SCIENCE OF THE TOTAL ENVIRONMENT
·
2022
·
IF 10.753
Jianzhang Gao,Jiadong Wang,Jiaqi Chen,Shitao Liao,Meng Cao,Fuqiu Ma,Yun Xue,Yongde Yan
Electrochemical techniques are considered promising applications to immobilize uranium in alkaline wastewater in order to prevent its migration into groundwater and soil. In this work, the results of electrochemical and Atomic Force Microscope (AFM) demonstrate a successful immobilization of uranyl in the carbonate system by U(VI)-U(V), U(V)-U(IV) reduction, and U(V) disproportionation reactions. The results indicated that the electrochemical fixation rate in alkaline system could reach more than 99%. The valence state of uranium is the key factor affecting its migration in the working system. Where, the analysis of the immobilized samples by X-ray photoelectron spectroscopy (XPS) revealed that pHs, current density, and the presence of foreign cations significantly affect the valence state of uranium in the immobilized samples. Under same conditions, the reduction reactions of U(VI)-U(V) and U(V)-U(IV) occurred easily. Where, at pH higher than 3.4 or the current density in the range of 0.5–20 mA/cm 2 , high content of U(V) and U(IV) in the immobilized products was obtained. Other conditions favored the occurrence of the electrolytic water reaction, and the immobilized samples were dominated by U(VI). It was found that the temperature showed the greatest effect on the electrochemical immobilization rate. Where, the electrochemical immobilization rate increased by about 1.8 times when the ambient temperature increased from 293.15 to 328.15 K. This study provides a new idea for the immobilization of uranium in alkaline wastewater and demonstrates the feasibility of electrochemical immobilization of uranium in alkaline systems.
研究领域:
环境科学
·
电化学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Polymers
·
2023
·Vol. 15
·期 8
·1917
·
IF 5
Siheng Zhao,Bo Xu,Hao Shan,Qinglei Zhang,Xiangdong Wang
This work investigated the effect of different valence states of phosphorus-containing compounds on thermal decomposition and flame retardancy of polyethylene terephthalate (PET). Three polyphosphates—PBPP with +3-valence P, PBDP with +5-valence P and PBPDP with both +3/+5-valence P—were synthesized. The combustion behaviors of flame-retardant PET were studied and the structure–property relationships between the phosphorus-based structures with different valence states and flame-retardant properties were further explored. It was found that phosphorus valence states significantly affected the flame-retardant modes of action of polyphosphate in PET. For the phosphorus structures with +3-valence, more phosphorus-containing fragments were released in the gas phase, inhibiting polymer chain decomposition reactions; by contrast, those with +5-valence phosphorus retained more P in the condensed phase, promoting the formation of more P-rich char layers. It is worth noting that the polyphosphate containing both +3/+5-valence phosphorous tended to combine the advantage of phosphorus structures with two valence states and balance the flame-retardant effect in the gas phase and condensed phase. These results contribute to guiding the design of specified phosphorus-based structures of flame-retardant compounds in polymer materials.Keywords:polyethylene terephthalate (PET);flame retardant;valence states;phosphate
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
·
2021
·Vol. 104
·期 10
·5148-5156
·
IF 3.784
Fang Guan,Yiquan Wu,Iva Milisavljevic,Xin Cheng,Shifeng Huang
Spinel-structured NiMn 2 O 4 ceramics, with different valence Ni sources, were originally prepared using Ni 2 O 3 and NiO as raw materials, and the effects of different valence Ni sources on their electrical properties were first investigated. XRD patterns show that both Ni 2 O 3 -based and NiO-based NiMn 2 O 4 ceramics are single cubic spinel structures. SEM/EDS images indicate that the NiMn 2 O 4 ceramics exhibited high density at the experiment-determined sintering temperatures. XPS results and Raman drifts prove that the Ni valence-induced changes in Mn ions at B sites played a significant role in the electrical properties and thermal stability of NiMn 2 O 4 ceramics. Compared with NiO-based NiMn 2 O 4 , the resistivity at 25°C ( ρ 25°C ) of Ni 2 O 3 -based NiMn 2 O 4 increased dramatically from 3109 to 106958 Ω cm, the thermal constant ( B 25 / 50 ) increased from 3264 to 4473 K, and the resistance shifts after annealing for 1000 h at 150°C decreased from 0.80% to 0.74%. The investigation of the relationship between the material properties and valence of Ni sources has provided a new and effective way for designing the spinel-structured negative temperature coefficient (NTC) materials by modulating the valence of ions at A sites in the raw materials.
