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Bian ZW, Cheng WC, Xie YX, Rahman MM, He W. Nano-hydroxyapatite-assisted enzyme-induced carbonate precipitation enhances Pb-contaminated aqueous solution and loess remediation. Front Bioeng Biotechnol 2024; 12:1410203. [PMID: 38994125 PMCID: PMC11236532 DOI: 10.3389/fbioe.2024.1410203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2024] [Accepted: 06/07/2024] [Indexed: 07/13/2024] Open
Abstract
Intensive agricultural activities could cause lead (Pb) bioaccumulation, threatening human health. Although the enzyme-induced carbonate precipitation (EICP) technology has been applied to tackle the aforesaid problem, the urease may denature or even lose its activity when subjected to a significant Pb2+ toxicity effect. To this end, the nano-hydroxyapatite (nHAP)-assisted EICP was proposed to reduce the mobility of Pb2+. Results indicated that a below 30% immobilization efficiency at 60 mM Pb2+ was attained under EICP. nHAP adsorbed the majority of Pb2+, preventing Pb2+ attachment to urease. Further, hydroxylphosphohedyphane or hydroxylpyromorphite was formed at 60 mM Pb2+, followed by the formation of cerussite, allowing hydroxylphosphohedyphane or hydroxylpyromorphite to be wrapped by cerussite. By contrast, carbonate-bearing hydroxylpyromorphite of higher stability (Pb10(PO4)6CO3) was developed at 20 mM Pb2+ as CO3 2- substituted the hydroxyl group in hydroxylpyromorphite. Moreover, nHAP helped EICP to form nucleated minerals. As a result, the EICP-nHAP technology raised the immobilization efficiency at 60 mM Pb2+ up to 70%. The findings highlight the potential of applying the EICP-nHAP technology to Pb-containing water bodies remediation.
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Affiliation(s)
- Zhao-Wei Bian
- School of Civil Engineering, Xi’an University of Architecture and Technology, Xi’an, China
- Shaanxi Jianke Construction Special Engineering Co., Ltd., Xi’an, China
| | - Wen-Chieh Cheng
- School of Civil Engineering, Xi’an University of Architecture and Technology, Xi’an, China
- Shaanxi Key Laboratory of Geotechnical and Underground Space Engineering (XAUAT), Xi’an, China
| | - Yi-Xin Xie
- School of Civil Engineering, Xi’an University of Architecture and Technology, Xi’an, China
- Shaanxi Key Laboratory of Geotechnical and Underground Space Engineering (XAUAT), Xi’an, China
| | - Md Mizanur Rahman
- UniSA STEM, ScaRCE, University of South Australia, Adelaide, SA, Australia
| | - Wenjie He
- School of Civil Engineering, Xi’an University of Architecture and Technology, Xi’an, China
- Shaanxi Key Laboratory of Geotechnical and Underground Space Engineering (XAUAT), Xi’an, China
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2
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Xie YX, Cheng WC, Xue ZF, Rahman MM, Wang L. Deterioration phenomenon of Pb-contaminated aqueous solution remediation and enhancement mechanism of nano-hydroxyapatite-assisted biomineralization. JOURNAL OF HAZARDOUS MATERIALS 2024; 470:134210. [PMID: 38581876 DOI: 10.1016/j.jhazmat.2024.134210] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Revised: 04/01/2024] [Accepted: 04/02/2024] [Indexed: 04/08/2024]
Abstract
Modern metallurgical and smelting activities discharge the lead-containing wastewater, causing serious threats to human health. Bacteria and urease applied to microbial-induced carbonate precipitation (MICP) and enzyme-induced carbonate precipitation (EICP) are denatured under high Pb2+ concentration. The nano-hydroxyapatite (nHAP)-assisted biomineralization technology was applied in this study for Pb immobilization. Results showed that the extracellular polymers and cell membranes failed to secure the urease activity when subjected to 60 mM Pb2+. The immobilization efficiency dropped to below 50% under MICP, whereas it due to a lack of extracellular polymers and cell membranes dropped to below 30% under EICP. nHAP prevented the attachment of Pb2+ either through competing with bacteria and urease or promoting Ca2+/Pb2+ ion exchange. Furthermore, CO32- from ureolysis replaced the hydroxyl (-OH) in hydroxylpyromorphite to encourage the formation of carbonate-bearing hydroxylpyromorphite of higher stability (Pb10(PO4)6CO3). Moreover, nHAP application overcame an inability to provide nucleation sites by urease. As a result, the immobilization efficiency, when subjected to 60 mM Pb2+, elevated to above 80% under MICP-nHAP and to some 70% under EICP-nHAP. The findings highlight the potential of applying the nHAP-assisted biomineralization technology to Pb-containing water bodies remediation.
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Affiliation(s)
- Yi-Xin Xie
- School of Civil Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China; Shaanxi Key Laboratory of Geotechnical and Underground Space Engineering (XAUAT), Xi'an 710055, China
| | - Wen-Chieh Cheng
- School of Civil Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China; Shaanxi Key Laboratory of Geotechnical and Underground Space Engineering (XAUAT), Xi'an 710055, China.
