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Zhang L, Zhang J, Zhou R, Si Y. β-tricalcium phosphate enhanced biomineralization of Cd 2+ and Pb 2+ by Sporosarcina ureilytica HJ1 and Sporosarcina pasteurii HJ2. JOURNAL OF HAZARDOUS MATERIALS 2024; 474:134624. [PMID: 38810579 DOI: 10.1016/j.jhazmat.2024.134624] [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: 03/25/2024] [Revised: 05/04/2024] [Accepted: 05/13/2024] [Indexed: 05/31/2024]
Abstract
Microbiologically induced CaCO3 precipitation (MICP) has been proposed as a potential bioremediation method to immobilize contaminating metals. In this study, carbonate mineralizing bacteria HJ1 and HJ2, isolated from heavy metal contaminated soil, was employed for Cd2+ and Pb2+ immobilization with or without β-tricalcium phosphate addition. Compared with the only treatments amended with strains, the combined application of β-tricalcium phosphate and HJ1 improved the immobilization rates of Cd and Pb by 1.49 and 1.70 times at 24 h, and the combined application of β-tricalcium phosphate and HJ2 increased the immobilization rates of Cd and Pb by 1.25 and 1.79 times. The characterization of biomineralization products revealed that Cd2+ and Pb2+ primarily immobilized from the liquid phase as CdCO3 and PbCO3, and the addition of β-tricalcium phosphate facilitated the formation of Ca4.03Cd0.97(PO4)3(OH) and Pb3(PO4)2. Also, the calcium source was related to the speciation of carbonate precipitation and improved the Cd and Pb remediation efficiency. This research demonstrated the feasibility and effectiveness of MICP combined with β-tricalcium phosphate in immobilization of Cd and Pb, which will provide a fundamental basis for future applications of MICP to mitigate soil heavy metal pollutions.
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Affiliation(s)
- Li Zhang
- Anhui Province Key Laboratory of Farmland Ecological Conservation and Pollution Prevention, College of Resources and Environment, Anhui Agricultural University, Hefei 230036, China
| | - Jie Zhang
- Anhui Province Key Laboratory of Farmland Ecological Conservation and Pollution Prevention, College of Resources and Environment, Anhui Agricultural University, Hefei 230036, China
| | - Runzhan Zhou
- Anhui Province Key Laboratory of Farmland Ecological Conservation and Pollution Prevention, College of Resources and Environment, Anhui Agricultural University, Hefei 230036, China
| | - Youbin Si
- Anhui Province Key Laboratory of Farmland Ecological Conservation and Pollution Prevention, College of Resources and Environment, Anhui Agricultural University, Hefei 230036, China.
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2
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Han L, Wang P, Jiang X, Wang Y, Cao S, Li J. Mechanism and effectiveness of enzymatically induced phosphate precipitation (EIPP) in stabilizing coexisting lead, zinc, and cadmium in tailings. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2024; 346:123618. [PMID: 38382727 DOI: 10.1016/j.envpol.2024.123618] [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: 12/19/2023] [Revised: 02/01/2024] [Accepted: 02/19/2024] [Indexed: 02/23/2024]
Abstract
Lead-zinc (Pb-Zn) tailings ponds carry the risk of multiple heavy metals (HMs) contamination and pile destabilization. This poses requirements for in-situ applicable, low-distribution, and effective stabilization/solidification (S/S) methods. For this, the novel enzymatically induced phosphate precipitation (EIPP) method was implemented in this study. Its mechanism and performance on stabilization of composite Pb, Zn, and cadmium (Cd) in tailings were explored and evaluated under typical erosion conditions for the first time. Results show that the EIPP stabilized HMs by chemically transforming the unstable carbonate-bound HMs to stable phosphate precipitates and by physically encapsulating tailings particles with newberyite precipitates. The stabilization effect on the three HMs was ranked as Pb > Zn > Cd. Comparing magnesium resources for the EIPP reactants, the EIPP utilizing Mg(CH3COO)2 was more effective at decontamination than MgCl2 because its special pre-activation and re-precipitation function enhanced the chemical transformation function of EIPP. The EIPP stabilization was confirmed to reduce simulated acid rain-leachable and bio-extractive HMs by about 90% and 60%, respectively. Under the prolonged acid attack, treated HMs were ultimately leached through the dissolution mechanism. Zn exhibited significant instability in highly acidic conditions (pH = 2.5-3.5), where its cumulative leaching toxicity after long-term dissolution warrants attention. Overall, EIPP presents a novel and effective strategy for on-site mitigation of composite HMs pollution.
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Affiliation(s)
- Lijun Han
- State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan, 430071, China; IRSM-CAS/HK PolyU Joint Laboratory on Solid Waste Science, Wuhan, 430071, China
| | - Ping Wang
- State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan, 430071, China; IRSM-CAS/HK PolyU Joint Laboratory on Solid Waste Science, Wuhan, 430071, China
| | - Xiqing Jiang
- State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan, 430071, China; School of Civil Engineering, Zhengzhou University, Zhengzhou, Henan, 450001, China
| | - Yaoyi Wang
- State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan, 430071, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Shiyu Cao
- State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan, 430071, China; IRSM-CAS/HK PolyU Joint Laboratory on Solid Waste Science, Wuhan, 430071, China
| | - Jiangshan Li
- State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan, 430071, China; IRSM-CAS/HK PolyU Joint Laboratory on Solid Waste Science, Wuhan, 430071, China.
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3
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Chen X, Zhou X, Fan Z, Peng Z, Lu Q. Competitive encapsulation of multiple heavy metals by magnesium potassium phosphate cement: Hydration characteristics and leaching toxicity properties. WASTE MANAGEMENT (NEW YORK, N.Y.) 2024; 177:115-124. [PMID: 38320451 DOI: 10.1016/j.wasman.2024.01.046] [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: 09/18/2023] [Revised: 01/09/2024] [Accepted: 01/27/2024] [Indexed: 02/08/2024]
Abstract
Magnesium potassium phosphate cement (MKPC) is increasingly used in the solidification/stabilization (SS) of heavy metal (HM) pollutants. However, research on composite HM pollutants remains limited. In this study, four heavy metals (Pb/Zn/Cu/Cd) were individually and simultaneously introduced into MKPC systems with different magnesium/phosphorus (M/P) molar ratios. The introduction of HMs altered the extent of hydration and morphology of MgKPO4·6H2O. Among the MKPC pastes, those with M/P = 2 and 3 had the highest HM solidification efficiency and strength, respectively. The HM solidification efficiency of all specimens exceeded 99 %. In samples with M/P = 3, the codoping of four HMs slightly increased the M/P ratio, thereby increasing MgKPO4·6H2O content and enhancing strength. Pb could generate additional low-solubility precipitates, such as PbHPO4, Pb3 (PO4)2, Pb5 (OH) (PO4)3, and Pb (OH)2, which easily accumulated in pores and were encapsulated by MgKPO4·6H2O, leading to the highest solidification efficiency of Pb by MKPC. Pb and Cu could also form the composite phosphate products Pb2Cu (PO4)3 (OH)·4H2O, thus promoting the S/S effect of Cu. Therefore, the use of MKPC with M/P ratio of 2-3 for the S/S of complex pollutants containing Pb and Cu is a promising approach.
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Affiliation(s)
- Xia Chen
- Research Center of Water Engineering Safety and Disaster Prevention of Ministry of Water Resources, Changjiang River Scientific Research Institute, Wuhan 430010, Hubei, China.
| | - Xian Zhou
- Research Center of Water Engineering Safety and Disaster Prevention of Ministry of Water Resources, Changjiang River Scientific Research Institute, Wuhan 430010, Hubei, China.
