Search

We have developed a gold recovery method utilizing the thiosulfate leaching and cementation onto silicon (Si) powder. In this process, copper (oxidizing agent for gold dissolution) was also recovered after gold recovery. In this work, we tried to monitor the recovery behavior in order to improve selectivity of metals. For experimentation, an ammonium thiosulfate solution containing 1 mM (M: mol dm−3) sodium gold(I) sulfite and 5 mM copper(II) sulfate was prepared (pH 13). We immersed a gold wire in the solution and measured the rest potential during the recovery process using Si powder. The potential of gold wire shifted to negative direction at the start and end of gold and copper recovery. We discussed the potential shift by measuring polarization curves of gold wire in the ammonium thiosulfate solution under various conditions. The efficient recovery of high-purity gold would be achieved by monitoring the potential of gold.

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%. [ABSTRACT FROM AUTHOR]

The article focuses on evaluating the weed control effectiveness of a microcapsule formulation of the herbicide EPTC, synthesized for the first time in Iran, as an alternative to conventional formulations. It study also investigates the impact of the herbicide extender, Ammonium thiosulfate, at different doses and application methods on weed control.

Introduction The effectiveness of herbicides is influenced not only by the active ingredients and their toxicity but also by the formulation of the herbicide. Conventional herbicide formulations include wettable powder and emulsifiable concentrate (EC). EC formulations are prepared by mixing the active ingredient with solvents and surfactants. However, these formulations can have negative phytotoxic effects due to hazardous solvents and can be unsafe for operators during application. As an alternative to EC formulations, capsule suspension (CS) formulation has been considered. EPTC is a thiocarbamate herbicide used to control the growth of germinating annual weeds, including broadleaves, grasses, and sedges, in crops such as tobacco in Iran. EPTC acts by inhibiting cuticle formation during the early stages of seedling growth. It is available in formulated products such as emulsifiable concentrate (EC) liquids containing up to 87.8% active ingredient and granular (G) formulations containing up to 25% active ingredient. However, there have been few studies on the production of microcapsule formulations of this herbicide. This experiment aimed to evaluate the weed control effectiveness of EPTC microcapsule formulation, which was synthesized for the first time in Iran. Additionally, the study examined the effect of the herbicide extender, Ammonium thiosulfate, at different doses and application methods. Materials and Methods To investigate the effectiveness of different herbicide formulations and application methods, a three-way factorial experiment was conducted in Tirtash Research and Education Center in Mazandaran province, Iran, during the 2014 growing season. The experiment followed a randomized complete design (CRD) with three replications. The factors studied in the experiment were: 1. Herbicide formulation: o Emulsifiable concentrate formulation (Eradicane® EC 82%) o Emulsifiable concentrate formulation with Ammonium thiosulfate o Microcapsule formulation 2. Herbicide dose: o 50% of the recommended active ingredient (2.46 kg a.i. ha-1) o 75% of the recommended active ingredient (3.69 kg a.i. ha-1) o 100% of the recommended active ingredient (4.92 kg a.i. ha-1) 3. Herbicide application method: o Soil-incorporated pre-planting o Pre-planting A control plot with no herbicide application was also included. Throughout the growing season, weed density, weed dry weight, and tobacco yield were measured. The relative weed control compared to the control treatment was used to evaluate the efficiency of the different treatments. The collected data was subjected to analysis of variance using Minitab (Version 18), and mean comparisons were performed using the honestly significant difference (HSD) test at a significance level of 0.05. Results and Discussion Based on the relative frequency of weeds, Setaria viridis L. and Amaranthus retroflexus L. were dominant species. The experimental results show the effects of formulation type, application dose and method of application on weed density and weed dry weight and tobacco yield were statistically significant difference. The microcapsule formulation increased weed control efficiency and tobacco yield significantly compared to EC formulation and the highest weed control performance and tobacco yield belong to the soil incorporated of microcapsule formulation with recommended dose. Conclusions The results indicated that the utilization of a microcapsule formulation allows for a 25% reduction in the application dose of the EPTC herbicide, without compromising weed control or tobacco yield. Consequently, there were no significant differences observed between applying 75% of the recommended dose using the microcapsule formulation and applying 100% of the recommended dose using the EC formulation, with or without the extender. Based on these findings, it is crucial to promptly mix the herbicide with the soil immediately after spraying in order to maintain the efficiency of EPTC. Furthermore, it was discovered that employing two-thirds of the recommended dose of the microcapsule formulation yields the same level of effectiveness as the recommended dose of other formulations. Additionally, incorporating the EPTC herbicide with soil in all formulations enhanced weed control efficacy. In contrast to previous research suggesting the positive impact of extender adjuvants such as ammonium thiosulfate on herbicide efficiency, this study did not observe similar effects. This discrepancy may be attributed to the varying soil and climatic conditions at the test site. [ABSTRACT FROM AUTHOR]

To remove H2S and HCN from acid gases, wet‐oxidative desulfurization such as the Takahax process can be applied. There, a continuous wastewater stream with high concentrations of ammonium thiosulfate and thiocyanate is discharged. By wet air oxidation of these salts at 473–573 K, fertilizer‐grade ammonium sulfate can be obtained. Thiosulfate wet air oxidation kinetics was investigated under industrially relevant conditions via the oxygen consumption rate in a high‐pressure reactor. Kinetic parameters were estimated with a dynamic reactor model. The experimental data was reproduced with a good average deviation of 2.17 %, and the applied reaction pathway is simple due to the high temperatures. This is an important step towards taylor‐made reactors for wet air oxidation of Takahax wastewater. [ABSTRACT FROM AUTHOR]

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%.

Ammonium sulfate (AMS) and ammonium thiosulfate (ATS) are two of the most common sulfur products applied during canola seeding in the Canadian Prairies. A better understanding of how application methods affect the efficiency of these products is warranted. A field trial was conducted on a clay loam soil in Pense, Saskatchewan to evaluate the effect of seed row and side banded sulfur applications on canola yield and quality. Plots received 34 kg ha-1 sulfur either from AMS or ATS applied during seeding either in the seed row (SR) or side banded (SB). A treatment without sulfur was included as a control. All plots received the same amounts of all other nutrients. Results showed that average seed yields increased for all sulfur-treated plots, however, only side banded applications (AMS(SB): 4020 kg ha-1, ATS (SB): 3883 kg ha-1) were significantly better than the control (3072 kg ha-1). Side banded sulfur applications generally produced more protein than seed row applications and were significantly different from the control. AMS (SB) had the highest protein content (21.07%) while the control had the least (18.13%). Oil content was similar except for AMS (SB) (46.72%) which was significantly lower than the control (48.68%). However, this oil difference was more than compensated by the increased yield from AMS (SB). Applying AMS and ATS in the seed row can decrease the yield and protein response that might otherwise be seen when these products are side banded. There were no significant differences in the measured parameters between AMS and ATS. [ABSTRACT FROM AUTHOR]

