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46 results on '"Cai, Guiyuan"'

16. Rapid oxidation and deep As(III) purification from water using gelatin-supported iron-based metal-organic framework aerogel coupled with H2O2:Preparation, performance and mechanism

Author

Cai, Guiyuan, Tian, Yu, Li, Lipin, Zhang, Jun, Zuo, Wei, Wang, Qinyu, Liu, Tao, Ma, Lina, Zhang, Yifeng, Cai, Guiyuan, Tian, Yu, Li, Lipin, Zhang, Jun, Zuo, Wei, Wang, Qinyu, Liu, Tao, Ma, Lina, and Zhang, Yifeng

Abstract

Metal-organic frameworks (MOFs) are considered a reliable adsorbent for controlling arsenic contamination. However, developing rapid and efficient MOF adsorbents with the capability of easy recovery is still challenging. Herein, we prepared a three-dimensional porous MIL-88A-Fe/gelatin aerogel (PMGA) with macroscopic size and coupled it with H2O2 to fabricate a heterogeneous catalytic oxidation adsorption system to remove As(III) in water. The green synthesis strategy of this catalyst by foaming and low-temperature carbonization not only avoided the use of toxic chemical crosslinkers but also endowed PMGA with a rich hierarchical porous structure and exposed more active sites. Thus, the PMGA/H2O2 system was able to reduce the concentration of As(III) from 1106 to below 10 µg/L and simultaneously realize the complete oxidation of As(III) to As(V) in only 120 min. Meanwhile, the system exhibited an excellent saturation adsorption capacity (24.863 mg/g) for As(III), superior to most similar bio-based or iron-based materials. Quenching experiments, EPR and DFT calculations showed that the active species (surface •OOH and surface •OH) generated by the Fenton-like interaction between the exposed (1 0 0) facet of MIL-88A-Fe in PMGA and H2O2 played an essential role in promoting the oxidative removal of As(III). Moreover, the reaction system could work efficiently for As(III) in a wide pH range and was hardly affected by other substances such as chlorides, sulfates, carbonates, silicates, and humic acids. Simultaneously, the fixed bed column filled with PMGA could stably and continuously treat As(III) in groundwater. Therefore, this study not only broadens the horizon for the development and design of 3D functional materials but also provides a new strategy in water purification to eliminate arsenic pollutants using Fe-MOF aerogels.

Published
2024

17. Sulfite activation of Fe-Mn bimetallic oxides for rapid oxidative removal of As(III) in water:Involvement of active Mn(III)

Author

Cai, Guiyuan, Tian, Yu, Li, Lipin, Zhang, Wenxuan, Huang, Rui, Zhang, Jun, Wang, Qinyu, Xu, Hua, Zhang, Yifeng, Cai, Guiyuan, Tian, Yu, Li, Lipin, Zhang, Wenxuan, Huang, Rui, Zhang, Jun, Wang, Qinyu, Xu, Hua, and Zhang, Yifeng

Abstract

The activation of sulfite [S(IV)] by transition metals, a new generation of advanced oxidation processes, has been widely studied for water purification. However, the application of this process to oxidize and remove arsenite [As(III)] from water through Fe-based S(IV) activation and the associated mechanisms are not fully understood. In particular, rapid removal of As(III) and secondary metal contamination have presented challenges. Herein, we develop a novel sea urchin-like magnetic Fe-Mn bimetallic oxides (FeMnO)-activated S(IV) process to address these issues. Under neutral pH, the FeMnO/S(IV) system achieved a 99.2 % removal of As(III) within only 10 min with residual arsenic concentration below 10 µg/L, and the removed As(III) was fully oxidized to arsenate [As(V)]. Additionally, FeMnO was recyclable and capable of treating actual arsenic-contaminated water. Furthermore, the oxidation mechanism of non-radical active trivalent manganese [Mn(III)] was discovered during the reaction between the FeMnO/S(IV) system and As(III). The FeMnO catalyst activated S(IV) to generate oxysulfur radicals (i.e., SO5•–, SO4•– and SO3•–), but they were not the primary oxidizing species for As(III). Instead, As(III) oxidation was mainly attributed to the active Mn(III) generated by the electron transfer between the FeMnO catalyst and SO5•– radicals. The discovery of active Mn(III) species in this work may provide a new avenue for developing novel Fe-Mn-type adsorbents to purify arsenic-contaminated water.