| | - Zeyu Fan
- Research Center of Water Engineering Safety and Disaster Prevention of Ministry of Water Resources, Changjiang River Scientific Research Institute, Wuhan 430010, Hubei, China
| | - Ziling Peng
- Research Center of Water Engineering Safety and Disaster Prevention of Ministry of Water Resources, Changjiang River Scientific Research Institute, Wuhan 430010, Hubei, China
| | - Qi Lu
- Research Center of Water Engineering Safety and Disaster Prevention of Ministry of Water Resources, Changjiang River Scientific Research Institute, Wuhan 430010, Hubei, China
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Liu R, Liu S, Sun S, Cao X, Lin J, Peng J, Ji F, Ma R. Medical waste incineration fly ash-based magnesium potassium phosphate cement: Calcium-reinforced chlorine solidification/stabilization mechanism and optimized carbon reduction process strategy. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2024; 357:120749. [PMID: 38552517 DOI: 10.1016/j.jenvman.2024.120749] [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: 11/30/2023] [Revised: 02/28/2024] [Accepted: 03/20/2024] [Indexed: 04/14/2024]
Abstract
The traditional solidification/stabilization (S/S) technology, Ordinary Portland Cement (OPC), has been widely criticized due to its poor resistance to chloride and significant carbon emissions. Herein, a S/S strategy based on magnesium potassium phosphate cement (MKPC) was developed for the medical waste incineration fly ash (MFA) disposal, which harmonized the chlorine stabilization rate and potential carbon emissions. The in-situ XRD results indicated that the Cl- was efficiently immobilized in the MKPC system with coexisting Ca2+ by the formation of stable Ca5(PO4)3Cl through direct precipitation or intermediate transformation (the Cl- immobilization rate was up to 77.29%). Additionally, the MFA-based MKPC also demonstrated a compressive strength of up to 39.6 MPa, along with an immobilization rate exceeding 90% for heavy metals. Notably, despite the deterioration of the aforementioned S/S performances with increasing MFA incorporation, the potential carbon emissions associated with the entire S/S process were significantly reduced. According to the Life Cycle Assessment, the potential carbon emissions decreased to 8.35 × 102 kg CO2-eq when the MFA reached the blending equilibrium point (17.68 wt.%), while the Cl- immobilization rate still remained above 65%, achieving an acceptable equilibrium. This work proposes a low-carbon preparation strategy for MKPC that realizes chlorine stabilization, which is instructive for the design of S/S materials.
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Affiliation(s)
- Runjie Liu
- College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen, 518060, China
| | - Shiwei Liu
- College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen, 518060, China
| | - Shichang Sun
- College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen, 518060, China
| | - Xing Cao
- Shenzhen Engineering Lab of Flexible Transparent Conductive Films, School of Materials Science and Engineering, Harbin Institute of Technology (Shenzhen), Shenzhen, 518055, China
| | - Junhao Lin
- Department of Civil and Environmental Engineering, Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
| | - Juan Peng
- Shenzhen Environmental Technology Group Co. LTD, Shenzhen, 518010, China
| | - Fei Ji
- Shenzhen Environmental Technology Group Co. LTD, Shenzhen, 518010, China
| | - Rui Ma
- College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen, 518060, China.
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Pavlík Z, Záleská M, Pavlíková M, Pivák A, Nábělková J, Jankovský O, Jiříčková A, Chmel O, Průša F. Simultaneous Immobilization of Heavy Metals in MKPC-Based Mortar-Experimental Assessment. MATERIALS (BASEL, SWITZERLAND) 2023; 16:7525. [PMID: 38138666 PMCID: PMC10744662 DOI: 10.3390/ma16247525] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Revised: 11/30/2023] [Accepted: 12/04/2023] [Indexed: 12/24/2023]
Abstract
Heavy metal contamination, associated with the increase in industrial production and the development of the population in general, poses a significant risk in terms of the contamination of soil, water, and, consequently, industrial plants and human health. The presence of ecotoxic heavy metals (HMs) thus significantly limits the sustainable development of society and contributes to the deterioration of the quality of the environment as a whole. For this reason, the stabilization and immobilization of heavy metals is a very topical issue. This paper deals with the possibility of the simultaneous immobilization of heavy metals (Ba2+, Pb2+, and Zn2+) in mortar based on magnesium potassium phosphate cement (MKPC). The structural, mechanical, and hygric parameters of mortars artificially contaminated with heavy metals in the form of salt solutions were investigated together with the formed hydration products. In the leachates of the prepared samples, the content of HMs was measured and the immobilization ratio of each HM was determined. The immobilization rate of all the investigated HMs was >98.7%, which gave information about the effectiveness of the MKPC-based matrix for HM stabilization. Furthermore, the content of HMs in the leachates was below the prescribed limits for non-hazardous waste that can be safely treated without any environmental risks. Although the presence of heavy metals led to a reduction in the strength of the prepared mortar (46.5% and 57.3% in compressive and flexural strength, respectively), its mechanical resistance remained high enough for many construction applications. Moreover, the low values of the parameters characterizing the water transport (water absorption coefficient Aw = 4.26 × 10-3 kg·m-2·s-1/2 and sorptivity S = 4.0 × 10-6 m·s-1/2) clearly demonstrate the limited possibility of the leaching of heavy metals from the MKPC matrix structure.
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Affiliation(s)
- Zbyšek Pavlík
- Department of Materials Engineering and Chemistry, Faculty of Civil Engineering, Czech Technical University in Prague, Thákurova 7, 166 29 Prague, Czech Republic; (M.Z.); (M.P.); (A.P.)
| | - Martina Záleská
- Department of Materials Engineering and Chemistry, Faculty of Civil Engineering, Czech Technical University in Prague, Thákurova 7, 166 29 Prague, Czech Republic; (M.Z.); (M.P.); (A.P.)
| | - Milena Pavlíková
- Department of Materials Engineering and Chemistry, Faculty of Civil Engineering, Czech Technical University in Prague, Thákurova 7, 166 29 Prague, Czech Republic; (M.Z.); (M.P.); (A.P.)
| | - Adam Pivák
- Department of Materials Engineering and Chemistry, Faculty of Civil Engineering, Czech Technical University in Prague, Thákurova 7, 166 29 Prague, Czech Republic; (M.Z.); (M.P.); (A.P.)
| | - Jana Nábělková
- Department of Sanitary and Ecological Engineering, Faculty of Civil Engineering, Czech Technical University in Prague, Thákurova 7, 166 29 Prague, Czech Republic;
| | - Ondřej Jankovský
- Department of Inorganic Chemistry, Faculty of Chemical Technology, University of Chemistry and Technology, Technická 5, 166 28 Prague, Czech Republic; (O.J.); (A.J.); (O.C.); (F.P.)
| | - Adéla Jiříčková
- Department of Inorganic Chemistry, Faculty of Chemical Technology, University of Chemistry and Technology, Technická 5, 166 28 Prague, Czech Republic; (O.J.); (A.J.); (O.C.); (F.P.)
| | - Oskar Chmel
- Department of Inorganic Chemistry, Faculty of Chemical Technology, University of Chemistry and Technology, Technická 5, 166 28 Prague, Czech Republic; (O.J.); (A.J.); (O.C.); (F.P.)
| | - Filip Průša
- Department of Inorganic Chemistry, Faculty of Chemical Technology, University of Chemistry and Technology, Technická 5, 166 28 Prague, Czech Republic; (O.J.); (A.J.); (O.C.); (F.P.)
- Department of Metals and Corrosion Engineering, Faculty of Chemical Technology, University of Chemistry and Technology, Technická 5, 166 28 Prague, Czech Republic
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6
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Mi R, Zhang Z, Ji W, Liu S, Kai MF, Lin K, Tan Y. Solidification/stabilisation behaviours of Zn 2+ in magnesium potassium phosphate cement: Experiments and density functional theory study. ENVIRONMENTAL RESEARCH 2023; 231:116247. [PMID: 37245576 DOI: 10.1016/j.envres.2023.116247] [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: 02/13/2023] [Revised: 05/16/2023] [Accepted: 05/26/2023] [Indexed: 05/30/2023]
Abstract
The solidification/stabilisation behaviours of Zn2+ in magnesium potassium phosphate cement (MKPC) have not been thoroughly investigated. Herein, a series of experiments and a detailed density functional theory (DFT) study were conducted to investigate the solidification/stabilisation behaviours of Zn2+ in MKPC. The results showed that the compressive strength of MKPC reduced with the addition of Zn2+ because the formation of MgKPO4·6H2O (the main hydration product in MKPC) was delayed with the addition of Zn2+, as discovered by the crystal characteristics, and because Zn2+ exhibited a lower binding energy in MgKPO4·6H2O compared to Mg2+, as revealed by DFT results. Additonally, Zn2+ had little influence on the structure of MgKPO4·6H2O, and Zn2+ existed in MKPC as the formation of Zn2(OH)PO4, which was decomposed in the range of around 190-350 °C. Moreover, there were a lot of well-crystallised tabular hydration products before the addition of Zn2+, but the matrix was comprised of irregular prism crystals after adding Zn2+. Furthermore, the leaching toxicity of Zn2+ of MKPC was much smaller than the requirements of Chinese and European standards.
