Pub Date : 2021-09-08DOI: 10.3389/fenvc.2021.692025
F. Lacan, L. Artigue, J. Klar, C. Pradoux, J. Chmeleff, R. Freydier
Multi-collector inductively coupled plasma mass spectrometers (MC-ICPMS) are widely used for Fe isotope measurements. The latter may be perturbed by interferences (notably from Cr and Ni) and matrix effects (notably from major elements), caused by elements remaining in the samples after purification. We quantified some of these perturbations and our ability to correct them whenever possible, using Thermo Neptune and Neptune Plus MC-ICPMS with a 57-58Fe double-spike mass bias correction. 54Cr and 58Ni isobaric interference corrections were found to be extremely efficient up to Cr/Fe=0.12 and Ni/Fe=0.04 (g/g natural Fe). Matrix effects were found negligible up to at least Na/Fe=175, Mg/Fe=10, K/Fe=1.5, and Mo/Fe=75 (g/g natural Fe). 28Si2 + interference was found negligible up to Si/Fe=50. Finally, we found that calcium and aluminum could cause significant interferences (e.g., 40Ca16O and 27Al2 +), for Ca/Fe ≥ 2.5 and Al/Fe ≥ 2.5. The perturbation intensity relative to the Ca/Fe ratio was found dependent on the measurement conditions (plateau width). While working with samples with potentially high calcium or aluminum contents (such as calcite minerals or tests, bones and teeth, or marine samples and crustal rocks), we recommend to carefully take into account Ca and Al while tuning the instrument and checking the measurement accuracy with isotopic standards (i.e., doping the isotopic standard with Ca and Al levels comparable to those of the samples).
多收集器电感耦合等离子体质谱仪（MC-ICPMS）被广泛用于Fe同位素的测量。后者可能受到干扰（特别是来自Cr和Ni）和基质效应（特别是主要元素）的干扰，这些干扰是由纯化后残留在样品中的元素引起的。我们使用Thermo Neptune和Neptune Plus MC-ICPMS进行57-58Fe双尖峰质量偏差校正，量化了其中一些扰动，并在可能的情况下进行了校正。54Cr和58Ni等压干涉校正被发现是非常有效的，直到Cr/Fe=0.12和Ni/Fe=0.04（g/g天然Fe）。发现基体效应可忽略不计，至少达到Na/Fe=175、Mg/Fe=10、K/Fe=1.5和Mo/Fe=75（g/g天然Fe）。28Si2+的干扰可忽略不计，直至Si/Fe=50。最后，我们发现当Ca/Fe≥2.5和Al/Fe≥2.5%时，钙和铝会引起显著的干扰（如40Ca16O和27Al2+）。发现相对于Ca/Fe比的扰动强度取决于测量条件（平台宽度）。在处理可能具有高钙或铝含量的样品（如方解石矿物或测试、骨骼和牙齿，或海洋样品和地壳岩石）时，我们建议在调整仪器和用同位素标准检查测量精度时仔细考虑Ca和Al（即，用与样品相当的Ca和Al水平掺杂同位素标准）。
{"title":"Interferences and Matrix Effects on Iron Isotopic Composition Measurements by 57Fe-58Fe Double-Spike Multi-Collector Inductively Coupled Plasma Mass Spectrometry; the Importance of Calcium and Aluminum Interferences","authors":"F. Lacan, L. Artigue, J. Klar, C. Pradoux, J. Chmeleff, R. Freydier","doi":"10.3389/fenvc.2021.692025","DOIUrl":"https://doi.org/10.3389/fenvc.2021.692025","url":null,"abstract":"Multi-collector inductively coupled plasma mass spectrometers (MC-ICPMS) are widely used for Fe isotope measurements. The latter may be perturbed by interferences (notably from Cr and Ni) and matrix effects (notably from major elements), caused by elements remaining in the samples after purification. We quantified some of these perturbations and our ability to correct them whenever possible, using Thermo Neptune and Neptune Plus MC-ICPMS with a 57-58Fe double-spike mass bias correction. 