Leaching Of Sb Research Articles

Arsenic and antimony removal by oxidative aqueous leaching of IGCC fly ash during germanium extraction

Recovery of germanium (Ge) from the fly ash produced as a by-product of the integrated coal gasification combined cycle (IGCC) may be a potential source of this valuable element. Water-based Ge extraction procedures are environmentally friendly but non-selective, and some impurities such as As, Sb, and Ni, are also extracted. The leaching of As, Sb and Ni in water Ge extraction was carried out using oxic conditions in different oxidising atmospheres. Experimental results showed that the oxidative aqueous leaching of IGCC fly ash diminished the leachability of these impurities without altering Ge extraction yields. Dissolved oxygen in aqueous leaching led to the formation of Fe-(oxy)hydroxides structures from the oxidation of Fe-sulphides contained in IGCC fly ash, which diminished the concentration of metals and metalloids in the leachates through co-precipitation, adsorption or ion exchange mechanisms. The oxidation of Fe-sulphides and the formation of Fe-(oxy)hydroxides proved to be the limiting step of the process. The oxidative leaching of As and Sb showed a similar trend, being subsequently removed in the neoformed structures. The removal process was less efficient for Ni. The most selective water extraction for Ge was obtained with pure oxygen at 90°C and a stirring speed above 750min−1.

Potential Risk of Arsenic and Antimony Accumulation by Medicinal Plants Naturally Growing on Old Mining Sites

It was found that some of the medicinal plants accumulate increased amounts of toxic elements like Cd or Pb. Less is known about the accumulation of other hazardous elements like arsenic (As) and antimony (Sb) in these species. The present paper investigated selected medicinal plants naturally growing on old mining sites in Slovakia, Central Europe, contaminated by As and Sb. Both these elements are nonessential for plants and, in higher level, might be phytotoxic. The soil concentration of As and Sb at three different localities extensively used for mining of Sb ores in former times highly exceed values characteristic for noncontaminated substrates and ranged between 146 and 540 mg kg−1 for As and 525 and 4,463 mg kg−1 for Sb. Extraction experiments of soils show differences between As and Sb leaching, as the highest amount of mobile As was released in acetic acid while Sb was predominantly released in distilled water. In total, seven different plant species were investigated (Fragaria vesca, Taraxacum officinale, Tussilago farfara, Plantago major, Veronica officinalis, Plantago media, and Primula elatior), and the concentration of investigated elements in shoot ranged between 1 and 519 mg kg−1 for As and 10 and 920 mg kg−1 for Sb. Differences in the bioaccumulation of As and Sb as well as in the translocation of these elements from root to shoot within the same species growing on different localities have been found. This indicate that efficiency of As and Sb uptake might vary between individual plants of the same species on different sites. Increased bioaccumulation of As and Sb in biomass of investigated plants might be dangerous for human when used for traditional medicinal purposes.

Antimony leaching from MSWI bottom ash: Modelling of the effect of pH and carbonation

Development of treatment methods to reduce Sb leaching from municipal solid waste incinerator (MSWI) bottom ash, such as accelerated carbonation, is being complicated by insufficient understanding of Sb geochemistry. The leaching of antimonate (Sb(V)) and antimonite (Sb(III)) in MSWI bottom was studied as a function of pH and degree of carbonation. While total (Sb(V) + Sb(III)) leaching was lowest (1.2 mg kg −1) at the natural pH (i.e. 10.6) of uncarbonated bottom ash, HPLC-ICP-MS analysis showed that acidification and carbonation increased Sb(V) leaching, but decreased Sb(III) leaching, probably because Sb ( III ) ( OH ) 4 - became less stable. PHREEQC geochemical modelling suggested that Sb(V) concentrations approached equilibrium with the romeites, i.e. calcium antimonates, Ca 1.13Sb 2(OH) 0.26·0.74H 2O at pH = 10.6 and Ca[Sb(OH) 6] 2 at pH = 8. It is hypothesised that not interaction with ettringite but dissolution of romeite controls antimonate leaching in the pH range 8–11 in MSWI bottom ash, because while Ca is preferentially leached from romeite, the mineral structures containing more Ca at higher pH are less soluble. A model was proposed where acidification and carbonation both lead to lower Ca 2+ and/or hydroxyl concentration, which removes Ca 2+ and hydroxyls from the romeite structure and leads to comparably higher Sb(V) concentration in equilibrium with romeite. Sb solubility depends on pH and Ca 2+ availability in this model, which has implications for bottom ash valorisation and risk assessment.

