Leachability Of Lead Research Articles

Widespread lead contamination of imported low-cost jewelry in the US

Recent recalls of lead-contaminated jewelry and the death of a Minnesota child by lead poisoning after swallowing a jewelry charm have highlighted the hazards of leaded jewelry to children. We sought to determine the extent of lead contamination in inexpensive, imported jewelry available in United States retail stores. A total of 139 jewelry items were purchased from ten retail store chains in five different geographic locations. Samples were digested in nitric acid followed by atomic absorption analysis. Accessibility of lead was analyzed by leaching a subset of heavily leaded samples in 0.07 M hydrochloric acid. Almost half (42.6%) of the items assayed were heavily leaded, exceeding 80% lead by weight. Average lead content for all items tested was 44.0%, and one or more heavily leaded items were found in samples from each retail store and each geographic location. Six of ten samples tested for leachability of lead exceeded the US Consumer Product Safety Commission guidelines of 175 microg accessible lead. Our results show that much inexpensive children's and costume jewelry imported and sold in the US is heavily leaded. Given the high neurotoxicity of lead to young children, inexpensive jewelry items pose a potential yet avoidable threat to children's health.

The Determination of Contaminant Release from the PBO-Fe2O3-SiO2-Na2O Vitrification System, Using Industrial Solid Waste or Artificial Mixtures

In the current study, the leachability of lead from the PbO-Fe2O3-SiO2-Na2O vitrification system was examined by the application of DIN 38414 S4 and TCLP (Toxicity Characteristic Leaching Procedure) standard leaching tests. Various compositions, containing industrial or artificially created solid waste, were examined. Among the main conclusions from the results obtained was that the initial lead content, expressed as PbO and varied between 4–24% w/w, does not influence directly the release of lead from the vitrified samples. The other oxides, as well as other factors e.g. crystal formation on the glass surface, proved to be more important. Similar data were obtained regarding the content of iron oxide (the initial content of Fe2O3 varied from 30–54% w/w), although in this case the sodium concentrations measured in the leachates were generally found to increase with increasing initial iron oxide content and with the respective formation of crystals. The stoichiometry of lead and sodium, as measured in the leachates, was not constant for all the examined cases, showing that the mechanism of release depends upon the initial compositions and the presence of crystals on the glass surface. Improved results, regarding leachability and homogeneity without the presence of crystallites on the glass surface, were obtained when the initial ratio SiO2/Na2O (% w/w) was 2.33. By maintaining this ratio and when the examined waste was gradually added in the initial composition, the results obtained, concerning sodium concentration and pH values, can be described mathematically, by introducing an appropriate constant factor.

Stabilization/solidification of lead-contaminated soil using cement and rice husk ash

This paper presents the findings of a study on solidification/stabilization (S/S) of lead-contaminated soil using ordinary Portland cement (OPC) and rice husk ash (RHA). The effects of varying lead concentrations (in the form of nitrates) in soil samples on the physical properties of their stabilized forms, namely unconfined compressive strength (UCS), setting times of early mixtures and changes in crystalline phases as well as chemical properties such as leachability of lead, pH and alkalinity of leachates are studied. Results have indicated that usage of OPC with RHA as an overall binder system for S/S of lead-contaminated soils is more favorable in reducing the leachability of lead from the treated samples than a binder system with standalone OPC. On the other hand, partial replacement of OPC with RHA in the binder system has reduced the UCS of solidified samples.