The effects and decomposition of ammonium thiosulfate and guanyl thiourea, a nitrification inhibitor, are discussed. When ammonium thiosulfate and guanyl thiourea are used as nitrification inhibitors, leaching of ammonium nitrate from calcium ammonium nitrate in soil is reduced, while the yields and nitrogen intake of the plant are increased. When ammonium thiosulfate and guanyl thiourea are used, labor costs are reduced without any loss of product yield or quality. The use of ammonium nitrate products containing ammonium thiosulfate and guanyl thiourea reduced the nitrogen requirement for maximum efficiency. In this study, the effect of ammonium thiosulfate and guanylthiourea on calcium ammonium nitrate and how it affects nitrogen concentration under fertilization conditions were discussed. however, the results obtained by monitoring the loss of nitrogen concentration and the change in nitrate and ammonium concentrations over a specified time period indicate that the ammonium thiosulfate and guanylthiourea used are the best choice as an inhibitor candidate.

Maize (Zea mays L.) yield increases from sulfur (S) fertilizer have recently been documented in Iowa, but responses have not been consistent. The objective for this study was to evaluate the response of juvenile maize to S applied as ammonium sulfate (AMS), ammonium thiosulfate (ATS), and S-enhanced mono-ammonium phosphate (MAPS). Clarion loam (Typic Haplaquolls), Fayette silt loam (Typic Hapludalfs), and Muscatine silt loam (Aquic Hapludolls) were collected from eroded hillslopes in Iowa, and amended with 0, 22, 34, and 45 kg S ha−1. Maize (Pioneer 36N71) seedlings were planted in pots, placed in a controlled-climate chamber, and harvested after 21 days. Fertilizer S increased maize shoot dry matter (DM) when AMS was applied to Clarion loam, and when S from any source was applied to Muscatine silt loam. Sulfur fertilizer had no effect on DM accumulation in Fayette silt loam. Whole-plant S concentrations were generally higher than the control for all S sources. The agronomic efficiency of S (DM yield per unit applied) was greatest for the Muscatine soil, and was not related to S source or application rate. Early season growth of maize in Iowa may benefit from S fertilizer application, but the response may be site-specific. [ABSTRACT FROM AUTHOR]

Sluggish sulfur redox kinetics and incessant shuttling of lithium polysulfides (LiPSs) greatly influence the electrochemical properties of lithium-sulfur (Li-S) batteries and their practical applications. For this reason, ammonium thiosulfate (AMTS) with effective redox regulation capability has been proposed as a functional electrolyte additive to promote the bidirectional conversion of sulfur species and inhibit the shuttle effect of soluble LiPSs. During discharging, the S 2 O 3 2- in AMTS can trigger the rapid reduction of LiPSs from long chains to short chains by a spontaneous chemical reaction with sulfur species, thereby decreasing the accumulation of LiPSs in the electrolyte. During charging, the NH 4 + in the AMTS enhances the dissociation/dissolution of Li 2 S 2 /Li 2 S by hydrogen-binding interactions, which alleviates the electrode surface passivation and facilitates the reversible oxidation of short-chain sulfides back to long chains. The enhanced bidirectional redox kinetics brought about by AMTS endows Li-S cells with high reversible capacity, excellent cycle stability, and rate capability even under lean electrolyte conditions. This work not only illustrates an effective redox regulation strategy by an electrolyte additive but also investigates its catalytic reaction mechanism and Li corrosion behavior. The crucial criteria for screening additives that enable bidirectional redox mediation analogous to AMTS are summarized, and its application perspectives/challenges are further discussed.

Thinning is essential and important for the quality of peach and nectarine crops because of its impact on fruit size and next season's flower bud initiation, but hand-thinning is a costly practice and an unacceptable alternative. Researchers have been trying to introduce new thinners for almost thirty years, replacing hand-thinning. In this study, the quantitative and qualitative effects of some compounds used as thinning agents were examined on the 'Alberta' peaches and the 'Sun King' nectarines. This study has been carried out in a commercial orchard in Semirom, Isfahan, Iran during 2015–2016. Treatments included lime-sulfur (6%, 8% and double application of 6%), 10 mL L−1 fish oil, ammonium thiosulfate (20, 25 mL L−1and double application of 20 mL L−1), the plant growth regulator Apogee (300, 450 mg L−1 and double application of 300 mg L−1), hand-thinning of flowers (at full bloom) and hand-thinning of fruits (at pit hardening). The temperature at the application time of treatments on peach and nectarine trees was above 15°C and the sky was sunny. Results showed that all of the treatments, except for 300 and 450 mg L−1 Apogee significantly thinned the fruit to 61%. The treatments increased fruit weight (42%), volume (46%), total soluble solids (TSS) (28%), TSS/titratable acidity (TA) ratio (47%) and color (37%) as compared to control. However, there were no significant differences in TA of fruits among the samples. In terms of yield, various treatments differed significantly. The highest yield for Alberta peach was achieved by the control (123 kg/tree) and the lowest yield was obtained for the single application of 20 mL L−1 ammonium thiosulfate (85.41 kg/tree). In 'Alberta' peaches, the biggest fruit (125 cm3) was observed with the double application of 20 mL L−1 ammonium thiosulfate and fruit-thinning by 114 cm3. Double application of these chemicals often resulted in more blossom thinning than a single application. The blossoms and fruits were hand-thinned by 120 cm3 and 116 cm3, respectively. Double applications of 6% lime-sulfur and 10 mL L−1 fish oil gave the largest fruit size (115 cm3) of 'Sun King' nectarines. Trees under fruit and blossom-thinning, ammonium thiosulfate and lime-sulfur treatments showed the good return blossom in the second year. [ABSTRACT FROM AUTHOR]

The use of galvanic interactions between zero-valent aluminum (ZVAl) and activated carbon (AC) to recover gold (Au) ions is a promising technique to overcome the challenges due to the poor recovery in ammonium thiosulfate systems, but the applicability to practical Au ore processing remains elusive so far. The present study describes (1) the recovery of Au ions from low Au concentrations, which are typical concentrations used in Au ore processing; and (2) an investigation into the effects of various coexisting base metal ions that can be present in pregnant ore-leached solutions. The results showed that high Au recovery (i.e., over 85%) was obtained even at low Au concentrations under the following conditions: 1:1 of 0.15 g of ZVAl and AC with 10 mL of ammonium thiosulfate solution containing 5 mg/L of Au ions at 25 °C for 1 h in an anoxic atmosphere. Selected coexisting metal ions (i.e., copper, iron, cobalt, nickel, and zinc) were studied to establish their effects on Au recovery, and the results showed that the Au recovery was enhanced (about 90%) when copper ions coexist in the solution with minimal effects from other competing base metal ions.

