Use Of Thiosulfate Research Articles

A Pretreatment of Refractory Gold Ores Containing Sulfide Minerals to Improve Gold Leaching by Ammonium Thiosulfate: A Model Experiment Using Gold Powder and Arsenic-Bearing Sulfide Minerals

The use of thiosulfate to extract gold from refractory ores is promising because of its non-toxicity and high selectivity. Sulfide minerals (i.e., pyrite, arsenopyrite, chalcopyrite), major gold carriers in refractory gold ores, however, hinder gold extraction due to the high consumption of a lixiviant. In this study, a new method to improve gold extraction from sulfide bearing gold ores is proposed based on the model experiments using a mixture of gold powder and arsenopyrite-bearing sulfide (HAsBS) ore. The effects of HAsBS ore on gold leaching in ammonium thiosulfate solutions were investigated, and it was found that gold extraction in the presence of HAsBS ore was suppressed because of the unwanted decomposition of thiosulfate on the surface of sulfide minerals. To improve gold extraction in the presence of the sulfide minerals, this study investigated the effects of the pretreatment of HAsBS ore using ammonium solutions containing cupric ions and confirmed that HAsBS ore was oxidized in the pretreatment and its surface was covered by the oxidation products. As a result, thiosulfate consumption was minimized in the subsequent gold leaching step using ammonium thiosulfate, resulting in an improvement in gold extraction from 10% to 79%.

Enhanced and selective gold recovery from phone waste: Use of thiosulfate, dissolved oxygen, and an agriculture-based, low-cost adsorbent

Efficient methods were proposed to improve the gold recovery from printed circuit boards (PCBs) in mobile phones. Gold was selectively extracted in the form of Au(S2O3)23− using Na2S2O3-CuSO4-NH3-O2/N2 system. Under optimal conditions (temperature: 25 °C; stirring: 200 rpm; O2/N2: 3.0/0.5 L/min; time: 3 h; Na2S2O3: 160 mmol/L; CuSO4: 120 mmol/L; NH3: 0.7 mol/L (pH 9.9); solid/liquid: 4 g/L), 98% of gold was extracted. The extracted gold was adsorbed by corncob-based activated carbon (CACw), which was prepared using pyrolyzed wood vinegar. The modification of CACw with mercaptobenzothiazole (MBT), forming MBT-CACw, which displayed maximum adsorption efficiency of 49.9 mg/g. The optimal pH for adsorption was found to be 7.5 at 40 °C with 0.2 mol/L (NH4)2S2O3. The adsorption was described by the pseudo-second-order model and the Freundlich isotherm, owing to the high affinity of MBT-CACw for the sulfur donor. Copper was eluted from the loaded MBT-CACw using 0.7 mol/L (NH4)2S2O3 followed by the gold elution with 40% v/v CH3OH. The two-step elution recovered 98.7% of copper and 97.6% of gold. These findings suggest that the oxygen-assisted extraction, combined with the adsorption conducted using low-cost, agriculture-based adsorbent and selective elution, is an eco-friendly approach to efficiently recovering gold from e-waste.

Transformation of sulfur and nitrogen compounds by sulfidogenic and phototrophic bacteria under the influence of sodium fluoride and potassium bromide