Effects of cement on redistribution of trace metals and dissolution of organics in sewage sludge and its inorganic waste-amended products

The suitability of using cement-stabilized sludge products as artificial soils in earth works was evaluated. The sludge products investigated were cemented sludge, cement-treated clay-amended sludge (SS + MC), and cement-treated copper slag-amended sludge (SS + CS). The leachability of lead (Pb), zinc (Zn), copper (Cu), and chromium (Cr) were assessed using the sequential extraction technique, toxicity characteristic leaching procedure (TCLP), NEN 7341 availability test, and column leaching test. The results indicated that Zn leachability was reduced in all the cement-stabilized sludge products. In contrast, Cu was transferred from the organic fraction to the readily leachable phases in the cement-stabilized sludge products and therefore exhibited increased leachability. The increased Cu leachability could be attributed to dissolution of humic substances in the sludge as a result of elevated pH. Good correlation between dissolved organic carbon (DOC) and heavy metal leaching from the cement-stabilized sludge products was observed in the column leaching experiment. Even with a cement percentage as small as 12.5%, calcium silicate hydrate (C–S–H) was formed in the SS + MC and SS + CS products. Inclusion of the marine clay in the SS + MC products could reduce the leaching potentials of Zn, and this was the great advantage of the marine clay over the copper slag for sludge amendment.

Utilization of secondary lead slag as construction material

Secondary lead slag, a waste product from battery smelting using CaCO 3 as flux, has been investigated for its use as an admixture and/or aggregate in the production of concrete blocks. The slag was added as partial replacements of cement and/or aggregate. The results revealed that the oxide components of the slag were similar to those of ordinary Portland cement (OPC). The CaO content in the slag is 6.2 times less than that in OPC, while its iron content, as FeO, is 15.1 times higher. Interestingly, it also possesses magnetic property. All samples exhibited higher compressive strengths than that of the sample without slag (STD) which increased with increasing the slag contents and ages. The highest compressive strength was of the sample containing 20% slag as cement substituent and 100% slag as aggregate replacement owing to 259% of that of the STD at 60 days. All samples showed higher water absorption than that of the STD. The higher the slag contents, the more the water absorption. The absorption was, as expected, decreased with ages. Magnetic property of the slag plays an important role in the properties of the concrete blocks. For environmental concern, leachability of lead (Pb) from all samples was also carried out.

Utilizing a database to interpret leaching characteristics of lead from bottom ashes of municipal solid waste incinerators

This study focuses on evaluation and quantification of factors affecting leachability of lead from bottom ashes of municipal solid waste incinerators (MSWI) by utilizing a database. The database, which was constructed with data collected from sources such as research papers, questionnaires and reports, consists of 1149 data sets on 508 MSWI plants. Factors chosen as affecting lead leachability included: pH in the leachate, loss on ignition of bottom ash, total content of lead, and content of main elements such as Fe, Mn, Si and Al. The lead leachability was reduced to a minimum at neutral pH, increased with increasing pH and, especially, showed an abrupt increase at pH levels above 12. The main factor controlling the pH of the leachate appeared to be leachable Ca 2+ originating from portlandite (Ca(OH) 2). Leaching concentration increased with increasing total contents of lead, and the relationship between leaching of lead and loss on ignition showed no distinct tendencies. The lead leaching ratio increased with decreasing total contents of Si, Mn and Fe. It is evident, therefore, that these numerous factors determine the leachability of lead in a simultaneous and complex manner.

Leachability of Lead and Cadmium from Cementitious Wastes

AbstractIn this paper, the leachability of lead and cadmium from cementitious waste was investigated to determine the leaching mechanism of these heavy metals from a cement matrix so that a more appropriate leaching test can be designed. The leaching studies were carried out using a modified Toxicity Characteristic Leaching Procedure (TCLP), and variations in leaching parameters such as leachate pH, the duration of agitation, the particle size, and the liquid to solid ratio were investigated. The main finding of these studies was that the leachability of Pb and Cd in cementitious waste was highly dependent on the pH of the leachate. Other findings included: (i) the leachability of metals initially decreased with increasing leaching duration but increased after the leachate pH reached equilibrium; (ii) the particle size of the cementitious waste affected the rate of leaching of alkalinity from cement and hence the leachability of the heavy metal ions; and (iii) the total metals in the leachate, increased with increasing liquid to solid ratio. Overall, the TCLP was found to be inappropriate for assessing the leachability of heavy metals from cementitious waste due to the high buffering capacity of the calcium ions in the cement. This maintained the pH of the leachate at a value where heavy metals are insoluble. The test was found to underestimate the concentration of heavy metal ions leached from cementitious waste relative to the concentration in the actual landfill environment.