This study compared the relative effectiveness of two products recently introduced as nitrification inhibitors with other materials used to inhibit nitrification. Four soils were treated with 0, 0.2, 1, 5, and 25 mg kg−1 of nitrapyrin (NP), a new microencapsulated nitrapyrin product (ENP), dicyandiamide (DCD), a new maleic-itaconic polymer product (MIP), and ammonium thiosulfate (ATS). The soils were also treated with 200 mg N kg−1 as urea, and percent inhibition of nitrification determined after 2 or 4 weeks of incubation. After 4 weeks, similar levels of nitrification inhibition were provided by 1 mg kg−1 of NP (72%), 5 mg kg−1 of ENP (79%), and 25 mg kg−1 of DCD (73%), averaged across soil. After 4 weeks with a sandy soil, the highest rate of MIP and ATS provided 15 and 36% inhibition, respectively. MIP and ATS were ineffective at inhibiting nitrification when added to the other three soils. Abbreviations: ATS: ammonium thiosulfate; DCD: dicyandiamide; ENP: encapsulated nitrapyrin; MIP: maleic-itaconic polymer; NP: nitrapyrin; UAN: urea-ammonium nitrate liquid fertilizer [ABSTRACT FROM AUTHOR]

Cadmium sulphide (CdS) thin-films have been electrodeposited using two electrode system to be used as the hole back diffusion barrier (hbdb) layer for graded bandgap solar cells with p-type windows. Cadmium acetate dihydrate [Cd(CH3COO)2·2H2O] and ammonium thiosulphate [(NH4)2S2O3] have been used as the cadmium (Cd) and sulphur (S) precursors respectively. In this work, CdS layers have been grown on glass/FTO (fluorine doped tin oxide) substrates at cathodic potentials ranging from 1300 to 1460 mV in order to find the best growth voltage. N-type conductivity is observed for all the layers and band-gap ranged between ~ 2.36 and ~ 2.40 eV for as-deposited layers and ~ 2.31 and ~ 2.36 eV for air-annealed layers. X-ray diffraction (XRD) analysis revealed cubic/hexagonal mixed crystallinity for the as-grown layers which indicates a tendency of transiting towards hexagonal structure upon annealing. Compositional and morphological characteristics of the layers have been investigated with energy dispersive X-ray (EDX) and scanning electron microscopy (SEM) respectively. [ABSTRACT FROM AUTHOR]

Highlights • Lime Sulphur is a strong pollenicide. • Ammonium thiosulfate, lime sulphur, mineral oil and vegetal oil arrest apple pollen tube development. • Ammonium thiosulfate is extremely caustic on the floral parts. • Benzyladenine, GA 4+7 +BA, and NAA promote blossom thinning, and improve fruit quality. • Ammonium thiosulfate and mineral oil promote blossom thinning when applied at 90% full bloom. Abstract The objective of this study was to investigate the mechanism of action of the treatments: Ammonium thiosulfate (ATS), benzyladenine (BA), GA 4+7 +BA, foliar fertilizer, lime sulphur (LS), LS + mineral oil, mineral oil, NAA, urea, and vegetal oil in the interaction of these treatments with: 1) pollen grain germination, 2) stigma/style pollen tube (PT) development, and 3) the effectiveness of the treatments in field conditions on decreasing crop load and enhancing fruit quality of 'Fuji More' apple trees. In experiment 1 it was evaluated the effect of the treatments in inhibiting the in vitro pollen germination of 'Maxi Gala' apples. In Experiment 2 it was evaluated in vivo 'Maxi Gala' pollen germination in 'Fuji' pistils to assess the effect of the treatments applied 24 h before and after the pollination, in three portions of the styles. In experiment 3 it was evaluated the effect of the treatments sprayed at 90% full bloom in a commercial 'Fuji More' apple orchard on the variables: fruit set, crop load, yield efficiency, mean fruit weight, cluster size, fruit height and diameter, total soluble solids, flesh firmne, mean seed number, skin russet and red color. ATS reduced in vitro pollen germination and caused the greatest damage to the stigmas/styles, while in the field, it was effective to reduce crop load. Treatments containing LS were the most effective to reduce in vitro pollen germination, but the in vivo essay, mode of action seemed to be related to arresting pollen tube growth, and in the field these treatments caused severe russeting. Mineral and vegetal oil do not have direct effect on pollen germination, but arrest pollen tube growth, and in field conditions mineral oil and ATS reduced crop load. All growth regulators (BA, GA 4+7 + BA, and NAA decreased greatly crop load and increased fruit weight and quality. [ABSTRACT FROM AUTHOR]

In this work, the results of recovering gold from ammoniacal thiosulfate solutions through cementing and electrodeposition were studied and analyzed. In cementation, the kinetic aspects of gold precipitation were analyzed using zinc and aluminum powder as cementing agents. The variations in the concentrations of the reducing agents, copper and gold as a function of time were analyzed to evaluate the influence of the previous deoxygenation and the activation energy was determined. The gold recoveries were greater than 98% for both reducers. The results showed that zinc is better cement, since aluminum, despite having a higher reaction speed, destroys thiosulfate. The highest consumption of zinc and aluminum was due to the deposition of copper, a ratio was observed (1: 1) and (2: 5) respectively. In zinc cementation, the gold concentrations were taken as a function of time for different reaction temperatures, the linearized form of the Arrenius equation was graphed to obtain the activation energy (Ea) which was found to be 15.43 KJ / mol. This value responds to a diffusive control for the reaction, and is similar to that found for processes with prior deoxygenation. This would indicate that, unlike the cementation of gold from cyanide solutions, the deoxygenation of these solutions would not be necessary. The experimental data of the electrolysis were adjusted to a model C = f (t) with R2 greater than 0.94. This allowed the calculation of the gold mass transfer coefficient (0.80 x10-6 m/s). This result is in the same order as that obtained by other authors for the electrodeposition of gold of cyanized solutions, (1.3x10-6 m / s) for a fluid velocity of 4.80x10-3 m / s. A final recovery of gold was obtained (92.1%) and copper co-precipitation was confirmed. [ABSTRACT FROM AUTHOR]

