulfides with aqueous H2O2 in acetonitrile. The corresponding peroxo complexes (Bu4N)3[Nb(O2)W5O18] (3) and (Bu4N)4[PW11Nb(O2)O39] (4), formed upon interaction of 1 and 2 with H2O2, are able to oxidize sulfides to sulfoxides and sulfones under stoichiometric conditions. The product analysis of the oxidation of thianthrene 5‐oxide, competitive sulfide–sulfoxide oxidation and Hammett plot implicated electrophilic oxidative properties of 4 and a complex oxidative nature of 3. Protonation of peroxo complex 3 leading to the formation of the peroxo species (Bu4N)2[HNb(O2)W5O18] (5) strongly increases its electrophilicity, which has a great impact on its reactivity and sulfoxidation selectivity. Nb‐peroxopolyoxotungstates of the Lindqvist and Keggin structures, (Bu4N)3[Nb(O2)W5O18] and (Bu4N)4[PW11Nb(O2)O39], catalyze oxidation of thioethers with H2O2 and are able to oxidize them under stoichiometric conditions to produce sulfoxides and sulfones. Protonation of the Lindqvist peroxo complex strongly increases its reactivity and sulfoxidation selectivity. [ABSTRACT FROM AUTHOR]

A previously unknown inorganic–organic hybrid polyoxidometalate constructed from oxalate‐functionalized tetra‐ZrIV‐substituted dimeric silicotungstate, (NH4)3Na5K6[Zr4(µ3‐O)2(µ‐OH)2(ox)2(SiW10O37)2]·23H2O (1, ox = oxalate) has been synthesized under mild hydrothermal conditions and characterized by FTIR spectroscopy, elemental analysis, thermogravimetric analysis, single‐crystal and powder X‐ray diffraction. Compound 1 contains a centrosymmetric polyoxidoanion structure with two [SiW10O37]10– units sandwiching a [Zr4(µ3‐O)2(µ‐OH)2(ox)2]6+ cluster. The catalytic performances of 1 involving oxygenation reactions of thioethers by H2O2 were evaluated, showing that 1 is an excellent catalyst for the catalytic oxidation of thioethers to sulfoxides/sulfones. A new tetra‐ZrIV‐substituted dimeric silicotungstate with two [SiW10O37]10– units sandwiched by an oxalate‐functionalized Zr4 cluster was made and characterized. This was used as a catalyst for catalyzing the oxidation of various thioethers with H2O2, showing excellent catalytic performance. [ABSTRACT FROM AUTHOR]

Graphical abstract A green, new, and efficient catalyst was successfully synthesized by the immobilization of Co as a transition metal on SBA-15 Then, this mesostructured material was characterized by TGA, SEM, FT‐IR, ICP, BET and X-ray mapping analytical. The prepared catalyst was used for the oxidation of sulfides the synthesis of polyhydroquinoline derivatives. The use of non-toxic materials, easy separation, easy operation, high yields of the products are the most important advantages of this method. Abstract In this work, a green and novel catalyst was prepared through immobilization of cobalt complex on the surface of mesostructured SBA-15 and characterized by TGA, SEM, FT‐IR, EDX, ICP, BET and X-ray mapping analytical methods. This mesostructural material was used as an efficient and green interphase catalyst for the oxidation reactions and synthesis of polyhydroquinoline derivatives. All reactions were performed in short times and good yields. Moreover, the prepared catalyst could be used up to six runs without significant degradation in its catalytic activity or cobalt leaching. [ABSTRACT FROM AUTHOR]

