Extraction Efficiency Of Pb Research Articles

Development of a dispersive micro-solid phase extraction method based on using cobalamin as a green adsorbent for the extraction of Cd(II) and Pb(II) from oil samples

ABSTRACT A dispersive micro-solid phase extraction procedure using cobalamin as a green sorbent has been developed for the extraction of Cd(II) and Pb(II) ions from oil samples. At first, a desired amount of oil sample was dissolved in chloroform. Then, the specified amount of cobalamin was added and vortexed. After centrifuging, the separated solid particles were dissolved in nitric acid solution. Finally, the analytes were analysed by flame atomic absorption spectrometry. Effects of different analytical parameters such as amounts of sample and cobalamin, vortex time, complexing agent amount, type and volume of dissolving solvent, and temperature on the extraction efficiency of Pb(II) and Cd(II) ions were investigated and optimised. Under optimised conditions, calibration curves were established with the linear ranges of 1.5–150 μg Kg−1 for Cd(II) and 1–150 μg Kg−1 for Pb(II). The detection limits were found to be 0.48 and 0.34 µg Kg−1 along with extraction recoveries of 89.1% and 94.8% for Cd(II) and Pb(II) ions, respectively. The proposed method demonstrated good repeatability, with the relative standard deviation ranging from 3.8% to 4.1% (n = 6, C = 10 μg Kg−1 of each cation). Finally, the method was successfully applied to determine the concentrations of Cd(II) and Pb(II) ions in various oil samples.

Effect of different ramie (Boehmeria nivea L. Gaud) cultivars on the adsorption of heavy metal ions cadmium and lead in the remediation of contaminated farmland soils

Abstract Heavy metal ions, including cadmium (Cd) and lead (Pb), are serious pollutants in farmland soils. The effective removal of heavy metals is an important task in soil remediation. This study aimed to evaluate the ability of seven ramie (Boehmeria nivea L. Gaud) cultivars to remove heavy metals. Results showed that the seven ramie varieties grew well in Cd and Pb polluted soils. The aboveground biological tissues and raw fiber yield of “Zhongzhu1” were 20.71 and 24.61 Mg ha−1 per year, respectively, which were significantly higher than those of the six other varieties. Cd levels in each ramie part can be arranged as husks > root > stem bone > leaf > raw fiber, while Pb levels in each ramie part can be arranged as root > leaf > husks > stem bone > raw fiber. The Cd content in the shoots of “Zhongzhu1” was 19.89 mg kg−1, and the Pb content of the aboveground shoots of “Shiqianzhugenma” was 9.41 mg kg−1. The extraction efficiency of Cd in “Zhongzhu1” was greatly higher than those of the six other varieties. The extraction efficiency of Pb was similar in all varieties. Our observations suggest that ramie can be used to remove toxic ions (Cd and Pb). This study provides a new understanding of planting ramie for heavy metal removal from contaminated soils.

Enhanced performance of emulsion liquid membrane prepared with aid of hydrodynamic cavitation for effective removal of Pb (II) from aqueous feed phase: Optimization using Artificial Neutral Networks modeling

The present study deals with preparation of emulsion liquid membrane (ELM) in hydrodynamic cavitation system using organic phase containing Aliquat 336 carrier, diluents i.e., kerosene and Span 80 surfactant and stripping phase (0.1 M NaOH solution). Further experimental investigation on extraction/removal of Pb (II) from feed solution containing Pb (II) was conducted with the use of hydrodynamic cavitationally prepared ELM. Influence of the several process parameters like carrier concentration, surfactant concentration, strength of stripping solution, cavitation time and size of orifice during preparation of ELM phase and ELM to feed water ratio on extraction/removal of Pb (II) from feed solution was investigated during experimental runs. Almost 100% removal/extraction efficiency Pb (II) from feed solution was observed with the use hydrodynamically prepared ELM for the optimized condition of 2 mm orifice diameter, 1:05 ELM to feed water ratio, 0.1 M NaOH strength of stripping solution, 3% (v/v) Span 80 surfactant concentration, and 1% (v/v) carrier concentration. Further, artificial neural network (ANN) modeling was used for the prediction of % extraction efficiency of Pb (II) from feed solution. Hence, the use of hydrodynamic cavitation-based novel process for synthesizing ELM having outstanding stability is possible for removal/extraction of Pb (II) from aqueous feed phase.

