Silver sulfide leaching with a copper-thiosulfate solution in the absence of ammonia

Leaching from silver sulfide.using a copper-thiosulfate solution in the absence of ammonia was investigated. It is found that silver sulfide could be effectively dissolved in the copper-thiosulfate system without ammonia. The effects of thiosulfate concentration, cop- per-to-thiosulfate ratio, agitation vigorousness, pH values, and dissolved gases on the leaching of silver sulfide with the copper-thiosulfate solution were studied. A maximum extraction of 95.1% was achieved with the 0.12 mol/L thiosulfate and the 0.048 rnol/L copper sulfate. It is shown that copper-to-thiosulfate ratio is an important factor in silver sulfide dissolution and oxygen is not needed to leach silver sulfide, which leads to the instability of the leaching system at high copper-to-thiosulfate ratio. On the other hand, the silver extraction is not affected by the pulp pH values.

Biooxidation-thiosulfate leaching of refractory gold concentrate

A process of biooxidation followed by thiosulfate leaching of gold from refractory gold concentrate was investigated.Mineralogical studies on the concentrate showed that very fine gold grains(<10μm)were encapsulated in pyrite and arsenopyrite,while the proportion of monomer gold was only 21%.The gold-bearing sample was identified as a high-sulfur fine-sized wrapped-type refractory gold concentrate.The gold leaching efficiency obtained by direct cyanidation was only 59.86%.After biooxidation pretreatment,the sulfide minerals were almost completely decomposed,92 wt%of the mineral particles of the biooxidation residue were decreased to<38μm,and the proportion of monomer gold in the biooxidation residue was over 86%.Meanwhile,the gold content in the biooxidation residue was enriched to 55.60 g/t,and the S,Fe,and As contents were reduced to approximately 19.8 wt%,6.97 wt%,and 0.13 wt%,respectively.Ammoniacal thiosulfate was used for gold extraction from the biooxidation residue of the refractory gold concentrate.The results showed that the optimal reagent conditions were 0.18 M thiosulfate,0.02 M copper(II),1.0 M ammonia,and 0.24 M sulfite.Under these conditions,a maximum gold leaching efficiency of 85.05%was obtained.

Pretreatment and thiosulfate leaching of refractory gold-bearing arsenosulfide concentrates

A hydrometallurgical process for refractory gold-bearing arsenosulfide concentrates at ambient temperature and pressure was presented, including fine grinding with intensified alkali-leaching （FGIAL）, enhanced agitation alkali-leaching （EAAL）, thiosulfate leaching and displacement. Experimental results on a refractory gold concentrate showed that the total consumption of NaOH in alkaline leaching is only 41% of those theoretically calculated under the conditions of full oxidization for the same amount of arse- nides and sulfides transformed into arsenates and sulfates, and 72.3% of gold is synchro-dissoluted by thiosulfate self-generated during alkaline leaching. After alkaline leaching, thiosulfate leaching was carried out for 24 h. The dissolution of gold is increased to 91.9% from 4.6% by cyanide without the pretreatment. The displacement of gold by zinc powder in the solution gets to 99.2%. Due to an amount of thiosulfate self-generated during alkaline leaching, the reagent addition in thiosulfate leaching afterwards is lower than the normal.

KINETICS OF GOLD LEACHING FROM SULFIDE GOLD CONCENTRATES WITH THIOSULFATE SOLUTION

The reaction process for leaching gold from sulfide gold concentrates containing copperwith ammonia-ammonium thiosulfate solution containing copper（Ⅱ）can be divided into initialstage and later stage of reaction.Initial stage of reaction is controlled by interface reaction.Lat-er stage of reaction is controlled by diffusion process of reaction through solid products layer.Whole leaching process is under the control of corrosion reaction of pyrite bearing gold.Actionof ammonium sulfate in the system is probably as follows:（1）NH4+ and NH3 forms a buffer so-lution;（2）SO42-ion inhibites the oxidation and decomposition of S2O32-ion.Cu2+ion in thesystem acts as an oxidant and oxygen makes the Cu2-regenerate.