Abstract A mineralogical characterization was carried out in samples of refractory gold ore with 59 g/ton, according to fire assays, which were taken from a previous leaching process with ammonium thiosulfate. The potential window used to evaluate the cathodic and anodic processes was chosen knowing that gold and copper reduction, and thiosulfate and Cu(I) species oxidation occurs in it. The leaching process consisted of a pretreatment of the mineral (in ammonium hydroxide and copper sulfate during 12 h with and without air bubbling) followed by leaching (in ammonium thiosulfate solution and EDTA at a pH ∼ 10 during 24 h with mechanical stirring at a rate of 250 rpm) which rendered a gold-release of 81.57%. When oxidants and stabilizers like Cu(II), NH 3 and EDTA are present in thiosulfate based leaching solutions, the chemistry turns complex, and the partial reduction of copper, and redissolution of gold may occur. This fact and the low gold concentration make the electrowinning process especially difficult. Characterization techniques such as polarized light microscopy, X-Ray Diffraction, Rietveld quantification, and Automated Digital Imaging System, were chosen to track the process mineralogy of the sample, and the results prior to the leaching revealed association, size, and shape of each mineral occurrence; it was found that the mineral composition was pyrite crystals, exhibiting subhedral and inequigranular morphology (75%); galena crystals (10%); sphalerite (1.8%); chalcopyrite and arsenopyrite crystals (<3%); and free gold (<1%). The rest of the sample was comprised of aluminosilicate phases such as quartz and muscovite. After the leaching process, the main feature found was some accumulation of individual pyrite grains with corrosion grooves, and decrease in the particle size; on the other hand, the dissolution of the accompanying phases, with respect to the galvanic interactions, evidenced the next sequence of dissolution: I/E = pyrite > galena > M3 > sphalerite. Rietveld quantification suggested changes in the ratio of the main phases: pyrite decreased from 75.6% up to 65.7%; quartz increased from 21.1% up to 31.3%; galena decreased from 10.4% up to 7.6%; sphalerite decreased from 1.8% up to 1.1%. It is worth saying that the presence of precipitated amorphous phases was not observed. Graphical abstract Unlabelled Image Highlights • The leaching tests showed that when a refractory gold ore is accompanied by several phases of sulfides such as pyrite, galena, sphalerite, arsenopyrite, the galvanic interactions increase the dissolution of the sulfide minerals that have lower rest potential. • After the pretreatment process with ATSC solution, the dissolution of the accompanying phases concerning the galvanic interactions evidenced the next sequence of dissolution: I/E = pyrite > galena > ore > sphalerite. • The crystals of the various mineral phases that are present in the ore evidenced superficial corrosion after the thiosulfate pretreatment, showing grooves, cracks, and pores. • Arsenopyrite and sphalerite were the most/fully oxidized phases, and there was left only traces of them at the end of the process indicating that they are the least resistant to the oxidation process. • Rietveld quantification showed that the process mineralogy after the pretreatment with thiosulfate for the ore rendered changes in the proportions of the primary minerals: Pyrite decreased from 75.6 up to 65.7; quartz increased from 21.1 up to 31.3; galena decreased from 10.4 up to 7.6; Sphalerite decreased from 1.8 up to 1.1; Gold decreased from 0.2 up to 0.1. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Plant Science is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Ammonium thiosulfate is an alternative lixiviant for the hydrometallurgical treatment of sulfide gold ores. The present study is primarily focused on ammonium thiosulfate leaching of gold (Au) and silver (Ag) from the sulfide ore (Sunshin mine in Korea). The main chemical composition of the concentrate was Au (84 ppm), Ag (852 ppm), Fe (18.9%), Si (23.2%), and S (21.1%). The effects of various parameters on the process, such as leaching time (1–4 h), ammonium thiosulfate concentration (0.05–0.5 M), copper sulfate (CuSO4), concentration (0.05–0.25 M), solid to liquid ratio (0.2–0.5), and reaction temperature (40–60 °C) were systematically examined. Optimum Au leaching efficiency (>99%) was obtained under the following leaching conditions: 0.5 M ammonium thiosulfate with 0.05 M CuSO4 concentration, 0.2 S/L ratio at 60 °C for 2 h. The results indicate that the behavior of Ag was similar to that of Au. Almost complete dissolution of Ag occurred under following leaching conditions: 0.5 M ammonium thiosulfate with 0.05 M CuSO4 concentration at 60 °C for 4 h. This study would be useful in understanding the eco-friendly leaching systems of Au and Ag during the hydrometallurgical process of sulfide gold ore.

Artisanal Small Scale Gold Mining (ASGM) in Jampang Kulon produces tailing waste that contains heavy metals harmful to the environment. The taining, however, still contains gold metal (Au). Phytomining can be a solution in environmentally friendly gold mining by planting hyperakumulator plants on tailings and then extract its biomass. To increase the accumulation of gold in plant biomass, fertilizer is needed to enhance plants growth and chelate is necessary to increase the solubility of Au. This research aimed to know the effect of ammonium thiosulphate and compost on Au accumulation in vetiver grass (Vetiveria zizanioides L.) grown on tailings. This research used a completely randomized design with two factors, the dose of compost ; T0 (2.5 kg polybag-1), T1 (1.25 kg polybag-1), T2 (0 kg polybag-1) and the dose of ammonium thiosulphate ; K0 (0 g kg-1), K1 (5 g kg-1), K2 (10 g kg-1). The results showed that the addition of 10 g ammonium thiosulphate kg-1 significantly increased the accumulation of Au by 46% in plant roots and 35% in plant shoot related to control. While the addition of 1.25 kg compost polybag-1 could increase the accumulation of Au by 39% in plant roots.

Self-fertile cherry cultivars can produce an excessive crop of small fruits with low sugar content. In order to prevent overcropping and provide high quality fruits, chemical thinning of flowers is required. Ammonium thiosulfate (ATS), surfactants and plant oils are used to thin flowers, mostly in apple and peach. The purpose of this research was to compare the effectiveness of the blossom thinners ATS, surfactant Silwet and rapeseed oil (Ogriol) in reducing fruit set of the self-fertile sweet cherry cultivars Alex and Sunburst and their potential to improve fruit quality. At lower rates (1 and 2%) ATS did not consistently reduce fruit set, while at higher rate (3%) it produced visible phytotoxicity on the leaves. ATS treatments did not increase the average weight and diameter of fruits. 10 and 30 ml/l Ogriol application did not reduce fruit set significantly or improve fruit quality of self-fertile sweet cherries. The surfactant Silwet applied at the rates of 1 or 3 ml/l was found to consistently thin self-fertile sweet cherry cultivars, leading to better fruit quality.