Published
2024

19. Identifying biomarkers related to motor function in chronic stroke: A fNIRS and TMS study.

Author

Cai, Guiyuan, Xu, Jiayue, Zhang, Cailing, Jiang, Junbo, Chen, Gengbin, Chen, Jialin, Liu, Quan, Xu, Guangqing, and Lan, Yue

Abstract

Background: Upper limb motor impairment commonly occurs after stroke, impairing quality of life. Brain network reorganization likely differs between subgroups with differing impairment severity. This study explored differences in functional connectivity (FC) and corticospinal tract (CST) integrity between patients with mild/moderate versus severe hemiplegia poststroke to clarify the neural correlates underlying motor deficits. Method: Sixty chronic stroke patients with upper limb motor impairment were categorized into mild/moderate and severe groups based on Fugl‐Meyer scores. Resting‐state FC was assessed using functional near‐infrared spectroscopy (fNIRS) to compare connectivity patterns between groups across motor regions. CST integrity was evaluated by inducing motor evoked potentials (MEP) via transcranial magnetic stimulation. Results: Compared to the mild/moderate group, the severe group exhibited heightened premotor cortex–primary motor cortex (PMC–M1) connectivity (t = 4.56, p < 0.01). Absence of MEP was also more frequent in the severe group (χ2 = 12.31, p = 0.01). Bayesian models effectively distinguished subgroups and identified the PMC–M1 connection as highly contributory (accuracy = 91.30%, area under the receiver operating characteristic curve [AUC] = 0.86). Conclusion: Distinct patterns of connectivity and corticospinal integrity exist between stroke subgroups with differing impairments. Strengthened connectivity potentially indicates recruitment of additional motor resources to compensate for damage. These findings elucidate the neural correlates underlying motor deficits poststroke and could guide personalized, network‐based therapies targeting predictive biomarkers to improve rehabilitation outcomes. [ABSTRACT FROM AUTHOR]

Published
2024
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25. Neurophysiological characterization of stroke recovery: A longitudinal TMS and EEG study.

Author

Ding, Qian, Chen, Jixiang, Zhang, Shunxi, Chen, Songbin, Li, Xiaotong, Peng, Yuan, Chen, Yujie, Chen, Junhui, Chen, Kang, Cai, Guiyuan, Xu, Guangqing, and Lan, Yue

Subjects
STROKE, EVOKED potentials (Electrophysiology), TRANSCRANIAL magnetic stimulation, ELECTROENCEPHALOGRAPHY, FUNCTIONAL connectivity
Abstract

Aims: Understanding the neural mechanisms underlying stroke recovery is critical to determine effective interventions for stroke rehabilitation. This study aims to systematically explore how recovery mechanisms post‐stroke differ between individuals with different levels of functional integrity of the ipsilesional corticomotor pathway and motor function. Methods: Eighty‐one stroke survivors and 15 age‐matched healthy adults participated in this study. We used transcranial magnetic stimulation (TMS), electroencephalography (EEG), and concurrent TMS‐EEG to investigate longitudinal neurophysiological changes post‐stroke, and their relationship with behavioral changes. Subgroup analysis was performed based on the presence of paretic motor evoked potentials and motor function. Results: Functional connectivity was increased dramatically in low‐functioning individuals without elicitable motor evoked potentials (MEPs), which showed a positive effect on motor recovery. Functional connectivity was increased gradually in higher‐functioning individuals without elicitable MEP during stroke recovery and influence from the contralesional hemisphere played a key role in motor recovery. In individuals with elicitable MEPs, negative correlations between interhemispheric functional connectivity and motor function suggest that the influence from the contralesional hemisphere may be detrimental to motor recovery. Conclusion: Our results demonstrate prominent clinical implications for individualized stroke rehabilitation based on both functional integrity of the ipsilesional corticomotor pathway and motor function. [ABSTRACT FROM AUTHOR]

Published
2024
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32. Intermittent Theta Burst Stimulation Increases Natural Oscillatory Frequency in Ipsilesional Motor Cortex Post-Stroke: A Transcranial Magnetic Stimulation and Electroencephalography Study

Author

Ding, Qian, primary, Chen, Songbin, additional, Chen, Jixiang, additional, Zhang, Shunxi, additional, Peng, Yuan, additional, Chen, Yujie, additional, Chen, Junhui, additional, Li, Xiaotong, additional, Chen, Kang, additional, Cai, Guiyuan, additional, Xu, Guangqing, additional, and Lan, Yue, additional

Published
2022
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45. Self-enhanced and efficient removal of arsenic from waste acid using magnetite as an in situ iron donator

Author

Xing Zhu, Qi Xianjin, Yonggang Wei, Kongzhai Li, Hua Wang, Cai Guiyuan, and Hao Fengyan