Frequency of use controls chemical leaching from drinking-water containers subject to disinfection

Microbial-, and chemical-based burden of disease associated with lack of access to safe water continues to primarily impact developing countries. Cost-effective health risk-mitigating measures, such as of solar disinfection applied to microbial-contaminated water stored in plastic bottles have been increasingly tested in developing countries adversely impacted by epidemic water-borne diseases. Public health concerns associated with chemical leaching from water packaging materials led us to investigate the magnitude and variability of antimony (Sb) and bromine (Br) leaching from reused plastic containers (polyethylene terephthalate, PET; and polycarbonate, PC) subject to UV and/or temperature-driven disinfection. The overall objective of this study was to determine the main and interactive effects of temperature, UV exposure duration, and frequency of bottle reuse on the extent of leaching of Sb and Br from plastic bottles into water. Regardless of UV exposure duration, frequency of reuse (up to 27 times) was the major factor that linearly increased Sb leaching from PET bottles at all temperatures tested (13–47 °C). Leached Sb concentrations (∼360 ng L −1) from the highly reused (27 times) PET bottles (minimal Sb leaching from PC bottles, <15 ng L −1) did not pose a serious risk to human health according to current daily Sb acceptable intake estimates. Leached Br concentrations from both PET and PC containers (up to ∼15 μg L −1) did not pose a consumer health risk either, however, no acceptable daily dose estimates exist for oral ingestion of organo-brominated, or other plasticizers/additives compounds if they were to be found in bottled water at much lower concentrations. Additional research on potential leaching of organic chemicals from water packaging materials is deemed necessary under relevant environmental conditions.

Co-leaching of brominated compounds and antimony from bottled water

A fast-growing bottled water market is occasionally challenged by reports calling for contaminant leaching from water-contact materials (plastics). Our focus was on leaching of antimony (Sb) and brominated compounds expressed by total soluble bromine (Br) measurements, including those of polybrominated diphenyl ethers (PBDE). Studies are lacking on concomitant leaching of two or more inorganic plastic constituents from the same bottle. A market-representative basket survey of bottled water was initiated in Boston, USA supermarkets. Bottled water classes sampled were: i) non-carbonated (NCR), ii) carbonated (CR), and iii) non-carbonated and enriched (NCRE). Plastic bottle materials sampled were: polyethylene terephthalate (PET), high-density polyethylene (HDPE), polystyrene (PS), and polycarbonate (PC). Storage conditions for the 31 bottled water samples were: 23 °C temperature, no-shaking and 12 h/12 h light/dark for 60 days of equilibration. Average Br and Sb concentrations after 60-days of storage followed the order of NCR < CR = NCRE, and NCR < CR < NCRE, respectively, suggesting that the presence of dissolved carbon dioxide in CR samples coupled to additions of flavors and color to NCRE could explain the elevated leaching of Br and Sb. Combining all bottled water classes and plastic material types, a highly significant ( p < 0.001) correlation was observed between log-transformed soluble Br and Sb concentrations, suggesting similar leaching behavior. Among samples with the highest soluble Br concentrations, BDE-209 congener was qualitatively confirmed in three out of four bottled water samples. The PC, HDPE, and PS samples exhibited significantly ( p < 0.05) lower Sb and Br leaching than PET. Upon quantitative validation of PBDE leaching from certain plastic bottles into water, a revisit to existing PBDE exposure assessment reports will be deemed necessary.