Abstract The inhibitory effect of thiourea (TUA), ammonium thiosulfate (TSA) and amidosulfonic acid (ASA) on the reactivity of fly ash air was investigated using a thermobalance at different heating rates (5, 10 and 20 K min−1). A model fly ash (activated carbon + 50 wt% CuCl 2 ·2H 2 O, pyrolyzed at 700 °C and washed) was used as carbonaceous material. Adding CuCl 2 ·2H 2 O to the activated carbon led to an increased rate of decomposition with the air's oxygen. TUA and TSA behaved in a similar way, accelerating the decomposition of the model fly ash. ASA also accelerated the decomposition but to a lower extent. We postulate that the increase in decomposition rate is caused by a reaction between carbonaceous material and N and S-containing compounds. The formation of nitrogenated and sulphured compounds was confirmed by TG-MS. A kinetic model based on a single reaction of order 0.6 showed very good correlations with all the heating rates tested in oxidant atmosphere. Graphical abstract Image 1 Highlights • Inhibiting fly ash reactivity by N and S compounds was studied in a thermobalance. • The presence of N and S compounds accelerated the decomposition of the fly ash. • The compounds evolved during TG runs was monitored by TG-MS. • A kinetic model of a single reaction with nth order was proposed. [ABSTRACT FROM AUTHOR]

Highlights • Au extraction from waste mobile phone PCBs decreased at high S/L. • Extracted Au ions were re-deposited onto Cu and Al in PCBs by cementation. • Individually, amounts of Cu or Al in PCBs had negligible effects on Au cementation. • Synergistic effects of Cu and Al enhanced Au cementation via galvanic interactions. Abstract Ammonium thiosulfate solution is an ideal lixiviant to extract gold (Au) from electronic wastes (E-wastes) because it is non-toxic, less corrosive, and more selective than conventional cyanide or halide solutions. It was reported recently, however, that Au leaching efficiency in ammonium thiosulfate medium dramatically decreased at high solid-to-liquid ratios (S/L), even though the amounts of reagents used were in excess. To understand how this occurred, leaching experiments were conducted using printed circuit boards (PCBs) from waste mobile phones, and Au distribution in the leaching residues was examined by scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX). Significant amounts of Au were found together with copper (Cu) and aluminum (Al), implying that extracted Au ions were likely re-deposited during leaching onto Cu and Al found in PCBs via cementation (i.e., reductive deposition). A more detailed elucidation of this phenomenon by cementation experiments using pure Cu and/or Al powders indicates that these metals could only recover Au ions alone via cementation at very high amounts, however, this process became more extensive when Cu and Al powders were suspended together in solution even though the amounts of the individual metals were much lower. Electrochemical experiments (chronoamperometry) in ammonium thiosulfate solutions containing Au ions using an Al working electrode also showed that Au ion cementation was dramatically enhanced when Cu powder was present in solution, and the bulk of Au was cemented on Cu powder rather than on the Al electrode. These results suggest that coexistence of Cu and Al interfered with the extraction of Au in ammonium thiosulfate medium at high S/L because of the enhanced re-deposition of extracted Au via galvanic interaction. [ABSTRACT FROM AUTHOR]

The efficacy of three different doses of ammonium thiosulfate (ATS), potassium thiosulfate (KTS) and BA (6-benzyladenine) on fruit quality, yield and return bloom was evaluated in this present experiment on 'Deveci' pear (Pyrus communis, L.). All treatments were compared to an unsprayed control and hand fruit thinning. The highest fruit set was achieved with BA treatments. It was significantly reduced in KTS rates compared to control and other thinning treatments. KTS sprays create a statistically significant increase in fruit diameter and fruit weight, while ATS and BA have had no dramatic effect. Hand fruit thinning has resulted in heavier fruit at harvest similar to KTS with 2%. Thinners increased the percentage of fruit to ≥75 mm in diameter and proportions to 250-500 g fruit weight. In the control trees, the ratio of fruit to ≥75 mm diameter was 57%, the 75% or more of which was in hand thinning and chemical thinners. The proportion of fruits within 250-500 g fruit weight group was found in the highest KTS doses. No physiological disorder as bitter pit, water core, and aging disorder and phytotoxicity were observed in fruit samples. Study results show that 2% KTS significantly reduce crop load and increased fruit quality in 'Deveci' pear. Therefore, it can be used as an alternative to hand fruit thinning in the 'Deveci' pear to achieve high fruit quality. But, neither flower nor fruit thinners induced return bloom in 'Deveci' pear. [ABSTRACT FROM AUTHOR]

Electrodeposition of zinc sulphide (ZnS) was achieved from electrolytic bath containing zinc sulphate monohydrate (ZnSO4·H2O) and ammonium thiosulphate ((NH4)2S2O3) in a two-electrode electroplating configuration. The cyclic voltammetric studies show that ZnS layers can be electroplated between (1350 and 1550) mV. The grown layers were characteristically explored for their structural, optical, morphological and electronic properties using X-ray diffraction (XRD) and Raman spectroscopy, UV-Visible spectrophotometry, scanning electron microscopy (SEM), photoelectrochemical (PEC) cell and DC conductivity measurements respectively. The structural analysis shows that crystalline ZnS can be deposited within a narrow cathodic deposition range between (1420 and 1430) mV. The UV-Visible spectrophotometry shows that the bandgap of both as-deposited and heat-treated ZnS films are in the range of ~ (3.70 to 3.90) eV. The SEM shows small grains depicting the wetting property of ZnS. The PEC results show that the electroplated ZnS below 1425 mV is p-type and above 1425 mV is n-type under both as-deposited and heat treated condition. The DC conductivity shows that the highest resistivity is at the inversion growth voltage (Vi) for the ZnS layers. The glass/FTO/n-ZnS/n-CdS/n-CdTe/Au devices were fabricated using crystalline-ZnS and amorphous-ZnS buffer layers. The devices were explored using current-voltage (I-V) and capacitance-voltage (C-V) techniques. As expected, devices fabricated with c-ZnS show improved device parameters (ideality factor n = 1.60, depletion width W = 1092 nm, open-circuit voltage Voc=730 mV, short-circuit current density Jsc=34.1 mAcm−2, fill factor FF = 0.57, conversion efficiency η = 14.2%) when compared to device parameters (n = 1.85, W = 900 nm, Voc=720 mV, Jsc=29.9 mAcm−2, FF = 0.52, η = 11.2%) of these devices fabricated with a-ZnS buffer layers. [ABSTRACT FROM AUTHOR]