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Affiliation(s)
- Renjie Mi
- Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hong Kong, China
| | - Zhibin Zhang
- College of Civil Science and Engineering, Yangzhou University, Yangzhou, 225127, China
| | - Weiming Ji
- Singapore Centre for 3D Printing, School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798, Singapore
| | - Shichang Liu
- College of Civil Science and Engineering, Yangzhou University, Yangzhou, 225127, China
| | - M F Kai
- Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hong Kong, China.
| | - Kui Lin
- Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hong Kong, China
| | - Yongshan Tan
- College of Civil Science and Engineering, Yangzhou University, Yangzhou, 225127, China.
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7
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Liu S, Cao X, Yang W, Liu R, Fang L, Ma R, Peng J, Zheng S, Ji F. Preparation of magnesium potassium phosphate cement from municipal solid waste incineration fly ash and lead slag co-blended: Ca-induced crystal reconstruction process and Pb-Cl synergistic solidification mechanism. JOURNAL OF HAZARDOUS MATERIALS 2023; 457:131690. [PMID: 37257382 DOI: 10.1016/j.jhazmat.2023.131690] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 04/07/2023] [Accepted: 05/22/2023] [Indexed: 06/02/2023]
Abstract
Higher chlorine (Cl) content than lead (Pb) content in municipal solid waste incineration fly ash (MSWIFA) impeded the practical application of Pb5(PO4)3Cl-derived magnesium potassium phosphate cement (MKPC) preparation strategy. Herein, Pb/Ca-rich lead slag (LS) was co-blended with MSWIFA to prepare MKPC for the synergistic treatment of both two solid wastes and the Pb-Cl solidification. The results showed that the resulting 15-15 (15 wt% MSWIFA and 15 wt% LS incorporation) sample achieved 25.44 MPa compressive strength, and Pb and Cl leaching toxicity was reduced by 99.18 % and 92.80 %, respectively. The X-ray diffraction (XRD) and transmission electron microscopy (TEM) analyses showed that Pb2+, Ca2+, phosphate and Cl- formed PbxCa5-x(PO4)3Cl in samples. The formation of PbxCa5-x(PO4)3Cl was also demonstrated by the high-angle annular dark field scanning transmission electron microscope (HAADF-STEM), while differences in the lattice characteristics of PbxCa5-x(PO4)3Cl and Pb5(PO4)3Cl were found. In-situ XRD indicated that Ca2+ accelerated the transformation of Pb2+ to Pb5(PO4)3Cl. After co-precipitating with Ca2+ to form PbxCa5-x(PO4)3Cl, Pb2+ continuously substituted Ca2+ to eventually transform to Pb5(PO4)3Cl. This work informs the synergistic treatment of MSWIFA and LS and offers new insights into the reaction mechanism between Pb2+, phosphate and Cl- under Ca2+ induction.
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Affiliation(s)
- Shiwei Liu
- College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen 518060, China
| | - Xing Cao
- Shenzhen Engineering Lab of Flexible Transparent Conductive Films, School of Materials Science and Engineering, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, China
| | - Weichen Yang
- College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen 518060, China
| | - Runjie Liu
- College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen 518060, China
| | - Lin Fang
- College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen 518060, China
| | - Rui Ma
- College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen 518060, China.
| | - Juan Peng
- Shenzhen Environmental Technology Group Co. LTD, Shenzhen 518010, PR China
| | - Shuaifei Zheng
- Shenzhen Environmental Technology Group Co. LTD, Shenzhen 518010, PR China
| | - Fei Ji
- Shenzhen Environmental Technology Group Co. LTD, Shenzhen 518010, PR China
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Tan Y, Zhang Z, Yang D, Dong J, Cheng X, Yu H. Immobilization of Zn(Ⅱ) and Cu(Ⅱ) in basic magnesium-sulfate-cementitious material system: Properties and mechanism. JOURNAL OF HAZARDOUS MATERIALS 2023; 446:130720. [PMID: 36610345 DOI: 10.1016/j.jhazmat.2023.130720] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Revised: 12/29/2022] [Accepted: 12/31/2022] [Indexed: 06/17/2023]
Abstract
To solve the environmental problems caused by heavy metal pollution, a new cementitious material (basic magnesium sulfate cement, BMSC) was developed for the solidification of Cu2+/Zn2+. First, the effects of different amounts of Cu2+/Zn2+ on the properties (compressive strength, setting time, pH, and leaching toxicity) of the BMSC were investigated. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS) were used to investigate the effects of different amounts of Cu2+/Zn2+ on the phase and microstructure of BMSC. The results showed that Cu2+/Zn2+ inhibited the hydration of BMSC, reduced compressive strength, and prolonged the setting time. The results of the leaching tests showed that the BMSC system exhibited high immobilization efficiency (up to 99%) for Cu2+/Zn2+. Further, the BMSC solidification matrix exhibited excellent acid resistance (compressive strength >40 MPa after 28 days of immersion). The physical phase analysis showed that the main phases of BMSC were the 5Mg(OH)2-MgSO4-7 H2O (5-1-7) phase and Mg(OH)2, and the crystal structure refinement analysis suggested that Cu2+/Zn2+ ions were substituted with Mg2+ in the 5-1-7 phase. It was confirmed that the solidification mechanism of BMSC on Cu2+/Zn2+ is mainly performed by chemical complexation and ionic substitution.
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Affiliation(s)
- Yongshan Tan
- College of Civil Science and Engineering, Yangzhou University, Yangzhou 225127, China.
| | - Zhibin Zhang
- College of Civil Science and Engineering, Yangzhou University, Yangzhou 225127, China
| | - Dingyi Yang
- College of Civil Science and Engineering, Yangzhou University, Yangzhou 225127, China.
| | - Jinmei Dong
- Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008, China
| | - Xiangyi Cheng
- College of Civil Science and Engineering, Yangzhou University, Yangzhou 225127, China
| | - Hongfa Yu
- Department of Civil and Airport Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China
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Yang Z, Liu Z, Zhao F, Yu L, Yang W, Si M, Liao Q. Organic acid, phosphate, sulfate and ammonium co-metabolism releasing insoluble phosphate by Klebsiella aerogenes to simultaneously stabilize lead and cadmium. JOURNAL OF HAZARDOUS MATERIALS 2023; 443:130378. [PMID: 36444069 DOI: 10.1016/j.jhazmat.2022.130378] [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: 08/30/2022] [Revised: 11/06/2022] [Accepted: 11/08/2022] [Indexed: 06/16/2023]
Abstract
Here, a novel phosphate-solubilizing bacterium (PSB), Klebsiella aerogenes Wn was applied to develop an environmental-friendly method to simultaneously stabilize Pb and Cd. The maximum dissolved phosphate was up to 701.36 mg/L by the strain Wn. The high performance liquid chromatography (HPLC) and Pearson correlation analyses showed that the acetic acid produced by the strain Wn was significantly positively associated with the released phosphate. Moreover, 100% of 500 mg/L of Pb and 100 mg/L of Cd were simultaneously stabilized in the classical NBRIP medium and the major products were Pb5(PO4)3Cl, Ca7.7Cd0.8(PO4)8(H2O)2.4 and CdS, respectively. In addition, the bacterial genome and transcriptome analyses showed that the pentose phosphate pathway (PPP), pyruvate metabolism pathway, thiamine metabolic pathway, sulfate reduction and ammonium bio-transformation were coupled to promote releasing insoluble phosphate and stabilizing Pb and Cd. In the metabolism networks, the critical genes of gcd, aceE, thiE, thiS and cysH, etc. were significantly up-regulated. Our results are beneficial to deeper understand the molecular mechanisms of releasing insoluble inorganic phosphate by PSBs and develop a technology prototype to simultaneously stabilize Pb and Cd using the PSBs.
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Affiliation(s)
- Zhihui Yang
- Institute of Environmental Science and Engineering, School of Metallurgy and Environment, Central South University, 410083 Changsha, China; Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution, 410083 Changsha, China
| | - Zixin Liu
- Institute of Environmental Science and Engineering, School of Metallurgy and Environment, Central South University, 410083 Changsha, China
| | - Feiping Zhao
- Institute of Environmental Science and Engineering, School of Metallurgy and Environment, Central South University, 410083 Changsha, China; Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution, 410083 Changsha, China
| | - Lin Yu
- Institute of Environmental Science and Engineering, School of Metallurgy and Environment, Central South University, 410083 Changsha, China
| | - Weichun Yang
- Institute of Environmental Science and Engineering, School of Metallurgy and Environment, Central South University, 410083 Changsha, China; Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution, 410083 Changsha, China
| | - Mengying Si
- Institute of Environmental Science and Engineering, School of Metallurgy and Environment, Central South University, 410083 Changsha, China; Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution, 410083 Changsha, China
| | - Qi Liao
- Institute of Environmental Science and Engineering, School of Metallurgy and Environment, Central South University, 410083 Changsha, China; Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution, 410083 Changsha, China.