The effect of phosphate application on the mobility of antimony in firing range soils

Chemical and biogenic sources of phosphate are commonly accepted in situ treatment methods for immobilization of lead (Pb) in soil. The metalloid antimony (Sb), commonly associated with Pb in the environment, exists as either a neutral species or a negatively charged oxyanion. Antimony is used in the manufacture of bullets as a hardening agent, constituting approximately 3% of the bullet mass. Technological solutions to reduce the migration of metals from small arms firing range (SAFR) soils for environmental compliance purposes must be robust with respect to multi-component systems containing both cationic and anionic contaminants. The effect of varying physico-chemical soil properties on Sb mobility post-firing was assessed in this study for six soil types using common analytical protocols and methods related to regulatory criteria. The sands (SM and SP) demonstrated the greatest Sb solubility in post-firing leachate samples and therefore were selected to evaluate the effects of five commercially available stabilization amendments on Sb mobility. Enhanced Sb leaching was experimentally confirmed in the phosphate-treated soils compared to both the untreated control soil and the sulfur-based amendment, and thus suggests competition for negative sorption sites between Sb and phosphate. However, the 5% Buffer Block® calcium phosphate amendment did not exhibit the same enhanced Sb release. This can be attributed to the inclusion of aluminum hydroxide in the amendment composition. Technologies are needed that will adequately immobilize Pb without mobilizing oxyanions such as Sb. Further research will be required to elucidate binding mechanisms and redox conditions that govern the mobility of Sb on SAFRs.

Effects of three amendments on extractability and fractionation of Pb, Cu, Ni and Sb in two shooting range soils

Contamination of shooting range soils with toxic trace elements, in particular Pb and Sb, is of increasing environmental concern worldwide. We studied the extractability of Sb, and other metals in two shooting range soils: a calcareous soil (pH 8) with low organic carbon (0.5%) and a non-calcareous soil (pH 6.3) with elevated organic carbon content (5%). Both soils contained total concentrations of around 500 mg kg −1 Pb, 65 mg kg −1 Cu, 100 mg kg −1 Zn and 20 mg kg −1 Sb. We tested the effects of Ca(OH) 2, phosphate and sodium humate amendments on metals and Sb extractability. Extracts with H 2O and NaNO 3 contained 0.02–0.05% of the total Zn and Pb; 0.1–0.5% of total Ni and Cu and ∼1% of total Sb. Sequential extraction procedure of Zeien and Brümmer resulted in similar percentages for the sum of the two most labile fractions (F1 + F2) in two soils: 10% Pb, and 15–20% Sb. Water and NaNO 3-extractable Sb concentrations increased after phosphate addition, but were not affected by the addition of sodium humate. The results show that leaching of Sb from shooting ranges into ground and surface waters may generate a serious environmental risk under widely different soils conditions.

Investigation of accelerated and natural carbonation of MSWI fly ash with a high content of Ca

The application of accelerated carbonation and natural carbonation to treat municipal solid waste incinerator (MSWI) fly ash was presented. The influence of reaction time and the liquid-to-solid (L/S) ratio, which both affect the reactivity of CO 2, was evaluated to determine their impact on the quality of carbonation. The optimum carbonation reaction of fly ash was found to occur when an L/S of 0.25 was used. Carbonation decreased the leaching of Pb, Cu, Zn and As, but increased the leaching of Cd and Sb. Based on the leaching of these six heavy metals, the optimum pH of the carbonated fly ash was 9.5–10.5. The release of soluble salts such as SO 4, Cl and F changed little following carbonation, and their release occurred independently of pH. The release potential and leaching behavior of carbonated fly ash were further evaluated using the three-step sequential extraction procedure proposed by the commission of the European Communities Bureau of Reference (BCR). The results of the BCR analyses revealed that carbonation exerted a significant effect on the heavy metal fractions in steps 1 and 2, but little effect on the distribution of heavy metals in step 3 and residue fraction. Physical and chemical changes induced by carbonation were presented and discussed.

