ENVIRONMENTAL RESEARCH
·
2024
·
IF 7.7
Wenhao Wang,Xingyu Wang,Xuechen Wu,Jinhua Zhang,Hejie Qin,Jinxiang Li
Nanoscale zerovalent iron (nZVI) has been extensively applied in water pollution control. However, the reactivity of nZVI toward contaminants is mainly limited by its corrosion and agglomeration. In this study, the nZVI modified by sulfidation coupled with carboxymethyl cellulose (CMC) (C-S-nZVI) was synthesized and characterized by TEM and electrochemical techniques. Taking Cr(VI) as the contaminant, it was found that the sulfidation could couple with CMC modification to not only enhance the reactivity of nZVI toward Cr(VI), but also regulate the sedimentation activity and corrosion activity of nZVI in water. Particularly, the optimal k obs (0.0816 min −1 ) obtained by the C-S-nZVI one -0.16 (i.e., one-step sulfidation and its S/Fe molar ratio was 0.16) was approximately 27.2 times higher than that by the nZVI (0.0030 min −1 ). Moreover, based on the correlation analysis of the ternary activities, this study confirmed that the reactivity of C-S-nZVI toward Cr(VI) was negatively correlated with its sedimentation activity (slope = −0.7623, R = 0.59) and corrosion activity (slope = −0.0171, R = 0.56), respectively. XPS and TEM results further revealed that CMC could couple with iron sulfides (FeS x ) to enhance the mass transfer of Cr(VI) toward nZVI and subsequent electron transfer from Fe 0 core to out, ultimately improving the reduction of Cr(VI) by nZVI. Overall, this study introduced a new evaluation method based on the ternary activity of nZVI, providing theoretical support for the practical application of nZVI-based technology.
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高影响因子
CHEMICAL GEOLOGY
·
2025
·
IF 3.6
Changjin Liang,Honghai Wu,Yaowei Li,Yufeng Guan
Ferrihydrite (Fh) can usually transform into phases with higher crystallinities. This may greatly alter Fh adsorption capacity for chromium ions, thereby affecting their immobilizations and fates. Foreign elements [e.g., lanthanum (La)] as impurities can become incorporated into Fh. Herein, the effect of La-substitution into Fh and the influence of the presence of Cr(VI) on Fh phase transformation and fate of Cr(VI) were investigated. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Electro-chemical impedance spectroscopy (EIS), and X-ray photoelectron spectroscopy (XPS) and other test methods were employed to probe phase changes after the Fe(II)-induced La-substituted Fh (La-Fh) transformations. At pH 5.5, no neoformed phase was observed until 7 d for La-Fh or pure Fh at 1 mM Fe(II) aq, but all La-Fh systems underwent transformations at 5 mM Fe(II)aq. A low pH and Fe(II)aq level favored lepidocrocite (Lp) to form, whereas goethite (Gt) was the predominant phase rather than Lp as pH increased to 7.2 with higher level Fe(II)aq. However, the La-substitution inhibits the La-Fh transformation rate and path. This made 5 % La-Fh transformed to Lp after 30 d at pH 7.2 and 1 mM Fe(II)aq. The La-release was present to some extent during the transformation process. Either the inhibition to La-Fh transformation or the La-slow release favors the retention of early-adsorbed Cr(VI) on iron-mineral surface. The added Cr(VI) might promote the La-Fh transformation even under a lower-level Fe(II), primarily attributed to the rapid reduction of Cr(VI) to Cr(III) by Fe(II), which produced more liable Fe(III) in addition to the Cr(III) that can improve the mineral conductivity, thereby enhancing the La-Fh transformation. Mechanisms responsible for the Fe(II)-induced La-Fh transformation companying the La slow-release are proposed to provide insights into the reduction and immobilization of Cr(VI) under anaerobic conditions, thus demonstrating that La-Fh is a promising material for application in Cr-contaminated site remediation.