Pharmacokinetics of sodium thiosulfate in Guinea pig perilymph following middle ear application

Hypothesis： To determine the pharmacokinetics of sodium thiosulfate in the inner ear perilymph following middle ear application in Guinea pigs. Background： Cisplatin chemotherapy is often associated with a dose-dependent high frequency senso- rineural hearing loss. Sodium thiosulfate has been shown to reduce cisplatin-induced ototoxicity when given intravenously, but this may limit the tumoricidal effects of the chemotherapy. Recent animal studies looking at middle ear application of sodium thiosulfate have shown prevention of outer hair cell and hearing loss, but the perilymph pharmacokinetics have not yet been established. Methods： Twenty Guinea pig ears were split into two groups and administered sodium thiosulfate to the middle ear at either a concentration of 250 mg/mL or 50 mg/mL for 30 min. Perilymph samples were then obtained serially through the round window over 6 h. Sodium thiosulfate concentrations were obtained using high-pressure liquid chromatography. Results： The 250 mg/mL group had a maximum perilymph concentration of 7.27 mg/mL （±0.83） that decreased to 0.94 mg/mL （±0.03） over 6 h. The 50 mg/mL group had an initial concentration of 1.63 mg/mL （±0.17） and was undetectable after 1 h. The half-life of sodium thiosulfate within perilymph was 0.74 h. Conclusions： and Relevance： The results of this study show that sodium thiosulfate is capable of diffusing through round window and into the inner ear perilymph. Peak levels decline over several hours after exposure. This has a potential application as a localized therapy in the prevention of cisplatin induced ototoxicity.

Novel Reduction of Sodium Alkyl Thiosulfates to Disulfides with TiCl_4/Sm System

Sodium alkyl thiosulfates(Bunte salts) can be readily reduced to the corresponding disulfides with TiCl4/Sm system in good to excellent yields under mild conditions

ANODIC OXIDATION OF THIOSULFATE IONS IN GOLD LEACHING

The regularities of anodic oxidation of thiosulfate ions on a gold electrode have been investigated using electrochemical methods in order to improve gold extraction. Effects of ammon, copper-ammon ions, pH and sulphite on anodic oxidation of thiosulfate ions have been examined in details. Results show that the anodic oxidation of thiosulfate ions is an inreversible reaction whose oxidizing peak potential is 620 mV/SCE in the absence of ammon. Oxidation rate increases with concentration of thiosulfate ions, but not in linear relation. It is also shown that ammon has significant effects on the oxidation of thiosulfate ions by causing great decrease in oxidation rate and negative shift of peak potential. The degrees of the rate decrease and negative shift increase with ammon concentration. When ammon concentration is increased to 1. 0 mol/L, the oxidation rate decreases to one fourth of that without ammon and the peak potential shifts from 620 mV/SCE to 350 mV/SCE.

Anti-proliferative potential of sodium thiosulfate against HT 29 human colon cancer cells with augmented effect in the presence of mitochondrial electron transport chain inhibitors

Objective:To compare the anti-proliferative effect of sodium thiosulfate on human colorectal cancer cells(HT-29)and normal small intestine cells(IEC6).Methods:Cells(HT-29 and IEC6)were treated with different concentrations of sodium thiosulfate ranging from 0.5 m M to 80 m M for 24 h.Cell viability was measured via crystal violet and MTT assays.HT-29 cells were further treated in the presence and absence of mitochondrial electron transport chain(ETC)inhibitors,KATP channel opener and closer and H2S inhibitors for 24 h followed by sodium thiosulfate in order to study their respective roles in the anti-proliferative activity of sodium thiosulfate.Results:The IC50 values of sodium thiosulfate on HT-29 cells were 40.93 m M and 42.45 m M by crystal violet and MTT assay whereas,in the case of IEC6 cells,the values were 45.17 m M and 47.22 m M.The inhibition of endogenous H2S enzymes and KATP channel induced no change in the anti-proliferative capacity of sodium thiosulfate.However,the anti-proliferative activity of sodium thiosulfate was enhanced in the presence of mitochondrial ETC inhibitors.Conclusions:HT-29 cell growth is effectively attenuated by sodium thiosulfate and the anti-proliferative activity of sodium thiosulfate is enhanced in the presence of mitochondrial ETC inhibitors.