Reducing apple crop load during bloom can increase fruit size and promote annual bearing when compared with crop reduction at later timings. In this study, we compared the efficacy of chemical blossom-thinning strategies on 'Golden Delicious' and 'Gala' apple trees. Several blossom-thinning treatments were evaluated, including 1) unthinned control (control), 2) hand-thinned (HT) at bloom, 3) liquid lime sulfur + Stylet- Oil (LS + SO), 4) ammonium thiosulfate (ATS), 5) endothall (ET), and 6) naphthaleneacetamide (NAD). Chemical treatments were applied twice during bloom, using a predictive model to determine application timings. Blossom thinner effects on pollen tube growth, fruit set, and yield responses were evaluated. LS + SO and ATS reduced the number of pollen tubes that entered the style for 'Golden Delicious' by 75%and 63%, respectively. ET and NAD did not affect the number of pollen tubes that entered the style. In one of 2 years, LS + SO resulted in a near-ideal crop load and increased fruit weight. ATS was effective in reducing initial fruit set in 'Golden Delicious' and 'Gala', but did not reduce whole-tree crop density. ET reduced crop load in all experiments but caused excessive spur leaf injury and negatively affected fruit size of 'Gala' but not 'Golden Delicious'. NAD had limited efficacy on 'Golden Delicious' at the concentrations and application timings used in this trial. When used as the sole method of crop load management, none of the chemistries evaluated over-thinned or increased fruit injury. However, ET caused excessive thinning when evaluated as part of a commercial crop load management program on 'Gala'. Of the products evaluated, LS + SO provided the best overall thinning response. [ABSTRACT FROM AUTHOR]

The influence of ultrasound and microwaves on extraction of copper, nickel, and cobalt from manganese deep-sea nodules by reductive ammoniacal leaching in the presence of ammonium thiosulfate as a reducing agent was studied. The ultrasonic ammoniacal leaching provides higher metals extraction, while the effect of microwaves on the metals extraction under the studied leaching conditions is insignificant. In general, increasing leaching temperature increases significantly extraction of the metals of interest. At high temperatures, extraction efficiencies of copper, nickel, and cobalt decrease over longer leaching duration as a result of decomposition of the metals amino-complexes and reverse precipitation of metals. However, during the ultrasonic leaching at a temperature of 85 °C, the extraction of nickel remains almost unchanged over longer leaching durations and does not follow the decreasing course, observed in the extraction of copper and cobalt. The finding suggests that nickel can be selectively extracted from the nodules by the ultrasonic leaching. The maximal extraction efficiency of copper, nickel, and cobalt was 83%, 71%, and 32%, respectively, when the reductive ultrasonic ammoniacal leaching was carried out at 85 °C for 90 min. In the presence of microwaves, the maximal extraction efficiency of copper, nickel, and cobalt was 67%, 48%, and 8%, respectively, when the reductive ultrasonic ammoniacal leaching was carried out at the output power of 60W for 210 min. [ABSTRACT FROM AUTHOR]

This study evaluated the ability of Brassica napus for extracting gold (Au), silver (Ag) and copper (Cu) from a mine tailings, with the inoculation of two Aspergillus niger strains, and the application of ammonium thiocyanate (NH 4 SCN) or ammonium thiosulfate [(NH 4 ) 2 S 2 O 3 ]. After seven weeks of growth inoculated or non-inoculated plants were applied with 1 or 2 g kg −1 of either NH 4 SCN or (NH 4 ) 2 S 2 O 3 , respectively. Eight days after the application of the chemical compounds, plants were harvested for determining the total dry biomass, and the content of Au, Ag, and Cu in plant organs. Application of (NH 4 ) 2 S 2 O 3 or NH 4 SCN resulted in enhanced Au-accumulation in stems (447% and 507%, respectively), while either (NH 4 ) 2 S 2 O 3 + Aspergillus , or NH 4 SCN increased the Au-accumulation in roots (198.5% and 404%, respectively) when compared to the control. Treatments with (NH 4 ) 2 S 2 O 3 or (NH 4 ) 2 S 2 O 3 + Aspergillus significantly increased (P ≤ 0.001) the accumulation of Ag in leaves (677% and 1376%, respectively), while NH 4 SCN +  Aspergillus , and (NH 4 ) 2 S 2 O 3 enhanced the accumulation in stems (7153% and 6717.5%). The Ag-accumulation in roots was stimulated by NH 4 SCN+  Aspergillus , and (NH 4 ) 2 S 2 O 3 +  Aspergillus (132.5% and 178%, respectively), when compared to the control. The combination of NH 4 SCN+ Aspergillus significantly enhanced the Cu-accumulation in leaves (228%); whereas NH 4 SCN+  Aspergillus , or (NH 4 ) 2 S 2 O 3 +  Aspergillus resulted in greater accumulation of Cu in stems (1233.5% and 1580%, respectively) than the control. Results suggest that either NH 4 SCN or (NH 4 ) 2 S 2 O 3 (with or without Aspergillus ) improved the accumulation of Au and Ag by B. napus . Accumulation of Au and Ag in plant organs overpassed the hyperaccumulation criterion (> 1 mg kg −1 of plant biomass); whereas Cu-accumulation in stems and roots also overpassed such criterion (> 1000 mg kg −1 ) by applying either NH 4 SCN or (NH 4 ) 2 S 2 O 3 +  A. niger . [ABSTRACT FROM AUTHOR]

Utilization of bacterial volatilization can be problematic to remediate mercury (Hg)-contaminated soils because most of the Hg in soils is bound to soil particles. The objective of this study was to develop a two-stage system (chemical extraction followed by microbial reduction) for Hg-contaminated soil remediation. The tasks were to (1) select the extraction reagents for Hg extraction, (2) assess the effects of extraction reagents on the growth of Hg-reducing bacterial strains, and (3) evaluate the effectiveness of Ca 2+ and Mg 2+ addition on merA gene (Hg reductase) induction. Bacterial inhibition was observed with the addition of 0.1 M ethylenediaminetetraacetic acid or citric acid. Up to 65% of Hg was biotransformed (Hg concentration = 69 mg/kg) from the soils after a 24 h extraction using 0.5 M ammonium thiosulfate. Ca 2+ and Mg 2+ were selected because they have the same electric charge as Hg and the studied groundwater contained high concentrations of Ca 2+ and Mg 2+ . Results showed that the addition of 200 mg/L Ca 2+ or 650 mg/L Mg 2+ could reach effective merA induction. In the two-stage experiment, 120 mg/kg Hg-contaminated soils were extracted with 2 rounds of extraction processes for 10 h using 0.5 M ammonium thiosulfate. Approximately 77% of Hg was extracted from the soils after the first-step extraction process. Up to 81% of Hg 2+ was transformed from the washing solution via the biotransformation processes with Enterobacter cloacae addition and Ca 2+ and Mg 2+ supplementation. The two-stage remedial system has the potential to be developed into a practical technology to remediate Hg-contaminated sites. [ABSTRACT FROM AUTHOR]