Influence of operational conditions, waste input and ageing on contaminant leaching from waste incinerator bottom ash: A full-scale study

Leaching of metals and Cl from fresh, naturally aged, and lab-scale aged bottom ashes generated during full-scale incineration experiments with different operational conditions (OC) and waste input (WI) was assessed. Although significant differences in the bulk contents of the generated bottom ashes were observed between the individual experiments, addition of 5.5 wt.% PVC, 11.1 wt.% chromated-copper–arsenate impregnated wood, 14.2 wt.% automotive shredder residue, 1.6 wt.% shoes, and 0.5 wt.% batteries to the normal municipal solid waste received at the incinerator (in six individual experiments) had no significant effect on metal leaching from the bottom ash. Likewise, changes in OC (furnace oxygen level and air distribution) could not be correlated to changes in leaching. The effects on metal leaching from ageing were generally larger than the effects from changes in OC and WI. Ash ageing caused a significant decrease in leaching of Cu, Zn, and Pb while leaching of Sb and particularly Cr increased. For Cl, a clear correlation between the bulk contents and leaching was observed for bottom ash generated in experiments with changes in WI. Comparison of leaching data obtained in this study with leaching from “typical” aged Danish bottom ash revealed no significant differences when the typical variations in leaching data over time and between different Danish incinerators were accounted. Generally, this indicates that metal leaching from bottom ash is not sensitive to limited changes in WI and OC as suggested in this paper, only Cl − leaching appeared to be affected.

Contamination of Bottled Waters with Antimony Leaching from Polyethylene Terephthalate (PET) Increases upon Storage

Antimony concentrations were determined in 132 brands of bottled water from 28 countries. Two of the brands were at or above the maximum allowable Sb concentration for drinking water in Japan (2 microg/L). Elevated concentrations of Sb in bottled waters are due mainly to the Sb2O3 used as the catalyst in the manufacture of polyethylene terephthalate (PET(E)). The leaching of Sb from PET(E) bottles shows variable reactivity. In 14 brands of bottled water from Canada, Sb concentrations increased on average 19% during 6 months storage at room temperature, but 48 brands of water from 11 European countries increased on average 90% under identical conditions. A mineral water from France in PET(E), purchased in Germany, yielded 725 ng/L when first tested, but 1510 ng/L when it was stored for 6 months at room temperature; the same brand of water, purchased in Hong Kong, yielded 1990 ng/L Sb. Pristine groundwater containing 1.7+/-0.4 ng/L Sb (n = 6) yielded 26.6+/-2.3 ng/L Sb (n = 3) after storage in PET(E) bottles from Canada for 6 months versus 281+/-38 ng/L Sb (n = 3) in PET(E) bottles from Germany. Tap water bottled commercially in PET(E) in December 2005 contained 450+/-56 ng/L Sb (n = 3) versus 70.3+/-0.3 ng/L Sb (n = 3) when sampled from a household faucet in the same village (Bammental, Germany), and 25.7+/-1.5 ng/L Sb (n = 3) from a local artesian flow.

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To shed light on the leaching of Sb from mine wastes containing stibnite, two series of experiments were conducted. In one experiment, polished slabs of a museum-grade stibnite and a mixed-sulfide ore sample containing 28% Sb were subjected to accelerated weathering at 100% humidity and 31-35C for 37-44 days. After leaching with distilled water, insoluble weathering products remaining on the test specimens were examined with a variety of spectroscopic techniques including transmission electron microscopy, electron energy loss spectroscopy, synchrotronradiation X-ray photoelectron spectroscopy and X-ray absorption near-edge spectroscopy. In another experiment, semi-polished slabs of a mixed-sulfide ore containing 3% Sb were submerged in distilled water and the evolution of leachate chemistry was monitored over a period of 147 weeks. The results show that galvanic interaction plays an important role in dictating the extent of Sb leaching under both subaerial and subaqueous conditions. Thus, detailed mineralogical characterization is indispensable in predicting the leaching of Sb from mine wastes containing mixed sulfides. Additional