Removal of heavy metals in medical waste incineration fly ash by Na2EDTA combined with zero-valent iron and recycle of Na2EDTA: Acolumnar experiment study

ABSTRACT In this study, an effective circulating system was developed to remove heavy metals in medical waste incineration (MWI) fly ash. MWI fly ash (MWIFA)-column experiments were performed to remove Cu, Pb, Zn, Cd, and Ni from MWIFA using EDTA disodium (Na2EDTA). Iron-column experiments were conducted to study the removal effect of zero-valent iron on the five heavy metals from washing wastewater. Toxicity Characteristic Leaching Procedure (TCLP) test method was employed to evaluate heavy metals toxicity of MWIFA residues generated after 0–0.2 mol/L Na2EDTA solution treated. After being washed by 0.2 mol/L Na2EDTA solution, TCLP leaching values of Cu, Pb, Zn, Cd, and Ni were the lowest and satisfied the standard (GB 5085.3–2007), and the leaching values were 58.4 ± 2.0 mg/L, 2.81 ± 0.14 mg/L, 64.3 ± 4.0 mg/L, 0.156 ± 0.005 mg/L, 0.381 ± 0.006 mg/L. Concentrations of Cu, Pb, Zn, Cd, and Ni in iron-column effluent were reduced by 99.7%, 91.6%, 91.6%, 75.4%, and 75.7%, respectively. Na2EDTA was recovered and recycled to the removal of heavy metals from MWIFA. Comparing new Na2EDTA solution with recycled Na2EDTA solution, recycled Na2EDTA and water could be reutilized to dispose MWIFA. The removal efficiencies of Cu, Pb, Zn, Cd, and Ni by recycled 0.2 mol/L Na2EDTA solution were 67.1%, 68.8%, 63.2%, 73.9%, 50.7%, respectively, the removal efficiencies using recovered Na2EDTA decreased by 2.6%, 3.9%, 3.3%, 4.2%, and 1.6%, respectively. Successive batch experiments were also conducted to evaluate industrialization potential and reusable times for recycled Na2EDTA. After four recirculation cycles, extraction efficiencies of Pb and Cd (removal efficiency at different cycles divided by removal efficiency of new Na2EDTA) declined toward 80%. Results from this research indicated that this circulating system possessed industrialization potential. Implications: An effective circulating system was developed to remove heavy metals in MWI fly ash (MWIFA). Integration of Na2EDTA with Fe0 promoted the removal of heavy metals from MWIFA. Na2EDTA, NaCl and water were stepwise extracted from iron-column effluent, respectively. Recovered Na2EDTA can still effectively remove heavy metals from MWIFA. Results from this research indicated that this circulating system possessed industrialization potential.

Microcapsule dispersion of poly(calix[4]arene-piperazine) for hazardous metal cations removal from waste water