Speciation and transport of heavy metals and macroelements during electroremediation.

Electroremediation makes treatment of contaminated clay soils possible. The external electrical field causes several transport processes and changes in soil chemistry. This study concerns the leachability and transport of calcium, magnesium, copper, zinc, lead, nickel manganese, chromium, and iron during treatment with an electric field of soil from a chlor-alkali factory. As expected, most elements were removed from the acidic part of the soil and accumulated in the zone where pH changed from acidic to alkaline. However, acidic leaching of the soil in this zone did not mobilize the elements. Lead formed both an anionic complex which electromigration transported toward the anode as well as a cationic lead fraction which moved toward the cathode. The anionic complex could be lead sulfate. Lead from both fractions was strongly attached to the soil after treatment. The low availability of metals and macroelements after electrokinetic remediation could make electroremediation, excavation, and deposition of the accumulation zone an alternative for the treatment of contaminated soils.

Leachability and content of heavy metals in incombustible residues from resource recovery facilities

The heavy metal leachability and contents of incombustible residues (IR) generated from municipal resource recovery facilities were investigated. It was found that IR from residential bulky waste have both a higher heavy metals content and heavy metals leachability than IR from incombustible residential waste. Further, eluate concentrations for lead from some IR samples were as high as those from typical municipal solid waste (MSW) fly ash. Leaching experiments using four lysimeters were performed. It was found that lead concentrations in leachate from the lysimeters containing only IR were very high, although leachate concentrations from those lysimeters containing mixtures of IR and MSW bottom ash decreased more rapidly. These findings suggest that codisposal of IR with bottom ash could significantly decrease the leachability of lead.

Leachability and content of heavy metals in incombustible residues from resource recovery facilities

The heavy metal leachability and contents of incombustible residues (IR) generated from municipal resource recovery facilities were investigated. It was found that IR from residential bulky waste have both a higher heavy metals content and heavy metals leachability than IR from incombustible residential waste. Further, eluate con- centrations for lead from some IR samples were as high as those from typical municipal solid waste (MSW) fly ash. Leaching experiments using four lysimeters were performed. It was found that lead concentrations in leachate from the lysimeters containing only IR were very high, although leachate concentrations from those lysimeters containing mixtures of IR and MSW bottom ash decreased more rapidly. These findings suggest that codisposal of IR with bottom ash could significantly decrease the leachability of lead.

Understanding Environmental Leachability of Electric Arc Furnace Dust

Dust from production of steel in an electric arc furnace (EAF) contains a mixture of elements that pose a challenge for both recovery and disposal. This paper relates the leachability of six Canadian EAF dusts in four leaching tests [distilled water, Ontario Regulation 347 Leachate Extraction Procedure, Amount Available for Leaching (AALT), and pH 5 Stat] to their mineralogy. Chromium and nickel contaminants in EAF dust are largely unleachable (<5% available in AALT and pH 5 Stat), as they are found with the predominant spinel ferrite phase in EAF dust. However, even a small proportion of oxidized chromium can result in significant leachate concentrations of highly toxic chromate. The leachability of zinc (7–50% available), lead (2–17% available), and cadmium (9–55% available) can be significant, as large fractions of these contaminants are found as chlorides and oxides. The leaching of these metals is largely controlled by pH. The acid neutralization capacity of the EAF dusts appeared to be controlled by...