Abstract Aqueous geochemistry data together with sulfur and oxygen isotope ratios of minerals and dissolved sulfate in ground and surface water were assessed in six mining areas including five metalliferous mines and one coal mine in various regions in South Korea. The δ34S sulfate values effectively reflected characteristic sulfur isotopic ratios of minerals in each mine area, and the δ18O sulfate values of mining-affected water (adit water and leachate) were depleted than those of background water. A plot of δ18O sulfate values versus the logarithmic sulfate concentration revealed a good linear negative relationship (R2 = 0.78) for 219 samples spanning six mines in different regions. The observed range of δ18O sulfate values spanned the region where most of oxygen is derived from molecular oxygen for samples with low sulfate concentrations and the region of 100% oxygen derived from water molecules when sulfate concentrations were highest. This suggests that enhanced sulfide oxidation by ferric iron incorporating water-derived oxygen exponentially increases sulfate concentrations in mining areas. In addition, the lower and upper limits of sulfate in the plot could be defined as the atmospheric sulfate input and saturation of gypsum, respectively. The observed relationship between δ18O sulfate and sulfate concentration based on field data can further be used for semi-quantitative interpretation of oxygen isotopic ratios of sulfate in mine areas in terms of pyrite oxidation pathways. Graphical abstract Image 1 Highlights • Surface and ground water from mining regions were investigated to evaluate sulfide oxidation pathways. • A plot between δ18O sulfate and logarithmic sulfate concentration showed a linear negative relationship. • Signature of δ18O sulfate suggested that sulfide oxidation is enhanced exponentially by ferric iron. • Upper and lower limits of δ18O sulfate reflect the proportion range of oxygen from water molecule. [ABSTRACT FROM AUTHOR]

Sulfoxides are substances used in the synthesis of valuable complexes and as drugs in medicine. Sulfides were selectively oxidized to the corresponding sulfoxides in proper yields with (H2O2) hydrogen peroxide applying a vanadium (IV) Schiff base complex in the role of a catalyst in glacial acetic acid in the role of solvent beneath mild conditions. For the conversion of sulfides to sulfoxides of various catalysts are applied. It must be noted that in our previous article, the vanadyl complexes (VOY1) synthesized were applied as a catalyst in the epoxidation of styrene (Zabardasti and Shangaie, J Iran Chem Soc 13:1875-1886, 2016) but in the new work, vanadium (IV) complexes with Schiff base ligands derived from 2,3-diaminopyridine were used to as catalyst for the oxidation of sulfides to sulfoxides with H2O2. To the most of our information, there is not any literature description on the selective oxidation of sulfides to sulfoxides by means of a vanadium (IV) Schiff base complex with N, O donor ligand derived from 2,3-diaminopyridine catalyst beneath these conditions. Dimethyl sulfide was chosen as a pattern substrate for optimization experiments. Oxidation of sulfides was functioned at 25 °C temperature in the attendance of a catalytic quantity of the vanadium (IV) complex or (VOY1) utilizing 20% H2O2 in the role of the oxidant, Scheme 1 and glacial acetic acid in the role of the solvent. [ABSTRACT FROM AUTHOR]

Highlights • A geochemical method to calculate carbonate weathering from acid rain. • SO 4 , NO 3 , Ca, NH 4 and H are the main anions and cations (>15%) in acid rainfall. • The average proportion of carbonate weathering by acid rain is 36%. • The proportion represents an upper limit for carbonate weathering by acid rain. Abstract Carbonate weathering by CO 2 is considered to play an important role in the global carbon cycle. In acid rain-affected areas, the carbon cycle can be impacted by acid rain weathering. When previous studies have considered all possible weathering processes including H 2 SO 4 in rainfall, sulfide oxidation and agricultural activities, this study proposed a geochemical method to specifically calculate the extent of carbonate weathering by acid rain using hydrogeochemical data from karstic spring and rainfall. This method has considered the H concentration and nitrification of NH 4 in rain during recharge, and provided the upper limit of the weathering amount. Seasonal sampling for spring (wet and dry season) was conducted from a typical carbonate area in Jiaoshi, Chongqing, SW China, with annual rain pH values ranging from 3.94 to 4.70. The major hydrogeochemistry types of spring are HCO 3 –Ca and HCO 3 –Ca·Mg. The average proportion of carbonate weathering by acid rain is estimated to be 36 ± 15%. The quantitative geochemical method provided in this study is important for understanding the hydrogeochemical processes in acid rain areas and for calculating CO 2 sources & sinks of carbonate weathering. [ABSTRACT FROM AUTHOR]

In this work, we have described the versatility of low metal loading copper nanoparticles immobilized on nanocellulose for the controlled and selective oxidation of sulfides to sulfoxides and primary alcohols to aldehydes using green oxidant at room temperature. Aromatic, aliphatic and heterocyclic sulfides were oxidized to their corresponding sulfoxides with high yields without formation of over oxidized sulfones. Similarly, benzylic, allylic and aliphatic alcohols were selectively oxidized to aldehydes without traces of carboxylic acids in good to excellent yields.Graphical Abstract: [ABSTRACT FROM AUTHOR]