| | - Zhong-Fei Xue
- School of Civil Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China; Shaanxi Key Laboratory of Geotechnical and Underground Space Engineering (XAUAT), Xi'an 710055, China
| | - Md Mizanur Rahman
- Geotechnical Engineering, UniSA STEM, ScaRCE, University of South Australia, SA 5000, Australia
| | - Lin Wang
- School of Civil Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China; Shaanxi Key Laboratory of Geotechnical and Underground Space Engineering (XAUAT), Xi'an 710055, China
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3
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Hopwood JD, Casey H, Cussons M, Knott P, Humphreys PN, Andrews H, Banks J, Coleman S, Haley J. Spherulitic Lead Calcium Apatite Minerals in Lead Water Pipes Exposed to Phosphate-Dosed Tap Water. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:4796-4805. [PMID: 36920253 PMCID: PMC10061917 DOI: 10.1021/acs.est.2c04538] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Revised: 02/27/2023] [Accepted: 02/28/2023] [Indexed: 06/18/2023]
Abstract
Phosphate dosing is the principle strategy used in the United Kingdom to reduce the concentration of lead in tap waters supplied by lead water pipes. The mechanisms of phosphate-mediated lead control are not fully understood, but solid solutions of lead calcium apatite are thought to play an important role. This study investigated the microstructure of a lead pipe, supplied with high-alkalinity tap water, in which the lead calcium apatite crystals were spherulitic having rounded and dumb-bell-shaped morphologies. XRD, Fourier transform infrared spectroscopy, optical microscopy, Raman spectroscopy, scanning electron microscopy, and energy-dispersive spectroscopy showed that the lead pipe had a well-established inner layer of litharge; a middle layer containing lead calcium apatite spherulites, plumbonacrite, and some hydrocerussite; and an outer layer containing iron, lead, phosphorus, calcium, silicon, and aluminum. It was found that spherulitic lead calcium apatite could be grown in the laboratory by adding hydrocerussite to synthetic soft and hard water-containing phosphate, chloride, and citrate ions at pH 5.5 but not when the citrate was absent. This suggests that dissolved organic molecules might play a role in spherulite formation on lead water pipes. These molecules might inhibit the formation of lead calcium apatite, reducing the effectiveness of phosphate dosing in lead water pipes.
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Affiliation(s)
- Jeremy D. Hopwood
- School
of Applied Sciences, University of Huddersfield, Huddersfield HD1 3DH, U.K.
| | - Helen Casey
- School
of Applied Sciences, University of Huddersfield, Huddersfield HD1 3DH, U.K.
| | - Martin Cussons
- School
of Applied Sciences, University of Huddersfield, Huddersfield HD1 3DH, U.K.
| | - Porsha Knott
- School
of Applied Sciences, University of Huddersfield, Huddersfield HD1 3DH, U.K.
| | - Paul N. Humphreys
- School
of Applied Sciences, University of Huddersfield, Huddersfield HD1 3DH, U.K.
| | - Hayley Andrews
- Faculty
of Science and Engineering, Manchester Metropolitan
University, Manchester M15 6BH, U.K.
| | - Jenny Banks
- Yorkshire
Water, Yorkshire Water Services, Western House, Halifax Road, Bradford BD6 2SZ, U.K.
| | - Stephen Coleman
- Yorkshire
Water, Yorkshire Water Services, Western House, Halifax Road, Bradford BD6 2SZ, U.K.
| | - John Haley
- Yorkshire
Water, Yorkshire Water Services, Western House, Halifax Road, Bradford BD6 2SZ, U.K.
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4
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Singh S, Singh P, Bohidar HB. Phosphate‐Assisted Remediation of Pb(II) From Jarosite. ChemistrySelect 2023. [DOI: 10.1002/slct.202204153] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/06/2023]
Affiliation(s)
- Suneeti Singh
- Centre of Excellence for Advanced Research in Agricultural Nanotechnology The Energy and Resources Institute (TERI), TERI Gram, Gwal Pahari Gurugram 122001 India
| | - Pushplata Singh
- Centre of Excellence for Advanced Research in Agricultural Nanotechnology The Energy and Resources Institute (TERI), TERI Gram, Gwal Pahari Gurugram 122001 India
| | - Himadri B. Bohidar
- Centre of Excellence for Advanced Research in Agricultural Nanotechnology The Energy and Resources Institute (TERI), TERI Gram, Gwal Pahari Gurugram 122001 India
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5
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Fu H, Li X, Dai G, Bai M, Sheng W, Zhang X, Liu J, Wang L. Performance of oxalate-doped hydroxyapatite as well as relative contribution of oxalate and phosphate for aqueous lead removal. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 857:159596. [PMID: 36280073 DOI: 10.1016/j.scitotenv.2022.159596] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Revised: 10/08/2022] [Accepted: 10/17/2022] [Indexed: 06/16/2023]
Abstract
An oxalate-doped hydroxyapatite (O-HAP) was hydrothermally synthesized for aqueous lead (Pb) removal based on the solubility-limiting ability of oxalate and phosphate over pH range 4-9. Free Pb2+ activities in oxalate and/or phosphate systems were controlled by oxalate to form soluble ion pairs Pb-Ox (aq) and Pb-Ox22- at pH 4-7 while in preference to persist as PbHPO4 (aq) when pH ≥ 8. Both phosphate and oxalate exhibited excellent efficiency in reducing Pb solubility, causing over 99 % of Pb precipitated from solution following oxalate < oxalate-phosphate < phosphate. The Visual MINTEQ model overestimated dissolved Pb and free Pb2+ in nearly all of the reaction systems due to the ill-defined stability constants and solubility products for Pb ion-pair formation. The addition of phosphate acting as a buffer in Pb-oxalate systems tended to lessen the spontaneous pH shifts within 24 h to equilibrate proton release from Pb precipitation and hydrolysis, indicating lower solubility products and faster kinetics of Pb-phosphate mineral formation. The TEM-EDS, FTIR and XRD identified a block-shaped Pb-oxalate mineral phase as the only precipitate at acidic pH while substituted by phosphate to form rod-shaped Pb5(PO4)3OH and Pb3(PO4)2 precipitates as pH increased. The optimum hydrothermal conditions of O-HAP were 433 K, pH 9 and P/Ox doping ratio of 0.5 for 24 h. Batch experiments revealed the endothermic process of O-HAP toward Pb with the maximum adsorption capacity reaching 2333 mg/g at a pH of 7, reaction time of 12 h, initial Pb concentration of 600 mg/L and temperature of 308 K, which were best fitted with the pseudo-second-order kinetic model and Langmuir isotherm. The synergetic mechanisms of O-HAP for Pb removal involved dissolution-precipitation, adsorption and ion exchange. This study provides an insight in developing effective remediation strategies for heavy metal contamination by interacting between low-molecular-weight organic acids and secondary mineral phases.