研究领域:
材料科学
·
电子工程
✓ 已验证
DOI
高影响因子
JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS
·
2025
·
IF 6.2
Guodong Hong,Zhenqiang Yu,Dexin Kong,Taoli Huhe,Rui Shan,Haoran Yuan,Yong Chen
Currently, the selection of iron valence states in composite-modified magnetic biochar prepared by co-pyrolysis exhibits a high degree of blindness. Therefore, this study compares the performance of biochar preparation via co-pyrolysis of three different iron valences (Fe 2 + , Fe 3+ , and Fe 6+ ) and potassium oxalate (K 2 C 2 O 4 ) composite modification for tetracycline (TC) removal. The results indicate that the co-activation of potassium oxalate with different iron valences led to the formation of magnetic biochar with varying elemental contents, morphologies, and structures. Batch adsorption experiments demonstrate that KF3-BC has a high tetracycline removal rate over a wide pH range (3 – 11) and at high coexisting ion concentrations (1 – 100 mmol/L). Furthermore, experiments with synthetic swine wastewater in different matrices, the adsorption capacity of KF3-BC for TC (at a concentration of 100 mg/L) exceeds 81.09 mg/g. Additionally, under optimal conditions of 30 °C and pH = 5, the theoretical maximum adsorption capacity (Q max ) for TC is as follows: KF3-BC (236.91 mg/g) > KF6-BC (169.42 mg/g) > KF2-BC (51.34 mg/g) > BC (38.41 mg/g). The adsorption processes of KF2-BC, KF3-BC, and KF6-BC all conform to the Pseudo-second-order and Freundlich models, implying that TC adsorption occurs at the multilayer molecular adsorption on heterogeneous surfaces, primarily driven by chemisorption. The primary adsorption mechanism between KF-BCs and TC molecules is the π–π EDA interactions. Additionally, hydrogen bonding, cation–π complexation, electrostatic interactions, and pore filling also contribute to the adsorption process. This study can assist in selecting the optimal iron source and chemical activator for composite modification of biochar for the adsorption of TC in wastewater.
研究领域:
环境科学
·
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
POLYHEDRON
·
2025
·
IF 2.6
Jia-Peng Cao,Qianxiang Xu,Yuanhang Ren,Hehua Hui,Jining Shang,Bin Yue,Heyong He
Three Cu-based polyoxomolybdate coordination polymers, [Cu I x Cu II 1-x (mbpy)(H 2 O)][Cu II (mbpy)(H 2 O) 2 ][Na(HPO 4 )(H x PO 4 )-Mo 5 O 15 ]·5·.5H 2 O ( 1 ), Cu(mbpy)Mo 2 O 7 ( 2 ) and [(Cu II (mbpy))(Cu I y Cu II 1-y (mbpy))(H 2 O)(H y PO 4 )] 2 [H 3 PMo VI 10 Mo V 2 O 40 ]·H 2 O ( 3 ) (mbpy = 4,4′-dimethyl-2,2′-dipyridyl, 0 < x < 1, 0 < y < 1), have been hydrothermally synthesized. Single crystal X-ray diffraction analysis of compounds 1 – 3 indicates that three different types of polyoxomolybdate unit, namely Strandberg-type {P 2 Mo 5 }, dimeric {Mo 2 } and Keggin-type {PMo 12 }, are included, respectively. Compound 1 is constructed by Strandberg-type {P 2 Mo 5 } and Cu(mbpy) to form a dimeric unit. Compound 2 has a 1D nanorod-like structure connected by the simplest {Mo 2 } unit. Compound 3 is an isolated structure consisting of a Keggin-type {PMo 12 } and a {Cu 4 } unit. BVS and XPS studies demonstrate that both Cu + and Cu 2+ coexist in compounds 1 and 3 , and magnetic measurement indicates the existence of anti-ferromagnetic interactions in compounds 1 – 3 . We proposed three possible magnetic modes, namely {Cu 4 }, linear {Cu 2 } and {Cu 4 -Mo 2 }, to explain the complex magnetic behavior and try to use both magnetic study and the structure analysis to probe the Cu(I) centers in the compounds.
