查找使用阿拉丁产品的科研文献

L-glutamic acid-functionalized graphene oxide with characteristic of anti-stacking towards efficient adsorption-reduction removal of Cr(VI)

Yuxin Wang,Yueqi Chen,Fengjun Shan,Tingting Zhang,Zhenbin Zhang,Meijun Liu

Hexavalent chromium (Cr(VI)) pollution in aquatic environments has triggered constant worries. As one of the popular adsorbents, graphene oxide (GO) still confronts shortcomings in the Cr(VI) removal, including easy aggregation, limited adsorption amounts, monotonous type of functional groups, constant negative charge and unable valence conversion. Herein, L-glutamic acid (L-Glu) was utilized for GO functionalization through the solvothermal method to fabricate L-Glu/GO with the trait of anti-stacking for overcoming the above-mentioned drawbacks. Results proved that L-Glu/GO possessed the relatively large specific surface area and average pore diameters, various functional groups and variable surface charges. The as-prepared L-Glu/GO exhibited satisfying adsorption amounts with the changeable acid environment, adsorbent dosages and initial Cr(VI) concentrations. Besides, Cr(VI) adsorption process conformed to the pseudo-second-order kinetic model and the Langmuir isotherm model with q m for Cr(Ⅵ) of 71.12 mg·g –1 , almost 27 times higher than that of GO (2.64 mg·g –1 ) in pH = 2. The adsorption thermodynamics result portrayed the adsorption process was a spontaneous endothermic process. Additionally, L-Glu/GO possessed excellent reusability with q e of Cr(Ⅵ) of 57.19 mg·g –1 after five cycles, with the economic cost of ¥0.498·g –1 . More importantly, Cr(VI) was changed into Cr(III) during adsorption to accomplish the toxicity elimination due to existence of amine groups from L-Glu. On the whole, pore filling, anion-π interaction, electrostatic interactions, adsorption-reduction and coordination interaction jointly contributed to the Cr(VI) adsorption. This work provided the strategy for effectively enhancing the Cr(VI) adsorption capacity of GO and deepened the adsorption mechanism towards hazardous metal ions elimination.

Mechanochemical synthesis of nitrogen-modified microscale zero-valent iron for efficient Cr(VI) removal: The role of lattice strain

Tong Hu,Wenjun Zhou,Haijiao Xie

Lattice engineering of Fe 0 based on heteroatom doping holds great promise in water purification owing to their tunable geometric and electronic structure. However, there is limited understanding of how nitrogen atom in Fe 0 lattice structure affects its local microenvironment and corresponding reactivity toward target contaminants. Herein, microscale zero-valent iron with interstitial N doping (N-mZVI) was successfully prepared by a facile mechanochemical method for heavy metal pollution control. N-mZVI exhibited excellent reactivity for Cr(VI) elimination, and both removal efficiency and conversion rate could reach 100 %, which was 8.06 and 2.73 times higher than that of pristine ball milled mZVI, respectively. Besides, the rate constant of various heavy metals sequestration (Cr(VI), Ni(II), Pb(II), Cu(II), and Cd(II)) over N-mZVI was 61.3 ∼ 115.6-fold faster than that of pristine ball milled mZVI. N-mZVI was also demonstrated to be pH-universal, long-term stability, and environmental applicability. Experimental results and theoretical calculations indicated that tensile strain induced by interstitial N doping expanded Fe 0 lattice and weakened the lattice Fe-Fe interaction, thus significantly accelerating electron transport dynamics in Fe 0 core. Meanwhile, iron nitride species on the surface of N-mZVI promoted electron transfer from iron shell layer to heavy metals. This work comprehensively investigates the structure–property relationships of lattice engineering-based N-mZVI, and provides a new insight into rational design of modified mZVI with high reactivity.

