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Adsorption of fluoride on clay minerals and their mechanisms using X-ray photoelectron spectroscopy

Junyi DU, Daishe WU, Huayun XIAO, Ping LI

《环境科学与工程前沿（英文）》 2011年 第5卷 第2期   页码 212-226 doi: 10.1007/s11783-010-0255-5

摘要： This research investigates the adsorption mechanisms of fluoride (F) on four clay minerals (kaolinite, montmorillonite, chlorite, and illite) under different F concentrations and reaction times by probing their fluoride superficial layer binding energies and element compositions using X-ray photoelectron spectroscopy (XPS). At high F concentrations ( = 5–1000 mg·L ), the amount of F adsorbed ( ), amount of hydroxide released by clay minerals, solution F concentration, and the pH increase with increasing . The increases are remarkable at >50 mg·L . The increases significantly by continuously modifying the pH level. At <5–100 mg·L , clay minerals adsorb H to protonate aluminum-bound surface-active hydroxyl sites in the superficial layers and induce F binding. As the increases, F , along with other cations, is adsorbed to form a quasi-cryolite structure. At >100 mg·L , new minerals precipitate and the product depends on the critical Al concentration. At [Al ]>10 mol·L , cryolite forms, while at [Al ]<10 mol·L , AlF is formed. At low (0.3–1.5 mg·L ), proton transfer occurs, and the F adsorption capabilities of the clay minerals increase with time.

关键词： clay mineral     fluoride (F)     adsorption mechanism     X-ray photoelectron spectroscopy (XPS)    

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Removal of fluoride from water using titanium-based adsorbents

Zhijian LI, Shubo DENG, Xueying ZHANG, Wei ZHOU, Jun HUANG, Gang YU

《环境科学与工程前沿（英文）》 2010年 第4卷 第4期   页码 414-420 doi: 10.1007/s11783-010-0241-y

摘要： Three adsorbents including TiO , Ti-Ce, and Ti-La hybrid oxides were prepared to remove fluoride from aqueous solution. The Ti-Ce and Ti-La hybrid adsorbents obtained by the hydrolysis-precipitation method had much higher sorption capacity for fluoride than the TiO adsorbent prepared through hydrolysis. Rare earth (Ce and La) oxides and TiO exhibited a synergistic effect in the hybrid adsorbents for fluoride sorption. The sorption equilibrium of fluoride on the three adsorbents was achieved within 4 h, and the pseudo-second-order model described the sorption kinetics well. The sorption isotherms fitted the Langmuir model well, and the adsorption capacities of fluoride on the Ti-Ce and Ti-La adsorbents were about 9.6 and 15.1 mg·g , respectively, at the equilibrium fluoride concentration of 1.0 mg·L , much higher than the 1.7 mg·g on the TiO . The sorption capacities of fluoride on the three adsorbents decreased significantly when the solution pH increased from 3 to 9.5. The electrostatic interaction played an important role in fluoride removal by the three adsorbents, and Fourier transform infrared (FTIR) analysis indicated that the hydroxyl groups on the adsorbent surface were involved in fluoride adsorption.

关键词： fluoride adsorption     titanium dioxide     titanium-based adsorbent     sorption mechanism    

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Simultaneous removal of arsenate and fluoride from water by Al-Fe (hydr)oxides

Junlian QIAO, Zimin CUI, Yuankui SUN, Qinghai HU, Xiaohong GUAN

《环境科学与工程前沿（英文）》 2014年 第8卷 第2期   页码 169-179 doi: 10.1007/s11783-013-0533-0

摘要： Al-Fe (hydr)oxides with different Al/Fe molar ratios (4∶1, 1∶1, 1∶4, 0∶1) were prepared using a co-precipitation method and were then employed for simultaneous removal of arsenate and fluoride. The 4Al:Fe was superior to other adsorbents for removal of arsenate and fluoride in the pH range of 5.0–9.0. The adsorption capacity of the Al-Fe (hydr)oxides for arsenate and fluoride at pH 6.5±0.3 increased with increasing Al content in the adsorbents. The linear relationship between the amount of OH released from the adsorbent and the amount of arsenate or fluoride adsorbent by 4Al:Fe indicated that the adsorption of arsenate and fluoride by Al-Fe (hydr)oxides was realized primarily through quantitative ligand exchange. Moreover, there was a very good correlation between the surface hydroxyl group densities of Al-Fe (hydr)oxides and their adsorption capacities for arsenate or fluoride. The highest adsorption capacity for arsenate and fluoride by 4Al:Fe is mainly ascribed to its highest surface hydroxyl group density besides its largest pH . The dosage of adsorbent necessary to remove arsenate and fluoride to meet the drinking water standard was mainly determined by the presence of fluoride since fluoride was generally present in groundwater at much higher concentration than arsenate.