Subjects
Environmental Engineering, Iron, 0208 environmental biotechnology, chemistry.chemical_element, Environmental pollution, 02 engineering and technology, 010501 environmental sciences, 01 natural sciences, Arsenic, chemistry.chemical_compound, Hazardous waste, Scorodite, Prospective Studies, Waste Management and Disposal, Dissolution, 0105 earth and related environmental sciences, Water Science and Technology, Civil and Structural Engineering, Magnetite, Supersaturation, Precipitation (chemistry), Ecological Modeling, Hydrogen Peroxide, Hydrogen-Ion Concentration, Pollution, Ferrosoferric Oxide, 020801 environmental engineering, chemistry, Environmental chemistry
Abstract

High arsenic-containing waste acid from the heavy nonferrous metallurgical sector (Cu, Pb, Zn, Ni, Sn, etc.), one of the most dangerous arsenic hazardous wastes with extremely high arsenic concentrations, has presented enormous challenges to the environment and caused severe environmental pollution over the past few decades due to the lack of affordable and environmentally friendly disposal technologies. Here, we report a green process for the self-enhanced and efficient removal of arsenic from waste acid using magnetite as an in situ iron donator. Firstly, the room-temperature predissolution of magnetite in waste acid provides initial iron ions as a starting precipitator of arsenic, simultaneously providing a suitable pH range and an active surface that are ready for the nucleation and growth of scorodite. Afterwards, arsenic is precipitated in form the of scorodite, which is driven by a mutually improved cycle composed of arsenic precipitation and magnetite dissolution on the surface of magnetite particles. This cycle creates a low supersaturation of iron and constant pH in the waste acid, ensuring the continuous precipitation of arsenic as well-crystallized and environmentally stable scorodite by using magnetite as an in situ iron donator via the reaction of 2Fe3O4 + 6H3AsO4 + H2O2 = 6FeAsO4 + 10H2O. Under optimal conditions, including a 6-h room-temperature predissolution, a 12-h atmospheric reaction at 90 °C and a pH of 2.0 with a magnetite dosage at the Fe3O4/As molar ratio (the molar ratio of Fe3O4 in magnetite to As in waste acid) of 1.33, 99.90% of arsenic was successively removed from waste acid with an initial arsenic concentration of 10300 mg/L. In combination with the good adaptability of this process, the performed case study and prospective process show the successful removal of arsenic from waste acid as well as great potential for large-scale applications.

Published
2018

46. Limonite as a source of solid iron in the crystallization of scorodite aiming at arsenic removal from smelting wastewater

Author

Yonggang Wei, Bo Shu, Li Xuezhu, Kongzhai Li, Xin Zhang, Xing Zhu, Hua Wang, Qi Xianjin, Yongkui Li, and Cai Guiyuan

Subjects
inorganic chemicals, 020209 energy, Strategy and Management, chemistry.chemical_element, 02 engineering and technology, Industrial and Manufacturing Engineering, law.invention, law, Scorodite, 0202 electrical engineering, electronic engineering, information engineering, Crystallization, Arsenic, 0505 law, General Environmental Science, Limonite, Supersaturation, Renewable Energy, Sustainability and the Environment, Precipitation (chemistry), Chemistry, 05 social sciences, Metallurgy, Building and Construction, Wastewater, visual_art, Smelting, 050501 criminology, visual_art.visual_art_medium
Abstract

Removal of arsenic from aqueous solution in the form of scorodite is one of the promising processes for the disposal of arsenic-containing wastewater. While it suffers from the strict reaction conditions including high Fe/As molar ratio, narrow pH range, and low Fe/As supersaturation when the liquid iron sources of Fe2+/Fe3+ are used as the iron sources. We proposed to use limonite as an in situ solid iron source to promote scorodite crystallization via heterogeneous nucleation for the effective removal of arsenic from high-arsenic smelting wastewater. Under the condition of 90 °C, limonite dosage at an Fe/As molar ratio of 4 and pH of 1.5, 99.6% of arsenic in the smelting wastewater (As 10300 mg/L and sulphuric acid 72500 mg/L) was precipitated in the form of well-crystallized and environmentally stable scorodite with a particle size around 4.6 μm. Limonite acts as an in situ iron donator and seeds, allowing a low iron supersaturation in the solution during the arsenic precipitation and transformation into scorodite. Moreover, the residual arsenic concentration in the filtrate obtained from the abovementioned scorodite synthesis could be further lowered to 0.1 μg/L using fresh limonite in virtue of its high arsenic adsorbability. The proposed process shows a great potential for the arsenic removal from smelting wastewater, which will advance the large-scale disposal of arsenic-bearing wastewater and provide an important insight into the application of solid iron source for scorodite synthesis and arsenic fixation.

Published
2021

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