Efficient Removal of Cr(VI) Ions by a Novel Magnetic 4-Vinyl Pyridine Grafted Ni3Si2O5(OH)4 Multiwalled Nanotube

Chunmei Xiao,Jianming Lin

The contamination of water systems by heavy metals greatly threatens human health and ecological safety. An efficient adsorbent is critical for the removal of these contaminants. In this work, magnetic Ni3Si2O5(OH)4 nanotubes (NTs) have been synthesized via in situ hydrothermal reduction and further functionalized by grafting poly(4-vinyl pyridine) (P4VP) brushes on its surface via atom transfer radical polymerization. Characterizations by Fourier transform infrared, X-ray diffraction, thermogravimetric analysis, transmission electron microscopy, and X-ray photoelectron spectroscopy proved that P4VP was successfully grafted on the surface of magnetic Ni3Si2O5(OH)4 NTs. The resultant Ni3Si2O5(OH)4-g-P4VP NTs are efficient nanosorbents for removing Cr(VI) anions from water. The Cr(VI) adsorption capacity of Ni3Si2O5(OH)4-g-P4VP NTs reaches 1.49 mmol/g at a pH of 3. The pseudo-second-order kinetic model and the Freundlich isothermal model are suitable to describe the adsorption process. The analysis using Weber–Morris and Boyd models indicates that both intraparticle diffusion and external film diffusion affect the Cr(VI) adsorption process. The adsorption enthalpy is estimated to be 18.37 kJ/mol. More than 90% of the Cr(VI) adsorption capacity of the Ni3Si2O5(OH)4-g-P4VP NTs remains after eight adsorption and desorption cycles.

Preparation of core-shell structure Ag@TiO2 plasma photocatalysts and reduction of Cr(VI): Size dependent and LSPR effect

Jiwen Li,Yaqian Duan,Linlin Wang,Jingjun Ma

The poor light absorption and low carrier separation efficiency of Titanium dioxide (TiO 2 ) limit its further application. The introduction of plasma metal Ag have the potential to solve these drawbacks owing to its plasma resonance effect. Thus core-shell structure Ag@TiO 2 plasma photocatalysts was prepared by using facile reduction method in this work. More specifically, Ag@TiO 2 composite catalysts with different Ag loading amounts were prepared in the presence of surfactant PVP. Ag@TiO 2 demonstrates excellent light absorption performance and photoelectric separation efficiency compared with pure TiO 2 . As a result, it displays excellent performance of Cr(VI) reduction under visible light. The optimal composite catalysts Ag@TiO 2 –5P achieves exceptional visible-light-driven photocatalytic Cr(VI) reduction efficiency of 0.01416 min −1 that is 2.29 times greater than pure TiO 2 . To investigate the role of PVP, we also synthesized Ag@TiO 2 -5 without PVP. The experimental results show that although Ag@TiO 2 -5 Cr(VI) reduction performance is superior to pure TiO 2 , it significantly decreases compared with Ag@TiO 2 –5P. The results of TEM and optoelectronic testing show that agglomeration of Ag particles leads to a decrease in the photoelectric separation efficiency of Ag@TiO 2 -5. The smaller Ag particles provide more active sites and demonstrating a stronger overall local surface plasmon resonance (LSPR) effect. DMPO spin-trapping ESR spectra testing indicates that ∙O 2 − and ∙OH are the main reactive species. This research provides a potential strategy to prepare Ag-based plasma photocatalysts for environment protection.

Riboflavin-mediated reactivation of aged nano zero-valent iron by Shewanella oneidensis MR-1 for sustained Cr(VI) detoxification

Chengyu Yang,Jie Wei,Yixuan Li,Yuanhao Peng,Xuan Wu,Xianrui Zhang,Yingxin Ding,Shumi Lu,Chongling Feng,Chao Huang