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Affiliation(s)
- Haojie Fu
- Key Laboratory of Eco-chemical Engineering, Taishan Scholar Advantage and Characteristic Discipline Team of Eco-chemical Process and Technology, Qingdao University of Science and Technology, Qingdao 266042, PR China; College of Environment and Safety Engineering, Qingdao University of Science and Technology, Qingdao 266042, PR China
| | - Xinxin Li
- Key Laboratory of Eco-chemical Engineering, Taishan Scholar Advantage and Characteristic Discipline Team of Eco-chemical Process and Technology, Qingdao University of Science and Technology, Qingdao 266042, PR China; College of Environment and Safety Engineering, Qingdao University of Science and Technology, Qingdao 266042, PR China.
| | - Guoqing Dai
- Key Laboratory of Eco-chemical Engineering, Taishan Scholar Advantage and Characteristic Discipline Team of Eco-chemical Process and Technology, Qingdao University of Science and Technology, Qingdao 266042, PR China; College of Environment and Safety Engineering, Qingdao University of Science and Technology, Qingdao 266042, PR China
| | - Maojuan Bai
- College of Environment and Safety Engineering, Qingdao University of Science and Technology, Qingdao 266042, PR China
| | - Wei Sheng
- China Railway Construction Bridge Engineering Bureau Group Co., Ltd, Zhaoyuan 265400, PR China
| | - Xu Zhang
- School of Architecture and Urban Planning, Shandong Jianzhu University, Jinan 250101, PR China
| | - Juan Liu
- Key Laboratory of Eco-chemical Engineering, Taishan Scholar Advantage and Characteristic Discipline Team of Eco-chemical Process and Technology, Qingdao University of Science and Technology, Qingdao 266042, PR China; College of Environment and Safety Engineering, Qingdao University of Science and Technology, Qingdao 266042, PR China.
| | - Lei Wang
- Key Laboratory of Eco-chemical Engineering, Taishan Scholar Advantage and Characteristic Discipline Team of Eco-chemical Process and Technology, Qingdao University of Science and Technology, Qingdao 266042, PR China; College of Environment and Safety Engineering, Qingdao University of Science and Technology, Qingdao 266042, PR China; College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao 266042, PR China
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6
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Harmon SM, Tully J, DeSantis MK, Schock MR, Triantafyllidou S, Lytle DA. A holistic approach to lead pipe scale analysis: Importance, methodology, and limitations. AWWA WATER SCIENCE 2022; 4:0. [PMID: 35586783 DOI: 10.1002/aws2.1278] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
With lead service lines (LSLs) remaining for decades to come, scale analyses are critical to helping limit lead exposure from drinking water. This laboratory has used an integrated suite of analytical techniques to characterize the elemental composition, mineral identification, and physical features of scales, helping the water industry to evaluate, predict, and reduce lead corrosion. The methods used in this laboratory to prepare and analyze the LSL scale, and guidance to achieving reliable and meaningful results, are described. Primary methods include the following: optical microscopy, powder X-ray diffraction, inductively coupled plasma spectroscopy, X-ray fluorescence, scanning electron microscopy with energy dispersive spectroscopy, combustion and coulometric analyses of C and S, and X-ray absorption spectroscopy. Examples of associated pitfalls and ways to avoid them are provided, including pipe excavation/transport, sample preparation, analysis, and data interpretation. Illustrative examples are presented of practical scale analysis questions that could be answered by combinations of pipe scale analyses.