A hybrid catalyst based on monoprotonated divanadium-substituted phosphotungstate ([γ-HPV2W10O40]4−) was synthesized and used for the selective oxidation of sulfides. The catalytic system was carried out in water with hydrogen peroxide at room temperature. Unprecedented turnover numbers (TONs) for all substrates were obtained, which are much higher than previous reports. [ABSTRACT FROM AUTHOR]

Hydrogen sulfide is a toxic and usually undesirable by-product of the anaerobic treatment of sulfate-containing wastewater. It can be removed through microaeration, a simple and cost-effective method involving the application of oxygen-limiting conditions (i.e., dissolved oxygen below 0.1 mg L−1). However, the exact transformation pathways of sulfide under microaerobic conditions are still unclear. In this paper, batch experiments were performed to study biochemical and chemical sulfide oxidation under microaerobic conditions. The biochemical experiments were conducted using a strain of Sulfuricurvum kujiense. Under microaerobic conditions, the biochemical sulfide oxidation rate (in mg S L−1 d−1) was approximately 2.5 times faster than the chemical sulfide oxidation rate. Elemental sulfur was the major end-product of both biochemical and chemical sulfide oxidation. During biochemical sulfide oxidation elemental sulfur was in the form of white flakes, while during chemical sulfide oxidation elemental sulfur created a white suspension. Moreover, a mathematical model describing biochemical and chemical sulfide oxidation was developed and calibrated by the experimental results. [ABSTRACT FROM AUTHOR]

Abstract Micro-aerobic condition has proven to be effective in enhancing sulfide oxidation to elemental sulfur (S0) during integrated simultaneous desulfurization and denitrification process (ISDD). In this study we investigated and compared the performance and microbial community of ISDD process operating under initially anoxic, then micro-aerobic and finally switch back to anoxic condition. For all the three tested scenarios, comparable bioreactor performance in terms of sulfate (95.0 ± 4.4%, 90.6 ± 3.8%, 89.8 ± 3.5%) and nitrate (∼100%) removal was achieved. However, a shift of ISDD bioreactor from micro-aerobic to anoxic environment clearly increased the S0 production (30.6%), relative to that at initial anoxic condition (14.2%). Further anoxic bioreactor operation with different influent nitrate concentrations also obtained satisfactory performance particularly in terms of S0 production. Microbial community analysis results showed that functional microorganisms selectively enriched at micro-aerobic condition, particularly sulfide-oxidizing bacteria (SOB), could also function well and enhance S0 production when bioreactor switching from micro-aerobic to anoxic environment. We proposed that micro-aerobic strategy could function as a bio-selector and provide a new idea in functional microorganisms selectively enrichment for wastewater treatment. Highlights • Performance of ISDD process shifting from micro-aerobic to anoxic was explored. • Satisfactory reactor performance was achieved after operating condition switchover. • Selectively enriched microbe function well when switching back to anoxic. • Micro-aerobic strategy could function as a bio-selector for microbe enrichment. [ABSTRACT FROM AUTHOR]

A novel oxo-diperoxo tungsten(VI) complex, [WO(O2)2(Hphox)], was prepared by reaction of WO3 in H2O2 with an oxazine-type ligand, 2-(2′-hydroxylphenyl)oxazine (Hphox). The complex was characterized by FTIR, 1H NMR and elemental analysis. The single-crystal X-ray diffraction studies revealed a seven-coordinate tungsten center with a distorted octahedral geometry. The [WO(O2)2(Hphox)] complex was applied as a catalyst in efficient and selective oxidation of sulfide to sulfoxide using 30% H2O2 or UHP (urea hydrogen peroxide) as oxidants. This catalyst showed excellent catalytic activities and high selectivities in producing a variety of aryl and alkyl sulfoxides under mild conditions. To get an insight into the mechanisms of oxidation of sulfides, the mechanistic studies were monitored by UV-Vis spectroscopy. [ABSTRACT FROM AUTHOR]