Aging-induced surface passivation of nano zero-valent iron (nZVI) significantly diminishes its reactivity for Cr(VI) reduction, thereby impeding its practical application in environmental remediation. Herein, we propose a novel system integrating aged nZVI (AnZVI), Shewanella oneidensis MR-1, and the endogenous electron shuttle riboflavin (RF) to overcome the passivation limitations and enhance Cr(VI) removal. Remarkably, the AnZVI/MR-1/RF system achieved complete removal of 20 mg L − 1 Cr(VI) within 3 h, outperforming AnZVI/MR-1 and AnZVI alone by 23.8 % and 36.6 %, respectively. Mechanistic investigations revealed that RF mediated direct interfacial contact between AnZVI and MR-1, promoting microbial reduction of the AnZVI passivation layer. Electrochemical analyses confirmed RF’s critical role as an electron mediator in accelerating charge transfer between AnZVI and MR-1. Three-dimensional fluorescence mapping (3D-EEM) analysis revealed microbial extracellular polymeric substances (EPS) contributions to chromium immobilization processes. The immobilization of chromium is primarily attributed to the reduction of Cr(VI) to insoluble Cr(III) species, in conjunction with adsorption and surface complexation mechanisms. TEM validated a significant reduction in the thickness of the iron passivation layer, resulting in the exposure of the underlying Fe⁰ core and a resultant enhancement in reductive capacity. This work provides a robust strategy to overcome AnZVI’s limitations by coupling microbial activity with electron shuttling, offering new insights into sustainable remediation via biotic-abiotic synergies.

The performance of mordenite-dispersed and stabilized ferrous sulfide composites for the removal of Cr(VI) from aqueous solutions

Yixin Pan,Leilei Sun,Zhixin Yu,Xiahui Guo,Lujia Chen,Man Huang

In this study, a composite material (FeS-Mor) of nano ferrous sulfide (FeS) and mordenite was prepared by coprecipitation method using mordenite as a stabilizer to prevent the aggregation of FeS to achieve the purpose of efficient removal of chromium from water. Experimental results revealed that the optimum pH for Cr(VI) removal was ∼ 2 with a removal capacity of 199.0 mg/g and efficiency of 99.5 % at 303 K. Common co-existing cations of Na + , Ca 2+ and K + promoted the removal efficiency, while Mg 2+ inhibited the removal of Cr(VI). While Common anions of SO 4 2− , CO 3 2− , Cl − and NO 3 − inhibited chromium removal. The pseudo-second-order kinetics model fitted the kinetic removal of Cr(VI) onto FeS-Mor composites best under absent/present co-existing cations, indicating that chemical reduction and complexation dominated the removal process. The thermodynamic results were best described with the Freundlich model and showed an endothermic process of Cr(VI) removal. The FeS-Mor composites with FeS:Mor mass ratio in the range of 1:1–1:2 exhibited the best performance in removal efficiency and reusability. These results reveal that introducing mordenite to develop an efficient FeS-based nanocomposite system can significantly improve the performance of chromium remediation from aqueous solutions.

The self-boosting ultrafast removal of Cr(VI) and organic dye in textile wastewater through sulfite-induced redox processes

Yijin Yuan,Qi Tian,Longzhu Hou,Richuan Rao,Chengli Yao,Haoyan Zhu

The treatment of textile wastewater containing harmful metal ions poses a significant challenge in industrial applications due to its environmental impact. In this study, the use of sulfite for treating simulated dye wastewater containing New Coccine (NC) and Cr(VI) was investigated. The removal of NC was influenced by the redox reaction between Cr(VI) and sulfite, demonstrating a strong self-boosting effect of Cr(VI) on NC removal. Remarkable NC decoloration (95%) and Cr(VI) reduction (90%) were achieved within 1 min, highlighting the effectiveness of the treatment. Quenching experiments and electron paramagnetic resonance (EPR) technology confirmed that singlet oxygen ( 1 O 2 ) was the main oxidative agent for organic dye removal and SO 4 •− , •OH and Cr(V) were also identified as key contributors to NC degradation. The Cr(VI)/sulfite system exhibited higher efficiency in degrading azo dyes, such as NC and Congo Red (CR), compared to non-azo dyes like Methylene Blue (MB). This superiority may be attributed to the action of Cr(V) on azo groups. Additionally, the COD removal experiments were conducted on the actual dye wastewater, showing the excellent performance of the Cr(VI)/Sulfite system in treating industrial textile wastewater. This approach presents a promising strategy for effective “waste control by waste”, offering great potential for addressing challenges related to dye wastewater treatment and environmental pollution control in practical industrial scenarios.