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10
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Cao X, Zhang Q, Yang W, Fang L, Liu S, Ma R, Guo K, Ma N. Lead-chlorine synergistic immobilization mechanism in municipal solid waste incineration fly ash (MSWIFA)-based magnesium potassium phosphate cement. JOURNAL OF HAZARDOUS MATERIALS 2023; 442:130038. [PMID: 36166907 DOI: 10.1016/j.jhazmat.2022.130038] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Revised: 09/05/2022] [Accepted: 09/18/2022] [Indexed: 06/16/2023]
Abstract
The high chlorine (Cl) and lead (Pb) content characteristics of municipal solid waste incineration fly ash (MSWIFA) pose environmental risks and hinder resource utilization. Herein, an MSWIFA-based magnesium potassium phosphate cement (MKPC) preparation strategy was developed, which allowed the MSWIFA recycling and the Pb-Cl synergistic immobilization without the washing pretreatment. The compressive strength of the resulting 10 wt% MSWIFA-based MKPC was 28.44 MPa, with over 99.2% reduction in leaching toxicity of Pb and Cl. The high-angle annular dark field scanning transmission electron microscope (HAADF-STEM) and X-ray absorption spectroscopy (XAS) analyzes showed that Pb, phosphate and Cl- formed Pb5(PO4)3Cl in MKPC. In-situ X-ray diffraction (XRD) tests showed that Pb3(PO4)2 was gradually transformed to Pb5(PO4)3Cl through a dissolution-precipitation process. The formation energy, Bader charge, charge density difference and density of states (DOS) of Pb5(PO4)3Cl were analyzed by first-principles calculations, confirming that Pb5(PO4)3Cl was more thermodynamically stable than Pb3(PO4)2 and PbCl2 and that electronic interactions between Pb-p, O-p, P-p and Cl-p orbits were the origin of Pb-Cl synergistic immobilization. This work provides a new strategy for the resource utilization of MSWIFA without washing pretreatment, and provides an in-depth understanding of the Pb-Cl synergistic immobilization mechanism.
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Affiliation(s)
- Xing Cao
- College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen 518060, China
| | - Qiushi Zhang
- College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen 518060, China
| | - Weichen Yang
- College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen 518060, China
| | - Lin Fang
- College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen 518060, China
| | - Shiwei Liu
- College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen 518060, China
| | - Rui Ma
- College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen 518060, China.
| | - Kai Guo
- College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen 518060, China
| | - Ning Ma
- China Electronic System Engineering Co.,Ltd, Beijing 100040, China
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11
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Rozbahani M, Goodarzi AR, Lajevardi SH. Coupling effect of superfine zeolite and fiber on enhancing the long-term performance of stabilized/solidified Pb-contaminated clayey soils. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023; 30:4203-4218. [PMID: 35965302 DOI: 10.1007/s11356-022-22453-7] [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: 03/25/2022] [Accepted: 08/05/2022] [Indexed: 06/15/2023]
Abstract
The focus of the present study was on the applicability of superfine zeolite (SZ) and polypropylene fibers in improving the geo-environmental parameters as well as the durability of cement-based stabilized/solidified low plasticity clay containing different dosages of Pb. The leaching data revealed that while adding a low range (≤ 7.5%) of sole cement even in the severely polluted soils could fully eliminate the Pb bioavailability, the metal retention capacity might portray a marked sensitivity to the acid-washing process. A major reduction was also observed in the mechanical/leaching performance of those samples after undergoing the wetting-drying (w-d) cycle, especially at a high proportion of Pb, which could weaken the cementation bonding dramatically; hence, much more cement was needed to pass the required stabilization/solidification (S/S) standards. Besides, the micro level tests indicated that the application of SZ (with 25% cement replacement) would alleviate the Pb declining impact on the S/S reactions and modify the porous network of soil. As a result, the specimens amended by cement-SZ (CSZ) were more functional (~ 1.4 times) in immobilizing the toxic ions than the cement alone was. However, the CSZ admixture might not perfectly restrain the w-d forces/deteriorations. Such a potential drawback was found to be solvable by the insertion of fiber, in which case, an enhancement in the ductility and the metal capsulation could be also manifested. In fact, the CSZ/fiber treatment could form a well-intertwined matrix, showing high success rates in stabilizing/solidifying the contaminated soils alongside a significant decrease (~ 2-folds) in the quantity of needed amount of cement to give the S/S satisfactory operation under the harsh environmental conditions.
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Affiliation(s)
- Mazaher Rozbahani
- Department of Civil Engineering, Arak Branch, Islamic Azad University, Arak, Iran
| | - Amir Reza Goodarzi
- Faculty of Engineering, Hamedan Branch, Islamic Azad University, Hamedan, Iran.
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12
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Yang W, Cao X, Zhang Q, Ma R, Fang L, Liu S. Coupled microwave hydrothermal dechlorination and geopolymer preparation for the solidification/stabilization of heavy metals and chlorine in municipal solid waste incineration fly ash. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 853:158563. [PMID: 36087669 DOI: 10.1016/j.scitotenv.2022.158563] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 08/15/2022] [Accepted: 09/02/2022] [Indexed: 06/15/2023]
Abstract
To improve the degradation efficiency of persistent organic pollutants (POPs) in municipal solid waste incineration fly ash (MSWIFA), as well as to overcome the difficulties of subsequent hydrothermal liquid and hydrothermal slag treatment, a two-step treatment strategy of microwave hydrothermal degradation coupled with geopolymer immobilization was proposed. Results showed that the optimal process parameters for microwave hydrothermal dechlorination were a temperature of 220 °C, a time of 1 h, and NaOH addition of 10 wt%. Microwaves accelerated the OH- mediated hydrolysis reactions and promoted the breaking of CCl bonds, leading to dechlorination. The compressive strength of the 20 % MSWIFA-based geopolymers reached 75.79 MPa, and the immobilization rate of the heavy metals (HMs) and Cl- surpassed 90 %. Alkaline environment provided by microwave hydrothermal promoted the formation of Ca(OH)2, which subsequently formed Friedel's salt (3CaO•Al2O3•CaCl2•10H2O) with Cl- in the geopolymer. The charge density difference and density of states (DOS) of Friedel's salt were analyzed by first-principles calculations, confirming that the existence of strong interactions between Ca-s, Al-p, O-p, and Cl-p states was the chemical mechanism of Cl- immobilization. The Friedel's salt and HMs were encapsulated by geopolymers with dense silica-alumina tetrahedral frameworks, achieving the solidification/stabilization (S/S) of HMs and Cl-. This work provided a new approach for the environmentally sound and resourceful treatment of MSWIFA.
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Affiliation(s)
- Weichen Yang
- College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen 518060, China
| | - Xing Cao
- Shenzhen Engineering Lab of Flexible Transparent Conductive Films, School of Materials Science and Engineering, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, China
| | - Qiushi Zhang
- College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen 518060, China
| | - Rui Ma
- College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen 518060, China.
| | - Lin Fang
- College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen 518060, China
| | - Shiwei Liu
- College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen 518060, China
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13
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Zhang J, Niu W, Liu Z, Yang Y, Long W, Zhang Y, Dong B. Hydration Behavior of Magnesium Potassium Phosphate Cement: Experimental Study and Thermodynamic Modeling. MATERIALS (BASEL, SWITZERLAND) 2022; 15:8496. [PMID: 36499994 PMCID: PMC9739853 DOI: 10.3390/ma15238496] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/06/2022] [Revised: 11/16/2022] [Accepted: 11/17/2022] [Indexed: 06/17/2023]
Abstract
The microstructure and performance of magnesium potassium phosphate cement (MKPC), a kind of magnesium phosphate cement (MPC), are determined by the hydration products. In this paper, the hydration behavior of MKPC is investigated through various material characterization methods and thermodynamic modeling, including X-ray diffraction (XRD), thermogravimetric and differential scanning calorimeter (TG/DSC), scanning electron microscopy (SEM), mercury intrusion porosimetry (MIP) and GEMS software. The results of XRD, TG/DSC and SEM all indicate that K-struvite (MgKPO4·6H2O) is the main hydration product of MKPC. When the curing age is 1 day and 28 days, the TG data indicate that the mass loss of MKPC in the range of 60-200 °C is 17.76% and 17.82%, respectively. The MIP results show that the porosity of MKPC is 29.63% and 29.61% at the curing age of 1 day and 28 days, respectively, which indicates that the structure of MKPC becomes denser with the increase in curing age. In addition, the cumulative pore volume of MKPC at the curing age of 28 days is 2.8% lower than that at 1 day, and the pore diameters are shifted toward the small pores. Furthermore, the thermodynamic modeling is well suited to make an analysis of the hydration behavior of MKPC.