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Affiliation(s)
- Stephen M Harmon
- Office of Research and Development, Center for Environmental Solutions & Emergency Response, Water Infrastructure Division, Drinking Water Management Branch, U.S. Environmental Protection Agency, Cincinnati, Ohio, USA
| | - Jennifer Tully
- Office of Research and Development, Center for Environmental Solutions & Emergency Response, Water Infrastructure Division, Drinking Water Management Branch, U.S. Environmental Protection Agency, Cincinnati, Ohio, USA
| | - Michael K DeSantis
- Office of Research and Development, Center for Environmental Solutions & Emergency Response, Water Infrastructure Division, Drinking Water Management Branch, U.S. Environmental Protection Agency, Cincinnati, Ohio, USA
| | - Michael R Schock
- Office of Research and Development, Center for Environmental Solutions & Emergency Response, Water Infrastructure Division, Drinking Water Management Branch, U.S. Environmental Protection Agency, Cincinnati, Ohio, USA
| | - Simoni Triantafyllidou
- Office of Research and Development, Center for Environmental Solutions & Emergency Response, Water Infrastructure Division, Drinking Water Management Branch, U.S. Environmental Protection Agency, Cincinnati, Ohio, USA
| | - Darren A Lytle
- Office of Research and Development, Center for Environmental Solutions & Emergency Response, Water Infrastructure Division, Drinking Water Management Branch, U.S. Environmental Protection Agency, Cincinnati, Ohio, USA
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7
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Zhou Y, Li X, McBride MB. Aqueous solubility of Pb at equilibrium with hydroxypyromorphite over a range of phosphate concentrations. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2021; 23:170-178. [PMID: 33399599 DOI: 10.1039/d0em00430h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Hydroxypyromorphite (HPM) is a low-solubility Pb phosphate mineral that has the potential to limit solubility and bioavailability of Pb in soils and water. Because of reported uncertainty regarding the solubility product of this important mineral, we re-evaluated the solubility of Pb and activity of the free Pb2+ ion in aqueous suspensions of microcrystalline HPM equilibrated up to 30 days over a wide range of added soluble phosphate. A small addition of phosphate (0.1 mM) reduced Pb solubility as measured by ICP-OES, but greater phosphate additions (up to 50 mM) had no further effect in lowering HPM solubility. However, free Pb2+ ion activity measured by ion-selective electrode progressively decreased from about 10-6.5 with no added phosphate to 10-9 as soluble phosphate was increased. The effect of soluble phosphate in lowering Pb2+ activity is attributed to inhibited dissolution of HPM as well as increased Pb2+-phosphate ion pair formation in solution at higher solution concentrations of phosphate. Measurement of the ion activity products (IAP) of the solutions at equilibrium with HPM gave highly variable IAP values that were sensitive to pH and were generally not consistent with the reported solubility product of this mineral. The high variability of the IAPs for solutions with variable pH and phosphate concentrations indicates that dissolution-precipitation reactions of HPM are not described by a constant solubility product at equilibrium, possibly because of the incongruent dissolution behavior of this mineral at near-neutral pH.
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Affiliation(s)
- Yuting Zhou
- College of Environmental and Resource Science, Zhejiang University, Hangzhou, China
| | - Xinxin Li
- School of Environmental Science and Engineering, Shandong University, Qingdao, China
| | - Murray B McBride
- Section of Soil and Crop Sciences, Cornell University, Ithaca, NY 14850, USA.
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8
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Avasarala S, Orta J, Schaefer M, Abernathy M, Ying S, Liu H. Effects of residual disinfectants on the redox speciation of lead(ii)/(iv) minerals in drinking water distribution systems. ENVIRONMENTAL SCIENCE : WATER RESEARCH & TECHNOLOGY 2021; 7:357-366. [PMID: 34522388 PMCID: PMC8437151 DOI: 10.1039/d0ew00706d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
This study investigated the reaction kinetics on the oxidative transformation of lead(ii) minerals by free chlorine (HOCl) and free bromine (HOBr) in drinking water distribution systems. According to chemical equilibrium predictions, lead(ii) carbonate minerals, cerussite PbCO3(s) and hydrocerussite Pb3(CO3)2(OH)2(s), and lead(ii) phosphate mineral, chloropyromorphite Pb5(PO4)3Cl(s) are formed in drinking water distribution systems in the absence and presence of phosphate, respectively. X-ray absorption near edge spectroscopy (XANES) data showed that at pH 7 and a 10 mM alkalinity, the majority of cerussite and hydrocerussite was oxidized to lead(iv) mineral PbO2(s) within 120 minutes of reaction with chlorine (3 : 1 Cl2 : Pb(ii) molar ratio). In contrast, very little oxidation of chloropyromorphite occurred. Under similar conditions, oxidation of lead(ii) carbonate and phosphate minerals by HOBr exhibited a reaction kinetics that was orders of magnitude faster than by HOCl. Their end oxidation products were identified as mainly plattnerite β-PbO2(s) and trace amounts of scrutinyite α-PbO2(s) based on X-ray diffraction (XRD) and extended X-ray absorption fine structure (EXAFS) spectroscopic analysis. A kinetic model was established based on the solid-phase experimental data. The model predicted that in real drinking water distribution systems, it takes 0.6-1.2 years to completely oxidize Pb(ii) minerals in the surface layer of corrosion scales to PbO2(s) by HOCl without phosphate, but only 0.1-0.2 years in the presence of bromide (Br-) due the catalytic effects of HOBr generation. The model also predicts that the addition of phosphate will significantly inhibit Pb(ii) mineral oxidation by HOCl, but only be modestly effective in the presence of Br-. This study provides insightful understanding on the effect of residual disinfectant on the oxidation of lead corrosion scales and strategies to prevent lead release from drinking water distribution systems.
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Affiliation(s)
- Sumant Avasarala
- Department of Chemical and Environmental Engineering, University of California, Riverside, Riverside, CA 92521, USA
| | - John Orta
- Department of Chemical and Environmental Engineering, University of California, Riverside, Riverside, CA 92521, USA
| | - Michael Schaefer
- Department of Environmental Sciences, University of California, Riverside, Riverside, CA 92521, USA
| | - Macon Abernathy
- Department of Environmental Sciences, University of California, Riverside, Riverside, CA 92521, USA
| | - Samantha Ying
- Department of Environmental Sciences, University of California, Riverside, Riverside, CA 92521, USA
| | - Haizhou Liu
- Department of Chemical and Environmental Engineering, University of California, Riverside, Riverside, CA 92521, USA
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Grimes RT, Leginze JA, Zochowski R, Bennett JW. Surface Transformations of Lead Oxides and Carbonates Using First-Principles and Thermodynamics Calculations. Inorg Chem 2021; 60:1228-1240. [PMID: 33404221 DOI: 10.1021/acs.inorgchem.0c03398] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Lead (Pb)-containing solids find widespread commercial use in batteries, piezoelectrics, and as starting materials for synthesis. Here, we combine density functional theory (DFT) and thermodynamics in a DFT + solvent ion model to compare the surface reactivity of Pb oxides and carbonates, specifically litharge, massicot, and cerussite, in contact with water. The information provided by this model is used to delineate structure-property relationships for surfaces that are able to release Pb as Pb2+. We find that Pb2+ release is dependent on pH and chemical bonding environment and go on to correlate changes in the surface bonding to key features of the electronic structure through a projected density of states analysis. Collectively, our analyses link the atomistic structure to i) specific electronic states and ii) the thermodynamics of surface transformations, and the results presented here can be used to guide synthetic efforts of Pb2+-containing materials in aqueous media or be used to better understand the initial steps in solid decomposition.