New insight into the effects of p-benzoquinone on photocatalytic reduction of Cr(VI) over Fe-doped g-C3N4

Shi-Wen Lv,Jialu Pan,Xiaoran Wang,Yifan Shao,Yanqing Cong,Lin Che

It is of great significance to establish an effective method for removing Cr(VI) from wastewater. Herein, Fe-doped g-C 3 N 4 (namely Fe-g–C 3 N 4 –2) was synthesized and then employed as photocatalyst to conduct the test of Cr(VI) reduction. Notably, the embedding of Fe ion in g-C 3 N 4 can offer the Fe 2+ /Fe 3+ redox couples, so reducing the interfacial resistance of charge transfer and suppressing the recombination of photogenerated electrons and holes. The impurity energy levels will form in g-C 3 N 4 after the introduction of Fe ion , thereby boosting the light absorption capacity of catalyst. Thus, Fe-g–C 3 N 4 –2 showed good performance in photocatalytic Cr(VI) reduction, and the reduction efficiency of Cr(VI) can reach 39.9% within 40 min. Different with many previous studies, current work unexpectedly found that the addition of p -benzoquinone (BQ) can promote the Cr(VI) reduction, and the reduction efficiency of Cr(VI) over Fe-g–C 3 N 4 –2 was as high as 93.2% in the presence of BQ (1.5 mM). Further analyses showed that BQ can be reduced to hydroquinone (HQ) by photogenerated electrons, and UV light can also directly induce BQ to generate HQ by using H 2 O as the hydrogen donor . The HQ with reducing ability can accelerate the Cr(VI) reduction. In short, current work shared some novel insights into photocatalytic Cr(VI) reduction in the presence of BQ. Future research should consider possible reactions between photogenerated electrons and BQ. For the UV-induced photocatalysis , the suitability of BQ as the scavenger of O 2 •‒ must be given carefully consideration.

Nano zero-valent iron supported by macroporous styrene ion exchange resin for enhanced Cr(VI) removal from aqueous solution

Wei Gao,Dengjie Zhong,Yunlan Xu,Han Luo,Sijing Zeng

Novel functional fiber loaded with carbon dots for the deep removal of Cr(VI) by adsorption and photocatalytic reduction

Junfeng Xiao,Yuanpeng Cheng,Caixia Guo,Xiangting Liu,Bing Zhang,Siguo Yuan,Jiajia Huang

A novel functional fiber (PAN-CDs) loaded with carbon dots (CDs) with excellent photoreduction and adsorption properties for Cr(VI) was prepared via an amidization reaction between the CDs' carboxyl groups and amine groups on polyacrylonitrile (PAN)-based ion exchange fibers, which could completely preserve the fluorescence properties of the CDs. The photoluminescence (PL), photocatalysis and adsorption properties of PAN-CDs were characterized and analyzed. The PAN-CDs possess high adsorption capacity (297.6 mg/g) and excellent kinetic behavior (attaining adsorption equilibrium in 30 min) for Cr(VI) adsorption. Furthermore, the residual Cr(VI) (approximately 3 mg/L) after adsorption could be removed completely by subsequent photoreduction by the PAN-CDs. The Cr-saturated PAN-CDs could be easily separated by filtering and regenerated, with no observable decay of removal efficiency after five regeneration cycles. In addition, due to the PL quenching action of Cr(VI), the PAN-CDs can also be used as sensor for quantitative detection of trace Cr(VI) in aqueous solution.

Hybrid silsesquioxane-based porous polymer/chitosan aerogel for visible-light-driven degradation of antibiotics and reduction of Cr (VI)

Xiaohan Zhao,George K. Belousov,Sergei V. Kostjuk,Aliaksei Vaitusionak,Hongzhi Liu