关键词： Al-Fe (hydr)oxides     groundwater     adsorption     hydroxyl group     ligand exchange    

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Poly(vinylidene fluoride--hexafluoro propylene) membranes prepared via thermally induced phase separation

《化学科学与工程前沿（英文）》 2022年 第16卷 第5期   页码 720-730 doi: 10.1007/s11705-021-2098-y

摘要： A non-toxic and environmentally safe diluent, acetyl tributyl citrate, was employed to prepare poly(vinylidene fluoride)-co-hexafluoropropylene membranes via thermally induced phase separation. Effects of the polymer concentration on the phase diagram, membrane morphology, hydrophobicity, pore size, porosity and mechanical properties (tensile stress and elongation at break) were investigated. The results showed that the pore size and porosity tended to decrease with increasing polymer concentration, whereas the contact angle, liquid entry pressure and mechanical properties showed the opposite trend. In direct contact membrane distillation operation with 3.5 wt-% sodium chloride solution as the feed solution, the prepared membranes performed high salt rejection (>99.9%). Furthermore, the prepared membranes retained excellent performance in long-term stability tests regarding the permeate flux and salt rejection.

关键词： poly(vinylidene fluoride)-co-hexafluoropropylene     thermally induced phase separation     non-toxic diluent     direct contact membrane distillation    

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Preparation and characterization of poly (vinylidene fluoride)/TiO

Weiying LI, Xiuli SUN, Chen WEN, Hui LU, Zhiwei WANG

《环境科学与工程前沿（英文）》 2013年 第7卷 第4期   页码 492-502 doi: 10.1007/s11783-012-0407-x

摘要： Poly(vinylidene fluoride) (PVDF)/titanium dioxide (TiO ) hybrid membranes were prepared using nano-TiO as the modifier, and characterized by Transmission Electron Microscope (TEM), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), atomic force microscope (AFM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The characterization results demonstrated that nano-sized TiO particles dispersed homogeneously within the PVDF matrix, contributing to more hydroxyls and smoother surfaces. Moreover, permeate flux, retention factor, porosity, contact angle and anti-fouling tests were carried out to evaluate the effect of TiO concentration on the performance of PVDF membranes. Among all the prepared membranes, PVDF/TiO membrane containing 10 vol.% TiO exhibited the best hydrophilicity with an average pure water flux up to 237 L·m ·h , higher than that of unmodified PVDF membranes (155 L·m ·h ). Besides, the bovine serum albumin rejection of the hybrid membrane was improved evidently from 52.3% to 70.6%, and the contact angle was significantly lowered from 83° to 60°, while the average pore size and its distribution became smaller and narrower.

关键词： poly(vinylidene fluoride) (PVDF) membrane     nano-TiO2     anti-fouling performance     water treatment    

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investigation of novel tetraphenylvinyl hydrazone derivatives: efficient multimodal chemosensors for fluoride

《化学科学与工程前沿（英文）》 2023年 第17卷 第12期   页码 2061-2073 doi: 10.1007/s11705-023-2366-0

摘要： Herein, three novel tetraphenylethylene hydrazone chemosensors TC12, SC16, and TC16 are prepared for the selective detection of F−. Two NH and one C=N units are incorporated into the sensors for better colorimetric responses, whereas the tetraphenyl unit is in charge of the aggregation-induced emission effect. Among them, compounds SC16 and TC16 form stable gels with some organic solvents. All the tetrahydrofuran/H2O solutions of the three compounds exhibit aggregation-induced emission effect, whereby the fluorescence emission increases by varying degrees with the volume of poor solvent water. Moreover, good aggregation-induced emission effects are observed in the self-assembly of SC16 and TC16. As a sample chemosensor, TC12 in tetrahydrofuran responds to F− selectively with high sensitivity, with the colorimetric and fluorometric detection limits of 8.25 × 10−7 mol·L–1 and 2.69 × 10−7 mol·L–1, respectively. The reversible gel-sol-gel phase transition and color changes indicate that both SC16-dimethyl sulfoxide and TC16-ethyl acetate gels specifically respond to F– with good sensitivity. The detection results are well supported by ultraviolet-visible spectroscopy, fluorescent spectroscopy, and 1H nuclear magnetic resonance. More importantly, the driving forces of gelation are visually clarified through the single crystal X-ray analysis of compound TOMe.