研究领域:
材料化学
·
磁性材料
✓ 已验证
DOI
高影响因子
TALANTA
·
2024
·
IF 5.6
Peng’an Zhu,Jiangle Zhang,Jingjing Jin,Xing Huang,Xinfeng Zhang
Ferrous ion (Fe 2+ ) can indicate the redox situation of water and also plays an important role in maintaining the ecological balance of water bodies. However, due to the redox-active property of Fe 2+ , it is still a huge challenge to sensitively and accurately determine Fe 2+ especially in interstitial water. Herein, we prepared a ferrozine gel rod for valence fixation during sampling and subsequent smartphone-based detection of Fe 2+ . The electrode potential of the redox pair can be varied through the formation of Fe 2+ -ligand complexes, and when E complex was higher than E O 2 / OH − , the oxidation of Fe 2+ by O 2 was hindered, thus achieving the valence fixation of Fe 2+ . Six ligands were screened, and it was found that ferrozine could effectively increase the redox potential after complexing with Fe 2+ , and also exhibits an obvious color change while fixing the valence of Fe 2+ . To facilitate Fe 2+ detection, a cross-linked porous polymer gel rod prepared by acrylamide and sodium alginate was used to encapsulate the ferrozine molecules. The ferrozine gel rod enabled fixation the valence of Fe 2+ longer than 30 days, and the resulted purple-red color was pictured and analyzed by a smartphone. Ultimately, the developed ferrozine gel rod sensing system was able to achieve sensitive and linear detection of Fe 2+ in the range of 1–200 μM with the limit of detection as low as 0.33 μM, and it also exhibited excellent selectivity and anti-interference ability. The accuracy and reliability of the method was verified by the determination of Fe 2+ in spiked water samples and certified standard reference water samples. Finally, the ferrozine gel rod sensing system was successfully applied to in-situ detection of Fe 2+ in interstitial water, overlying water and upper water of lake and river. This facile system that enabled valence fixation and fast detection is promising for detection of Fe 2+ in environmental waters.
研究领域:
分析化学
·
环境科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Catalysts
·
2025
·Vol. 15
·期 3
·277
·
IF 4
Yunhan Pu,Huajie Zhang,Yanjun Li,Chuan Yu,Xiaofei Song,Chen Yang,Mingli Fu
The conversion of methane (CH4) to methanol (CH3OH) under mild conditions remains a significant challenge in catalysis. In this study, we introduce a method to adjust the surface valence states of copper species in Cu-ZSM-5 catalysts by annealing under different atmospheres (N2, air, and H2). Among these, the 10% Cu-ZSM-5 catalyst calcined in H2showed outstanding performance, achieving a methanol productivity of 8.08 mmol/(gcat·h) and 91% selectivity at 70 °C and 3 MPa using H2O2as the oxidant. Comprehensive characterization revealed that H2annealing optimized the Cu surface to a lower valence state (predominantly Cu+), enhancing CH4adsorption and promoting H2O2activation to generate ·OH and ·CH3radicals, which drive selective CH3OH formation. In situ DRIFTS and radical trapping experiments further confirmed the critical role of Cu+in facilitating C-H bond cleavage and suppressing overoxidation.
研究领域:
催化化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2024
·
IF 9.4
Chun Kong,Chuang Zhi,Zirui Wu,Wenqiang Yang,Juan Yang,Zhongti Sun
NiFe-(oxy)hydroxides are the most active transition metal oxide electrocatalysts for oxygen evolution reaction (OER) under the alkaline media. Herein, we controllably manipulated oxygen vacancy (V O )-tunable NiFe-(oxy) hydroxides that their OER performances possessed a volcano-type relationship with V O concentration, positively-correlated with Ni 3+ /Ni 2+ ratio. Theoretical simulations further unearthed the enhanced activation and dissociation of H 2 O by the inserting of V O . As a result, the optimal sample featuring the Ni 3+ /Ni 2+ ratio of 30.3 % and V O of 23.8 % exhibited the overpotential of 243 mV at the current density of 100 mA cm –2 , simultaneously lasting 120 h durability without any attenuation, exceding the most reported NiFe-(oxy)hydroxides. This work offers an innovative view to understand the OER performance using hypervalent Ni ratio induced by V O defects.
研究领域:
材料科学
·
电化学
·
能源科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2024
·
IF 8.1
Xianfa Zhang,Mingzhao Huang,Zuoming Zhou,Xiaodan Zhao,Guohua Jing
Sulfite activation with iron-based heterogeneous activators is a promising technology for the removal of organic contaminants from water. However, the slow valence transformation of >Fe(II)/>Fe(III) compromises sulfite activation efficiency. Regarding that the oxygen vacancy (Vo) can modulate the charge distribution and thus enhance >Fe(II)/>Fe(III) valence transformation via rapid electron transfer, Vo-enriched γ-Fe 2 O 3 is constructed for sulfite activation (simplified as the γ-Fe 2 O 3 -Vo/sulfite system). The γ-Fe 2 O 3 -Vo/sulfite system exhibits excellent abatement performance for iohexol (IOX) with the efficiency as high as 90.2 % within 1 h of reaction at pH 8.5, in which sulfate radicals (SO 4 •− ) and hydroxyl radicals (HO • ) are the major species. Electrochemical and DFT calculations reveal that Vo-enriched γ-Fe 2 O 3 possesses lower electrical impedance and the concomitant higher electron transfer efficiency. According to a series of characterizations, the enhance >Fe(II)/>Fe(III) valence transformation is confirmed to contribute to sulfite activation via the regulation of the electronic structure by the Vo. In addition, the degradation pathways of IOX are proposed by analyzing the degradation products of IOX by UPLC-QTOF-MS. Finally, the effects of different influencing factors on the degradation of IOX and the cyclic performance suggest the system shows strong resistance to interference and reusability, exhibiting superior application potential.