[Display omitted] • A long-term development of oxidation of sulfides in an AS soil field was simulated. • CEC had an important role in reproducing the soil pH profile observed in the field. • The simulated oxidation of mackinawite was three times faster than that of pyrite. Land drainage lowers the soil water table, which triggers enhanced oxidation of iron sulfide minerals in acid sulfate soils, causing acidification of fields and posing environmental hazards to aquatic ecosystems. The objective of this study was to develop a model for investigating the effects of oxidation of iron sulfide minerals and the cation exchange capacity (CEC) on the long-term evolution of pH, redox potential and solute concentrations in soil water and drain discharge. Two electron acceptors (oxygen and ferric iron) were included in the model. The model was implemented in the HP1 modeling platform (coupled HYDRUS-1D and PHREEQC-3) and applied to an acid sulfate soil profile of an agricultural field in Finland. The geochemical part of the model was tested against field observations. A comparison of different model versions showed that CEC had an essential role in mimicking the observed pH profile of soil. The drain discharge water quality was similar in the model versions both with and without CEC, but the buffering effect of CEC could be seen as lower iron concentrations. The oxidation of metastable iron sulfide minerals was three times faster than the oxidation of pyrite. Descriptions for the oxidation of both two minerals and for CEC were required to conduct long-term simulations that reproduce the observed geochemical state of a drained agricultural field. The HP1 modeling platform facilitated the testing of alternative chemical transformation processes of an AS soil profile in response to increased drainage efficiency after subsurface drainage installation. [ABSTRACT FROM AUTHOR]

Sulfide oxidation is a major component of the global sulfur cycle that requires consideration in isotope-based models of aquatic and sedimentary systems, but the isotope fractionations based on analyses of all three isotope ratios of sulfur ( 33 S/ 32 S, 34 S/ 32 S, 36 S/ 32 S) have yet to be documented for abiological sulfide oxidation processes. We present experimental determinations of the reaction rates and sulfur isotope fractionations associated with the oxidation of aqueous sulfide (principally HS − ) by molecular oxygen (‘autoxidation’) in high pH (≈9.8), low ionic strength carbonate/bicarbonate buffered solutions as a function of temperature (5–45 °C) and trace metal catalysis (ferrous iron, added [Fe 2+ ] ∼50–150 nM). Rates and isotope fractionations are quantified via the analysis of sulfide as a function of reaction progress over relatively low extents of reaction (ca. 33–47%). The oxidation of sulfide at pH = 9.8 and 25 °C without any catalyst added is associated with a computed second order rate constant ( k ) of ln k  = 3.49 ± 0.38 ( k in M −1  hr −1 ; 2 s.d., quadruple experiments) and major sulfur isotope discrimination of 34 ε P-R  = −5.85 ± 0.43‰ (2 s.d., duplicate experiments) that are both consistent with previous studies, and a corresponding minor sulfur isotope fractionation relationship of 33/34 θ = 0.509 ± 0.004 that translates to Δ 33 S P-R  = 0.033 ± 0.018‰ (2 s.d.). The dependence of 34 ε P-R on reaction rate due to either temperature or ferrous iron catalysis over the ranges we have studied is small (<∼1‰ in 34 ε P-R ) and similar values for 33/34 θ and Δ 33 S P-R are obtained for all conditions studied (e.g., mean of all 7 experiments: 33/34 θ = 0.5082 ± 0.0031 and Δ 33 S P-R  = 0.037 ± 0.014‰; 2 s.d.). These results indicate that the process of sulfide autoxidation has a mass dependence that is resolvable from the expectations of typical equilibrium isotope exchange. Values for 36/34 θ and Δ 36 S P-R may also exhibit deviations from typical equilibrium isotope exchange but are not resolved under all conditions studied. The shift in values of 33/34 θ and Δ 33 S (and potentially 36/34 θ and Δ 36 S) is consistent with the hypotheses that kinetic isotope effects can be associated with different mass laws than equilibrium processes or with reversibility occurring in the initial parts of the reaction network leading to oxidation products, but both hypotheses will likely require further investigation. We provide an example of how our experimentally calibrated ‘signature’ for sulfide autoxidation may be identified in natural data using the previously published δ 34 S and Δ 33 S values of dissolved sulfide in proximity to the oxic-sulfidic interface in the water column of the Cariaco Basin. The observation that the autoxidation of aqueous sulfide in high pH media is associated with a non-zero Δ 33 S P-R will influence how chemical oxidation processes are treated in environmental and global scale models of the sulfur cycle based on multiple sulfur isotopes. [ABSTRACT FROM AUTHOR]