Anthropogenically altered media are characterized by complex pollution, which contains a wide range of organic and inorganic pollutants, including halogen compounds. The influence of halides on transformed ecosystems, in particular, on their sulfidogenic and photosynthetic microbiota and its properties, remains insufficiently studied. The influence of sodium fluoride and potassium bromide at concentrations that are equal and 0.5–4.0 times differed from the maximum permissible concentrations (MPC) (MPC of fluorides and bromides are 0.0789 and 0.0025 mM, respectively) on the reduction of sulfate ions or sulfur (3.47 mM) by sulfidogenic bacteria of Desulfovibrio and Desulfuromonas genera, as well as on the use of thiosulfate or nitrite ions (4.167 mM) as electron donors of anoxygenic photosynthesis by phototrophic purple and green sulfur bacteria of Thiocapsa, Lamprocystis and Chlorobium genera, isolated from the Yavorivske Lake, was investigated. The biomass of bacteria was determined by the turbidimetric method, the content of H2S, SO42-, NО2ˉ and NО3ˉ in the cultural liquid – by the spectrophotometric method, the concentration of S2O32- – by the titrometric method. The intracellular glucose and glycogen content was determined enzymatically in cell-free extracts, using the analytical kit “Diagluc-2”. It was found that sodium fluoride and potassium bromide at concentrations 3.0–4.0 times higher than the MPC repress the biomass accumulation by bacteria Desulfovibrio sp. in the medium with sulfates 2.7−5.8 and 2.1−4.2 times, respectively, and inhibit the hydrogen sulfide production by them 1.8−3.4 and 2.0−3.2 times, respectively. NaF and KBr at concentrations that are equal and 2.0–4.0 times higher than the MPC repress the biomass accumulation by bacteria Desulfuromonas sp. in the medium with sulfur 2.2–6.9 and 2.1–5.6 times, respectively, and at concentrations 3.0–4.0 times higher than the MPC inhibit the hydrogen sulfide production by bacteria 1.9−3.7 and 2.0−2.7 times, respectively. Sodium fluoride and potassium bromide at concentration that 4.0 times exceeded the MPC inhibit the biomass accumulation by bacteria of Thiocapsa, Lamprocystis and Chlorobium genera in the medium with thiosulfates 2.0–2.3 and 1.7–2.0 times, respectively, reduce thiosulfate ions oxidation by them by 31.9–38.5 and 27.1–33.7%, respectively, compared to the control, but stimulate glycogen synthesis by cells of green sulfur bacteria by 106.7 and 64.0%, respectively. NaF and KBr at concentration 4.0 times higher than the MPC inhibit the biomass accumulation by phototrophic bacteria in the medium with nitrites 2.1−2.4 and 1.8−1.9 times, respectively, slow down nitrite ions oxidation by bacteria by 23.5–26.1 and 17.1–20.1%, respectively, compared to the control, but stimulate glycogen synthesis by cells of green sulfur bacteria by 134.7 and 115.0%, respectively. Glycogen content in Chlorobium limicola IMV K-8 cells grown in the media with Na2S2O3 or NaNO2 and NaF at concentration that 4.0 times exceeded the MPC was 81.33 and 84.13 mg/g of dry weight of cells, respectively. Fluoride ions showed a greater toxic effect on bacteria than bromide ions. The resistance of all tested bacteria strains to inorganic pollutants at high concentrations indicates their high biotechnological potential.

Separation of Ag and Cu from Their Aqueous Thiosulfate Complexes by UV-C Irradiation

In recent years, there has been renewed interest in the use of thiosulfate as a substitute for cyanide in silver leaching. Copper thiosulfate leaching without ammonia was applied to extract silver from silver sulfide, resulting in the production of Ag–Cu polymetallic thiosulfate complexes in solutions. It is necessary to separate Ag–Cu polymetallic thiosulfate complexes with the purposes of silver recovery and copper recycling. In this paper, the feasibility study on the use of UV-C irradiation to separate Ag–Cu polymetallic thiosulfate complexes was investigated based on the different photosensitivity of silver and copper. First, a kinetic study on the photolysis of silver and copper thiosulfate complexes by UV-C was investigated, indicating that the reactions follow first-order kinetics. The rate constant reactions were calculated, and it decreased with solution concentrations. On the other hand, the photoproducts of the silver and copper thiosulfate complexes were characterized by XRD and XPS in order to confirm the phase and chemical composition. It indicated that the silver photoproducts are Ag2S, S, Ag and the copper photoproducts are Cu2S, CuS, CuO, Cu, S. Finally, the four-step continuous separation of Ag–Cu polymetallic thiosulfate complexes by UV-C irradiation was investigated. The silver component was recovered with the accumulated recovery ratio of 97%, and the copper component was recycled with the accumulated recycle ratio of 51%, which made it possible for silver recovery and copper recycling.

Requirements for Efficient Thiosulfate Oxidation in Bradyrhizobium diazoefficiens.