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JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS
·
2025
·
IF 4.9
Nannan Huang,Shuhao Liang,Xiangyang Liang,Huining Chai,Yingjie Sun,Lili Lyu,Weiqiang Tan
The interfacial compatibility of heterojunction photocatalysts critically governs the interaction modes between constituent materials. Herein, a flower-like Bi-BDC-NH 2 /Ag 2 CO 3 heterostructure was fabricated via a simple ion-exchange solution method, serving as a robust photocatalyst for the efficient photocatalytic reduction of Cr(VI) in simulated wastewater under visible-light irradiation. Ag 2 CO 3 nanosheets were in-situ grown on the surface of three-dimensional Bi-BDC-NH 2 , forming an Ag 2 CO 3 -on-Bi-BDC-NH 2 type II heterojunction that establishes intimate interfacial contact, significantly accelerating the charge and mass transport dynamics. In comparison with pure Bi-BDC-NH 2 and Ag 2 CO 3 , the optimal Bi-BDC-NH 2 /Ag 2 CO 3 -50 (with a weight ratio of 0.5:1) exhibited dramatically enhanced photocatalytic activity, achieving 99% Cr(VI) reduction within 2 hours under visible light (>420 nm, 150 W xenon lamp). Mechanistic investigations, including energy band structure analysis, radical trapping experiments, and photoelectrochemical measurements, revealed that the heterojunction interface significantly promotes the separation and transfer of photogenerated electron-hole pairs. This work provides valuable insights into the rational design of MOF-based heterojunction photocatalysts and their applications in environmental remediation.
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DALTON TRANSACTIONS
·
2025
·
IF 3.3
Yanjia Zhou,Xiao-Dong Tang,Jingjing Li,Da-Yong Qing,Hong Wang
MIL-101(Cr) and MIL-100(Fe) are both representative MIL-type Metal-Organic-Frameworks (MOFs) materials, renowned for their large specific surface areas and size-tunable characteristics, making them suitable candidates for Li+ extraction from lithium-containing solvent. By introducing -NH2 functional groups and using LiNO3 as both a template and mineralizer, the functionalized MOF materials Li/NH2/MIL-101(Cr) and Li/NH2/MIL-100(Fe) were synthesized. Following modification, their Li+ adsorption capacities were increased, reaching 43.58 and 38.22 mg/g, respectively. The dosage of mineralizer, initial Li+ concentration, adsorbent dosage, solution pH value, and temperature all have an impact on the adsorption capacity of adsorbents. In addition, through the establishment of the pseudo-first-order kinetic model, pseudo-second-order kinetic model, as well as Langmuir and Freundlich thermodynamic models, it can be known that the adsorption of the materials belonged to monolayer chemisorption, and the adsorption process was exothermic. Furthermore, both adsorbents showed good reusability, retaining over 85% of their initial adsorption capacity after four adsorption-desorption cycles, highlighting their practical applicability in lithium recovery processes. In Mg-Li mixed solution systems, both materials exhibited exceptional Li+ selectivity. At a low Mg2+/Li+ ratio of 3, the separation factor (α) exceeded 80; even at a high Mg2+/Li+ ratio of 10, α remained near 50. Additionally, in systems with coexistence of multiple interfering ions, the distribution coefficient (Kd) followed the order: Li+ ≫ Mg2+ > Ca2+ > Na+ > K+. In the mixed systems, Li/NH2/MIL-101(Cr) and Li/NH2/MIL-100(Fe) exhibited certain separation effect for Li+ against competing cations.
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高影响因子
FUEL
·
2025
·
IF 7.5
Ying Li,Haibo Zhao
Ethylene production via chemical looping oxidative dehydrogenation (CL-ODH) of ethane faces a critical challenge in balancing conversion efficiency and selectivity due to competing oxygen species requirements. Here, we present a bifunctional composite catalyst (CrH/BiCZ) by physically integrating a Cr-HZSM5 (Cr-H) dehydrogenation (DH) catalyst with a Bi 2 O 3 -Ce 0.4 Zr 0.6 O 2 (Bi-CZ) selective hydrogen combustion (SHC) catalyst. This tandem system decouples ethane activation and hydrogen combustion, promoting the DH process of ethane through the in situ hydrogen combustion of the SHC catalyst. The Ce-Zr solid solution in Bi-CZ acts as an oxygen reservoir, enabling complete H 2 combustion within 3 min and suppressing carbon deposition. This rapid hydrogen combustion shifts the reaction equilibrium towards ethylene production. At 650 °C, the optimized CrH/BiCZ catalyst achieves 84.1 % ethylene selectivity at 43.0 % ethane conversion, and maintains exceptional stability over 36 redox cycles. This work establishes a scalable chemical looping strategy for efficient ethylene synthesis.