Microcapsule of 500 nm was fabricated through non-agitation solution polymerization, used 5, 11, 17, 23-tetra-t-butyl- 25, 26, 27, 28-tetrakis(chlorocarbonyl-methoxy) calix [4] arene (C4C) and piperazine (PIP) with or without agitation. It was the amphiphilic self-assembly of C4C that made microcapsule the unique product for C4C/PIP couple in chloroform. Fourier transform infrared spectrometry (FTIR) and the X-ray photoelectron spectroscopy (XPS) proved the successful preparation of microcapsule. Transmission electron microscope (TEM) showed that microcapsules uniformly scattered in chloroform as a colorless dispersion. Absorption-C4C/PIP ratio curve indicated that the optimum ratio is 1:3 by ultraviolet–visible spectroscopy (UV–Vis). Microcapsule was almost uniform and intact at the optimum concentration of 3 × 10−4 mol L−1 under the optimum ratio of C4C/PIP. TEM and dynamic light scattering (DLS) illustrated that non-agitation solution polymerization is a better method to prepare a dispersion of microcapsules. This dispersion can extract heavy metal cations from their aqueous solution and fixed them over the interface of the two liquid phases through the formation of floccule layer. Inductively coupled plasma optical emission spectroscopy (ICP-OES) data showed that extraction efficiencies of Pb(II), Zn(II), Cu(II), and Ce(II) ions were 98.85%, 100.00%, 99.56%, and 98.97%, respectively. Dilute nitric acid can dissociate floccule layer and release cations into water, meanwhile, renewing the dispersion. The recovery ratio was 77.50%, 62.96%, and 68.42% for Pb(II), Cu(II), and Ce(II) ions, respectively. For Zn(II) ions, the recovery efficiency was more than 99.99%.

Polydopamine-functionalized magnetic iron oxide for the determination of trace levels of lead in bovine milk

In this work, a novel sorbent based on polydopamine-functionalized magnetic ferric oxide (Fe3O4) was synthesized and applied for dispersive solid phase extraction of Pb(II) in bovine milk samples. The extracts were analyzed by flame atomic absorption spectrometry (FAAS). The sorbent was characterized with different analytical techniques (XRD, FT-IR, SEM, TEM, VSM and EDX). To reach the maximum extraction efficiency of Pb(II), some effective parameters on both adsorption and desorption steps were optimized with the aid of central composite design and response surface methodology. Under the optimal conditions, the method provided an enhancement factor of 40.5 corresponding to the absolute recovery of 81%. LOD and LOQ were found as 0.13 and 0.43 ng mL−1, respectively. The calibration curve was linear over the concentration range of 3.0–300 ng mL−1 (R2 = 0.9957). The intra and inter-day precisions (RSD%) of the method were calculated as 3.2% and 5.6%, respectively. Finally, the method was successfully applied for the determination of Pb(II) in different bovine milk samples. The Pb(II) content in one of the investigated milk samples was found to exceed the maximum permissible limit (20 μg L−1) set by Codex Alimentarius Commission. The relative recoveries were obtained within the range of 86.5–93.6.

Separation and Micro amount Determination of Pb (II) and Cd (II) Via Solvent Extraction Method

In this paper, laboratory prepared azo derivative 2-[(4-Formyl phenyl) azo]-4,5-diphenyl imidazole (FPAPI) has been used as complexing agents for extraction Pb(II) and Cd(II) ions from aqueous solutions. Spectroscopy study was at ?max=533nm for ion pair complex of Pb(II) and ?max=543nm for ion pair complex of Cd(II) and all effective parameters on the extraction process were also studied. The optimum pH results for giving higher extraction efficiency of Pb(II) and Cd(II) were 8 and 9 respectively. In addition to other parameters such as shaking time, thermodynamics, an organic solvent, interferences, electrolytes, the paper has adopted different methods to determine the most feasible structural geometry of extracted ion-pair complex of [1:1]2+, anion, [Pb-FPAPI]2+, 2NO3-, [Cd-FPAPI]2+, 2NO3-.

Leach of the weathering crust elution-deposited rare earth ore for low environmental pollution with a combination of (NH4)2SO4 and EDTA