54Cr and 58Ni isobaric interference corrections were found to be extremely efficient up to Cr/Fe=0.12 and Ni/Fe=0.04 (g/g natural Fe). Matrix effects were found negligible up to at least Na/Fe=175, Mg/Fe=10, K/Fe=1.5, and Mo/Fe=75 (g/g natural Fe). 28Si2 + interference was found negligible up to Si/Fe=50. Finally, we found that calcium and aluminum could cause significant interferences (e.g., 40Ca16O and 27Al2 +), for Ca/Fe ≥ 2.5 and Al/Fe ≥ 2.5. The perturbation intensity relative to the Ca/Fe ratio was found dependent on the measurement conditions (plateau width). While working with samples with potentially high calcium or aluminum contents (such as calcite minerals or tests, bones and teeth, or marine samples and crustal rocks), we recommend to carefully take into account Ca and Al while tuning the instrument and checking the measurement accuracy with isotopic standards (i.e., doping the isotopic standard with Ca and Al levels comparable to those of the samples).","PeriodicalId":73082,"journal":{"name":"Frontiers in environmental chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48062726","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-08-18DOI: 10.3389/fenvc.2021.756783
Xiaohang Lu, Zhe Ma, Lei Yi, Guangwu Zhang, Fuhong Chen, Feng-qing Han
{"title":"Corrigendum: The Composition and Distribution of Volatile Organic Compounds in Sediments of the East Taijinar Salt Lake in Northern Qinghai-Tibet Plateau","authors":"Xiaohang Lu, Zhe Ma, Lei Yi, Guangwu Zhang, Fuhong Chen, Feng-qing Han","doi":"10.3389/fenvc.2021.756783","DOIUrl":"https://doi.org/10.3389/fenvc.2021.756783","url":null,"abstract":"","PeriodicalId":73082,"journal":{"name":"Frontiers in environmental chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46524059","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-08-17DOI: 10.3389/fenvc.2021.703961
D. Sun, Zhihua Song, Yue Zhang, Yixiao Wang, Min Lv, Huitao Liu, Liyan Wang, Wenhui Lu, Jinhua Li, Lingxin Chen
Abuse and residues of antibiotics cause great harm to organisms and the environment. Appropriate sample pretreatment is usually required for sensitive determination, because of the low content presence of a variety of antibiotics in complicated matrices. Molecular-imprinting-based solid-phase extraction (MISPE) has been widely used for sample pretreatment of antibiotics, using molecularly imprinted polymers (MIPs) as adsorbents. Herein, we comprehensively review the recent advances of MISPE of antibiotics, followed by chromatographic analysis. Various solid-phase extraction (SPE) modes based on MIPs are briefly introduced, such as conventional SPE, dispersive SPE, magnetic SPE, matrix solid-phase dispersion, and pipette-tip SPE. Then, several emerging preparation techniques for antibiotics MIPs are summarized including surface imprinting, nanoimprinting, living/controlled radical polymerization, multitemplate imprinting, multifunctional monomer imprinting, and dummy template imprinting. Subsequently, applications of MISPE to analysis of a variety of antibiotics residues since 2018 are overviewed, including sulfonamides, quinolones, tetracycline, and others. Finally, the preparation and application of antibiotics MIPs are prospected.