Antimony leaching from uncarbonated and carbonated MSWI bottom ash

The recycling potential of municipal solid waste incinerator (MSWI) bottom ash may be limited by the leaching of antimony (Sb). Therefore, treatment methodologies need to be developed. The pH-dependent leaching behaviour of this oxyanion-forming element in fresh and weathered bottom ash is, however, not understood. Sb leaching was investigated in a wide range of both pH and extent of carbonation. Sb came close to equilibrium with calcium antimonate (Ca[Sb(OH) 6] 2) at acid and neutral pH. Therefore, adsorption experiments with synthetic calcite (CaCO 3), ettringite (Ca 6Al 2(SO 4) 3(OH) 12·26H 2O), gypsum (CaSO 4·2H 2O), and portlandite (Ca(OH) 2) and adsorption modelling to hydrous ferric oxides (HFO) and amorphous aluminium minerals (AAM) were conducted to investigate which minerals decrease Sb leaching below equilibrium with calcium antimonate. At pH > 12, calcium antimonate comes into solution due to portlandite formation, but the subsequent increase in Sb leaching is reduced due to strong interaction of Sb with portlandite and ettringite. Ettringite appears to be an important host mineral for Sb at the natural pH of mildly weathered bottom ash (11.8) because a minimum in leaching is observed. When pH is decreased below 10.5, ettringite dissolves and Sb comes into solution, approaching equilibrium with calcium antimonate near pH 9. Gypsum showed no affinity for Sb. The interaction of calcite with Sb was not clear. Adsorption modelling suggested that HFO, rather than AAM, control Sb leaching when pH < 9. During carbonation, Sb leaching first increased, most likely due to dissolution of ettringite. Then, Sb leaching decreased, since the pH became low enough to allow sorption by HFO.

Carbonation of MSWI-bottom ash to decrease heavy metal leaching, in view of recycling

The 0.1–2 mm fraction of a MSWI-bottom ash cannot be used as granular construction material because leaching of Cu exceeds Flemish limit values. In addition, leaching of Ba, Mo and Sb exceeds informal limit values. Leaching characteristics thus need to be improved. Carbonation was the chosen treatment method and this was performed by placing samples in a CO 2 chamber. The CO 2 percentage and the temperature of the chamber atmosphere, as well as the initial humidity of the samples, were varied to optimize carbonation parameters. Metal leaching was tested with the EN 12457 extraction test. Carbonation decreased Cu leaching from 3.3 to 1.0 mg/kg, but not yet to below the official limit value of 0.5 mg/kg. Leaching of Mo and Sb remained fairly constant or even increased after carbonation, but their limit values are only informal. Ba leaching decreased to below the informal limit value. Carbonation also caused Cr leaching to increase, in some cases to above the official limit value. Of the tested parameters, a CO 2 percentage of 10% and a carbonation temperature of 50 °C in the atmosphere, together with ash humidity between 13% and 25% appeared to give the best leaching results. The main carbonation reactions took place within the first 24 h.

Palladium-oxygenated compounds of the Gongo Soco mine, Quadrilátero Ferrífero, central Minas Gerais, Brazil

AbstractNew data on the Gongo Soco palladium-oxygenated compounds are presented for the first time since the work of Johnson and Lampadius (1837). A variety of PdO species is documented, always in association with Cu, Fe and Mn, and includes Pd(OH)2 or PdO.H2O, and phases with metal excess in relation to oxygen, interpreted as metastable. Their remarkable occurrence in ‘ouro preto’ (black gold) and jacutinga (auriferous itabirite/iron ore) is the result of mertieite-II alteration. It involves leaching of Sb and As, limited removal of Pd, and incorporation of Cu, Mn and Hg into PdO species. The locus of Hg-bearing PdO species in microfractures parallel to the enclosing gold-mineralized shear band suggests at least one low-temperature hydrothermal generation. The presence of a halite crystal attached to gold testifies to the involvement of Cl-saturated hydrothermal fluids in the oxidizing environment of jacutinga formation.

Reducing Sb-leaching from municipal solid waste incinerator bottom ash by addition of sorbent minerals

This paper investigates the mechanisms controlling Sb-leaching from fresh Municipal Solid Waste Incinerator (MSWI) bottom ash, as well as the possibilities of controlling the extent of Sb-leaching by the addition of sorbent minerals to the bottom ash. In alkaline MSWI bottom ash Sb is possibly incorporated in ettringite-like minerals. When weathering/carbonation continues the ettringite dissolves resulting in a mobilisation of Sb. At neutral pH values the leaching of Sb is likely to be controlled by sorption to amorphous Fe/Al-(hydr)oxides. It has been shown that Sb can effectively be removed from solution if salts of Fe(III) or Al(III) are added to the bottom ash. This addition of Fe(III)/Al(III)-salts leads to (1) the in-situ precipitation of Fe/Al-hydroxides and sorption/coprecipitation of contaminants such as Sb, and (2) a lower bottom ash pH and thus an increased affinity of oxyanions for sorption to Fe/Al-(hydr)oxides.