High concentration of ammonium sulfate, a typical leaching agent, was often used in the mining process of the weathering crust elution-deposited rare earth ore. After mining, a lot of ammonia nitrogen and labile heavy metal fractions were residual in tailings, which may result in a huge potential risk to the environment. In this study, in order to achieve the maximum extraction of rare earth elements and reduce the labile heavy metal, extraction effect and fraction changes of lanthanum (La) and lead (Pb) in the weathering crust elution-deposited rare earth ore were studied by using a compound agent of (NH4)2SO4-EDTA. The extraction efficiency of La was more than 90% by using 0.2% (NH4)2SO4-0.005 M EDTA, which was almost same with that by using 2.0% (NH4)2SO4 solution. In contrast, the extraction efficiency of Pb was 62.3% when use 0.2% (NH4)2SO4-0.005 M EDTA, which is much higher than that (16.16%) achieved by using 2.0% (NH4)2SO4 solution. The released Pb fractions were mainly acid extractable and reducible fractions, and the content of reducible fraction being leached accounted for 70.45% of the total reducible fraction. Therefore, the use of 0.2% (NH4)2SO4-0.005 M EDTA can not only reduce the amount of (NH4)2SO4, but also decrease the labile heavy metal residues in soil, which provides a new way for efficient La extraction with effective preventing and controlling environmental pollution in the process of mining the weathering crust elution-deposited rare earth ore.

Influence of EDTA and NTA on heavy metal extraction from sandy-loam contaminated soils

In this study, Pb, Cd, and Zn as heavy metal compounds were extracted from the sandy-loam soil; the soil was prepared synthetically inside the laboratory and also taken from the field by using EDTA and NTA as the chelating agents. By using EDTA 0.1M to extract the contaminants from the synthetically contaminated soil with single metal concentration of 500mg/kg, the efficiency of extracting Pb, Cd, and Zn in the first pore volume (PV) were found to be respectively 43.84%, 20.6%, and 43.7%; the corresponding amounts after the third PV for the contaminants were 85.25%, 83.2%, and 69.7%, respectively. The efficiency of NTA 0.1M in extracting Pb, Cd, and Zn in the first PV was 8.3%, 59.6%, and 14.87%, respectively; after the third PV, the corresponding efficiency reached to 21.8%, 83.56%, and 24.49%, respectively, for the contaminants. At pH 4.5, the efficiency of extracting Pb, and Zn using EDTA and NTA were higher than other levels of pH; and also, the maximum Cd extraction was achieved in pH 7. Considering the samples taken from the field, the extraction efficiency of Pb, Cd, and Zn using EDTA 0.1M after the fifth PV were 89.42%, 64.21%, and 63.5%, respectively.

Bioleaching mechanism of Zn, Pb, In, Ag, Cd and As from Pb/Zn smelting slag by autotrophic bacteria

A few studies have focused on release of valuable/toxic metals from Pb/Zn smelting slag by heterotrophic bioleaching using expensive yeast extract as an energy source. The high leaching cost greatly limits the practical potential of the method. In this work, autotrophic bioleaching using cheap sulfur or/and pyrite as energy matter was firstly applied to tackle the smelting slag and the bioleaching mechanisms were explained. The results indicated autotrophic bioleaching can solubilize valuable/toxic metals from slag, yielding maximum extraction efficiencies of 90% for Zn, 86% for Cd and 71% for In, although the extraction efficiencies of Pb, As and Ag were poor. The bioleaching performance of Zn, Cd and Pb was independent of leaching system, and leaching mechanism was acid dissolution. A maximum efficiency of 25% for As was achieved by acid dissolution in sulfursulfur oxidizing bacteria (S-SOB), but the formation of FeAsO4 reduced extraction efficiency in mixed energy source – mixed culture (MS-MC). Combined works of acid dissolution and Fe3+ oxidation in MS-MC was responsible for the highest extraction efficiency of 71% for In. Ag was present in the slag as refractory AgPb4(AsO4)3 and AgFe2S3, so extraction did not occur.