关键词： organogelator     tetraphenylvinyldrazone     single crystal     aggregation-induced emission effect     ion sensing    

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Pilot study for the treatment of sodium and fluoride-contaminated groundwater by using high-pressure

Xiaomao WANG,Hongwei YANG,Zhenyu LI,Shaoxia YANG,Yuefeng XIE

《环境科学与工程前沿（英文）》 2015年 第9卷 第1期   页码 155-163 doi: 10.1007/s11783-014-0740-3

摘要： High-pressure membrane process is one of the cost-effective technologies for the treatment of groundwater containing excessive dissolved solids. This paper reports a pilot study in treating a typical groundwater in Huaibei Plain containing excessive sodium, sulfate and fluoride ions. Three membrane systems were set up and two brands of reverse osmosis (RO), four low-pressure RO (LPRO) and one tight nanofiltration (NF) membranes were tested under this pilot study. An apparent recovery rate at about 75% was adopted. Cartridge filtration, in combination with dosing antiscalent, was not sufficient to reduce the fouling potential of the raw water. All RO and LPRO systems (except for the two severely affected by membrane fouling) demonstrated similar rejection ratios of the conductivity (~98.5%), sodium (~98.5%) and fluoride (~99%). Membrane fouling substantially reduced the rejection performance of the fouled membranes. The tight NF membrane also had a good rejection on conductivity (95%), sodium (94%) and fluoride (95%). All membranes rejected sulfate ion almost completely (more than 99%). The electricity consumptions for the RO, LPRO and NF systems were 1.74, 1.10 and 0.72 kWh?m treated water, respectively. The estimated treatment costs by using typical RO, LPRO and tight NF membrane systems were 1.21, 0.98 and 0.96 CNY?m finished water, respectively. A treatment process consisting of either LPRO or tight NF facilities following multi-media filtration was suggested.

关键词： reverse osmosis (RO)     nanofiltration (NF)     water quality standards     sodium     fluoride     cost estimation    

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Fluoride ions adsorption from water by CaCO enhanced Mn–Fe mixed metal oxides

《化学科学与工程前沿（英文）》 2023年 第17卷 第2期   页码 236-248 doi: 10.1007/s11705-022-2193-8

摘要： Novel CaCO3-enhanced Mn–Fe mixed metal oxides (CMFC) were successfully prepared for the first time by a simple-green hydrothermal strategy without any surfactant or template combined with calcination process. These oxides were then employed as an adsorbent for adsorptive removal of excess fluoride ions. The adsorbent was characterized by SEM, XPS, XRD, FTIR, and BET analysis techniques. The adsorption property of CMFC toward fluoride ion was analyzed by batch experiments. In fact, CMFC exhibited adsorption capacity of 227.3 mg∙g‒1 toward fluoride ion. Results showed that ion exchange, electrostatic attraction and chemical adsorption were the main mechanism for the adhesion of large amount of fluoride ion on the CMFC surface, and the high adsorption capacity responded to the low pH of the adsorption system. When the fluoride ion concentration was increased from 20 to 200 mg∙L‒1, Langmuir model was more in line with experimental results. The change of fluoride ion adsorption with respect to time was accurately described by pseudo-second-order kinetics. After five cycles of use, the adsorbent still maintains a performance of 70.6% of efficiency, compared to the fresh adsorbent. Therefore, this material may act as a potential candidate for adsorbent with broad range of application prospects.

关键词： mesoporous materials     metal oxides     fluoride ion     adsorption mechanism    

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Utilization of aluminum hydroxide waste generated in fluoride adsorption and coagulation processes for

Jiawei JU,Ruiping LIU,Zan HE,Huijuan LIU,Xiwang ZHANG,Jiuhui QU

《环境科学与工程前沿（英文）》 2016年 第10卷 第3期   页码 467-476 doi: 10.1007/s11783-015-0809-7

摘要： Although Al-based coagulation and adsorption processes have been proved highly efficient for fluoride (F) removal, the two processes both generate large amount of Al(OH) solid waste containing F (Al(OH) -F). This study aimed to investigate the feasibility of utilizing Al(OH) -F generated in Al(OH) adsorption (Al(OH) -F ) and coagulation (Al(OH) -F ) for the adsorption of cadmium ion (Cd(II)). The adsorption capacity of Al(OH) -F and Al(OH) -F for Cd(II) was similar as that of pristine aluminum hydroxide (Al(OH) ), being of 24.39 and 19.90 mg·g , respectively. The adsorption of Cd(II) onto Al(OH) -F and Al(OH) -F was identified to be dominated by ion-exchange with sodium ion (Na ) or hydrogen ion (H ), surface microprecitation, and electrostatic attraction. The maximum concentration of the leached fluoride from Al(OH) -F and Al(OH) -F is below the Chinese Class-I Industrial Wastewater Discharge Standard for fluoride (<10 mg·L ). This study demonstrates that the Al(OH) solid wastes generated in fluoride removal process could be potentially utilized as a adsorbent for Cd(II) removal.