The aim of present study was to develop a modified method of gold recovery from e-waste. Selective biosorption of gold from contact point of printed circuit board was achieved by using the combination of ammonium thiosulfate (AT) and Lactobacillus acidophilus (LA).Improvement in biosorption was due to the π-π interaction and resultant change in amide absorption bond between AT and LA, as evidenced by infrared spectroscopy. Selection was justified by some basic postulates of ionic radii and confirmed by inductively coupled plasma atomic emission spectroscopy. This methodology provides a unique leaching-sorption method for gold recovery and 85% of gold was recovered (from AT leachant) by the proposed combination. [ABSTRACT FROM AUTHOR]

The effect of different blossom thinners ammonium thiosulfate (ATS) (1%, 2%), Armothin (1.5%), Tergitol-TMN-6 (0.5%, 1%), applied on peach cv. Redhaven at 50-60% full bloom was evaluated in thinning experiments in south-west Slovenia. The photosynthesis inhibitor metamitron (0.05%) applied at 8 mm fruit diameter was evaluated as fruitlet thinner as well. Application of 2% ATS resulted in excessive thinning. The thinning effect of 1% ATS was also too strong in two out of three thinning experiments. The use of 0.05% metamitron did not cause any thinning effect on peach trees and gave similar results as the non-treated control. The effective fruit set reduction and increase of average fruit weight was achieved with 0.5% and 1% Tergitol application. In three-year experiment both Tergitol applications reduced fruit set toward hand thinned level, but the share of fruit from bigger size class was only once enhanced to the level of hand thinned trees. No sign of phytotoxicity was noticed on fruits in all thinner application treatments.

A novel process was studied to extract economic metals from refractory ores that are difficult to leach with cyanide and ammonium thiosulfate, such as the well-known mangano argentiferous minerals, which are minerals of manganese, iron, and silver. The mineral under consideration originates from the tailings of the Monte del Favor, Hostotipaquillo Jalisco, Mexico. The sample was characterized by x-ray diffractometry, atomic absorption spectroscopy, scanning electron microscopy, and microanalysis by energy-dispersive x-ray spectroscopy. First, the material was passed through a 100-mesh screen, and then it was subjected to reductive leaching by varying the liquid-solid ( L/ S) ratio from 2:1 to 10:1 (observations were carried out at a ratio of 5:1, which yielded higher extraction of manganese). With HSO and NaSO as the reducing agents, manganese extraction of up to 96.05% was achieved during the first 3 h with a mineral head of manganese 3.58%, acid consumption of 90.74 g/L, and sulfite consumption of 25.8 g/L. The mineral was then filtered and proceeded to neutralize the acidity, reaching a pH of 8 with calcium hydroxide. Then, the material was subjected to a new leaching of gold and silver values with ammonium thiosulfate. The L/ S ratio was varied (1:1, 2:1, 3:1, 4:1), and the contact time and the concentration of ammonium thiosulfate was investigated, while controlling the pH using Ca(OH) and NHCl. An L/ S ratio of 2:1 showed the best extraction of silver (97.06%) and gold (86.66%), and the thiosulfate consumption was 10.36 g/L. The mineral head of gold and silver was 0.30 g/ton and 310 g/ton, respectively. The pH was maintained between 9.8 and 8.4, such that ammonium thiosulfate stabilized with lime, and ammonium chloride did not suffer any decomposition. [ABSTRACT FROM AUTHOR]

The Venice Lagoon is worldwide considered as a typical example of the human impact on the surrounding ecosystem. The development of the industrial zone of Porto Marghera begun in 1917 as an extension of the Venice Port, in order to sustain activities related to oil and coal, as well as to exploit the railway system. Despite the recent decrease in the number of employees, Porto Marghera is still one of the most important chemical districts in Italy. This study reports early results from the ongoing in-situ phytoextraction of potentially toxic elements (Cd, Hg, Zn) within the industrial area of Porto Marghera. Two agronomic plant species with high annual biomass yield ( Helianthus annuus L., Brassica juncea (L.) Czern.) were used. This paper also reports the microcosms and mesocosms tests to evaluate the efficacy of the treatments to be applied to the in-situ phytoextraction process of the polluted site. The combined use of EDTA and Ammonium Thiosulfate during phytoextraction increases the efficiency of Cd, Hg, Zn removal from contaminated soil. [ABSTRACT FROM AUTHOR]

Dissolution of interfacial materials in spatially confined flow is an important physicochemical process. Here, we present a study of gold leaching, where the gold layer is removed from a microchannel wall within a high aspect ratio channel (8 μm × 4 mm cross-section; 1:500). The etchant is an aqueous solution of sodium thiosulfate, ammonium hydroxide, and copper sulfate. Optical transmission of the gold layer was used for quantitative, in situ, and real-time measurement of the layer thickness and its spatial uniformity along and across the channel. The onset of etching is not immediate, indicating that a passivation layer exists (even on ‘bare’ gold layers, where etching was delayed by approx. 2 min). Pre-treatment of the gold surface with an incomplete alkane thiol self-assembled monolayer (11-mercapto-1-undecanol) led to a later onset of etching and slower etching rate (5.5 nm/min) compared with that on ‘bare’ gold (6.2 nm/min). Flow profiles are reflected in the observed etch profiles. Upstream and downstream differences in etch rate are magnified for intermediate copper sulfate concentrations. This novel technique offers quantitative, in situ and real time monitoring of etching under controlled conditions in continuous laminar flow through microchannels, providing a valuable tool to understand various reactive processes in spatial confinement, such as heap or in-situ leaching in mineral processing. [ABSTRACT FROM AUTHOR]

The form of sulfur fertilizer can influence its behavior and crop response. A growth chamber study was conducted to evaluate five sulfur fertilizer forms (ammonium sulfate, ammonium thiosulfate, gypsum, potassium sulfate, and elemental sulfur) applied in seed row at 20 kg S ha−1alone, and in combination with 20 kg phosphorus pentoxide (P2O5) ha−1, to three contrasting Saskatchewan soils. Wheat, canola, and pea were grown in each soil for 8 weeks and aboveground biomass yields determined. The fate of fertilizer was evaluated by measuring crop sulfur and phosphorus concentration and uptake, and supply rates and concentrations of available sulfate and phosphate in the seed row. Canola was most responsive in biomass yield to the sulfur fertilizers. Sulfate and thiosulfate forms were effective in enhancing soil-available sulfate supplies in the seed row, crop sulfur uptake, and yield compared to the elemental sulfur fertilizer. Combination of sulfur fertilizer with monoammonium phosphate may provide some enhancement of phosphate availability, but effects were often minor. [ABSTRACT FROM PUBLISHER]