{"title":"Recent Advances in Molecular-Imprinting-Based Solid-Phase Extraction of Antibiotics Residues Coupled With Chromatographic Analysis","authors":"D. Sun, Zhihua Song, Yue Zhang, Yixiao Wang, Min Lv, Huitao Liu, Liyan Wang, Wenhui Lu, Jinhua Li, Lingxin Chen","doi":"10.3389/fenvc.2021.703961","DOIUrl":"https://doi.org/10.3389/fenvc.2021.703961","url":null,"abstract":"Abuse and residues of antibiotics cause great harm to organisms and the environment. Appropriate sample pretreatment is usually required for sensitive determination, because of the low content presence of a variety of antibiotics in complicated matrices. Molecular-imprinting-based solid-phase extraction (MISPE) has been widely used for sample pretreatment of antibiotics, using molecularly imprinted polymers (MIPs) as adsorbents. Herein, we comprehensively review the recent advances of MISPE of antibiotics, followed by chromatographic analysis. Various solid-phase extraction (SPE) modes based on MIPs are briefly introduced, such as conventional SPE, dispersive SPE, magnetic SPE, matrix solid-phase dispersion, and pipette-tip SPE. Then, several emerging preparation techniques for antibiotics MIPs are summarized including surface imprinting, nanoimprinting, living/controlled radical polymerization, multitemplate imprinting, multifunctional monomer imprinting, and dummy template imprinting. Subsequently, applications of MISPE to analysis of a variety of antibiotics residues since 2018 are overviewed, including sulfonamides, quinolones, tetracycline, and others. Finally, the preparation and application of antibiotics MIPs are prospected.","PeriodicalId":73082,"journal":{"name":"Frontiers in environmental chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-08-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42387134","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-08-10DOI: 10.3389/fenvc.2021.692810
Shuiping Xu, M. Liang, Yanmei Ding, Dunqiu Wang, Yinian Zhu, Linbo Han
In this study, a new generation chromium sorbent, mulberry stem biochar/Mn-Fe binary oxide composite (MBC-MFC), was fabricated by chemical precipitation on carbonized mulberry stem according to response surface methodology (RSM) results. RSM was more convenient to figure out the optimized preparation condition of MBC-MFC theoretically for achieving a maximum removal efficiency of Cr(VI) and total chromium (TCr), compared to labor-intensive orthogonal experiments. The RSM results showed that Fe/Mn concentration (CFe; CMn), MBC activation temperature after soaking in KOH solution (T), and pH during precipitation of Fe-Mn oxide were three main factors to significantly affect the efficiency of MBC-MFC (p < 0.05) in Cr(VI) and TCr removal. With the selected condition (C Fe = 0.28 mol/L; C Mn = 0.14 mol/L; T = 790°C; pH = 9.0), MBC-MFC was synthesized with a large surface area (318.53 m2/g), and the point of zero charge values of MBC-MFC was 5.64. The fabricated MBC-MFC showed excellent adsorption performance of Cr(VI) and TCr in an aqueous solution. The maximum Cr(VI) and TCr removal capacity of MBC-MFC was 56.18 and 54.97 mg/g (T = 25°C, pH = 3.0, t = 48 h, and dosage = 0.10 g/50 ml), respectively, and the maximum Cr(VI) adsorption of MBC-MFC was 4.16 times that of bare MBC, suggesting the synergistic effects of Fe/Mn oxides and MB on the performance of MBC-MFC in Cr(VI) and TCr removal. The adsorption mechanism of MBC-MFC on chromium was mainly contributed by surface complexation and electrostatic attraction. Our study offers valuable outlooks to develop high-performance biochar-based sorbents for heavy metal removal and sustainable environmental remediation.
{"title":"Synthesis, Optical Characterization, and Adsorption of Novel Hexavalent Chromium and Total Chromium Sorbent: A Fabrication of Mulberry Stem Biochar/Mn-Fe Binary Oxide Composite via Response Surface Methodology","authors":"Shuiping Xu, M. Liang, Yanmei Ding, Dunqiu Wang, Yinian Zhu, Linbo Han","doi":"10.3389/fenvc.2021.692810","DOIUrl":"https://doi.org/10.3389/fenvc.2021.692810","url":null,"abstract":"In this study, a new generation chromium sorbent, mulberry stem biochar/Mn-Fe binary oxide composite (MBC-MFC), was fabricated by chemical precipitation on carbonized mulberry stem according to response surface methodology (RSM) results. RSM was more convenient to figure out the optimized preparation condition of