研究领域:
环境科学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
Journal of Materials Chemistry B
·
2025
·
IF 5.7
Xin Liu,Peng Zhang,Mengjie Xu,Zihao Zhao,Xing Yin,Ximing Pu,Juan Wang,Xiaoming Liao,Zhongbing Huang,Shunze Cao,Guangfu Yin
Vanadium is a bioactive trace element with variable valence. Its pentavalent form has been confirmed to be capable of predominantly regulating the early and mid-stage osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) without tumor inhibition, while its tetravalent form exhibits tumor inhibition but only primarily modulates late osteogenic differentiation and angiogenesis. In this study, a multifunctional bone tissue scaffold consisting of mixed-valence vanadium-doped mesoporous bioactive glass and poly(lactic-co-glycolic acid) (V(IV/V)-MBG/PLGA) was developed to simultaneously inhibit the recurrence of osteosarcoma and promote the regeneration of operative bone defects. The in vitro results showed that the V(IV) and V(V) species could be sustainably released from V(IV/V)-MBG and complementarily enhance the proliferation, osteogenic differentiation, and mineralization of BMSCs by activating multiple signaling pathways throughout the whole osteogenesis process. More importantly, the co-existence of mixed-valent vanadium species was able to continuously stimulate the generation of excessive ROS and the depletion of GSH by synergistically supplying an appropriate ratio of V(IV) and V(V) to thermodynamically and kinetically maintain the stable self-circulation of the valence state alteration, thus inducing UMR-106 cell death. In a rat model, V(IV/V)-MBG/PLGA scaffolds effectively suppressed tumor invasion and promoted bone regeneration. These results suggest that V(IV/V)-MBG/PLGA scaffolds are a promising strategy for treating tumor-associated bone defects, offering dual tumor inhibition and bone regeneration.
研究领域:
材料科学
·
骨科医学
·
生物医学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Nanomaterials
·
2024
·Vol. 14
·期 23
·1930
·
IF 4.4
Sha Ni,Wenjing Wu,Zichao Yang,Min Zhang,Jianjun Yang
The Cu cocatalyst supported on the surface of TiO2photocatalysts has demonstrated unique activity and selectivity in photocatalytic CO2reduction. The valence state of copper significantly influences the catalytic process; however, due to the inherent instability of copper’s valence states, the precise role of different valence states in CO2reduction remains inadequately understood. In this study, CuOx/TiO2catalysts were synthesized using an in situ growth reduction method, and we investigated the impact of various valence copper species on CO2photocatalytic reduction. Our results indicate that Cu+and Cu0serve as primary active sites, with the selectivity for CH4and CO products during CO2photoreduction being closely related to their respective ratios on the catalyst surface. The adsorption and activation mechanisms of CO on both Cu+and Cu0surfaces are identified as critical factors determining product selectivity in photocatalytic processes. Furthermore, it is confirmed that Cu+primarily facilitates CH4production while Cu0is responsible for generating CO. This study provides valuable insights into developing highly selective photocatalysts.
研究领域:
材料科学
·
环境科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2020
·
IF 4.939
Zhenbao Zhang,Wulan Zhou,Ziwei Yang,Jiahui Jiang,Dengjie Chen,Zongping Shao
In this work, we have demonstrated that by modifying Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3-δ (BSCF) via phosphorous (P) incorporation, the hydrogen evolution reaction (HER) activity was boosted. Such P incorporation was realized through the lattice doping via an in situ method , or bulk/surface co-modification via an ex situ approach. Under optimal conditions, the derived P-doped and bulk/surface-modified BSCF exhibited η 0 of ~205 and ~159 mV, and η 10 of ~333 and ~309 mV in 1.0 M KOH, respectively. Such attractive performance resulted from multiple aspects, including the improved electrochemical active surface area , accelerated charge transfer kinetics, increased high-oxidation state of the Co cation within the Co 3+ /Co 4+ redox couple , and enlarged amount of lattice oxygen species. Moreover, the presence of amorphous regions and structure distortion of P-modified BSCF from the ex situ method greatly facilitated the HER.
研究领域:
材料科学
·
电化学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）