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Affiliation(s)
- Jinrui Zhang
- State Key Laboratory of Hydraulic Engineering Simulation and Safety, Tianjin University, Tianjin 300072, China
| | - Wenjun Niu
- State Key Laboratory of Hydraulic Engineering Simulation and Safety, Tianjin University, Tianjin 300072, China
| | - Zhen Liu
- State Key Laboratory of Hydraulic Engineering Simulation and Safety, Tianjin University, Tianjin 300072, China
| | - Youzhi Yang
- State Key Laboratory of Hydraulic Engineering Simulation and Safety, Tianjin University, Tianjin 300072, China
| | - Wujian Long
- Guangdong Province Key Laboratory of Durability for Marine Civil Engineering, Shenzhen University, Shenzhen 518060, China
| | - Yuanyuan Zhang
- Guangdong Province Key Laboratory of Durability for Marine Civil Engineering, Shenzhen University, Shenzhen 518060, China
| | - Biqin Dong
- Guangdong Province Key Laboratory of Durability for Marine Civil Engineering, Shenzhen University, Shenzhen 518060, China
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14
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Zhang Y, Wan Z, Wang L, Guo B, Ma B, Chen L, Tsang DCW. Designing Magnesium Phosphate Cement for Stabilization/Solidification of Zn-Rich Electroplating Sludge. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:9398-9407. [PMID: 35735903 DOI: 10.1021/acs.est.2c01450] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Electroplating sludge is a hazardous waste due to its high potential to leach toxic elements into the natural environment. To alleviate this issue, we tailored magnesium phosphate cement (MPC) as a low-carbon material for stabilization/solidification (S/S) of Zn-rich electroplating sludge. The interaction between MPC and ZnO was investigated to clarify the precipitate chemistry, microstructure transition, and chemical environment of Zn species in the MPC-treated Zn sludge system. Comprehensive characterization (by X-ray diffraction (XRD), 31P nuclear magnetic resonance (NMR), and extended X-ray absorption fine structure spectroscopy (EXAFS)) and thermodynamic modeling results revealed that the incorporated ZnO preferentially reacted with phosphate to form Zn3(PO4)2·2H2O/Zn3(PO4)2·4H2O, changing the orthophosphate environment in the MPC system. Stronger chemical bonding between Zn and phosphate in comparison to the bonding between Mg and phosphate also resulted in the formation of amorphous Zn3(PO4)2·2H2O/Zn3(PO4)2·4H2O. Zn3(PO4)2·4H2O precipitate appears to predominate at high {K+}{H+}{HPO42-} values, and the formation of Zn3(PO4)2·2H2O/Zn3(PO4)2·4H2O competed for the Mg sites in the MPC system, leading to the inhibition of formation of Mg-phosphate precipitates. Overall, this work uncovers the precipitate chemistry and microstructure transition of Zn species in the MPC system, providing new insights into the sustainable S/S of Zn-contaminated wastes by adopting MPC.
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Affiliation(s)
- Yuying Zhang
- Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
| | - Zhonghao Wan
- Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
| | - Lei Wang
- State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, China
| | - Binglin Guo
- Department of Earth Resources Engineering, Kyushu University, Fukuoka 819-0395, Japan
| | - Bin Ma
- Laboratory for Waste Management, Nuclear Energy and Safety, Paul Scherrer Institute, 5232 Villigen, Switzerland
| | - Liang Chen
- Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
| | - Daniel C W Tsang
- Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
- State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, China
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15
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Luo Z, Tang C, Hao Y, Wang Z, Yang G, Wang Y, Mu Y. Solidification/stabilization of heavy metals and its efficiency in lead-zinc tailings using different chemical agents. ENVIRONMENTAL TECHNOLOGY 2022; 43:1613-1623. [PMID: 33135954 DOI: 10.1080/09593330.2020.1845817] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2020] [Accepted: 10/24/2020] [Indexed: 06/11/2023]
Abstract
Lead-zinc tailings are generated during the mining process which is considered as hazardous solid waste due to its high heavy metal content and leachability in the natural state. At present, the most effective technology for disposing heavy metals in solid wastes is the solidification/stabilization (S/S) technique. In terms of S/S technology, chemical stabilization is one of the most potential and practical method. This paper aims to investigate the S/S property of four typical chemical agents (Na2S, NaH2PO4, TMT and Na2EDTA) on the heavy metals in lead-zinc tailings. The results reveal that the heavy metals lead and zinc in tailings are stabilized more effectively by using chelating agents TMT than by using inorganic chemical agents Na2S and NaH2PO4. When the dosage of TMT reaches 4%, the leaching concentration of lead and zinc is 0.18 and 14.60 mg/L according to toxicity characteristic leaching procedure (TCLP), and the stabilization efficiency of lead and zinc is 99.31% and 80.92%, respectively, while the leaching concentration of lead and zinc just drops to 0.41 and 16.00 mg/L with addition of 10% NaH2PO4. Furthermore, the leaching concentration of heavy metal lead in tailings treated by 4% Na2EDTA increases to 53.44 mg/L which far exceeds the standard of pollution control. Therefore, considering stabilization efficiency and dosage, TMT is the preferred agent for solidifying heavy metals in lead-zinc tailings.
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Affiliation(s)
- Zhongtao Luo
- School of Materials Science and Engineering, Zhengzhou University, Zhengzhou, People's Republic of China
| | - Changbo Tang
- School of Materials Science and Engineering, Zhengzhou University, Zhengzhou, People's Republic of China
| | - Yuhua Hao
- School of Materials Science and Engineering, Zhengzhou University, Zhengzhou, People's Republic of China
| | - Zhenhua Wang
- School of Materials Science and Engineering, Zhengzhou University, Zhengzhou, People's Republic of China
| | - Guangjun Yang
- School of Materials Science and Engineering, Zhengzhou University, Zhengzhou, People's Republic of China
| | - Yu Wang
- School of Materials Science and Engineering, Zhengzhou University, Zhengzhou, People's Republic of China
| | - Yuandong Mu
- School of Materials Science and Engineering, Zhengzhou University, Zhengzhou, People's Republic of China
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16
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Pan J, Gao B, Guo K, Gao Y, Xu X, Yue Q. Insights into selective adsorption mechanism of copper and zinc ions onto biogas residue-based adsorbent: Theoretical calculation and electronegativity difference. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 805:150413. [PMID: 34818798 DOI: 10.1016/j.scitotenv.2021.150413] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 09/13/2021] [Accepted: 09/14/2021] [Indexed: 05/22/2023]
Abstract
Modified biomass-based adsorption technique has attracted much attention in heavy metal ions removal, but selective adsorption behavior and mechanism of heavy metal ions adsorption onto biosorbent still need to be further clarified. Herein, a carboxylated biogas residue (BR-COOH) was prepared to remove the Cu2+ and Zn2+ from single/binary heavy metal ions solution and explore selective adsorption mechanism. The results exhibited that the adsorption capacities of BR-COOH for Cu2+ was higher than that for Zn2+ obviously, whether in the single or binary heavy metal ions solution. Meanwhile, the introduced carboxy groups were identified as the main sites for metal ions adsorption. Density functional theory (DFT) calculation results exhibited that the adsorption energy of Cu2+ (-0.51 eV) onto BR-COOH was lower than that of Zn2+ (-0.47 eV), indicating that the Cu2+ adsorbed on BR-COOH was more stable than Zn2+. Moreover, the metal ions adsorption capacity of BR-COOH was positively correlated with their electronegativity, which was due to that the metal ions with stronger electronegativity was more easily interacted with the negatively charged oxygen in carboxyl groups. The same results were also verified in the control experiment conducted with two other biosorbents. Therefore, the work provided a new and in-depth insight into selective adsorption of metal ions onto carboxylated biosorbent.