One of the many disparate lifestyles of Bradyrhizobium diazoefficiens is chemolithotrophic growth with thiosulfate as an electron donor for respiration. The employed carbon source may be CO2 (autotrophy) or an organic compound such as succinate (mixotrophy). Here, we discovered three new facets of this capacity: (i) When thiosulfate and succinate were consumed concomitantly in conditions of mixotrophy, even a high molar excess of succinate did not exert efficient catabolite repression over the use of thiosulfate. (ii) Using appropriate cytochrome mutants, we found that electrons derived from thiosulfate during chemolithoautotrophic growth are preferentially channeled via cytochrome c550 to the aa3-type heme-copper cytochrome oxidase. (iii) Three genetic regulators were identified to act at least partially in the expression control of genes for chemolithoautotrophic thiosulfate oxidation: RegR and CbbR as activators, and SoxR as a repressor.

Feasibility study on the use of thiosulfate to remediate mercury-contaminated soil

ABSTRACTThe feasibility of using sodium thiosulfate to remediate the mercury-contaminated soil around a local chemical plant in northeastern China has been investigated. Effects of solid-to-reagent ratio and temperature on mercury extraction from soil samples with thiosulfate solutions were examined. BCR (European Community Bureau of Reference) analysis indicated that more than 90% of weak acid soluble and reducible mercury in the soil sample could be extracted by thiosulfate solution. Mercury extraction kinetics can be described by the two-step first-order reaction model in which the readily extractable fraction and the less extractable fraction of mercury were associated with their own rate constants. Mercury extraction with thiosulfate solutions could be slightly promoted when the contaminated soil was pre-oxidized with hydrogen peroxide. The results suggest that thiosulfate is a potentially effective complexing lixiviant in mercury-contaminated soil remediation.

Characterization and Genome Analysis of the First Facultatively Alkaliphilic Thermodesulfovibrio Isolated from the Deep Terrestrial Subsurface.

Members of the genus Thermodesulfovibrio belong to the Nitrospirae phylum and all isolates characterized to date are neutrophiles. They have been isolated from terrestrial hot springs and thermophilic methanogenic anaerobic sludges. Their molecular signatures have, however, also been detected in deep subsurface. The purpose of this study was to characterize and analyze the genome of a newly isolated, facultatively alkaliphilic Thermodesulfovibrio from a 2 km deep aquifer system in Western Siberia, Russia. The new isolate, designated N1, grows optimally at pH 8.5 and at 65°C. It is able to reduce sulfate, thiosulfate or sulfite with a limited range of electron donors, such as formate, pyruvate, and lactate. Analysis of the 1.93 Mb draft genome of strain N1 revealed that it contains a set of genes for dissimilatory sulfate reduction, including sulfate adenyltransferase, adenosine-5′-phosphosulfate reductase AprAB, membrane-bound electron transfer complex QmoABC, dissimilatory sulfite reductase DsrABC, and sulfite reductase-associated electron transfer complex DsrMKJOP. Hydrogen turnover is enabled by soluble cytoplasmic, membrane-linked, and soluble periplasmic hydrogenases. The use of thiosulfate as an electron acceptor is enabled by a membrane-linked molybdopterin oxidoreductase. The N1 requirement for organic carbon sources corresponds to the lack of the autotrophic C1-fixation pathways. Comparative analysis of the genomes of Thermodesulfovibrio (T. yellowstonii, T. islandicus, T. àggregans, T. thiophilus, and strain N1) revealed a low overall genetic diversity and several adaptive traits. Consistent with an alkaliphilic lifestyle, a multisubunit Na+/H+ antiporter of the Mnh family is encoded in the Thermodesulfovibrio strain N1 genome. Nitrogenase genes were found in T. yellowstonii, T. aggregans, and T. islandicus, nitrate reductase in T. islandicus, and cellulose synthetase in T. aggregans and strain N1. Overall, our results provide genomic insights into metabolism of the Thermodesulfovibrio lineage in microbial communities of the deep subsurface biosphere.