LEACHING GOLD BY LOW CONCENTRATION THIOSULFATE SOLUTION

The effects of the concentrations of thiosulfate,copper and ammonia on the extraction of gold from sulfide gold concentrate have been studied.The results show that it is possible to reduce thiosulfate concentration.More than 95%of the gold could be extracted by a 0.2 mol/L thiosulfate leaching solution in two hours under suitable conditions.Therefore,the process of washing the residue was simplified,and the consumption and loss of thiosulfate carried by the washing residue were reduced.

Novel Reduction of Arylsulfonyl Chlorides and Sodium Alkyl Thiosulfates to Disulfides with TiCl_4/Zn System

T1Cl4/Zn system reduces arylsulfonyl chlorides and sedium aldyl thiosulfates to corresponding disulfides in moderate to good yields

Effects of thiosulfate and dissolved oxygen on crevice corrosion of Alloy 690 in high-temperature chloride solution

The crevice corrosion behavior of Alloy 690 was investigated in high-temperature chloride solution containing different concentrations of thiosulfate(S_(2)O_(3)^(2-)) and dissolved oxygen(DO). The S2O32- inhibited corrosion of Alloy 690 through consuming oxygen in aerated chloride solution. In deaerated chloride solution,the S_(2)O_(3)^(2-) was reduced to S° and S^(2-) and subsequently incorporated into the oxide films, which promoted the pitting corrosion at locations of both TiN inclusions and matrix inside the crevice during the crevice corrosion as well as influenced the composition and thickness of the oxide films. The effect mechanisms of S_(2)O_(3)^(2-) and DO on crevice corrosion in high-temperature chloride solution are discussed.

Role of oxygen and ammonium ions in silver leaching with thiosulfate–ammonia–cupric ions

The dissolution of silver with thiosulfate and copper ions was studied in a batch-stirred reactor at 25 °C in the absence and presence of various ammonium ions and oxygen concentrations in the aqueous solution. Leaching silver with 4 mg L-1oxygen in the aqueous solution requires high concentration of ammonium and thiosulfate ions. High silver dissolution is achieved at pH of high cupric tetraamine concentration, around pH 9.8, but a high degradation of thiosulfate ions is resulted from their oxidation by the presence of oxygen. When the oxygen concentration is below 1 mg L-1, dissolved silver thiosulfate species are fairly stable and the degradation of thiosulfate ions in the aqueous solution is low. Under these conditions,high silver dissolution is attained using low thiosulfate concentration. At the oxygen concentration of 4 mg L-1,dissolved silver thiosulfate species precipitate out of the aqueous solution significantly affecting silver dissolution.Precipitation of dissolved silver thiosulfate species occurs because of oxidation of the thiosulfate bonding to the silver.

Oxidation inhibition of sulfite in dual alkali flue gas desulfurization system

A laboratory-scale well-mixed thermostatic reactor with continuously blasting air was used to investigate the oxidation inhibition of sulfite in dual alkali flue gas desulfurization （FGD） system. The effects of operating parameters such as pH value and catalyst concentration on the oxidation were studied. Sodium thiosulfate was used in the system, and was found that it significantly inhabited the sulfite oxidation. In the absence of catalyst, sodium thiosulfate at 12.67 mmol/L had an inhibition efficiency of approximately 98%. While in the presence of catalyst, sodium thiosulfate at 26.72 mmol/L had an inhibition efficiency less than 85.0%. The oxidation reaction order of sulfite in the sodium thiosulfate was determined to be -1.90 and 4）.55 in the absence and presence of the catalyst, respectively. Apparent activation energy of oxidation inhibition was calculated to be 53.9 kJ/mol. Pilot tests showed that the consumption rate of thiosulfate agreed well with the laboratory-scale experimental results.