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Affiliation(s)
- Jingwen Pan
- Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Qingdao 266237, PR China
| | - Baoyu Gao
- Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Qingdao 266237, PR China.
| | - Kangying Guo
- Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Qingdao 266237, PR China
| | - Yue Gao
- Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Qingdao 266237, PR China.
| | - Xing Xu
- Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Qingdao 266237, PR China
| | - Qinyan Yue
- Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Qingdao 266237, PR China
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17
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Zhang Q, Cao X, Sun S, Yang W, Fang L, Ma R, Lin C, Li H. Lead zinc slag-based geopolymer: Demonstration of heavy metal solidification mechanism from the new perspectives of electronegativity and ion potential. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2022; 293:118509. [PMID: 34793905 DOI: 10.1016/j.envpol.2021.118509] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Revised: 11/09/2021] [Accepted: 11/13/2021] [Indexed: 06/13/2023]
Abstract
Lead-zinc slag (LZS) is a solid waste product that is rich in silicon and aluminum and has enormous resource potential for functional environmental functional geopolymer materials. Unfortunately, the solidification mechanism of heavy metals in geopolymers is still unclear, which is detrimental to the heavy metal solidification of LZS. In this study, we comprehensively studied and demonstrated the solidification mechanisms of Pb and Zn in geopolymers, based on the preparation of high-performance LZS-based geopolymers (compressive strength up to 89.3 MPa, and Pb and Zn solidification efficiency up to 93.1% and 90.0%, respectively). Thereafter, the solidification mechanism differences between Pb and Zn were explained by electronegativity and ion potential. Due to the ionic potential order of Zn2+> Pb2+> Na+, both Zn2+ and Pb2+ could exchange with Na+ in the geopolymer. In addition, due to the electronegativity order of Pb > Si > Zn, Pb could attack the [SiO4] structure and form covalent bonds in the Pb-O structure, while Zn did not (shown by Raman spectroscopy). As a result, Pb simultaneously solidified in the geopolymer through covalent bonding and ion exchange, while Zn was solidified mainly by ion exchange. Thus, this work provides new perspectives and ideas for the solidification mechanisms of heavy metals in geopolymers.
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Affiliation(s)
- Qiushi Zhang
- College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen, 518060, China
| | - Xing Cao
- College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen, 518060, China
| | - Shichang Sun
- College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen, 518060, China; Research Center for Water Science and Environmental Engineering, Shenzhen University, 518055, China
| | - Weichen Yang
- College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen, 518060, China
| | - Lin Fang
- College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen, 518060, China
| | - Rui Ma
- College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen, 518060, China.
| | - Chenghua Lin
- College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen, 518060, China
| | - Haowen Li
- Micro Optical Instruments (Shenzhen) Inc, 518129, China; Guangdong Engineering Research Center for Intelligent Spectroscopy, 518118, China
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18
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Zhou B, Zhu H, Xu S, Du G, Shi S, Liu M, Xing F, Ren J. Effect of phosphogypsum on the properties of magnesium phosphate cement paste with low magnesium-to-phosphate ratio. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 798:149262. [PMID: 34375242 DOI: 10.1016/j.scitotenv.2021.149262] [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: 04/27/2021] [Revised: 07/06/2021] [Accepted: 07/22/2021] [Indexed: 06/13/2023]
Abstract
The incorporation of phosphogypsum (PG) in magnesium potassium phosphate cement (MPPC) can promote the utilization of PG not only by utilising the phosphate impurity in PG, but also by immobilising the heavy metals with MPPC. This paper investigates the feasibility of the incorporation of PG in preparing MPPC. Both early age properties, including workability and setting time, and hardened properties of compressive strength and microstructure, of PG-incorporated MPPC paste were investigated, and the hydration mechanism was explored. The results indicated that the addition of PG increased the workability of MPPC and extended the setting time of MPPC. However, incorporation of 20% PG slightly reduced the compressive strength because higher PG content led to the loose microstructure. Moreover, the addition of PG did not change the formation of hydration product, while it only reduced the hydration heat. Finally, compared to PG, the concentration of leached heavy metals of MPPC with PG was significantly reduced after 28 days curing.
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Affiliation(s)
- Bo Zhou
- Guangdong Provincial Key Laboratory of Durability for Marine Civil Engineering, College of Civil and Transportation Engineering, Shenzhen University, Shenzhen 518060, China
| | - Haiyan Zhu
- School of Architecture and Planning, Yunnan University, Kunming 650051, China
| | - Shengye Xu
- Guangdong Provincial Key Laboratory of Durability for Marine Civil Engineering, College of Civil and Transportation Engineering, Shenzhen University, Shenzhen 518060, China
| | - Guanhong Du
- Guangdong Provincial Key Laboratory of Durability for Marine Civil Engineering, College of Civil and Transportation Engineering, Shenzhen University, Shenzhen 518060, China
| | - Shi Shi
- Department of Civil, Environmental and Geomatic Engineering, University College London, London WC1E 6BT, UK
| | - Min Liu
- Guangdong Provincial Key Laboratory of Durability for Marine Civil Engineering, College of Civil and Transportation Engineering, Shenzhen University, Shenzhen 518060, China
| | - Feng Xing
- Guangdong Provincial Key Laboratory of Durability for Marine Civil Engineering, College of Civil and Transportation Engineering, Shenzhen University, Shenzhen 518060, China
| | - Jun Ren
- School of Architecture and Planning, Yunnan University, Kunming 650051, China.
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19
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Chen X, Ma R, Luo J, Huang W, Fang L, Sun S, Lin J. Co-microwave pyrolysis of electroplating sludge and municipal sewage sludge to synergistically improve the immobilization of high-concentration heavy metals and an analysis of the mechanism. JOURNAL OF HAZARDOUS MATERIALS 2021; 417:126099. [PMID: 34229391 DOI: 10.1016/j.jhazmat.2021.126099] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 04/13/2021] [Accepted: 05/06/2021] [Indexed: 06/13/2023]
Abstract
To improve the harmless treatment of high-concentration heavy metals (HMs) in electroplating sludge (ES), this study tried to combine the microwave pyrolysis technology and the addition of municipal sewage sludge (MS) to synergistically improve the immobilization of high-concentration HMs in ES. The results showed that the immobilization rate of HMs was less than 75% in ES pyrolysis biochar. Notably, the immobilization rate of HMs up to 98.00% in co-pyrolysis biochar. Finally, it was found by various characterizations that the organic carbon and inorganic minerals in MS played an important role in the immobilization of HMs through physical and chemical effects. HMs reacted with inorganic minerals to form HMs crystalline minerals (e.g., CuCl, Cu2NiSnS4, and NiSi2, ZnS) to realize the immobilization of HMs. The addition of organic carbon was conducive to the formation of biochar with higher carbon crystallinity (ID/IG = 0.96) and larger specific surface area (52.50 m2 g-1), thereby enhancing the physical adsorption to HMs. Meanwhile, the complexation reaction between HMs and functional groups such as -OH, Si-O-Si could also further improve the immobilization of HMs. Therefore, this study provided a technical and theoretical basis for the harmless disposal of waste containing multiple HMs with high-concentrations.
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Affiliation(s)
- Xing Chen
- College of Chemistry and Environmental Engineering, Shenzhen University, No. 3688, Nanhai Road, Nanshan District, Shenzhen 518060, China
| | - Rui Ma
- College of Chemistry and Environmental Engineering, Shenzhen University, No. 3688, Nanhai Road, Nanshan District, Shenzhen 518060, China
| | - Juan Luo
- College of Chemistry and Environmental Engineering, Shenzhen University, No. 3688, Nanhai Road, Nanshan District, Shenzhen 518060, China
| | - Wentao Huang
- College of Chemistry and Environmental Engineering, Shenzhen University, No. 3688, Nanhai Road, Nanshan District, Shenzhen 518060, China
| | - Lin Fang
- College of Chemistry and Environmental Engineering, Shenzhen University, No. 3688, Nanhai Road, Nanshan District, Shenzhen 518060, China
| | - Shichang Sun
- College of Chemistry and Environmental Engineering, Shenzhen University, No. 3688, Nanhai Road, Nanshan District, Shenzhen 518060, China; Research Center for Water Science and Environmental Engineering, Shenzhen University, 518055, China.
| | - Junhao Lin
- School of Environment, Harbin Institute of Technology, Harbin 150090, China
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20
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Pu S, Zhu Z, Song W, Wang H, Huo W, Zhang J. A novel acidic phosphoric-based geopolymer binder for lead solidification/stabilization. JOURNAL OF HAZARDOUS MATERIALS 2021; 415:125659. [PMID: 33773251 DOI: 10.1016/j.jhazmat.2021.125659] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Revised: 03/09/2021] [Accepted: 03/11/2021] [Indexed: 06/12/2023]
Abstract
Many contaminated sites are acidic and the existing binders are mainly alkaline materials. Alkaline binders are used to treat contaminated sites in acidic environments and the solidification/stabilization (S/S) effect is affected by acid corrosion. Therefore, good application prospects exist in developing a binder suitable for the treatment of acidic contaminated sites. In this paper, a new acidic phosphoric-based geopolymer (named APG binder) was synthesized with fly ash as a raw material and aluminum dihydrogen phosphate as the reactant, and the APG binder was used for Pb2+ S/S for the first time. The pH of the APG binder with Pb2+ ranged from 2.56 to 4.09 during 7-28 days of curing, and its compressive strength with Pb2+ exceeded 10 MPa at 28 days. Moreover, Pb2+ had a significant impact on the APG binder compressive strength, and when the Pb2+ content was 0.6%, the APG binder yielded a maximum compressive strength of 6.5, 9.1 and 14.28 MPa at 7, 14, and 28 days, respectively. Furthermore, the compressive strength correlated well with pH and electrical conductivity. The proposed APG binder had a better S/S effect on Pb2+ than that of cement and alkali-activated geopolymers in acidic environments. The stabilization mechanism of the APG binder for Pb2+ included chemical precipitation, physical adsorption and encapsulation.