Silver leaching with the thiosulfate–nitrite–sulfite–copper alternative system

In the recent years, several silver leaching technologies have been investigated in order to find out an alternative and sustainable leaching process; one of these alternatives is the thiosulfate. The main research line is focused in the use of thiosulfate with copper as a catalyst and ammonia as a cupric ion stabilizer; however, the ammonia is also another toxic reagent. For that reason, an alternative-new leaching system using thiosulfate–nitrite and copper ions was investigated in this work. This new leaching system is able to dissolve silver without the use of cyanide or ammonia due to the cupric–ammonia complexes in-situ production, which is possible through the reaction of the nitrite and the cupric ions at neutral pH and NO2:Cu molar ratio of 30:1, according to silver leaching experiments and thermodynamic predictions.On the other hand, the effect of sulfite concentration was studied in the leaching solution revealing that the reductive ability of the sulfite ions has a negative effect on the silver leaching kinetics and recovery. It was also found that an increase in the pH of the leaching solution from 7 to 9.6 promotes the precipitation of copper hydroxide species which inhibits the silver leaching kinetics.Finally, copper–ammonia complex formation was also confirmed in the silver leaching by the UV–Visible spectroscopy technique. The solid leaching residues obtained at neutral pH were analyzed by X-ray diffraction and scanning electron microscopy showing the formation of a copper hydroxysulfate species called antlerite; this result was also confirmed by species distribution diagrams.

Use of elemental sulfur and thiosulfate as electron sources for water denitrification.

This study aims at comparing the sulfur-based autotrophic and mixotrophic denitrification performances in fixed-bed bioreactors to reveal the impact of alkalinity source, methanol supplementation and use of thiosulfate as electron source. Three different columns were operated. Reactor 1 was packed with elemental sulfur (3-5mm) and limestone (1-3mm). The second reactor (reactor 2) was packed with elemental sulfur (3-5mm) and bicarbonate was used as alkalinity source. In the third reactor (reactor 3), thiosulfate and bicarbonate were used as electron and alkalinity sources, respectively. Nearly complete autotrophic denitrification was attained at loading rates of 0.1, 0.36, and 0.1g NO3 (-)-N/(L day) in reactors 1, 2 and 3, respectively. Sulfate generated in autotrophic denitrification processes was nearly stoichiometric. Stimulating simultaneous heterotrophic and autotrophic denitrification by dozing methanol increased denitrification rate up to 0.72g NO3 (-)-N/(L day), decreased alkalinity requirement, and reduced sulfate generation.

Effects of Thiosulfate on the Adsorption of Arsenate on Hematite With a View to Phytoextraction

A study was carried out to evaluate how the adsorption process of arsenate on hematite is influenced by the presence of thiosulfate ion. The competition in sorption between the two anions was examined in relation to potential use of thiosulfate as an additive for phytoextraction in arsenic contaminated soils. Results obtained from sorption isotherms can be described according to the Langmuir equation which allows, by comparing adsorption maxima, a quantitative evaluation of the effect of increasing concentration of thiosulfate on arsenate adsorption. Due to the competition between the two anions for available sites on hematite, arsenic sorption decreased at increasing thiosulfate concentration. The negligible effect of ionic strength on the sorption process, strongly suggests that thiosulfate can substitute arsenate ions in the inner sphere complexes on the surface of hematite. The interpretation of the As adsorption process on hematite in terms of distribution coefficient (K d) shows that thiosulfate ions competing for sorption on the same surface may significantly reduce the arsenate adsorption and enhance the release of arsenic in the liquid phase of soil. Results have a direct influence on the applicability of phytoextraction in arsenic contaminated soils since plants can uptake arsenic only from the liquid phase. The obtained results can explain the increase in As concentration in plants, reported in a recent paper in which the addition of thiosulfate was shown to promote As phytoavailability.

The Effect of Thiosulphate on Arsenic Bioavailability in a Multi Contaminated Soil. A Novel Contribution to Phytoextraction

In this study it was evaluated on a laboratory scale (microcosm), the possibility of using ammonium thiosulphate in assisted phytoextraction for the simultaneous removal of mercury and arsenic from multi- contaminated industrial soil. The species selected were Brassica juncea and Lupinus albus the addition of thiosulfate to the soil greatly promoted the uptake and translocation of both contaminants in the aerial parts of the plants. Mercury concentration in the aerial parts reached in B. juncea 120 mg/kg approximately 40 times the value of the control). The concentration of arsenic also increased significantly in the shoots of B. juncea (14.3 mg/kg), where the value in the control was negligible. Similar trends were obtained for L. albus The results confirmed the known positive effects of thiosulphate in increasing mercury bioavailability for plants, moreover they showed the ability of thiosulphate to mobilize arsenic and significantly to promote its uptake by plants. The increase of arsenic bioavailability, promoted by thiosulfate addition, could be attributed to the competition between arsenate and sulphate ions for the same active sites in the soil surfaces, with the release of arsenic in the soil solution. The use of thiosulfate appears to have great potential since it is a common fertilizer used to promote plant growth and is able to increase the uptake by plants of mercury and arsenic. The simultaneous increase of both contaminants uptake by plants, using a single additive, will provide new insights into the phytoextraction technology in terms of cost and time reduction.