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Affiliation(s)
- Ryan T Grimes
- Department of Chemistry and Biochemistry, University of Maryland, Baltimore County, Baltimore, Maryland 21250, United States
| | - Joshua A Leginze
- Department of Chemistry and Biochemistry, University of Maryland, Baltimore County, Baltimore, Maryland 21250, United States
| | - Robert Zochowski
- Department of Chemistry and Biochemistry, University of Maryland, Baltimore County, Baltimore, Maryland 21250, United States
| | - Joseph W Bennett
- Department of Chemistry and Biochemistry, University of Maryland, Baltimore County, Baltimore, Maryland 21250, United States
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DeSantis MK, Schock MR, Tully J, Bennett-Stamper C. Orthophosphate Interactions with Destabilized PbO 2 Scales. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:14302-14311. [PMID: 33103420 PMCID: PMC7739375 DOI: 10.1021/acs.est.0c03027] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
This research presents two case studies in which a change in the disinfectant from free chlorine to chloramine caused an increase in lead corrosion. In both systems, the predominantly tetravalent lead (PbO2) scales destabilized as a result of disinfectant change. Orthophosphate corrosion control was used in both systems, and the effect of this treatment chemical on the destabilized PbO2 scales was examined. The absence of chemical reactivity between PbO2 and phosphorus is well known, and this research confirms that phosphorus does not interact with the legacy PbO2 scales. Instead, phosphorus and calcium were found to permeate through the destabilized PbO2 material and react with divalent lead [Pb(II)] at the surface of a basal litharge (PbO) layer. This reaction precipitated a crystalline lead phosphate in both systems, which could not be specifically identified by any known powder diffraction files. Further analysis suggested that the compound formed was not the typically modeled hydroxypyromorphite but rather a calcium-substituted hydroxypyromorphite. During scale formation, calcium is frequently bound to the Pb(II) phosphate crystal lattice structure, causing measurable crystal lattice distortion in powder X-ray diffraction patterns. The results of this study illustrate the longevity of legacy scales and how disequilibrium compounds persist long after treatment changes have been made.
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Affiliation(s)
- Michael K DeSantis
- Center for Environmental Solutions and Emergency Response, Water Infrastructure Division, U.S. Environmental Protection Agency, 26 W. Martin Luther King Dr., Cincinnati, Ohio 45268, United States
| | - Michael R Schock
- Center for Environmental Solutions and Emergency Response, Water Infrastructure Division, U.S. Environmental Protection Agency, 26 W. Martin Luther King Dr., Cincinnati, Ohio 45268, United States
| | - Jennifer Tully
- Center for Environmental Solutions and Emergency Response, Water Infrastructure Division, U.S. Environmental Protection Agency, 26 W. Martin Luther King Dr., Cincinnati, Ohio 45268, United States
| | - Christina Bennett-Stamper
- Center for Environmental Solutions and Emergency Response, Water Infrastructure Division, U.S. Environmental Protection Agency, 26 W. Martin Luther King Dr., Cincinnati, Ohio 45268, United States
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11
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Del Olmo G, Ahmad A, Jensen H, Karunakaran E, Rosales E, Calero Preciado C, Gaskin P, Douterelo I. Influence of phosphate dosing on biofilms development on lead in chlorinated drinking water bioreactors. NPJ Biofilms Microbiomes 2020; 6:43. [PMID: 33097725 PMCID: PMC7585443 DOI: 10.1038/s41522-020-00152-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Accepted: 09/24/2020] [Indexed: 12/22/2022] Open
Abstract
Phosphate dosing is used by water utilities to prevent plumbosolvency in water supply networks. However, there is a lack of knowledge regarding biofilm formation on lead and plastic materials when phosphate concentrations are modified in drinking water systems. In this study, biofilms were grown over lead coupons and PVC tubes in bioreactors supplied with local drinking water treated to provide different phosphate doses (below 1, 1 and 2 mg/L) over a period of 28 days. A range of commercial iron pellets (GEH104 and WARP) were tested aiming to maintain phosphate levels below the average 1 mg/L found in drinking water. Changes in biofilm community structure in response to three different phosphate treatments were characterised by Illumina sequencing of the 16S rRNA gene for bacteria and the ITS2 gene for fungi. Scanning electron microscopy was used to visualise physical differences in biofilm development in two types of materials, lead and PVC. The experimental results from the kinetics of phosphate absorption showed that the GEH104 pellets were the best option to, in the long term, reduce phosphate levels while preventing undesirable turbidity increases in drinking water. Phosphate-enrichment promoted a reduction of bacterial diversity but increased that of fungi in biofilms. Overall, higher phosphate levels selected for microorganisms with enhanced capabilities related to phosphorus metabolism and heavy metal resistance. This research brings new insights regarding the influence of different phosphate concentrations on mixed-species biofilms formation and drinking water quality, which are relevant to inform best management practices in drinking water treatment.