Soil fumigation is important for food production but has the potential to discharge toxic chemicals into the environment, which may adversely affect human and ecosystem health. A field experiment was conducted to evaluate the effect of applying ammonium thiosulfate fertilizer to the soil surface prior to fumigating with 1,3-dichloropropene (1,3-D). The ammonium thiosulfate solution was applied as a spray with minimal water to minimize the effect on emissions from saturating (e.g. sealing) the soil pores with water. Two independent data sets were collected for determining the emission rate. One data set was used with three micrometeorological approaches: aerodynamic, integrated horizontal flux and theoretical profile shape; the other dataset with two indirect, back calculation methods that used the CALPUFF and ISCST3 dispersion models. Using the five methodologies, the 1,3-D emission rate was obtained for 16 days. The maximum emission rates ranged from 7 to 20 μg m − 2 s − 1 , the maximum 24-hour averaged emission rates ranged from 5 to 13 μg m − 2 s − 1 , and the total 1,3-D emissions ranged from 12 to 26%. Comparing to fumigation without ammonium thiosulfate spray revealed that emissions were reduced from 3% (CALPUFF) to 29% (ADM). Using a simulation model, ammonium thiosulfate spray would be expected to reduce emissions by almost 21%. These data provide evidence that emissions of 1,3-D can be reduced by spraying ammonium thiosulfate fertilizer on the soil surface prior to soil fumigation, and provides another emission-reduction strategy to those recently reported (e.g., deep injection, water seals and organic amendments). [ABSTRACT FROM AUTHOR]

• A recombinant strain E. coli DH5α J23106 overexpressing merB gene was constructed to degrade MeHg. • DH5α J23106 degraded MeHg more than 81.6% in culture medium under anoxic/oxic conditions. • DH5α J23106 degrade newly produced and intrinsic MeHg in actual Hg-contaminated sediment. • Anoxic/oxic aging of MeHg in sediment decreased its degradation by DH5α J23106. • Ammonium thiosulfate leaching, combined with DH5α J23106, enhanced the degradation of MeHg in sediment. Sediment is the primary hotspot for microbial production of toxic and bio-accumulative methylmercury (MeHg). Common remediation strategies such as sediment dredging and capping can be too expensive and cannot degrade MeHg efficiently. Here, we constructed an Escherichia coli strain overexpressing merB gene (DH5α J23106) and assessed the effectiveness of this recombinant strain in degradation of MeHg in culture medium and sediment. DH5α J23106 can efficiently degrade MeHg (with initial concentration from 0.01 to 50 ng/mL) to more than 81.6% in a culture medium under anoxic and oxic conditions. Enriched isotope addition (199HgCl 2) revealed that this recombinant strain can degrade 78.6% of newly produced Me199Hg in actual sediment, however the biodegradation decreased to 36.3% for intrinsic MeHg. Degradation of spiked MeHg after aging in anoxic and oxic sediments further demonstrated DH5α J23106 can efficiently degrade newly produced MeHg and the degradation decreased with aging significantly, especially for oxic sediment. Eight sediments were further assessed for the biodegradation of aged MeHg by DH5α J23106 under oxic conditions, with degradation ratios ranging from 9.0% to 66.9%. When combined with (NH 4) 2 S 2 O 3 leaching, the degradation of MeHg increased by 15.8–38.8% in on-site and off-site modes through enhanced MeHg bioavailability in some of these sediments. Thus, this recombinant strain DH5α J23106 can degrade MeHg efficiently and have the potential for remediating bioavailable MeHg in contaminated sediments. [Display omitted] [ABSTRACT FROM AUTHOR]

In this study, a new approach “sulfur-oil agglomeration” for gold flotation was put forward to recover gold particles in laboratory and industrial scale experiments. The optimum recovery of gold was obtained by adding (NH 4 ) 2 S 2 O 3 , oil emulsions and sulfur into the mill, together with butyl xanthate as the collector in weak acidic pulp adjusted by H 2 SO 4 . Fundamental concepts of gold flotation were considered, including the sulfur-oil-gold agglomeration mechanisms and the role of (NH 4 ) 2 S 2 O 3 . The possible mechanism had been put forward: (1) nature of (NH 4 ) 2 S 2 O 3 is complex, it renders the oxidized gold surface cleaned, the exposed fresh surface shows strong natural oleophilicity; (2) in weak acidic pulp, S decomposed from (NH 4 ) 2 S 2 O 3 , a highly hydrophobic/oleophilic material, agglomerated with gold; (3) then the oil droplets overspread the gold surfaces and the collision of these oil wetted particles caused formation of “liquid bridges” each upon them. As a result, the fine gold particles in the beginning were converted to the masses in the form of sulfur-gold-oil which were bonded together by liquid bridges. Meanwhile, the sulfur could strengthen the adsorption of collectors on gold surface, as well as the floating size range of gold is widen, and the recovery of gold is significantly improved. Industrial trials conducted at Yunnan, China showed that an average gold recovery of 87.39% into a concentrate assaying 25.84 g/t Au from a feed of 1.8–3.0 g/t could be achieved by the aid of sulfur-oil agglomeration method. [ABSTRACT FROM AUTHOR]

Differently-treated crops straw is being widely used to fertilize soil, while the potential impacts of straw amendment on the biogeochemistry and phytoavailability of mercury in contaminated soils are largely unknown. In the present study, differently-treated rice straw (dry straw, composted straw, straw biochar, and straw ash) was incorporated into mercury-contaminated soil at an environment relevant level (1/100, w/w), and mercury speciation, methylmercury (MeHg) phytoavailability (using ammonium thiosulfate extraction method, validated elsewhere) and bioaccumulation (in Indian mustard Brassica junceas ) were quantified. Our results indicated that incorporating straw biochar or composted straw into soil would decrease phytoavailable MeHg levels, possibly due to the strong binding of MeHg with particulate organic matter in amended straw (‘MeHg immobilization effect’). Consequently, MeHg accumulation in aboveground tissue of Indian mustard harvested from straw biochar-amended soil decreased by 20% compared to the control. Differently, incorporation of dry straw resulted in elevated MeHg levels in soil (‘Mercury methylation effect’). Decomposition of amended dry straw in soil would evidently increase DOC levels (averagely 40%–195% higher than the control), which may subsequently mobilize MeHg in the soil (‘MeHg mobilization effect’). Accordingly, incorporation of dry straw led to increased phytoavailable MeHg levels in the soil and doubled MeHg accumulation in Indian mustard. Our results provided the first evidence that incorporating differently-treated rice straw into soil could have diverse effects on mercury biogeochemistry and phytoavailability, which should be taken into account in risk assessment or soil remediation. [ABSTRACT FROM AUTHOR]