Using polysorbate 40-stabilized gold nanoparticles in colorimetric assays of hydrogen cyanide in cyanogenic glycoside-containing plants

This study presents a convenient and homogeneous method for the selective detection of hydrogen cyanide in cyanogenic glycoside-containing plants using polysorbate 40-stabilized gold nanoparticles (PS 40-AuNPs). Neutral PS 40 molecules stabilized citrate-capped AuNPs in a high-salinity solution. When the plant tissue is damaged, β-glucosidase rapidly hydrolyzes cyanogenic glycosides to produce hydrogen cyanide. The addition of the released hydrogen cyanide to a solution of PS 40-AuNPs resulted in the formation of AuCN(s) on the NP surface and Au(CN)2− in an aqueous solution. The removal of PS 40 molecules from the NP surface rendered the AuNPs unstable in a high-salinity solution, leading to NP aggregation. We used surface-assisted laser desorption/ionization time-of-flight mass spectrometry to detect the formation of AuCN(s). This probe was also successfully used to determine the total cyanide in cassava roots, peach kernels, and loquat kernels. When the three cyanogenic glycoside-containing plants were separately heated, this probe was capable of monitoring the removal of hydrogen cyanide during heating. In addition, the use of thiosulfate to detoxify the three cyanogenic glycoside-containing plants was evaluated using PS 40-AuNPs.

The deportment of mercury during thiosulfate leaching and resin-in-pulp recovery of gold from ores

This paper reports on the behavior of mercury and its compounds during the thiosulfate leaching and recovery of gold. Thiosulfate solutions are shown to dissolve Hg0 and Hg2Cl2 to a similar extent as cyanide, but the leaching of HgS is significantly slower in thiosulfate solutions compared to cyanide. Hence, the use of thiosulfate may be an option for treating ores containing high levels of cinnabar, especially since the legislation concerning the discharge or sale of mercury is becoming more restrictive. The deportment of mercury during gold thiosulfate loading and recovery using a strongly basic anion-exchange resin was also studied. Although the mercury thiosulfate complex loads on the resin, the adsorption is weaker than for gold, with an equilibrium constant between gold and mercury of 51. Resin loaded with gold, mercury and copper was pre-eluted with thiosulfate (to remove copper) and eluted with a chloride and sulfite eluant. The majority of the mercury is eluted by the eluant and, hence, its deportment closely follows gold and the eluate would need to be treated to remove either mercury during or prior to gold electrowinning.

Calcifilaxis severa en paciente en hemodiálisis

Calciphylaxis is a serious disease with a poor prognosis due to the limited therapeutic options. Avoiding this complication through prevention is essential. As more specific treatments, the use of thiosulfate, bisphosphonates and hyperbaric chamber can be considered.

The illustrative use of thiosulfate in the formation of new three-dimensional hybrid structures

Examples of 3D cadmium thiosulfate based inorganic–organic hybrid compounds have been shown to be active photocatalysts using sunlight.

Treatment of vascular calcification

A variety of potential therapies for vascular calcification, based either on the underlying biology or physical chemistry or solely on empiric observations in patients, may be effective but lack rigorous testing. Pasch et al. provide convincing evidence that sodium thiosulfate prevents medial vascular calcification in uremic rats. Although this provides some scientific basis for the clinical use of thiosulfate, uncertainty about mechanism of action and safety still remains.