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Affiliation(s)
- Shaoyun Pu
- School of Transportation, Southeast University, Nanjing 211189, Jiangsu, China.
| | - Zhiduo Zhu
- School of Transportation, Southeast University, Nanjing 211189, Jiangsu, China.
| | - Weilong Song
- School of Transportation, Southeast University, Nanjing 211189, Jiangsu, China
| | - Hairong Wang
- School of Transportation, Southeast University, Nanjing 211189, Jiangsu, China
| | - Wangwen Huo
- School of Transportation, Southeast University, Nanjing 211189, Jiangsu, China
| | - Jie Zhang
- School of Transportation, Southeast University, Nanjing 211189, Jiangsu, China
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21
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Zhang Y, Wang L, Chen L, Ma B, Zhang Y, Ni W, Tsang DCW. Treatment of municipal solid waste incineration fly ash: State-of-the-art technologies and future perspectives. JOURNAL OF HAZARDOUS MATERIALS 2021; 411:125132. [PMID: 33858099 DOI: 10.1016/j.jhazmat.2021.125132] [Citation(s) in RCA: 108] [Impact Index Per Article: 36.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Revised: 01/07/2021] [Accepted: 01/08/2021] [Indexed: 06/12/2023]
Abstract
Municipal solid waste incineration (MSWI) fly ash is considered as a hazardous waste that requires specific treatment before disposal. The principal treatments encompass thermal treatment, stabilization/solidification, and resource recovery. To maximize environmental, social, and economic benefits, the development of low-carbon and sustainable treatment technologies for MSWI fly ash has attracted extensive interests in recent years. This paper critically reviewed the state-of-the-art treatment technologies and novel resource utilization approaches for the MSWI fly ash. Innovative technologies and future perspectives of MSWI fly ash management were highlighted. Moreover, the latest understanding of immobilization mechanisms and the use of advanced characterization technologies were elaborated to foster future design of treatment technologies and the actualization of sustainable management for MSWI fly ash.
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Affiliation(s)
- Yuying Zhang
- Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
| | - Lei Wang
- Institute of Construction Materials, Technische Universität Dresden, 01062 Dresden, Germany.
| | - Liang Chen
- Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
| | - Bin Ma
- Laboratory for Concrete & Construction Chemistry, Swiss Federal Laboratories for Materials Science and Technology (Empa), 8600 Dübendorf, Switzerland
| | - Yike Zhang
- State Key Laboratory of Energy Clean Utilization, Zhejiang University, Hangzhou 310027, China
| | - Wen Ni
- School of Civil and Resource Engineering, University of Science and Technology Beijing, 100083, China
| | - Daniel C W Tsang
- Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China.
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22
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Wang Z, Liu L, Gong Z, Zhang H, Wu J. Study on the ecological risk of heavy metals during oily sludge incineration with CaO additive. JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH. PART A, TOXIC/HAZARDOUS SUBSTANCES & ENVIRONMENTAL ENGINEERING 2021; 56:797-803. [PMID: 34061708 DOI: 10.1080/10934529.2021.1927598] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 04/27/2021] [Accepted: 05/02/2021] [Indexed: 06/12/2023]
Abstract
In order to explore the effect of CaO on the ecological risk of chromium (Cr), copper (Cu) and zinc (Zn) in Oily sludge (OS), the incineration experiments of OS with and without calcium oxide (CaO) additive were carried out respectively in a horizontal tube furnace at the temperature ranging from 800 °C to 1000 °C. Furthermore, the ecological risk based on Risk Assessment Code (RAC) of Cr, Cu and Zn in OS, bottom ash from OS incineration (OSA) and bottom ash from OS incineration in the presence of CaO additive (OSA-CaO) were investigated in this work. The results showed that most of the Cr and Cu in OS remained in bottom ash, while Zn volatilized with the flue gas. At the same time, the RAC of Cr, Cu and Zn in OS decreased significantly after incineration. Compared with OSA, CaO obviously promoted the stabilization of Cr and Cu in OSA-CaO, but had little effect on the behavior of Zn. Moreover, CaO also reduced the RAC of Cu and Zn in samples, and reduced its harm to ecosystem. This study supplied essential data and theoretical support for the industrial treatment of OS, and was of great help to the harmless treatment of OS.
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Affiliation(s)
- Zhenbo Wang
- College of New Energy, China University of Petroleum (East Chian), Qingdao, China
| | - Lei Liu
- Yantai Wanhua Chemical Design Institute Co. Ltd, Yantai, China
| | - Zhiqiang Gong
- State Grid Shandong Electric Power Research Institute, Jinan, China
| | - Haoteng Zhang
- College of New Energy, China University of Petroleum (East Chian), Qingdao, China
| | - Jinhui Wu
- College of New Energy, China University of Petroleum (East Chian), Qingdao, China
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23
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Zhu J, Gao W, Ge L, Zhao W, Zhang G, Niu Y. Immobilization properties and adsorption mechanism of nickel(II) in soil by biochar combined with humic acid-wood vinegar. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2021; 215:112159. [PMID: 33799133 DOI: 10.1016/j.ecoenv.2021.112159] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2020] [Revised: 03/05/2021] [Accepted: 03/14/2021] [Indexed: 06/12/2023]
Abstract
Biochar (BC) combined with humic acid (HA) and wood vinegar (WV) was designed and prepared as an inexpensive, effective, and environmentally friendly immobilization material (BHW) for metal-polluted soil. The influences of the wood vinegar and humic acid on the immobilization properties and adsorption mechanism of this new material were also investigated. The remediation performance was evaluated using a laboratory-made, nickel-contaminated soil with a Ni2+ concentration of 200 mg per kg surface soil (top 20 cm from agricultural land). The results indicated that the immobilization ratio sequence of nickel (II) in the soil was BC< BH< BHW. The maximum adsorption capacity increased in the same order: BC< BH< BHW. All three adsorption isotherms were better fitted by the Freundlich model, which were consistent with the surface heterogeneity of the remediation materials. The cause of this surface heterogeneous migration may be due to the increase in oxygen-containing groups in the BC introduced by the HA and WV. The WV can increase the number of the oxygen-containing groups in the BC combined with HA, which enhanced the adsorption and immobilization of Ni2+ ions. The results suggested that BHW is recommended for the remediation of metal-contaminated soils, because of its high efficacy, economic feasibility, environmental and food safety.
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Affiliation(s)
- Junfeng Zhu
- Key Laboratory of Degraded and Unused Land Consolidation Engineering, the Ministry of Natural Resources of the People's Republic of China, 710075, China; Shaanxi Key Research Laboratory of Chemical Additives, College of Chemistry and Chemical Engineering, Shaanxi University of Science & Technology, Xi'an 710021, China.