MBC-MFC theoretically for achieving a maximum removal efficiency of Cr(VI) and total chromium (TCr), compared to labor-intensive orthogonal experiments. The RSM results showed that Fe/Mn concentration (CFe; CMn), MBC activation temperature after soaking in KOH solution (T), and pH during precipitation of Fe-Mn oxide were three main factors to significantly affect the efficiency of MBC-MFC (p < 0.05) in Cr(VI) and TCr removal. With the selected condition (C Fe = 0.28 mol/L; C Mn = 0.14 mol/L; T = 790°C; pH = 9.0), MBC-MFC was synthesized with a large surface area (318.53 m2/g), and the point of zero charge values of MBC-MFC was 5.64. The fabricated MBC-MFC showed excellent adsorption performance of Cr(VI) and TCr in an aqueous solution. The maximum Cr(VI) and TCr removal capacity of MBC-MFC was 56.18 and 54.97 mg/g (T = 25°C, pH = 3.0, t = 48 h, and dosage = 0.10 g/50 ml), respectively, and the maximum Cr(VI) adsorption of MBC-MFC was 4.16 times that of bare MBC, suggesting the synergistic effects of Fe/Mn oxides and MB on the performance of MBC-MFC in Cr(VI) and TCr removal. The adsorption mechanism of MBC-MFC on chromium was mainly contributed by surface complexation and electrostatic attraction. Our study offers valuable outlooks to develop high-performance biochar-based sorbents for heavy metal removal and sustainable environmental remediation.","PeriodicalId":73082,"journal":{"name":"Frontiers in environmental chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45778557","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-07-19DOI: 10.3389/fenvc.2021.719300
I. Zohar, P. Haruzi
The associations of elements upon a heterogeneous surface may control nutrients or pollutants sorption and release, having agricultural and environmental implications. This chemical behavior can be elucidated by spatial spectroscopy, followed by image analysis. The purpose of this paper is to present a working procedure for image analysis using the free program ImageJ that can be applied for dot maps of three or more elements produced by solid-state spectroscopy. Detailed step-by-step instructions lead to visual and quantitative information regarding elements associations. The working procedure was demonstrated for P, Al and Ca dot maps produced by scanning electron microscopy energy dispersive spectroscopy (SEM-EDS) for surfaces of Al-based water treatment residuals (Al-WTRs), a by-product of drinking water pretreatment with alum coagulant. Al-WTR was reused to adsorb the macro-nutrient P from polluted soil leach and dairy wastewater (WW). Surficial P onto Al-WTR, SL-Al/O-WTR, and WW-Al/O-WTR (0.56, 0.93, and 2.15%, respectively) displayed sorption dynamics, mostly with Al and Ca. Quantification of the spatial proportions of individual elements and their associations indicated P-Al pool > P-Ca pool (45–24% and 17–7%, respectively). Upon introducing P-rich dairy wastewater, the behavior of P sorption by Al and Ca changed and became more clustered. A ternary phase of P-Al-Ca covered 38% of the area with signal, compared to 4.3 and 4.6% of the area in Al-WTR and SL-Al-WTR, where it was limited to particles edges only. Thus, the presented protocol may promote employing image analysis for geochemical applications, elucidating chemical behavior and affinities. Advantages and pitfalls are discussed.
{"title":"Image Analysis for Spectroscopic Elemental Dot Maps: P, Al, and Ca Associations in Water Treatment Residuals as a Case Study","authors":"I. Zohar, P. Haruzi","doi":"10.3389/fenvc.2021.719300","DOIUrl":"https://doi.org/10.3389/fenvc.2021.719300","url":null,"abstract":"The associations of elements upon a heterogeneous surface may control nutrients or pollutants sorption and release, having agricultural and environmental implications. This chemical behavior can be elucidated by spatial spectroscopy, followed by image analysis. The purpose of this paper is to present a working procedure for image analysis using the free program ImageJ that can be applied for dot maps of three or more elements produced by solid-state spectroscopy. Detailed step-by-step instructions lead to visual and quantitative information regarding elements associations. The working procedure was demonstrated for P, Al and Ca dot maps produced by scanning electron microscopy energy dispersive spectroscopy (SEM-EDS) for surfaces of Al-based water treatment residuals (Al-WTRs), a