Effect of α-Ketoglutarate on Cyanide-induced Biochemical Alterations in Rat Brain and Liver

Objective To investigate the biochemical changes in rat brain and liver following acute exposure to a lethal dose of cyanide, and its response to treatment of α-ketoglutarate （α-KG） in the absence or presence of sodium thiosulfate （STS）. Methods Female rats were administered 2.0 LD50 potassium cyanide （KCN; oral） in the absence or presence of pre-treatment （-10 rain）, simultaneous treatment （0 rain） or post-treatment （＋2-3 min） of α-KG （2.0 g/kg, oral） and/or STS （1.0 g/kg, intraperitoneal, -15 min, 0 rain or ＋ 2-3 min）. At the time of onset of signs and symptoms of KCN toxicity （2-4 min） and at the time of death （5-15 min）, various parameters particularly akin to oxidative stress viz. cytochrome oxidase （CYTOX）, superoxide dismutase （SOD）, glutathione peroxidase （GPx）, reduced glutathione （GSH） and oxidized glutathione （GSSG） in brain, and CYTOX, sorbitol dehydrogenase （SDH）, alkaline phosphatase （ALP）, GSH and GSSG in liver homogenate were measured. Results At both time intervals brain CYTOX, SOD, GPx, and GSH significantly reduced （percent inhibition compared to control） to 24%, 56%, 77%, and 65%, and 44%, 46%, 78%, and 57%, respectively. At the corresponding time points liver CYTOX and GSH reduced to 74% and 63%, and 44% and 68%, respectively. The levels of GSSG in the brain and liver, and hepatic ALP and SDH were unchanged, Pre-treatment and simultaneous treatment of α-KG alone or with STS conferred significant protection on above variables. Post-treatment was effective in restoring the changes in liver but failed to normalize the changes in the brain. Conclusions Oral treatment with α-KG alone or in combination with STS has protective effects on cyanide-induced biochemical alterations in rat brain and liver.

Silver dissolution in a novel leaching system: Reaction kinetics study

Effective silver recovery is usually restricted by either environmental pollution or high recovery costs. To tackle the issues, this study introduces a novel method for the effective recovery of silver by utilizing the alkaline sodium thiosulfate-potassium ferricyanide leaching system. The reaction kinetics of silver dissolution in this system was investigated via the rotating disk electrode technology. The influences of important parameters, including the rotation speed, sodium thiosulfate concentration, potassium ferricyanide concentration, and temperature, on the silver dissolution rate were systematically investigated. The activation energy was measured to be 17.96 kJ·mol^(-1) when the silver dissolution was controlled by a diffusion process. When the silver dissolution was in the region of mixed control, the reaction orders of ferricyanide and thiosulfate were found to be 0.57 and 0.19, respectively, and the reaction orders of ferricyanide and thiosulfate were 0.55 and 0.22, respectively, when the silver dissolution was controlled by surface reaction. This study has great potential for the development of an environmentally friendly silver recovery process from end-of-life products.

Non-uremic calciphylaxis associated with alcoholic hepatitis: A case report

BACKGROUND Calciphylaxis is a form of vascular calcification more commonly associated with renal disease. While the exact mechanism of calciphylaxis is poorly understood,most cases are due to end stage kidney disease. However, it can also be found in patients without kidney disease and in such cases is termed non-uremic calciphylaxis for which have multiple proposed etiologies.CASE SUMMARY We describe a case of a thirty-year-old morbidly obese Caucasian female who had a positive history of alcoholic hepatitis and presented with painful calciphylaxis wounds of the abdomen, hips, and thighs. The hypercoagulability panel showed low levels of Protein C and normal Protein S, low Antithrombin Ⅲ and positive lupus anticoagulant and negative anticardiolipin. Wound biopsy confirmed the diagnosis of non-uremic calciphylaxis in the setting of alcoholic liver disease. The calciphylaxis wounds did not improve when Sodium Thiosulfate was used alone. The patient underwent a series of bedside and surgical debridement. Broad spectrum antibiotics were also used for secondary wound bacterial infections. The patient passed away shortly after due to sepsis and multiorgan failure.CONCLUSION Non-uremic Calciphylaxis can occur in the setting of alcoholic liver disease. The treatment of choice is still unknown.