关键词： Al(OH)3     fluoride     cadmium     adsorption     reclamation     sequential extraction    

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Pressure drop analysis on the positive half-cell of a cerium redox flow battery using computational fluid dynamics: Mathematical and modelling aspects of porous media

Fernando F. Rivera, Berenice Miranda-Alcántara, Germán Orozco, Carlos Ponce de León, Luis F. Arenas

《化学科学与工程前沿（英文）》 2021年 第15卷 第2期   页码 399-409 doi: 10.1007/s11705-020-1934-9

摘要： Description of electrolyte fluid dynamics in the electrode compartments by mathematical models can be a powerful tool in the development of redox flow batteries (RFBs) and other electrochemical reactors. In order to determine their predictive capability, turbulent Reynolds-averaged Navier-Stokes (RANS) and free flow plus porous media (Brinkman) models were applied to compute local fluid velocities taking place in a rectangular channel electrochemical flow cell used as the positive half-cell of a cerium-based RFB for laboratory studies. Two different platinized titanium electrodes were considered, a plate plus a turbulence promoter and an expanded metal mesh. Calculated pressure drop was validated against experimental data obtained with typical cerium electrolytes. It was found that the pressure drop values were better described by the RANS approach, whereas the validity of Brinkman equations was strongly dependent on porosity and permeability values of the porous media.

关键词： CFD simulation     porous media     porous electrode     pressure drop     redox flow battery    

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Development of soft kernel durum wheat

Craig F. MORRIS

《农业科学与工程前沿（英文）》 2019年 第6卷 第3期   页码 273-278 doi: 10.15302/J-FASE-2019259

摘要：

Kernel texture (grain hardness) is a fundamental and determining factor related to wheat ( spp.) milling, baking and flour utilization. There are three kernel texture classes in wheat: soft and hard hexaploid ( ), and very hard durum ( subsp. ). The genetic basis for these three classes lies with the Puroindoline genes. Phenotypically, the easiest means of quantifying kernel texture is with the Single Kernel Characterization System (SKCS), although other means are valid and can provide fundamental material properties. Typical SKCS values for soft wheat would be around 25 and for durum wheat≥80. Soft kernel durum wheat was created via homeologous recombination using the mutation, which facilitated the transfer of ca. 28 Mbp of 5DS that replaced ca. 21 Mbp of 5BS. The 5DS translocation contained a complete and intact locus and both puroindoline genes. Expression of the puroindoline genes in durum grain resulted in kernel texture and flour milling characteristics nearly identical to that of soft wheat, with high yields of break and straight-grade flours, which had small particle size and low starch damage. Dough water absorption was markedly reduced compared to durum flour and semolina. Dough was essentially unchanged and reflected the inherent gluten properties of the durum background. Pasta quality was essentially equal-to-or-better than pasta made from semolina. Agronomically, soft durum germplasm showed good potential with moderate grain yield and resistance to a number of fungal pathogens and insects. Future breeding efforts will no doubt further improve the quality and competitiveness of soft durum cultivars.

关键词： soft durum wheat     grain hardness     puroindolines     milling     baking     pasta     noodles    

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dimensional lycopodium with hydrophobic nature and interconnected nano-channels into polyvinylidene fluoride

《化学科学与工程前沿（英文）》 2023年 第17卷 第9期   页码 1162-1182 doi: 10.1007/s11705-022-2276-6

摘要： In the present research, for the first time, lycopodium as a novel nanofiller was incorporated into a polyvinylidene fluoride matrix to fabricate lycopodium/polyvinylidene fluoride flat-sheet membrane for desalination applications by vacuum membrane distillation process. The prepared lycopodium/polyvinylidene fluoride membranes and lycopodium were characterized by field emission scanning electron microscopy, X-ray diffraction, Fourier transform infrared, energy dispersive X-ray, and mapping analyses. Water contact angle and liquid entry pressure measurements were also performed. Response surface methodology was applied to optimize membrane structure and performance. The optimized lycopodium/polyvinylidene fluoride membrane exhibits superior performance compared to the neat polyvinylidene fluoride membrane in terms of flux, salt rejection, water contact angle, and hydrophobicity. In vacuum membrane distillation experiments, using a 15000 ppm NaCl solution as a feed at 70 °C, the neat polyvinylidene fluoride membrane, optimum membrane, and agglomerated membrane (with high lycopodium loading) demonstrated 3.80, 25.20, and 14.83 LMH flux and 63.30%, 99.99%, 99.96% salt rejection, respectively. This improvement in flux and salt rejection of the optimized membrane was related to the presence of lycopodium with hydrophobic nature and interconnected nano-channels in membrane structure. It was found that lycopodium, as the most hydrophobic material, effectively influences the membrane performance and structure for membrane distillation applications.