A silsesquioxane-based hybrid porous polymers (PCS-SC-3) was successfully constructed via free-radical polymerization. • PCS-SC-3 exhibited efficient visible-light-driven photocatalytic performance for simultaneous Cr (VI) reduction and tetracycline degradation. • A flexible chitosan-based hybrid aerogel (PCS-SCA) was fabricated, achieving over 96% antibiotic removal efficiency with excellent reusability. A new organic semiconductor molecule 9, 9′, 9″, 9‴-(4-(trifluoromethyl)-4′-vinyl-[1, 1′-biphenyl]-2, 3, 5, 6-tetrayl) tetrakis-carbazole (StTCbzCF 3 ), was synthesized and subsequently copolymerized with octavinylsilsesquioxane (OVS) and 9-vinylcarbazole via azobisisobutyronitrile (AIBN)-initiated free-radical polymerization, yielding organic-inorganic hybrid porous polymers (PCS-SC-x (x = 1, 2, and 3; where x denotes the mass percentage of StTCbzCF 3 in the synthesized polymers: 20% (x = 1), 40% (x = 2), 60% (x = 3)). Among these materials, PCS-SC-3 exhibited a high specific surface area (478 m 2  g −1 ), a large Stokes shift (115 nm), and stable fluorescence. Notably, in the absence of sacrificial agents, 93% of Cr (VI) was photocatalytically reduced to the less toxic Cr (III) within 95 min under simulated sunlight, while >90% removal was retained after five cycles. In addition, PCS-SC-x (x = 1, 2, 3) was also demonstrated to function as a visible-light-driven photocatalyst for tetracycline hydrochloride (TCH) degradation. More than 95% of TCH was degraded within 75 min under visible light irradiation, with an initial pseudo-first-order rate constant of 0.0641 min −1 , which was higher than most previously reported photocatalysts. In the coexisting Cr (VI)/TCH system, the removal of both pollutants was enhanced; with the Cr (VI) reduction rate constant reaching 0.0713 min −1 , which was 2.05 times that obtained in the single-component system, indicating enhanced simultaneous remediation of the two pollutants. Radical-trapping experiments revealed that superoxide radicals (·O₂ − ) played a dominant role in the degradation pathway. PCS-SC-3 was further integrated with chitosan to fabricate a monolithic aerogel (PCS-SCA), which enabled efficient antibiotic degradation in a continuous-flow system and maintained a TCH removal efficiency of >96% after five cycles. This work provides a scalable, metal-free strategy for the integrated remediation of Cr (VI) and antibiotic contaminants and offers a facile and environmentally friendly route for the fabrication of flexible hybrid aerogels for practical water-treatment applications.

Efficient adsorption H3AsO4 and Cr(VI) from strongly acidic solutions by La-Zr bimetallic MOFs: Crystallinity role and mechanism

Caiyun Han,Jing Xie,Xize Min

Due to the non-degradable of heavy metal, adsorption has been extensively applied to abatement it. Most studies were focused on uptake metal ions via electrostatic attraction and ion exchange, and load molecule H 3 AsO 4 from strongly acidic wastewater was still challenging. To solve the problem, bimetallic La–Zr MOFs was facilely fabricated in this work, and the fcu topology structure of La-Zr MOFs was remained well under the investigate crystallization time and crystallization temperature. However, the crystallinity of the obtained La-Zr MOFs was influenced by the synthesized factors. The obtained La–Zr MOFs was employed as adsorbent to removal Cr(VI) and As(V), and the performance was evaluated by the batch experiment. The result indicated that the adsorption performance of Cr(VI) and As(V) was positively correlated with the crystallinity , and the optimal sample was 1LaUN 12 . From the XPS characterization, it was found that H 3 AsO 4 was successfully uptake over 1LaUN 12 surface, and the maximum monolayer adsorption capacity was 83.40 mgH 3 AsO 4 /g via ligand exchange and coordination reactions with La−OH and Zr−OH. In addition, the sample 1LaUN 12 also exhibited the excellent Cr(VI) load performance, and the maximum monolayer adsorption capacity of Cr(VI) was 222.5 mg/g. Above 40% Cr(VI) was reduced to Cr(III) by amino groups, and immobilized over the surface of 1LaUN 12 . Eventually, 1LaUN 12 displayed a good structural stability in the acidic medium, which was in favor of removing Cr(VI) and As(V) efficiently from strongly acidic solutions.