| | - Weichun Gao
- Shaanxi Key Research Laboratory of Chemical Additives, College of Chemistry and Chemical Engineering, Shaanxi University of Science & Technology, Xi'an 710021, China
| | - Lei Ge
- Key Laboratory of Degraded and Unused Land Consolidation Engineering, the Ministry of Natural Resources of the People's Republic of China, 710075, China
| | - Wentian Zhao
- Shaanxi Key Research Laboratory of Chemical Additives, College of Chemistry and Chemical Engineering, Shaanxi University of Science & Technology, Xi'an 710021, China
| | - Guanghua Zhang
- Shaanxi Key Research Laboratory of Chemical Additives, College of Chemistry and Chemical Engineering, Shaanxi University of Science & Technology, Xi'an 710021, China
| | - Yuhua Niu
- Shaanxi Key Research Laboratory of Chemical Additives, College of Chemistry and Chemical Engineering, Shaanxi University of Science & Technology, Xi'an 710021, China
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Wang Z, Wei B, Wu X, Zhu H, Wang Q, Xiong Z, Ding Z. Effects of dry-wet cycles on mechanical and leaching characteristics of magnesium phosphate cement-solidified Zn-contaminated soils. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2021; 28:18111-18119. [PMID: 33405163 DOI: 10.1007/s11356-020-11977-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Accepted: 12/04/2020] [Indexed: 06/12/2023]
Abstract
Although magnesium phosphate cement (MPC) is conventionally deemed effective in heavy metal-contaminated soil remediation, the variations of its mechanical and leaching characteristics under the action of dry-wet cycles remain unclear as yet. This paper primarily addressed the effect of dry-wet cycles and fly ash on MPC-solidified zinc-contaminated soil via a disparate group of experiments. In this study, solidified cylindrical samples were subjected to different drying-wetting cycles ranging in times from 0 to 10 with varying content of fly ash. We then measured the mass loss, the unconfined compressive strength, and the Zn2+ leaching concentration of the leachate for the samples undergoing specified cycles. In addition, X-ray diffraction (XRD) and scanning electron microscopy (SEM) tests were conducted to explore the mechanism of MPC-solidified zinc-contaminated soil with fly ash. The results indicate that the Zn2+ concentration in the leaching solution increases rapidly with the number of cycles for 0-3 cycles and then tends to flatten out. Moreover, the unconfined compressive strength of the samples without fly ash decreases with an increasing dry-wet cycles. For the samples with various fly ash contents, in contrast, their unconfined compressive strength experiences an initial rise and a subsequent decline owing to the development of dry-wet cycles. With the purpose of facilitating practical applications, the appropriate fly ash content (approximately 20%) was estimated in terms of the enhanced dry-wet cycles durability of the solidified soil and unconfined compressive strength, according to the limited experimental measurements undertaken (for the Zn2+ concentration of 0.5). The role of dry-wet cycles in the physical and leaching properties of MPC-solidified soil may be of major practical significance.
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Affiliation(s)
- Zhe Wang
- Institute of Geotechnical Engineering, Zhejiang University of Technology, 288 Liuhe Road, Hangzhou, 310023, China
| | - Binpin Wei
- Institute of Geotechnical Engineering, Zhejiang University of Technology, 288 Liuhe Road, Hangzhou, 310023, China
| | - Xuehui Wu
- Institute of Geotechnical Engineering, Zhejiang University of Technology, 288 Liuhe Road, Hangzhou, 310023, China
| | - Hangjun Zhu
- Institute of Geotechnical Engineering, Zhejiang University of Technology, 288 Liuhe Road, Hangzhou, 310023, China
| | - Qiaokan Wang
- Zhejiang Province Institute of Architectural Design and Research, 18 Anji Road, Hangzhou, 310006, China
| | - Zhuang Xiong
- Zhejiang Scientific Research Institute of Transport, 704-23, Qingshan Heling Community, Heting Street, Qingshan Town, Hangzhou, 310069, China
| | - Zhouxiang Ding
- Department of Mechanical Engineering, The University of Saskatchewan, Saskatoon, Saskatchewan, SK S7N 5A9, Canada.
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25
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Deng Q, Lai Z, Yan T, Wu J, Liu M, Lu Z, Lv S. Effect of Cr (III) on hydration, microstructure of magnesium phosphate cement, and leaching toxicity evaluation. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2021; 28:15290-15304. [PMID: 33231852 DOI: 10.1007/s11356-020-11780-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Accepted: 11/19/2020] [Indexed: 06/11/2023]
Abstract
The pollution caused by chromium and its compounds has caused severe harm to the environment, and waste stabilization/solidification containing these contaminants by magnesium phosphate cement (MPC) is one of the best ways to address this problem. If the mechanism between Cr3+ and MPC can be understood, it will significantly improve the latter's solidification performance with respect to ameliorating Cr pollution. In this paper, the compressive strength, microstructure, pH in the process of sample hydration, and leaching toxicity of solidified forms were studied by adding various amounts of Cr3+ into MPC. The setting time of MPC decreased at first and then increased as the Cr3+ concentration increased. The added Cr3+ reacted with the phosphate ions to form mineral phases, which changed the MPC matrix structure. The matrix's compressive strength was higher when the M/P ratio (MgO/KH2PO4 mass ratio) was smaller. When the concentration of Cr3+ was constant, and the M/P ratio was low (< 4:1), the matrix's compressive strength increased as the M/P ratio increased. The presence of Cr3+ changed the system's pH and affected the hydration products' morphology; this trend strengthened as the Cr3+ concentration increased. The highest leaching concentration of Cr3+ was 0.255 mg/L, and the concentration decreased as the M/P ratio decreased. During solidification, the appropriate proportion of MPC can be selected according to the concentration of Cr3+ to achieve better solidification performance.
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Affiliation(s)
- Qiubai Deng
- School of Materials Science and Engineering, State Key Laboratory of Environmental Friendly Energy Materials, Southwest University of Science and Technology, Mianyang, 621010, Sichuan, China
| | - Zhenyu Lai
- School of Materials Science and Engineering, State Key Laboratory of Environmental Friendly Energy Materials, Southwest University of Science and Technology, Mianyang, 621010, Sichuan, China.
| | - Tao Yan
- School of Materials Science and Engineering, State Key Laboratory of Environmental Friendly Energy Materials, Southwest University of Science and Technology, Mianyang, 621010, Sichuan, China
| | - Jie Wu
- School of Materials Science and Engineering, State Key Laboratory of Environmental Friendly Energy Materials, Southwest University of Science and Technology, Mianyang, 621010, Sichuan, China
| | - Mengliang Liu
- School of Materials Science and Engineering, State Key Laboratory of Environmental Friendly Energy Materials, Southwest University of Science and Technology, Mianyang, 621010, Sichuan, China
| | - Zhongyuan Lu
- School of Materials Science and Engineering, State Key Laboratory of Environmental Friendly Energy Materials, Southwest University of Science and Technology, Mianyang, 621010, Sichuan, China
| | - Shuzhen Lv
- School of Materials Science and Engineering, State Key Laboratory of Environmental Friendly Energy Materials, Southwest University of Science and Technology, Mianyang, 621010, Sichuan, China
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26
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Yang Y, Zhao T, Jiao H, Wang Y, Li H. Potential Effect of Porosity Evolution of Cemented Paste Backfill on Selective Solidification of Heavy Metal Ions. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2020; 17:ijerph17030814. [PMID: 32012968 PMCID: PMC7037339 DOI: 10.3390/ijerph17030814] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 01/12/2020] [Accepted: 01/20/2020] [Indexed: 11/16/2022]
Abstract
Cemented paste backfill (CPB) is a common environmentally friendly mining approach. However, it remains undetermined whether CPB pollutes underground mine water. Tank leaching analysis of a CPB mass in distilled water was performed for 120 d, and water quality was tested in situ for a long-term pollution assessment. Computerized tomography was also used to determine the CPB micro-pore structure and ion-leaching mechanism. The dissolved Zn2+, Pb2+ and As5+ concentrations in the leachate peaked at 0.56, 0.11 and 0.066 mg/L, respectively, whereas the Co2+ and Cd2+ concentrations were lower than the detection limit. The CPB porosity decreased from 46.07% to 40.88% by soaking, and 80% of the pore diameters were less than 13.81 μm. The permeability decreased from 0.8 to 0.5 cm/s, and the quantity, length, and diameter of the permeate channels decreased with soaking. An in-situ survey showed novel selective solidification. The Zn2+ concentration in the mine water was 10-20 times that of the background water, and the Pb2+ concentration was 2-4 times the regulated value. Although the Pb2+ content decreased significantly with mining depth, there remains a serious environmental risk. Mine water pollution can be reduced by adding a solidifying agent for Pb2+ and Zn2+, during CPB preparation.
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Affiliation(s)
- Yixuan Yang
- Institute of Resources and Environment, Henan Polytechnic University, Jiaozuo 454000, China; (Y.Y.); (T.Z.)
| | - Tongqian Zhao
- Institute of Resources and Environment, Henan Polytechnic University, Jiaozuo 454000, China; (Y.Y.); (T.Z.)
| | - Huazhe Jiao
- International Joint Research Laboratory of Henan Province for Underground Space Development and Disaster Prevention, School of Civil Engineering, Henan Polytechnic University, Jiaozuo 454003, China;
- Correspondence:
| | - Yunfei Wang
- International Joint Research Laboratory of Henan Province for Underground Space Development and Disaster Prevention, School of Civil Engineering, Henan Polytechnic University, Jiaozuo 454003, China;
| | - Haiyan Li
- School of Materials Science and Engineering, Henan Polytechnic University, Jiaozuo 454003, China;
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