关键词： lycopodium     hydrophobicity     vacuum membrane distillation     desalination    

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组织工程模板中的生物相容性途径 Perspective

David F. Williams

《工程（英文）》 2018年 第4卷 第2期   页码 286-290 doi: 10.1016/j.eng.2018.03.007

摘要：

组织工程通过系统结合分子信号和力学信号对特定靶细胞进行有意可控刺激以组建新的组织，通常需要借助由生物材料构建的结构传递这些信号，并对生成的组织块塑形。这些结构之前被称为支架，如今被更准确地命名为模板，其规范却难以定义，主要因为该规范必须涉及为细胞组建新组织提供适宜的微环境，以及细胞与模板材料的相互作用符合构建新型可存活组织的需求。这些特点统称为生物相容性。然而，传统生物相容性的理论和公认机制（大多通过可移植的医学装置进行实验得出）不足以解释在组织工程过程中的现象。本文作者近期在特定的基于材料、生物学的途径方面重新定义了生物相容性。本文以上述途径为前提讨论了组织工程生物相容性的机制。

关键词： 生物材料     支架     机械力转导     炎症     拓扑    

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Resistance of large deformation of the Wushaoling Tunnel F7 soft fault

ZHAO Xufeng, CHEN Haiming, WANG Chunmiao

《结构与土木工程前沿（英文）》 2007年 第1卷 第1期   页码 123-127 doi: 10.1007/s11709-007-0013-3

摘要： In this article, the mechanical characteristics of the squeeze of the F7 fault of the Wushaoling Tunnel are analyzed. The measurements and techniques are proposed to resist the deformation. The result indicates that the method of construction to control the further squeeze deflection is appropriate.

关键词： F7     deformation     appropriate     construction     mechanical    

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标题 作者 时间 类型 操作

Adsorption of fluoride on clay minerals and their mechanisms using X-ray photoelectron spectroscopy

Junyi DU, Daishe WU, Huayun XIAO, Ping LI

期刊论文

Removal of fluoride from water using titanium-based adsorbents

Zhijian LI, Shubo DENG, Xueying ZHANG, Wei ZHOU, Jun HUANG, Gang YU

期刊论文

Simultaneous removal of arsenate and fluoride from water by Al-Fe (hydr)oxides

Junlian QIAO, Zimin CUI, Yuankui SUN, Qinghai HU, Xiaohong GUAN

期刊论文

Poly(vinylidene fluoride--hexafluoro propylene) membranes prepared via thermally induced phase separation

期刊论文

Preparation and characterization of poly (vinylidene fluoride)/TiO

Weiying LI, Xiuli SUN, Chen WEN, Hui LU, Zhiwei WANG

期刊论文

investigation of novel tetraphenylvinyl hydrazone derivatives: efficient multimodal chemosensors for fluoride

期刊论文

Distribution, enrichment mechanism and risk assessment for fluoride in groundwater: a case study of Mihe-Weihe

期刊论文

Pilot study for the treatment of sodium and fluoride-contaminated groundwater by using high-pressure

Xiaomao WANG,Hongwei YANG,Zhenyu LI,Shaoxia YANG,Yuefeng XIE

期刊论文

Fluoride ions adsorption from water by CaCO enhanced Mn–Fe mixed metal oxides

期刊论文

Utilization of aluminum hydroxide waste generated in fluoride adsorption and coagulation processes for

Jiawei JU,Ruiping LIU,Zan HE,Huijuan LIU,Xiwang ZHANG,Jiuhui QU

期刊论文

Pressure drop analysis on the positive half-cell of a cerium redox flow battery using computational fluid dynamics: Mathematical and modelling aspects of porous media

Fernando F. Rivera, Berenice Miranda-Alcántara, Germán Orozco, Carlos Ponce de León, Luis F. Arenas

期刊论文

Development of soft kernel durum wheat

Craig F. MORRIS

期刊论文

dimensional lycopodium with hydrophobic nature and interconnected nano-channels into polyvinylidene fluoride

期刊论文

组织工程模板中的生物相容性途径

David F. Williams

期刊论文

Resistance of large deformation of the Wushaoling Tunnel F7 soft fault

ZHAO Xufeng, CHEN Haiming, WANG Chunmiao

期刊论文