Sepsis:Evidence-based pathogenesis and treatment

Sepsis can develop during the body’s response to a critical illness leading to multiple organ failure,irreversible shock,and death.Sepsis has been vexing health care providers for centuries due to its insidious onset,generalized metabolic dysfunction,and lack of specific therapy.A common factor underlying sepsis is the characteristic hypermetabolic response as the body ramps up every physiological system in its fight against the underlying critical illness.A hypermetabolic response requires supraphysiological amounts of energy,which is mostly supplied via oxidative phosphorylation generated ATP.A by-product of oxidative phosphorylation is hydrogen peroxide(H2O2),a toxic,membranepermeable oxidizing agent that is produced in far greater amounts during a hypermetabolic state.Continued production of mitochondrial H2O2 can overwhelm cellular reductive(antioxidant)capacity leading to a build-up within cells and eventual diffusion into the bloodstream.H2O2 is a metabolic poison that can inhibit enzyme systems leading to organ failure,microangiopathic dysfunction,and irreversible septic shock.The toxic effects of H2O2 mirror the clinical and laboratory abnormalities observed in sepsis,and toxic levels of blood H2O2 have been reported in patients with septic shock.This review provides evidence to support a causal role for H2O2 in the pathogenesis of sepsis,and an evidence-based therapeutic intervention to reduce H2O2 levels in the body and restore redox homeostasis,which is necessary for normal organ function and vascular responsiveness.

Non-toxic, high selectivity process for the extraction of precious metals from waste printed circuit boards

The work presented here focused on the extraction of gold (Au), silver (Ag) and palladium (Pd) from electronic waste using a solution of ammonium thiosulfate. Thiosulfate was used as a valid alternative to cyanide for precious metal extractions, due to its non-toxicity and high selectivity. The interactions between sodium thiosulfate, total ammonia/ammonium, precious metal concentrations and the particle size of the waste printed circuit boards (WPCBs) were studied by the response surface methodology (RSM) and the principal component analysis (PCA) to maximize precious metal mobilization. Au extraction reached a high efficiency with a granulometry of less than 0.25 mm, but the consumption of reagents was high. On the other hand, Ag extraction depended neither on thiosulfate/ammonia concentration nor granulometry of WPCBs and it showed efficiency of 90% also with the biggest particle size (0.50 < Ø < 1.00 mm). Pd extraction, similarly to Au, showed the best efficiency with the smallest and the medium WPCB sizes, but required less reagents compared to Au. The results showed that precious metal leaching is a complex process (mainly for Au, which requires more severe conditions in order to achieve high extraction efficiencies) correlated with reagent concentrations, precious metal concentrations and WPCB particle sizes. These results have great potentiality, suggesting the possibility of a more selective recovery of precious metals based on the different granulometry of the WPCBs. Furthermore, the high extraction efficiencies obtained for all the metals bode well in the perspective of large-scale applications.

Sulfur-based autotrophic denitrification from the micro-polluted water

Eutrophication caused by high concentrations of nutrients is a huge problem for many natural lakes and reservoirs. Removing the nitrogen contamination from the low C/N water body has become an urgent need. Autotrophic denitrification with the sulfur compound as electron donor was investigated in the biofilter reactors. Through the lab-scale experiment,it was found that different sulfur compounds and different carriers caused very different treatment performances. Thiosulfate was selected to be the best electron donor and ceramsite was chosen as the suitable carrier due to the good denitrification efficiency, low cost and the good resistibility against the high hydraulic loads. Later the optimum running parameters of the process were determined. Then the pilot-scale experiment was carried out with the real micro-polluted water from the West Lake, China. The results indicated that the autotrophic denitrification with thiosulfate as electron donor was feasible and applicable for the micro-polluted lake water.

Nonpolar Na_(10)Cd(NO_(3))_(4)(SO_(3)S)_(4) Exhibits a Large Second-Harmonic Generation

Conventional wisdom says that nonpolar structures do not favorably produce strong second-harmonic generation(SHG)responses since the polarization in their microscopic functional groups are counteracted.Herein,we report the first nonlinear optical thiosulfate,Na_(10)Cd(NO_(3))_(4)(SO_(3)S)_(4),which crystallizes in a nonpolar space group of P−4.However,this thiosulfate exhibits a strong SHG response of about 4.2 times that of the benchmark KH2PO4,which is larger than those of polar sulfates.According to first-principles calculations and a flexible dipole model,the SHG enhancement is mainly ascribed to the larger flexibility of the S=S bond in the SO_(3)S tetrahedra in comparison with the S–O bond in the SO4 tetrahedra.These findings indicate that constructing flexible bonds is an effective strategy to design highperformance nonlinear optical materials regardless of polarity.