Dinking water quality: Impact of non‐lead‐based plumbing solders

Studies were done on the leaching of Ag, Cd, Cu, Pb, Sb, Sn and Zn from 95/5 Sn/Sb‐, 96/4 Sn/Ag‐, and 95.5/ 4.0/0.5 Sn/Cu/Ag‐soldered copper coupons into high‐purity, tap, treated and well water samples as a function of standing time in a static test on new plumbing. No significant leaching of Ag, Cd, Pb and Sb occurred from the above solders into the water samples. Tin was released into the water samples from all the solders. The amount of Cu released from soldered copper pipes was generally lower than that released from non‐soldered copper pipes, especially in the case of treated and well water samples, due to galvanic corrosion. The amount of Zn leached was well below the Guidelines (5 mg/1) for Canadian drinking water quality. Examination of the coupon surfaces using electron microprobe and X‐ray photoelectron spectroscopic techniques showed the presence of tin oxides due to galvanic corrosion.

Leaching of antimony, cadmium, copper, lead, silver, tin and zinc prom copper piping with non‐lead‐based soldered joints

Abstract Studies were done on the leaching of Ag, Cd, Cu, Pb, Sb, Sn and Zn from 95/5 Sn/Sb‐, 96/4 Sn/Ag‐, 94/6 Sn/Ag‐, and 95.5/4.0/0.5 Sn/Cu/Ag‐soldered copper pipes into high‐purity, tap, and well water samples as a function of standing time in a static test on new plumbing. There was no significant leaching of Ag, Cd, Pb, Sb and Sn from the above solders into the three types of water samples studied. The amount of Cu released from soldered copper pipes was lower than that released from non‐soldered copper pipes. The amount of Zn leached from the non‐Pb‐based solders studied was well below the Guidelines (<5 mg/1) for Canadian drinking water guality. Since the potential for public health hazard from Pb‐based solders in plumbing systems is significant, it is advisable to use these Pb‐free’ solders.

Antimoniferous mineralization from the Mid-European Saxothuringian Zone: mineralogy, geology, geochemistry and ensialic origin

In the North Bavarian Basement (FR Germany) as well as in the Thuringian Forest (GDR) both of which belonging to the Saxothuringian Zone antimony mineralizations have been worked up to the early fifties. Mineralogical and geological investigations led to the following classification of antimony ore deposits and -concentrations: Antimony in the black shales was concentrated during late diagenetic cementation along with copper. The sulpho-salt-bearing stibnite veins in the metamorphic country rocks of the granites are genetically associated with the granitic intrusions nearby. This is proved by trace element chemistry and structural as well as mineralogical features of those veins. U/Pb age dating of contemporaneous pitchblende from the »polymetallic uranium paragenesis« from Hoehensteinweg uranium deposit yielded a late Variscan age of formation for these veins of type 2. Early Paleozoic rocks (metavolcanics) are suggested to have been the parent material for these granite-related Sb concentrations. However the monotonous Sb veins are more akin to the basic protore in deeper crustal sections. The thermal aureole of a deep-seated heat source is preserved by the Ag/Sb ratio of galena in Pb-Zn veins (type 4), which shows a marked variation along the SW plunging Berga Anticline from increased Ag/Sb ratios near the core of the anticline towards reduced values in mining sites more peripheral to this fold structure. Pb isotopes of stibnite as well as Pb sulphides point to a crustal derivation of both elements. An in-situ re-deposition and leaching of Sb from the wall rocks as well as antimoniferous black shales may be ruled out. It has to be emphasized that intra-crustal mass movements (A subduction) and the late Vanscan igneous activity are the major factors controling release of Sb from the Early Paleozoic low metal concentrations within metavolcanic rocks and subsequent discharge of Sb-bearing fluids within joints and fractures related to late Variscan tectonic movements. A schematic exploration concept is outlined.