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Affiliation(s)
- Gonzalo Del Olmo
- Department of Civil and Structural Engineering, University of Sheffield, Sheffield, UK
| | - Arslan Ahmad
- KWR Water Cycle Research Institute, Groningenhaven 7, 3433, PE, Nieuwegein, The Netherlands
- KTH-International Groundwater Arsenic Research Group, Department of Sustainable Development, Environmental Science and Engineering, KTH Royal Institute of Technology, Teknikringen 10B, SE-100 44, Stockholm, Sweden
- Department of Environmental Technology, Wageningen University and Research (WUR), Droevendaalsesteeg 4, 6708, PB, Wageningen, The Netherlands
| | - Henriette Jensen
- Department of Chemical and Biological Engineering, University of Sheffield, Sheffield, UK
| | - Esther Karunakaran
- Department of Chemical and Biological Engineering, University of Sheffield, Sheffield, UK
| | - Esther Rosales
- Department of Civil and Structural Engineering, University of Sheffield, Sheffield, UK
| | | | | | - Isabel Douterelo
- Department of Civil and Structural Engineering, University of Sheffield, Sheffield, UK.
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Li G, Bae Y, Mishrra A, Shi B, Giammar DE. Effect of Aluminum on Lead Release to Drinking Water from Scales of Corrosion Products. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:6142-6151. [PMID: 32338882 DOI: 10.1021/acs.est.0c00738] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The occurrence of aluminum in scales on lead pipes is common. This study aimed to identify factors that influence Al accumulation on oxidized lead surfaces and to determine whether the presence of Al impacts Pb release from corrosion products to water. Al accumulation and Pb release were monitored both with and without the addition of phosphate as a corrosion inhibitor. Pb coupons with corrosion scales were exposed to chlorinated water for up to 198 days to investigate Al accumulation and Pb release. Al accumulation was facilitated by Pb corrosion products, but its accumulation was inhibited by phosphate addition. During the study period, the formation of Al deposits did not affect Pb release when phosphate was absent. In an Al-free system, the addition of 1.0 mg/L phosphate (as P) lowered the dissolved Pb concentration below 1.0 μg/L. In a system containing 200 μg/L Al, the emergence of phosphate's effect on Pb control was delayed, and the dissolved Pb concentration decreased but stabilized at a higher value (10-12 μg/L) than in the Al-free system. Phosphohedyphane (Ca2Pb3(PO4)3Cl) was formed in all phosphate-containing systems, and PbO2 was formed independent of phosphate addition. The effect of Al on Pb release was probably related to its influence on the composition and morphology of Pb-containing minerals on coupon surfaces. The laboratory study has unavoidable limitations in its ability to simulate all conditions in real lead service lines, but this study still highlights the importance of considering the influence of Al when designing Pb corrosion control strategies.
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Affiliation(s)
- Guiwei Li
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
- Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis, Missouri 63130, United States
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yeunook Bae
- Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis, Missouri 63130, United States
| | - Anushka Mishrra
- Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis, Missouri 63130, United States
| | - Baoyou Shi
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Daniel E Giammar
- Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis, Missouri 63130, United States
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Bae Y, Pasteris JD, Giammar DE. The Ability of Phosphate To Prevent Lead Release from Pipe Scale When Switching from Free Chlorine to Monochloramine. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:879-888. [PMID: 31834790 DOI: 10.1021/acs.est.9b06019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
For lead pipes that contain PbO2(s) as a major component of their scales, a change in the residual disinfectant from free chlorine to monochloramine can destabilize the PbO2(s) and result in dramatic increases in aqueous lead concentrations. Such a scenario occurred in Washington, D.C., in late 2000. That problem was ultimately addressed by the addition of phosphate as a corrosion inhibitor, but it took several months for lead levels to drop below regulatory values. This study sought to determine whether adding phosphate prior to switching the disinfectant could mitigate lead release. Using synthetic tap water and new lead pipes, we developed a set of lead pipes with scales rich in PbO2(s) and then studied their response to a change from free chlorine to monochloramine. Total lead concentrations remained below 10 μg/L for pipes that received phosphate prior to and during the switch. In contrast, total lead concentrations increased from less than 5 μg/L to more than 150 μg/L as a result of the disinfectant switch when phosphate was not present. Characterization of the pipe scales demonstrated that plattnerite (β-PbO2(s)) was the dominant component of the scale prior to the switch, and that the scale gradually transformed into one containing a lead phosphate solid chemically similar to phosphohedyphane (Ca2Pb3(PO4)3(Cl,F,OH)(s)) when phosphate was present.
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McBride MB, Kelch SE, Schmidt MP, Sherpa S, Martinez CE, Aristilde L. Oxalate-enhanced solubility of lead (Pb) in the presence of phosphate: pH control on mineral precipitation. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2019; 21:738-747. [PMID: 30895974 DOI: 10.1039/c8em00553b] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Here we study the precipitation of lead (Pb)-phosphate minerals over the pH range of 4.0 to 8.0 with and without oxalate, a ubiquitous and abundant low-molecular-weight organic acid derived from plants and microorganisms in environmental matrices. In the aqueous Pb-phosphate systems, phosphate precipitated Pb efficiently, reducing the dissolved Pb concentration below 1 μM at all the tested pH values, with the minimum solubility of about 0.1 μM measured at the intermediate pH of 6.0. The measured dissolved Pb and free Pb2+ ion activity were not in agreement with predictions from generally-accepted solubility products of the Pb phosphate minerals, particularly hydroxypyromorphite [Pb5(PO4)3OH]. Discrepancies between our measured Pb phosphate solubility products and older reported values are attributed to non-ideal behavior of these minerals (incongruent dissolution) as well as uncertainties in stability constants for soluble Pb-phosphate ion pairs. The presence of equimolar levels of oxalate and phosphate resulted in up to 250-fold increase in Pb solubility at acidic pH and about a 4-fold increase at pH 7.0, due to the strong suppression of Pb phosphate precipitation by oxalate and formation of soluble Pb-oxalate complexes. At pH 4.0 and 5.0, Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) identified a Pb-oxalate mineral phase as the only precipitate despite the presence of phosphate; in the absence of oxalate, Pb hydrogen phosphate, PbHPO4, stably formed under these acidic conditions. At pH 6.0 and greater, FTIR and XRD data revealed that Pb-phosphate [Pb3(PO4)2], and hydroxypyromorphite [Pb5(PO4)3OH] to a lesser extent, were the predominant precipitates both in the absence and presence of oxalate. Therefore, oxalate did not strongly interfere with Pb-phosphate mineral formation at aqueous pH greater than 6.0 but oxalate controlled Pb solubility at acidic pH values.