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JOURNAL OF HAZARDOUS MATERIALS
·
2025
·
IF 11.3
Shikai Li,Hanbing Gao,Rui Xu,Zhaohui Guo
Cation and oxyanion heavy metals possess opposite physical and chemical properties, which could be hard to simultaneous remediate in soil. In this study, layered double hydroxides from secondary aluminum ash (SAA-LDH) has been synthesized for soil remediation contaminated with heavy metals. The as-obtained SAA-LDH exhibit strong affinity for heavy metals, which could remove 193.50 mg‧g −1 of Cr(Ⅵ) and 175.84 mg‧g −1 of Cd(Ⅱ) within 2 h. Optimum acid-base resistance and selectivity guarantee the practice potential of SAA-LDH, which could remove above 85 % of Cd(Ⅱ) and Cr(Ⅵ) under widely pH range (from 4.00 to 10.00), capturing above 90 % of Cd(Ⅱ) and Cr(Ⅵ) under the interference of seven coexisting ions. Soil remediation tests and column leaching experiments further demonstrate that SAA-LDH could immobilize 98.32 % of Cd(Ⅱ) and 97.71 % of Cr(Ⅵ), preventing its migration. Density functional theory (DFT) manifests that SAA-LDH could remove Cd(Ⅱ) and Cr(Ⅵ) through isomorphic substitution and ion exchange respectively under single system. Under compound system, Cd(Ⅱ) fixed with isomorphic substitution could promote the immobilization of Cr(Ⅵ) onto SAA-LDH, constructing hyper-stable coordination structure. This study provides an effective approach to simultaneously recycle hazardous waste and remediate heavy metals contamination in soil.
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高影响因子
LANGMUIR
·
2025
·
IF 3.9
Dongfang Wang,Jie Wu,Ruohan Li,Xianghai Kong,Pan Zhao,Yanping Zhu,Zerong Song,Jinjing Xu,Ziyu You,Yuhao Wang,Qingchuan Wu,Dongqing Cai
White pollution, excessive heavy metals, and fertilizer leaching have become key issues restricting the development of agriculture. In this work, we prepared multifunctional starch mulch film (SMF/MAP/FeS) by loading ferrous sulfide (FeS) and monoammonium phosphate (MAP) onto commercial starch mulch film using poly(vinyl alcohol) for bonding. The removal efficiencies of Pb(II)/Cr(VI) for SMF/MAP/FeS could reach 97% and 93% in the aqueous solution. The adsorption isotherm, thermodynamic, and kinetics studies indicated that the adsorption process was an endothermic multimolecular-layer chemisorption. The main removal mechanisms for Pb(II)/Cr(VI) of SMF/MAP/FeS were precipitation and redox reactions. In addition, SMF/MAP/FeS not only possessed great thermal insulation and moisturizing properties but also could realize the slow release of NH4+. Furthermore, the maximum release rate of NH4+ for SMF/MAP/FeS could reach 93.4% during Pb(II)/Cr(VI) removal. At the same time, SMF/MAP/FeS has a good degradability at 50 d. A pot experiment indicated that SMF/MAP/FeS had a detoxifying effect on the Pb(II)/Cr(VI)-contaminated soil to promote the growth of pakchoi. Therefore, this study not only solves the problem of plastic and heavy metal pollution but also realizes the slow release of nutrients.