by-product of drinking water pretreatment with alum coagulant. Al-WTR was reused to adsorb the macro-nutrient P from polluted soil leach and dairy wastewater (WW). Surficial P onto Al-WTR, SL-Al/O-WTR, and WW-Al/O-WTR (0.56, 0.93, and 2.15%, respectively) displayed sorption dynamics, mostly with Al and Ca. Quantification of the spatial proportions of individual elements and their associations indicated P-Al pool > P-Ca pool (45–24% and 17–7%, respectively). Upon introducing P-rich dairy wastewater, the behavior of P sorption by Al and Ca changed and became more clustered. A ternary phase of P-Al-Ca covered 38% of the area with signal, compared to 4.3 and 4.6% of the area in Al-WTR and SL-Al-WTR, where it was limited to particles edges only. Thus, the presented protocol may promote employing image analysis for geochemical applications, elucidating chemical behavior and affinities. Advantages and pitfalls are discussed.","PeriodicalId":73082,"journal":{"name":"Frontiers in environmental chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46211885","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-07-16DOI: 10.3389/fenvc.2021.653867
Xiaohang Lu, Zhe Ma, Lei Yi, Guangwu Zhang, Fuhong Chen, Feng-qing Han
The main objective of this study was to explore the composition and distribution of volatile organic compounds (VOCs) and the factors that affect their distribution in the salt lake sediments. Thirteen sediment samples were collected from a depth profile in the East Taijinar Lake, China. VOCs of different samples were extracted by headspace solid phase microextraction. Gas chromatography-ion mobility spectrometry, gas chromatography-mass spectrometry, and X-ray diffraction were used to analyze the VOCs, n-alkanes, and minerals present in samples. Thirty-four VOCs were identified and classified into seven types, including terpenes, furans, esters, aldehydes, ketones, alcohols, and acids, apart from six contaminants. It was found that 24 of the most prevalent compounds in clay were on average 101.45% higher than those in sandstone and halite because of the sedimentary environment, while the remaining ten (2-acetylfuran, 2-pinene D, etc.) were on average 13.27% higher in sandstone and halite sediments than in clay. This can be attributed to their different biological sources, porosity, and higher salinity. Based on the Q-cluster analysis, the 13 sediment samples were split into two groups, including the group according to composition and the group based on distribution of VOCs. In this study, it was found that the VOCs correlate positively with detrital minerals, with Group I exhibiting a high content of detrital minerals (>25%), while Group II showed the opposite characteristics. The consumption of organic matter (OM) by microorganisms leads to the formation of VOCs in sediment. The values of carbon preference index and n-alkane further demonstrate that the organic matter of the two groups came from different sources, exogenous and endogenous. Pr/Ph ratios, Pr/C17, and Pr/C18 also suggest that the OM in all sediments was strongly affected by microorganisms in an anoxic environment. Together, these results demonstrate that the OM from different biological sources and microbial activities played a critical role in deciding the composition and distribution of VOCs in the sediment. This study also shows that the proportion of VOCs in halite was discernably higher than that in clay and sandstone and that the content of VOCs should be considered when studying OM in salt lake sediments.
{"title":"The Composition and Distribution of Volatile Organic Compounds in Sediments of the East Taijinar Salt Lake in Northern Qinghai-Tibet Plateau","authors":"Xiaohang Lu, Zhe Ma, Lei Yi, Guangwu Zhang, Fuhong Chen, Feng-qing Han","doi":"10.3389/fenvc.2021.653867","DOIUrl":"https://doi.org/10.3389/fenvc.2021.653867","url":null,"abstract":"The main objective of this study was to explore the composition and distribution of volatile organic compounds (VOCs) and the factors that affect their distribution in the salt lake sediments. Thirteen sediment samples were collected from a depth profile in the East Taijinar Lake, China. VOCs of different samples were extracted by headspace solid phase microextraction. Gas chromatography-ion mobility spectrometry, gas chromatography-mass spectrometry, and X-ray diffraction were used to analyze the