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Affiliation(s)
- Murray B McBride
- Soil and Crop Sciences Section, School of Integrative Plant Science, College of Agriculture and Life Sciences, Cornell University, Ithaca, USA.
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Jurgens BC, Parkhurst DL, Belitz K. Assessing the Lead Solubility Potential of Untreated Groundwater of the United States. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:3095-3103. [PMID: 30835445 DOI: 10.1021/acs.est.8b04475] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
In the U.S., about 44 million people rely on self-supplied groundwater for drinking water. Because most self-supplied homeowners do not treat their water to control corrosion, drinking water can be susceptible to lead (Pb) contamination from metal plumbing. To assess the types and locations of susceptible groundwater, a geochemical reaction model that included pure Pb minerals and solid solutions of calcite (Ca xPb1- xCO3) and apatite [Ca xPb5-x(PO4)3(OH; Cl; F)] was developed to estimate the lead solubility potential (LSP) for over 8300 untreated groundwater samples collected from domestic and public-supply sites between 2000 and 2016 in the U.S. The LSP is the calculated amount of Pb metal that could dissolve at 25 °C before a Pb-bearing mineral precipitates. About 33% of untreated groundwater samples had LSP greater than 15 μg/L-the USEPA action level for dissolved plus particulate forms of Pb. Five percent of samples had high LSP (above 300 μg/L) and tended to occur in the eastern and southeastern U.S. Measured Pb concentrations above 15 μg/L were rarely detected (<1%) but always coincided with high LSP values. Future work will provide a better understanding of the relation between water chemistry, Pb-mineral formation, and dissolved Pb concentrations in tap water.
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Affiliation(s)
- Bryant C Jurgens
- U.S. Geological Survey , California Water Science Center , Sacramento , California 95819 , United States
| | - David L Parkhurst
- U.S. Geological Survey , Water Mission Area, Scientist Emeritus , Lakewood , Colorado 80225 , United States
| | - Kenneth Belitz
- U.S. Geological Survey , National Water Quality Assessment Project , Northborough , Massachusetts 01532 , United States
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Tully J, DeSantis MK, Schock MR. Water quality–pipe deposit relationships in Midwestern lead pipes. ACTA ACUST UNITED AC 2019. [DOI: 10.1002/aws2.1127] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
| | | | - Michael R. Schock
- Office of Research and DevelopmentU.S. Environmental Protection Agency Cincinnati Ohio
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Tully J, DeSantis MK, Schock MR. Water quality-pipe deposit relationships in Midwestern lead pipes. AWWA WATER SCIENCE 2019; 1:https://doi.org/10.1002/aws2.1127. [PMID: 32632401 PMCID: PMC7336533] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The conventional wisdom of lead-scale solubility has been built over the years by geochemical solubility models, experimental studies, and field sampling utilizing multiple protocols. Rarely, have the mineral phases from scales formed in real-world drinking water lead service lines (LSLs) been compared to theoretical predictions. In this study, model predictions are compared to LSL scales from 22 drinking water distribution systems. The results show that only nine of the 22 systems had LSL scales that followed model predictions. The remaining systems had unpredictable scales some with unknown lead release characteristics demonstrating that predicting scale formation and lead release solely by models cannot be relied on in all cases to protect human health. Therefore, for many systems with LSLs, pilot studies with existing LSL scales will be necessary to evaluate and optimize corrosion control, and correspondingly, appropriate residential water sampling will be needed to demonstrate consistent and optimal system corrosion control.
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Affiliation(s)
- Jennifer Tully
- Geologist, Pegasus Technical Services, Inc.; Cincinnati, OH, USA, 26 W. Martin Luther King Dr., Cincinnati, OH 45268, 513-569-7043,
| | - Michael K DeSantis
- Geologist, Pegasus Technical Services, Inc.; Cincinnati, OH, USA, 26 W. Martin Luther King Dr., Cincinnati, OH 45268, 513-569-7939,
| | - Michael R Schock
- Chemist, US Environmental Protection Agency, Cincinnati, OH, USA, 26 W. Martin Luther King Dr., Cincinnati, OH 45268, 513-569-7412,
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Trace Voltammetric Determination of Lead at a Recycled Battery Carbon Rod Electrode. SENSORS 2019; 19:s19040770. [PMID: 30781864 PMCID: PMC6412861 DOI: 10.3390/s19040770] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Revised: 02/09/2019] [Accepted: 02/11/2019] [Indexed: 12/16/2022]
Abstract
Carbon rod electrodes (CREs) were obtained from recycled zinc–carbon batteries and were used without further modification for the measurement of trace concentrations of lead (Pb). The electrochemical behavior of Pb at these electrodes in a variety of supporting electrolytes was investigated by cyclic voltammetry. The anodic peaks obtained on the reverse scans were indicative of Pb being deposited as a thin layer on the electrode surface. The greatest signal–to–noise ratios were obtained in organic acids compared to mineral acids, and acetic acid was selected as the supporting electrolyte for further studies. Conditions were optimized, and it was possible to determine trace concentrations of Pb by differential pulse anodic stripping voltammetry. A supporting electrolyte of 4% v/v acetic acid, with a deposition potential of −1.5 V (vs. SCE) and a deposition time of 1100 s, was found to be optimum. A linear range of 2.8 µg/L to 110 µg/L was obtained, with an associated detection limit (3σ) of 2.8 µg/L. A mean recovery of 95.6% (CV=3.9%) was obtained for a tap water sample fortified with 21.3 µg/L.