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ACS Applied Materials & Interfaces
·
2022
·
IF 10.383
Shihai Miao,Yanjie Liang,Dongxun Chen,Ruiqi Shi,Xihui Shan,Yi Zhang,Fei Xie,Xiao-Jun Wang
Infrared-emitting phosphor-converted light-emitting diodes (LEDs) are desirable light sources for a very wide range of applications such as spectroscopy analysis, nondestructive monitoring, covert information identification, and night-vision surveillance. The most important aspect of infrared emitters for spectroscopy is to cover the widest possible wavelength range of emitted light. However, developing ultrabroad-band infrared emitters based on converter technology is still a challenging task due to the lack of suitable phosphor materials that emit in a wide wavelength range upon excitation from blue-emitting chips. Herein, this work demonstrates Cr3+-activated Mg2SiO4 infrared phosphors with a super wide infrared spectral range of 600 to 1400 nm and high internal quantum yield up to 80.4% upon 460 nm excitation. Site-selective occupancy of Cr3+ emitters in two different Mg sites in the Mg2SiO4 lattice results in two distinct broad emission bands peaking at 760 and 970 nm, both of which contribute to the ultrabroad-band infrared luminescence with a full width at half maximum (FWHM) of 419 nm. This is by far the broadest infrared emission to the best of our knowledge. On this basis, an ultrabroad-band infrared LED prototype has been fabricated by the combination of the Mg2SiO4:Cr3+ phosphor with a blue LED chip, which shows great potential for imaging and sensing applications. This work demonstrates that site-selective occupancy control of Cr ions is an effective strategy for developing ultrabroad-band Cr3+-doped phosphors.
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WATER AIR AND SOIL POLLUTION
·
2017
·Vol. 228
·期 8
·1-17
·
IF 1.702
Zeng Anrong,Zeng Anran
In this paper, quaternized β-cyclodextrin–montmorillonite composite (QCD-MMT) was obtained and absorption properties of Cr(VI), methyl orange and p-nitrophenol were studied. QCD was prepared by 2,3-epoxypropyltrimethylammonium chloride and β-cyclodextrin (β-CD). QCD-MMT was obtained by reaction between QCD and montmorillonite suspensions, which could be attributed to the montmorillonite cation ion exchange properties. β-CD cavities of this composite were expected to capture organic molecules through inclusion, while montmorillonite units acted as the adsorption sites for metals. QCD-MMT was characterized by FT-IR, elemental analysis, XRD, SEM-EDX, and TGA. Adsorptions of Cr(VI), methyl orange, and p-nitrophenol were highly dependent on adsorbent dose, initial concentration, temperature, contact time, and pH. Adsorption kinetics of Cr(VI), methyl orange, and p-nitrophenol followed the pseudo-second-order model. Meanwhile, adsorption of Cr(VI) fit better in the Freundlich model, inferring a multilayer adsorption, while the adsorption of methyl orange and p-nitrophenol fit better in Langmuir model, inferring a monolayer adsorption. Thermodynamic analysis showed that the adsorptions were all endothermic process and could be spontaneous at given temperature range, except for Cr(VI), of which adsorption should be at much higher temperature. Overall, QCD-MMT exhibited potential for practical applications in the treatment of both metal ions and organic pollutants.
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SEPARATION AND PURIFICATION TECHNOLOGY
·
2022
·
IF 9.136
Xiong Tao,Fengxi Chen,Jun Li,Yunling Liu,Xiaowu Hu,Rong Chen
Emerging Bi 2 S 3 -based nanotechnology has great potential in Cr(VI)-contaminated wastewater treatment . In this work, it was found for the first time that Bi 2 S 3 nanoparticles (BS-D) prepared from dual sulfur sources of L-cysteine and ammonium sulfide efficiently promoted Cr(VI) removal with excellent selectivity for simultaneous removal of Cr(VI) and Cu 2+ from aqueous solutions containing various co-existing ions (including Na + , K + , Ca 2+ , Zn 2+ , Ni 2+ , Cd 2+ , NO 3 – , SO 4 2− and Cl − ) at pH > 3, preferably at pH of 4.5. Besides, BS-D had stable performance for co-removal of Cr(VI) and Cu 2+ in five recycling tests. Kinetic and thermodynamic studies indicated that the adsorption of Cr(VI) or Cu 2+ by BS-D was a spontaneous endothermic process and conformed to pseudo-second-order kinetic model. The adsorbed Cr(VI) ions were partially reduced to Cr(III), which were leached into the solution at pH ≤ 3, inhibiting the adsorption of Cu 2+ on BS-D and its promotional effect on Cr(VI) removal by BS-D. The mutual promotional effects between Cu 2+ and Cr(VI) during their co-removal by BS-D were ascribed to electrostatic attraction between HCrO 4 − and Cu 2+ and smaller pH variation in mixed Cr(VI)-Cu 2+ solutions. Finally, potential applications of BS-D were demonstrated by co-removal of Cr(VI) and Cu 2+ from real electroplating wastewater and contaminated groundwater. This work provided a promising BS-D adsorbent for Cr(VI)-contaminated wastewater treatment, and shed insight on the influence of Cu 2+ on the Cr(VI) removal by BS-D.