VOCs, n-alkanes, and minerals present in samples. Thirty-four VOCs were identified and classified into seven types, including terpenes, furans, esters, aldehydes, ketones, alcohols, and acids, apart from six contaminants. It was found that 24 of the most prevalent compounds in clay were on average 101.45% higher than those in sandstone and halite because of the sedimentary environment, while the remaining ten (2-acetylfuran, 2-pinene D, etc.) were on average 13.27% higher in sandstone and halite sediments than in clay. This can be attributed to their different biological sources, porosity, and higher salinity. Based on the Q-cluster analysis, the 13 sediment samples were split into two groups, including the group according to composition and the group based on distribution of VOCs. In this study, it was found that the VOCs correlate positively with detrital minerals, with Group I exhibiting a high content of detrital minerals (>25%), while Group II showed the opposite characteristics. The consumption of organic matter (OM) by microorganisms leads to the formation of VOCs in sediment. The values of carbon preference index and n-alkane further demonstrate that the organic matter of the two groups came from different sources, exogenous and endogenous. Pr/Ph ratios, Pr/C17, and Pr/C18 also suggest that the OM in all sediments was strongly affected by microorganisms in an anoxic environment. Together, these results demonstrate that the OM from different biological sources and microbial activities played a critical role in deciding the composition and distribution of VOCs in the sediment. This study also shows that the proportion of VOCs in halite was discernably higher than that in clay and sandstone and that the content of VOCs should be considered when studying OM in salt lake sediments.","PeriodicalId":73082,"journal":{"name":"Frontiers in environmental chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47717517","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-06-14DOI: 10.3389/fenvc.2021.693509
Weigang Liu, Ke-lin Li, Xi Hu, Xinjiang Hu, Ruibin Zhang, Qi Li
With increasing aquatic heavy metal pollution and eutrophication, using algae to prepare novel adsorbent materials for remediating heavy metal pollution has recently attracted research attention worldwide. However, microalgae biochar exhibits poor adsorption capacity in certain conditions, and little is known regarding microalgae biochar modification using chitosan. Chitosan has been previously used to directly modify microalgae biochar; however, in this study, chitosan is used to modify algae powder used to prepare biochar. Therefore, in this study, chitosan was used as a microalgae biochar modifier to enhance its applicability and adsorption capacity. Accordingly, two new types of microalgae biochars, chitosan-biochar (CTS-BC) and biochar-chitosan (BC-CTS), were developed as an adsorbent material using Clostridium and adding chitosan as a modifier at different stages of its preparation. These developed microalgae biochars were characterized using Brunauer–Emmett–Teller surface area,X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and scanning electron microscopy. The adsorption processes of these biochars can be well described by a pseudo-second-order kinetic model. Pb2+ was dominantly adsorbed by microalgal biochar through chemisorption. Following chitosan modification, several mino, cyano, and aromatic ring groups were attached onto the surface of the microalgal biochar. The Pb2+ adsorption capacity of the chitosan-modified biochar was better than that of the unmodified biochar. The maximum Pb2+ adsorption capacity of CTS-BC under acidic conditions (pH = 5) was 9.41 mg g−1, whereas that of BC-CTS under alkaline conditions (pH = 9) was 9.94 mg g−1, both were higher than that of unmodified microalgae biochar under similar conditions. CTS-BC and BC-CTS possessed excellent stability and reusability for Pb(II) adsorption, the adsorption efficiency still remained above 50% even after three cycles. This study demonstrated that adsorbent materials having a stronger heavy-metal adsorption capacity can be prepared by adding chitosan during different stages of the microalgae biochar preparation process.