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Zhao J, Giammar DE, Pasteris JD, Dai C, Bae Y, Hu Y. Formation and Aggregation of Lead Phosphate Particles: Implications for Lead Immobilization in Water Supply Systems. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:12612-12623. [PMID: 30252454 DOI: 10.1021/acs.est.8b02788] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Phosphate is commonly added to drinking water to inhibit lead release from lead service lines and lead-containing materials in premise plumbing. Phosphate addition promotes the formation of lead phosphate particles, and their aggregation behaviors may affect their transport in pipes. Here, lead phosphate formation and aggregation were studied under varied aqueous conditions typical of water supply systems. Under high aqueous PO4/Pb molar ratios (>1), phosphate adsorption made the particles more negatively charged. Therefore, enhanced stability of lead phosphate particles was observed, suggesting that although addition of excess phosphate can lower the dissolved lead concentrations in tap water, it may increase concentrations of particulate lead. Adsorption of divalent cations (Ca2+ and Mg2+) onto lead phosphate particles neutralized their negative surface charges and promoted their aggregation at pH 7, indicating that phosphate addition for lead immobilization may be more efficient in harder waters. The presence of natural organic matter (NOM, ≥ 0.05 mg C/L humic acid and ≥ 0.5 mg C/L fulvic acid) retarded particle aggregation at pH 7. Consequently, removal of organic carbon during water treatment to lower the formation of disinfection-byproducts (DBPs) may have the additional benefit of minimizing the mobility of lead-containing particles. This study provided insight into fundamental mechanisms controlling lead phosphate aggregation. Such understanding is helpful to understand the observed trends of total lead in water after phosphate addition in both field and pilot-scale lead pipe studies. Also, it can help optimize lead immobilization by better controlling the water chemistry during phosphate addition.
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Affiliation(s)
- Juntao Zhao
- Department of Civil & Environmental Engineering , University of Houston , Houston , Texas 77004 , United States
| | - Daniel E Giammar
- Department of Energy, Environmental, and Chemical Engineering , Washington University in St. Louis , St. Louis , Missouri 63130 , United States
| | - Jill D Pasteris
- Department of Earth and Planetary Sciences , Washington University in St. Louis , St. Louis , Missouri 63130 , United States
| | - Chong Dai
- Department of Civil & Environmental Engineering , University of Houston , Houston , Texas 77004 , United States
| | - Yeunook Bae
- Department of Energy, Environmental, and Chemical Engineering , Washington University in St. Louis , St. Louis , Missouri 63130 , United States
| | - Yandi Hu
- Department of Civil & Environmental Engineering , University of Houston , Houston , Texas 77004 , United States
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Antao SM, Dhaliwal I. Lead apatites: structural variations among Pb 5(BO 4) 3Cl with B = P (pyromorphite), As (mimetite) and V (vanadinite). JOURNAL OF SYNCHROTRON RADIATION 2018; 25:214-221. [PMID: 29271770 DOI: 10.1107/s1600577517014217] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Accepted: 10/02/2017] [Indexed: 06/07/2023]
Abstract
The crystal structure of four Pb apatite samples, Pb5(BO4)3Cl, was refined with synchrotron high-resolution powder X-ray diffraction data, Rietveld refinements, space group P63/m and Z = 2. For this isotypic series, B = P5+ is pyromorphite, B = As5+ is mimetite and B = V5+ is vanadinite. The ionic radius for As5+ (0.355 Å) is similar to that of V5+ (0.335 Å), and this is twice as large as that for P5+ (0.170 Å). However, the c unit-cell parameter for mimetite is surprisingly different from that of vanadinite, although their unit-cell volumes, V, are almost equal to each other. No explanation was available for this peculiar c-axis value for mimetite. Structural parameters such as average 〈B-O〉 [4], 〈Pb1-O9〉 [9] and 〈Pb2-O6Cl2〉 [8] distances increase linearly with V (the coordination numbers for the cations are given in square brackets). Mimetite has a short Pb2-O1 distance, so the O1 oxygen atom interacts with the 6s2 lone-pair electrons of the Pb2+ cation that causes the Cl-Cl distance (= c/2) to increase to the largest value in the series because of repulsion, which causes the c-axis to increase anomalously. Although Pb apatite minerals occur naturally in ore deposits, they are also formed as scaly deposits in lead water pipes that give rise to lead in tap water, as was found recently in Flint, Michigan, USA. It is important to identify Pb-containing phases in water-pipe deposits.
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Affiliation(s)
- Sytle M Antao
- Department of Geoscience, University of Calgary, Calgary, Alberta, Canada T2N 1N4
| | - Inayat Dhaliwal
- Department of Geoscience, University of Calgary, Calgary, Alberta, Canada T2N 1N4
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