Lead leaching from pressure cookers

Leachability of lead by tap water and tamarind solution from Indian pressure cookers while cooking with and without a safety valve is studied. Lead contamination of food by cookers is not very high when compared to the daily intake of lead from various food items consumed by the Indian community. However, looking at the very wide range of lead levels leached from various brands of pressure cookers, it certainly seems possible to keep the lead contamination to the minimum by proper choice of the materials used in the manufacture of these pressure cookers. The rubber gasket, which is a very important component of any pressure cooker, contains the maximum lead concentration; the safety valve is another important source leading to lead contamination of cooked food.

98/04218 Long-term experience with non-catalytic nitrogen oxide removal in coal-fired boilers in the Czech Republic

The suitability of using cement-stabilized sludge products as artificial soils in earth works was evaluated. The sludge products investigated were cemented sludge, cement-treated clay-amended sludge (SS + MC), and cement-treated copper slag-amended sludge (SS + CS). The leachability of lead (Pb), zinc (Zn), copper (Cu), and chromium (Cr) were assessed using the sequential extraction technique, toxicity characteristic leaching procedure (TCLP), NEN 7341 availability test, and column leaching test. The results indicated that Zn leachability was reduced in all the cement-stabilized sludge products. In contrast, Cu was transferred from the organic fraction to the readily leachable phases in the cement-stabilized sludge products and therefore exhibited increased leachability. The increased Cu leachability could be attributed to dissolution of humic substances in the sludge as a result of elevated pH. Good correlation between dissolved organic carbon (DOC) and heavy metal leaching from the cement-stabilized sludge products was observed in the column leaching experiment. Even with a cement percentage as small as 12.5%, calcium silicate hydrate (C–S–H) was formed in the SS + MC and SS + CS products. Inclusion of the marine clay in the SS + MC products could reduce the leaching potentials of Zn, and this was the great advantage of the marine clay over the copper slag for sludge amendment.

Leachability of lead from lead tailings

Laboratory column studies were used to predict the effect on the leachability of lead when using fly ash or a fly ash/sludge mixture as a cover for a lead tailings site. A high pH fly ash cover produced a leachate with a pH 12. This was sufficiently high to allow for the formation of lead hydroxide complexes which are slightly soluble. Therefore, the leachate had an average lead concentration of about 5 mg L-1, while the pH in the leachate from the column with only tailings was 7.8 and a lead concentration below the detection limit (≤0.1 mg L-1). The fly ash cover changed the availability of the remaining lead, making it less available. Rainfall rate did not affect the fly ash cover, but did have an effect on the fly ash/sludge cover.

Leachability of lead from solidified cement-fly ash binders

Potential of partly replacing cement with class C fly ash to immobilize lead was investigated. Lead nitrate up to a concentrations of 10% (by weight of binder) was solidified with binders such as Type I Portland cement and a cement-fly ash (equal proportion) mixture. Pore fluid analyses indicated that lead increased the calcium and silicon concentration in the pore fluid during the initial period of hydration of cement and cement-fly ash mixtures. Addition of fly ash to cement reduced the initial and final setting times, but with the addition of lead nitrate setting times were increased. The compressive strength of the solidified cement decreased with the addition of fly ash and lead nitrate. Lead leachability from the solidified binder matrix was studied using the Toxicity Characteristic Leaching Procedure (TCLP) recommended by the U. S. Environmental Protection Agency (EPA). The quantity of Pb(II) leached was dependent on the initial lead nitrate concentration and the binder systems adopted. Lead solidified with cement-fly ash mixture showed a slightly less leaching compared to the cement binder. A simple model has been proposed to predict the leachability of Pb(II) from the binder matrix.