{"title":"Characteristics and Mechanism of Pb2+ Adsorption From Aqueous Solution Onto Biochar Derived From Microalgae and Chitosan-Modified Microalgae","authors":"Weigang Liu, Ke-lin Li, Xi Hu, Xinjiang Hu, Ruibin Zhang, Qi Li","doi":"10.3389/fenvc.2021.693509","DOIUrl":"https://doi.org/10.3389/fenvc.2021.693509","url":null,"abstract":"With increasing aquatic heavy metal pollution and eutrophication, using algae to prepare novel adsorbent materials for remediating heavy metal pollution has recently attracted research attention worldwide. However, microalgae biochar exhibits poor adsorption capacity in certain conditions, and little is known regarding microalgae biochar modification using chitosan. Chitosan has been previously used to directly modify microalgae biochar; however, in this study, chitosan is used to modify algae powder used to prepare biochar. Therefore, in this study, chitosan was used as a microalgae biochar modifier to enhance its applicability and adsorption capacity. Accordingly, two new types of microalgae biochars, chitosan-biochar (CTS-BC) and biochar-chitosan (BC-CTS), were developed as an adsorbent material using Clostridium and adding chitosan as a modifier at different stages of its preparation. These developed microalgae biochars were characterized using Brunauer–Emmett–Teller surface area,X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and scanning electron microscopy. The adsorption processes of these biochars can be well described by a pseudo-second-order kinetic model. Pb2+ was dominantly adsorbed by microalgal biochar through chemisorption. Following chitosan modification, several mino, cyano, and aromatic ring groups were attached onto the surface of the microalgal biochar. The Pb2+ adsorption capacity of the chitosan-modified biochar was better than that of the unmodified biochar. The maximum Pb2+ adsorption capacity of CTS-BC under acidic conditions (pH = 5) was 9.41 mg g−1, whereas that of BC-CTS under alkaline conditions (pH = 9) was 9.94 mg g−1, both were higher than that of unmodified microalgae biochar under similar conditions. CTS-BC and BC-CTS possessed excellent stability and reusability for Pb(II) adsorption, the adsorption efficiency still remained above 50% even after three cycles. This study demonstrated that adsorbent materials having a stronger heavy-metal adsorption capacity can be prepared by adding chitosan during different stages of the microalgae biochar preparation process.","PeriodicalId":73082,"journal":{"name":"Frontiers in environmental chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46013057","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-06-14DOI: 10.3389/fenvc.2021.660058
M. Coulibaly, N. Mazrui, S. Jonsson, R. Mason
Monomethylmercury (CH3Hg) is a neurotoxic pollutant that biomagnifies in aquatic food webs. In sediments, the production of CH3Hg depends on the bacterial activity of mercury (Hg) methylating bacteria and the amount of bioavailable inorganic divalent mercury (HgII). Biotic and abiotic reduction of HgII to elemental mercury (Hg0) may limit the pool of HgII available for methylation in sediments, and thus the amount of CH3Hg produced. Knowledge about the transformation of HgII is therefore primordial to the understanding of the production of toxic and bioaccumulative CH3Hg. Here, we examined the reduction of HgII by sulfidic minerals (FeS(s) and CdS(s)) in the presence of dissolved iron and dissolved organic matter (DOM) using low, environmentally relevant concentrations of Hg and ratio of HgII:FeS(s). Our results show that the reduction of HgII by Mackinawite (FeS(s)) was lower (<15% of the HgII was reduced after 24 h) than when HgII was reacted with DOM or dissolved iron. We did not observe any formation of Hg0 when HgII was reacted with CdS(s) (experiments done under both acidic and basic conditions for up to four days). While reactions in solution were favorable under the experimental conditions, Hg was rapidly removed from solution by co-precipitation. Thermodynamic calculations suggest that in the presence of FeS(s), reduction of the precipitated HgII is surface catalyzed and likely involves S−II as the electron donor. The lack of reaction with CdS may be due to its stronger M-S bond relative to FeS, and the lower concentrations of sulfide in solution. We conclude that the reaction of Hg with FeS(s) proceeds via a different mechanism from that of Hg with DOM or dissolved iron, and that it is not a major environmental pathway for the formation of Hg0 in anoxic environments.