Characterization of Herbaspirillum- and Limnobacter-Related Strains Isolated from Young Volcanic Deposits in Miyake-Jima Island, Japan

The role of microbes in the early development of ecosystems on new volcanic materials seems to be crucial to primary plant succession but is not well characterized. Here we analyzed the bacterial community colonizing 22-year-old volcanic deposits of the Miyake-jima Island (Japan) using culture-based and 16S rRNA gene clone library methods. The majority of 91 bacterial isolates were placed phylogenetically in two clusters (A and B) of the Betaproteobacteria. Cluster A (82% of isolates) was related to the genus Limnobacter and Cluster B (9%) was affiliated with the Herbaspirillum clade. The clone library analysis supported the predominance of Cluster B rather than Cluster A. Strain KP1-50 of Cluster B was able to grow on a mineral medium under an atmosphere of H(2), O(2), and CO(2) (85:5:10), and characterized by its large-subunit gene of ribulose 1,5-bisphosphate carboxylase/oxygenase (rbcL) and nitrogenase reductase gene (nifH). In contrast, strains of Cluster A did not grow chemolithoautotrophically with H(2), O(2), and CO(2) but increased their cell biomass with the addition of thiosulfate to the succinate medium, suggesting the use of thiosulfate as an energy source. From phenotypic characterization, it was suggested that the Cluster A and B strains were novel species in the genus Limnobacter and Herbaspirillum, respectively.

Adaptation of methane formation and enzyme contents during growth of Methanobacterium thermoautotrophicum (strain deltaH) in a fed-batch fermentor.

During growth of Methanobacterium thermoautotrophicum in a fed-batch fermentor, the cells are confronted with a steady decrease in the concentration of the hydrogen energy supply. In order to investigate how the organism responds to these changes, cells collected during different growth phases were examined for their methanogenic properties. Cellular levels of the various methanogenic isoenzymes and functionally equivalent enzymes were also determined. Cells were found to maintain the rates of methanogenesis by lowering their affinity for hydrogen: the apparent Km(H2) decreased in going from the exponential to the stationary phase. Simultaneously, the maximal specific methane production rate changed. Levels of H2-dependent methenyl-tetrahydromethanopterin dehydrogenase (H2-MDH) and methyl coenzyme M reductase isoenzyme II (MCR II) decreased upon entry of the stationary phase. Cells grown under conditions that favored MCR II expression had higher levels of MCR II and H2-MDH, whereas in cells grown under conditions favoring MCR I, levels of MCR II were much lower and the cells had an increased affinity for hydrogen throughout the growth cycle. The use of thiosulfate as a medium reductant was found to have a negative effect on levels of MCR II and H2-MDH. From these results it was concluded that M. thermoautotrophicum responds to variations in hydrogen availability and other environmental conditions (pH, growth temperature, medium reductant) by altering its physiology. The adaptation includes, among others, the differential expression of the MDH and MCR isoenzymes.

The leaching of silver sulfide with the thiosulfate–ammonia–cupric ion system

In recent years, there has been renewed interest in the use of thiosulfate as a substitute for cyanide in gold and silver leaching. Copper has been recognized to act as a catalyst in the process, and ammonia to stabilize the system. However, discrepancies exist in the literature concerning the oxidizing agent and, specifically in the case of silver sulfide (argentite), whether the leaching is oxidative or by substitution. The distinct mechanisms have implications concerning the feasibility of the process. The present study elucidates the chemistry of the leach through calculation of the species distribution and experiments on pure phase argentite, and also determines the role of the ammonia/thiosulfate concentration ratio. The experimental results on the pure phase show that the cupric ion reacts with thiosulfate to form the tetrathionate ion and a cuprous thiosulfate or ammonia complex, which liberates the silver by substitution in the solid phase. The results of leaching studies from a mineral concentrate indicate that, in addition to the cuprous ion concentration, the ammonia/thiosulfate ratio influences the silver extraction velocity: silver solubility and extraction are favored at low values of this quantity. A mathematical model for silver leaching in this system, which considers redox and complex equilibria, was developed. The experimental extractions were similar to those predicted by the model for low ammonia concentrations. Divergence from the simulated behavior was probably due to the slow reduction of the cupric ion at the high ammonia concentration (1 M).

Extraction of Mutagens from Chlorinated Poultry Chiller Water

ABSTRACTPoultry chiller water (PCW) was used as a model to study the formation of mutagens that can result from chlorinating waters of high organic content. The Ames Salmonella mutagenicity test was used to evaluate solvent extracts of PCW. Pentane gave satisfactory extraction of mutagens without the emulsion problem encountered with dichloromethane, permitting the use of pentane in continuous extractors. Use of thiosulfate to remove residual chlorine in samples resulted in low mutagenicity. Mutagens were formed within minutes of chlorination and continued to change in amount during the next 1‐2 hr. Mutagen formation was affected by pH and was proportional to chlorine dosage.