Bioleaching of heavy metals from contaminated sediments by the Aspergillus niger strain SY1

The objective of this study was to investigate the bioleaching of heavy metals from contaminated sediments by Aspergillus niger strain SY1. To achieve this, three targets were identified: (1) identify organic acids produced by the isolated A. niger strain SY1 from contaminated sediments, (2) compare the leaching ability and transformation of chemical speciation of heavy metals during the bioleaching processes, and (3) determine the toxic characteristic of sediment before and after bioleaching. The contaminated sediment was collected from the dredging of the Xihe River, China. The A. niger strain SY1 was isolated from this sediment. Bioleaching experiments were carried out in 250 ml autoclaved conical flasks with 10 g autoclaved sediment, 1 ml of spore suspension, and 99 ml culture medium; the flasks were placed in a shaking incubator (220 rpm) at 30 °C for 7 days. Toxicity characteristic leaching procedure (TCLP) tests were carried out according to USEPA-SW846 Method 1311, and the wheat and earthworm toxicity tests were carried out according to OECD “Guidelines for the Testing of Chemicals.” Fractionation of heavy metals was undertaken by the three-step sequential extraction procedure. The metabolites were determined with a HPLC system. There was 11.5 % leaching efficiency of Pb from the polluted sediment in the one-step bioleaching process; while in the two-step bioleaching process, the highest extraction efficiency of Pb was 65.4 %. In one-step bioleaching, 93.5 % Cd, 62.3 % Cu, and 68.2 % Zn were leached out; whereas, the highest metal extraction efficiencies of Cd, Cu, and Zn were 99.5, 56, 71.9, and 76.4 %, respectively, in two-step bioleaching. After the bioleaching, the metals remaining in the sediment were mainly found in the stable fractions. Cd, Pb, Cu, and Zn concentrations in extracted liquor of TCLP tests were reduced to far below the levels in two Chinese standards, and the sediment after bioleaching had a lower toxicity on wheat and earthworm. A. niger strain SY1 can effectively remove heavy metals in contaminated sediment. The bioleaching efficiencies of heavy metals in the two-step bioleaching were better than that in one-step bioleaching. After the bioleaching, metals remaining in the sediment were mainly found in the stable fractions, and the toxicity of it was reduced to a level for it to be used safely in landfill or used in land application. A. niger strain SY1 is a cost-effective, environmentally friendly, and efficient bioleacher of heavy metals.

LEACHING OF LEAD FROM SPENT MOTORCYCLE BATTERY IN HYDROCHLORIC ACID. PART II: SOLVENT EXTRACTION STUDIES

This work, constituting the second part of acid leaching of total Lead studied the extraction efficiency of Pb (II) by solvent extraction techniques by Dithizone in chloroform. The development of simple hydrometallurgical route for possible recovery of total lead from spent motorcycle battery ash leach liquor in hydrochloric acid solution has been investigated using combination of leaching, cementation, precipitation, solvent extraction and stripping techniques. The influence of extractant concentration on lead extraction and the extraction temperature on the total Lead extraction efficiency were examined. An extraction efficiency of 98% total Pb(II)was obtained by 0.01 mol/L Dithizone in chloroform at pH 8.3 from the initial 10g/L motorcycle ash leach liquor containing mainly 763.1 mg/L Pb, 4.3 mg/L Zn (10.7 mg/L after cementation) and 28.8mg/L Fe. Other constituents such as Cu, Mn, Ca and As whose concentrations in each case are less than 2mg/L after leaching, were first separated by cementation with zinc granules, followed by the total Iron removal by precipitating with 4mol/L ammoniacal solution to a pH 3.5 at 25±2 0C. Stripping of 98% total Pb(II) from dithizone extract by 0.1 mol/L hydrochloric acid solution was achieved. The values of thermodynamic data obtained on total Pb(II) extraction showed that the extraction by 0.01 mol/L Dithizone in chloroform is thermodynamicallyfavourable. Finally, a simple hydrometallurgical scheme for the operational procedures for the extraction of total Pb(II) from the spent motorcycle ash liquor was presented.