Bioavailability of lead from vitrified slagged aggregate

This study was conducted to determine the leachability of lead (Pb) from a vitrified slagged aggregate (VSA) into water, as well as the bioaccumulation of lead into specified tissues of sunfish ( Lepomis megalotis) maintained in aquaria containing VSA over a period of 100 days. The experiments consisted of solubility studies comparing the leaching or release of lead from 600 and 1200 g of VSA into aquaria. Over the course of the study, results indicate that relative to controls there occurred no leaching of lead from the VSA into the water. In addition, there was no apparent contribution of lead from the VSA with respect to bioaccumulation in the specified tissues of fish (gills, skeleton, skin and scales, muscle, and viscera). There was, however, a significant dose-dependent bioaccumulation of lead in fish housed in aquaria containing a soluble salt of lead (50 and 100 ppb lead as lead nitrate). These studies indicate that bioaccessibility is an important component in determining the ultimate bioavailability of lead.

Leachability of Lead from Auto Shredder Residues: A Canadian Perspective

The concentration of the heavy metals; zinc, lead, cadmium, chromium and copper in the solid waste Auto Shredder Residue (ASR) have been measured and their leachability evaluated according to a variety of leaching tests currently employed in North America. The importance of pH and a buffering agent have been identified as key features in determining the leachability of these metals. The results of the study indicate that ASR, while it contains relatively high concentrations of the metals lead (0.28%) and copper (1.11%), when the material is subjected to standardized leaching tests only small quantities of these metals are solubilized and detected in the leachate. In addition, the ASR is capable of absorbing additional quantities of lead ions from solution, with the actual amounts being dependent upon the nature of the lead compounds.

Characterization of auto shredder residue — a Canadian perspective

Abstract Auto Shredder Residue (ASR) the solid wastes produced by the Canadian Ferrous metal Shredding Industry has been found to be an extremely heterogeneous material. By employing a systematic cone and quartering procedure on a sufficiently large representative sample, reasonably consistent and repeatable results can be obtained regarding the chemical and physical composition of the material. Although some variability was observed between samples from one operation the data obtained for the most part was consistent. Surprisingly the variation from operation to operation was not large and when differences in specific properties were noted they could be attributed to specific operational conditions noted at the time of sampling. Essentially, a typical sample of ASR from a Canadian shredding operation has a bulk density of 405 kg/m3 and contains 6% moisture. 18% of the material will have a particle size greater than 25.5 mm, with 37% fines less than 2 mm. The split between the organic and inorganic fraction as determined by ashing is 42% to 58% with the material having a calorific value of 11.8 MJ/kg. After iron: zinc and copper were the principle heavy metals present in the material at concentrations of about 1%. Lead at a concentration of about 0.25% was the next major heavy metal present. Concentrations of cadmium and chromium meanwhile were less than 0.05%. In terms of the leachability of these heavy metals from the ASR when measured by the Quebec test protocol, zinc was found to be the most leachable at concentrations of about 250 mg of Zn per litre of leachant. Cadmium, chromium and copper meanwhile leach out at levels usually less than 1 mg/l. When evaluated by the Quebec test protocol the leachability of lead from ASR is a potential problem with an average concentration of 7.0 mg/l, which exceeds the allowable limit of 5 mg/l.

Leachability of Lead from Selected Copper-Base Alloys

Abstract The Bureau of Mines has conducted research on the selective leaching of lead from copper-base alloys in high-purity water. The alloys in this study were selected as representatives of thos...

Leaching Characteristics of Lead and Cadmium From Waste-To-Energy Residues in Sea Water

Abstract Laboratory studies were conducted to determine leaching characteristics of waste-to-energy (WTE) residues in sea water to provide initial evaluation on the potential impact of WTE residues on the marine environment. Both loose and stabilized WTE residues were investigated for the leachability of lead (Pb) and cadmium (Cd) in sea water. Results of the study showed that loose WTE fly ash was very reactive in sea water; release of Pb and Cd occurred immediately (<0.5 hr) after the ash came in contact with sea water. Stabilization (treated with Portland cement and other additives), however, significantly reduced leaching of Cd and Pb. While ocean disposal of untreated WTE residues would not be advisable, utilization of stabilized WTE residues for beneficial uses should be investigated.