{"title":"Abiotic Reduction of Mercury(II) in the Presence of Sulfidic Mineral Suspensions","authors":"M. Coulibaly, N. Mazrui, S. Jonsson, R. Mason","doi":"10.3389/fenvc.2021.660058","DOIUrl":"https://doi.org/10.3389/fenvc.2021.660058","url":null,"abstract":"Monomethylmercury (CH3Hg) is a neurotoxic pollutant that biomagnifies in aquatic food webs. In sediments, the production of CH3Hg depends on the bacterial activity of mercury (Hg) methylating bacteria and the amount of bioavailable inorganic divalent mercury (HgII). Biotic and abiotic reduction of HgII to elemental mercury (Hg0) may limit the pool of HgII available for methylation in sediments, and thus the amount of CH3Hg produced. Knowledge about the transformation of HgII is therefore primordial to the understanding of the production of toxic and bioaccumulative CH3Hg. Here, we examined the reduction of HgII by sulfidic minerals (FeS(s) and CdS(s)) in the presence of dissolved iron and dissolved organic matter (DOM) using low, environmentally relevant concentrations of Hg and ratio of HgII:FeS(s). Our results show that the reduction of HgII by Mackinawite (FeS(s)) was lower (<15% of the HgII was reduced after 24 h) than when HgII was reacted with DOM or dissolved iron. We did not observe any formation of Hg0 when HgII was reacted with CdS(s) (experiments done under both acidic and basic conditions for up to four days). While reactions in solution were favorable under the experimental conditions, Hg was rapidly removed from solution by co-precipitation. Thermodynamic calculations suggest that in the presence of FeS(s), reduction of the precipitated HgII is surface catalyzed and likely involves S−II as the electron donor. The lack of reaction with CdS may be due to its stronger M-S bond relative to FeS, and the lower concentrations of sulfide in solution. We conclude that the reaction of Hg with FeS(s) proceeds via a different mechanism from that of Hg with DOM or dissolved iron, and that it is not a major environmental pathway for the formation of Hg0 in anoxic environments.","PeriodicalId":73082,"journal":{"name":"Frontiers in environmental chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46841351","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-05-14DOI: 10.3389/fenvc.2020.602426
Lu Shao
{"title":"Corrigendum: Grand Challenges in Emerging Separation Technologies","authors":"Lu Shao","doi":"10.3389/fenvc.2020.602426","DOIUrl":"https://doi.org/10.3389/fenvc.2020.602426","url":null,"abstract":"","PeriodicalId":73082,"journal":{"name":"Frontiers in environmental chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45472240","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-05-14DOI: 10.3389/fenvc.2021.660267
Xinyun Cui, C. Lamborg, C. R. Hammerschmidt, Yang Xiang, P. Lam
The downward flux of sinking particles is a prominent Hg removal and redistribution process in the ocean; however, it is not well-constrained. Using data from three U.S. GEOTRACES cruises including the Pacific, Atlantic, and Arctic Oceans, we examined the mercury partitioning coefficient, Kd, in the water column. The data suggest that the Kd varies widely over three ocean basins. We also investigated the effect of particle concentration and composition on Kd by comparing the concentration of small-sized (1–51 μm) suspended particulate mass (SPM) as well as its compositional fractions in six different phases to the partitioning coefficient. We observed an inverse relationship between Kd and suspended particulate mass, as has been observed for other metals and known as the “particle concentration effect,” that explains much of the variation in Kd. Particulate organic matter (POM) and calcium carbonate (CaCO3) dominated the Hg partitioning in all three ocean basins while Fe and Mn could make a difference in some places where their concentrations are elevated, such as in hydrothermal plumes. Finally, our estimated Hg residence time has a strong negative correlation with average log bulk Kd, indicating that Kd has significant effect on Hg residence time.
{"title":"The Effect of Particle Composition and Concentration on the Partitioning Coefficient for Mercury in Three Ocean Basins","authors":"Xinyun Cui, C. Lamborg, C. R. Hammerschmidt, Yang Xiang, P. Lam","doi":"10.3389/fenvc.2021.660267","DOIUrl":"https://doi.org/10.3389/fenvc.2021.660267","url":null,"abstract":"The downward flux of sinking particles is a prominent Hg removal and redistribution process in the ocean; however, it is not well-constrained. Using data from three U.S. GEOTRACES cruises including the Pacific, Atlantic, and Arctic Oceans, we examined the mercury partitioning coefficient, Kd, in the water column. The data suggest that the Kd varies widely over three ocean basins. We also investigated the effect of particle concentration and composition on Kd by comparing the concentration of small-sized (1–51 μm) suspended particulate mass (SPM) as well as its compositional fractions in six different phases to the partitioning coefficient. We observed an inverse relationship between Kd and suspended particulate mass, as has been observed for other metals and known as the “particle concentration effect,” that explains much of the variation in Kd. Particulate organic matter (POM) and calcium carbonate (CaCO3) dominated the Hg partitioning in all three ocean basins while Fe and Mn could make a difference in some places where their concentrations are elevated, such as in hydrothermal plumes. Finally, our estimated Hg residence time has a strong negative correlation with average log bulk Kd, indicating that Kd has significant effect on Hg residence time.","PeriodicalId":73082,"journal":{"name":"Frontiers in environmental chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42219365","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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