Determination of the Optimum Conditions for the Leaching of Lead from Zinc Plant Residues in NaCl–H2SO4–Ca(OH)2 Media by the Taguchi Method

This research is part of a continuing effort to reduce environmental conflicts and occupational hazards of lead-bearing zinc plant residues (ZPRs), and to break through this problem and recover lead of the wastes. The residue with an assay of 14.4% Pb was used in chloride leaching for lead recovery, and sulfate was controlled in the leaching stage by the addition of Ca(OH)2. In this paper, the effects of influential factors on extraction efficiency of Pb from ZPRs were investigated. Taguchi’s method based on orthogonal array design (OAD) has been used to arrange the experimental runs in order to maximize lead extraction from a ZPR. Orthogonal array (OA) L8(27) consisting of seven parameters, each with two levels, was employed to evaluate the effects of NaCl concentration (C = 300 and 400 g/L), stirring speed (R = 500 and 700 rpm), reaction temperature (T = 55 and 65 ◦C), reaction time (t = 1 and 8 h), liquid-to-solid ratio (L/S = 6 and 20), acidic pH (pHa = 2 and 3.5), and neutral pH (pHb = 4 and 5.5) on ...

Fraction Distributions of Lead, Cadmium, Copper, and Zinc in Metal‐Contaminated Soil before and after Extraction with Disodium Ethylenediaminetetraacetic Acid

: The fraction distributions of heavy metals have attracted more attention because of the relationship between the toxicity and their speciation. Heavy‐metal fraction distributions in soil contaminated with mine tailings (soil A) and in soil irrigated with mine wastewater (soil B), before and after treatment with disodium ethylenediaminetetraacetic acid (EDTA), were analyzed with Tessier's sequential extraction procedures. The total contents of lead (Pb), cadmium (Cd), copper (Cu), and zinc (Zn) exceeded the maximum permissible levels by 5.1, 33.3, 3.1, and 8.0 times in soil A and by 2.6, 12.0, 0.2, and 1.9 times in soil B, respectively. The results showed that both soils had high levels of heavy‐metal pollution. Although the fractions were found in different distribution before extraction, the residual fraction was found to be the predominant fraction of the four heavy metals. There was a small amount of exchangeable fraction of heavy metals in both contaminated soils. Furthermore, in this study, the extraction efficiencies of Pb, Cd, and Cu were higher than those of Zn. After extraction, the concentrations of exchangeable Pb, Cd, Cu, and Zn increased 84.7 mg·kg−1, 0.3 mg·kg−1, 4.1 mg·kg−1, and 39.9 mg·kg−1 in soil A and 48.7 mg·kg−1, 0.6 mg·kg−1, 2.7 mg·kg−1, and 44.1 mg·kg−1 in soil B, respectively. The concentrations of carbonate, iron and manganese oxides, organic matter, and residue of heavy metals decreased. This implies that EDTA increased metal mobility and bioavailability and may lead to groundwater contamination.

Leaching Behavior of Lead from Ultrasonically Treated MSWI Fly Ash

This study was conducted to evaluate the effect of ultrasound widely used for extraction of contaminants and for synthesis of complexes, on extraction and stabilization of heavy metals in MSWI fly ash. Ten grams of fly ash was treated at 10 of liquid–solid (L/S) ratio with and without ultrasonic irradiation of 20 kHz. The extractability of Pb from fly ash was enhanced by ultrasound at the acidic condition. At neutral and alkaline conditions, however, ultrasound did not affect the enhancement of extractability. The results of the maximum availability leaching test (MALT) of the residues treated under various pH conditions with or without ultrasound indicated that the stability of Pb in the fly ash residues was enhanced after ultrasonic irradiation irrespective of treated pH conditions. However, there was a critical point on the enhancement of lead stability in the residues even though the extraction efficiency of Pb decreased gradually with increasing ultrasonic intensity during fly ash treatment. Ultrasonic irradiation was effective for phosphate stabilization of Pb in fly ash. Irrespective of leaching tests, less amount of Pb was leached out from the phosphate stabilized residues treated with ultrasound than without ultrasound. The extraction efficiency of Pb from fly ash decreased with increasing treatment time but the fractions available for leaching at MALT increased with increasing treatment time. Conclusively, although the effect of ultrasound on the extraction of Pb from fly ash highly depends on the pH condition of solvent, the stability of lead in the fly ash residues can be enhanced with ultrasonic irradiation.