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WATER RESEARCH
·
2022
·
IF 13.4
Jingli Ren,Yutong Liu,Weimin Cao,Liyang Zhang,Fen Xu,Juan Liu,Yubo Wen,Jian Xiao,Lei Wang,Xiaoxiong Zhuo,Junfeng Ji,Yuanyuan Liu
Sediment-associated Fe(II) is a critical reductant for immobilizing groundwater contaminants, such as Cr(VI). The reduction reactivity of sediment-associated Fe(II) is dependent on its binding environment and influenced by the biogeochemical transformation of other elements (i.e., C, N and Mn), challenging the description and prediction of the reactivity of Fe(II) in natural sediments. Here, anaerobic batch experiments were conducted to study the variation in sediment-associated Fe(II) reactivity toward Cr(VI) in natural sediments collected from an intensive agricultural area located in Guangxi, China, where nitrate is a common surface water and groundwater contaminant. Then, a process-based model was developed to describe the coupled biogeochemical processes of C, N, Mn, Fe, and Cr. In the process-based model, Cr(VI) reduction by sediment-associated Fe(II) was described using a previously developed multirate model, which categorized the reactive Fe(II) into three fractions based on their extractabilities in sodium acetate and HCl solutions. The experimental results showed that Fe(II) generation was inhibited by NO 3 - and/or NO 2 − . After NO 3 − and NO 2 − were exhausted, the Fe(II) content and its reduction rate toward Cr(VI) increased rapidly. As the Fe(II) content increased, the three reactive Fe(II) fractions exhibited approximately linear correlations with aqueous Fe(II) concentrations ( C F e 2 + ), which was probably driven by sorptive equilibrium and redox equilibrium between aqueous and solid phases. The model results indicated that the reaction rate constants of the three Fe(II) fractions ( k n ) significantly increased with incubation time, and log( k n ) correlated well with C F e 2 + [ log ( k 1 ) = 2.84 C F e 2 + − 0.17 , log ( k 2 ) = 5.90 C F e 2 + − 2.49 and log ( k 3 ) = 3.09 C F e 2 + − 3.37 ]. The numerical model developed in this study provides an applicable method to describe and predict Cr(VI) removal from groundwater under dynamic redox conditions .
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Journal of Environmental Chemical Engineering
·
2022
·
IF 7.968
Chengcheng Shen,Li Gu,Sihao Chen,Yajuan Jiang,Peng Huang,Heng Li,Huayang Yu,Dong Xia
Effective utilization and resourcelization of sewage sludge into value-added by-products and insights into its environmental impacts during the fabrication process are urgent tasks to be tackled. Here, we adopt FeCl 3 to activate and functionalize sewage sludge to form FeCl 3 -activated biochars, which exhibited high adsorption capabilities for the treatment of toxic As(III) and Cr(VI) containing wastewaters. Kinetic studies suggested that the adsorption of As(III) and Cr(VI) species onto the biochar surface was attributed to physisorption and chemosorption, respectively. Equilibrium was reached after 3 h for the adsorption of Cr(VI), and slightly slower for that of As(III). Additionally, the structural stability of the adsorbent was maintained even in wastewater with high acidity (pH = 1), as corroborated by microscopic observations. Structural characterization of the adsorbents after adsorption showed that the excellent adsorption performance originated from adsorptive functionalities of the surface functional groups and the active Fe 3 O 4 particles forming Fe-O-As(III)/Fe-O-Cr(VI) complexes with the As(III)/Cr(VI) adsorbates. Evaluation via the green degree method demonstrated that transforming sewage sludge into biochar exerts very low impacts on the environment. Hence, this work offers a green alternative to convert the hazardous sewage sludge into value-added biochar materials, which can be further exploited as supporting frameworks for multifunctional catalysts or expanded to be investigated in reducing carbon footprints and energy conversion areas.
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