查找使用阿拉丁产品的科研文献

Rational design of BixFeyVO4/g-C3N4 heterojunction for photocatalytic reduction of Cr(VI)

Qiang Li,Hao Zhou,Meng Tan,Lingxuan Yang,Xiao Hu,Guoxiang Yang,Hao Du,Qing Wei,Qi Wang

High visible light utilization and rapid charge separation are of great importance for environmental photocatalysis . Single photocatalyst always suffers from high recombination of photogenerated electron-hole pairs and low redox ability. Elemental doping and heterojunction construction are effective approaches to improve the photocatalytic performance. Herein, we designed and synthesized a novel Bi x Fe y VO 4 /g-C 3 N 4 (BFC) binary heterojunction via facile coprecipitation followed by calcination processes. The doping of Fe endows BiVO 4 with narrower bandgap, which boosts its light response and redox ability. The construction of heterojunction facilitates charge separation that makes BFC heterojunction displaying much higher photocatalytic activity than those of single semiconductors. The highest Cr(VI) photoreduction rate ( k ) of BFC binary heterojunction is 78 (45) times of BiVO 4 (FeVO 4 ). Additionally, the binary heterojunction can still maintain high photoreduction efficiency (98%) of Cr(VI) even after five cycling tests showing excellent photocatalytic stability. This research provides novel idea for synergistic application of doping and heterojunction in environmental photocatalysis.

The overlooked role of Cr(VI) in micropollutant degradation under solar light irradiation

Tao Yang,Cui Huang,Linqian An,Ge Zeng,Juan Li,Changyu Liu,Xiaolong Xu,Jianbo Jia,Jun Ma

Hexavalent chromium (Cr(VI)) is ubiquitous in natural environments, whereas its role in the transformation of coexisting contaminants may have been overlooked. In this work, it was reported for the first time that the irradiation of Cr(VI) by solar light (solar light/Cr(VI) system) could effectively degrade various micropollutants with different structures. The removal efficiency of selected micropollutants was increased by 13.3–64.8% by the solar light/Cr(VI) system compared to that by direct solar photolysis. Meanwhile, the oxidation rates were enhanced by 2.2–21.5 folds, while they were negligible by Cr(VI) oxidation alone. Experiments by specific scavengers, probe compounds, fluorescence absorbance, and electron spin resonance analysis demonstrated that hydroxyl radical (•OH) was the major reactive species in the solar light/Cr(VI) system. Further experiments showed that the generation of •OH was closely related to the intermediate Cr(V) generated from Cr(VI) reduction, and Cr(V) could be re-oxidized back to Cr(VI). Increasing solution pH negatively affected model micropollutant (carbamazepine (CBZ)) degradation by the solar light/Cr(VI) system, mainly due to the decreased quantum yield of •OH at higher pH. Coexisting sulfate ions showed negligible effect on CBZ degradation in the solar light/Cr(VI) system, while the presence of bicarbonate , chloride, and humic acid inhibited CBZ degradation to varying degrees, owing to their diverse scavenging effects on •OH. Furthermore, moderate CBZ degradation was also achieved by natural solar light photolysis of Cr(VI). This study demonstrated the pivotal role of Cr(VI) in the transformation of micropollutants under solar irradiation, which advances the understanding of the fate of micropollutants in natural environments.

Cellulose bridged carbonate hydroxyapatite nanoparticles as novel adsorbents for efficient Cr(VI) removal

Jing Cui,Xinying Li,Shoucheng Ma,Wei Wei

Enhanced adsorption and photocatalytic Cr(VI) reduction and sterilization of defective MoS2/PVP

Yingge Zhang,Hongfen Li,Xiaolei Zhang,Hanfang Zhang,Wang Zhang,Hongwei Huang,Hongling Ou,Yihe Zhang

The exploration of novel nanomaterials to resolve the issues of water pollution with the aid of photocatalytic technology has always been a research hotspot. MoS 2 is acknowledged to be one of the promising photocatalysts for its interesting layered structure, suitable band gap, and good chemical stability. However, the fast recombination of photogenerated electrons and holes within the MoS 2 impedes its extensive application. Here, hydrophilic polymer (polyvinyl pyrrolidone, PVP) and sulfur vacancy (Vs) are simultaneously introduced into the MoS 2 nanosheets to achieve high-efficient photocatalytic hexavalent chromium Cr(VI) removal and antibacterial performance. The incorporation of PVP greatly enhances the adsorption capacity of MoS 2 , and creating Vs essentially strengthens the photogenerated carrier separation of MoS 2 . As a result, the Cr(VI) removal efficiency of MoS 2 -PVP with an appropriate Vs concentration is up to 99.5 % for 3 h. Meanwhile, MoS 2 -PVP with a relatively higher Vs concentration displays a superior Escherichia coli (E. coli) removal efficiency of 91.8 % within 30 min with the initial E. coli concentration of ∼1.0 × 10 7 CFU/mL. This study extends photocatalysts to a higher level in designing advanced materials for environmental remediation and establishes a feasible platform for emphasizing the versatility of defect engineering in regulating catalytic activity.

Efficient removal of Cr(VI) from aqueous solutions by polypyrrole/natural pyrite composites

Fen Zhang,Luyao Xi,Meiqi Zhao,Yaguang Du,Liying Ma,Shaohua Chen,Hengpeng Ye,Dongyun Du,Tian C. Zhang

Easily agglomeration of polypyrrole (PPy) significantly limits its practical applications. In this study, natural pyrite (NP) was applied to disperse PPy and overcome this agglomeration; a novel composite of PPy/NP was synthesized and applied for the efficient removal of hexavalent chromium [Cr(VI)] from aqueous solutions. Results showed that the PPy/NP composites exhibited better Cr(VI) removal performance than PPy alone. This enhanced removal capacity is attributed to the addition of NP, which prevents PPy agglomeration and reduces Cr(VI) to trivalent chromium[Cr(III)]; Cr(VI) removal was significantly dependent on the solution’s pH. The sorption kinetics of Cr(VI) with PPy/NP was described by the pseudo-second-order model and Elovich models, which highlight the chemicalsorption process. The sorption isotherm was well simulated by Langmuir model and the maximum adsorption capacity of Cr(VI) on PPy/NP was 261.78–395.26 mg/g at 303 – 323 K, which is significantly higher than that of PPy alone (124.84–194.17 mg/g). Thermodynamic analyses confirmed that this adsorption process was spontaneous and endothermic. PPy/NP composites could be used as a recyclable absorbents for four Cr(VI) reduction cycles without any evident loss in adsorption performance. The mechanism Cr(VI) removal by PPy/NP composites is attributed to ion exchange (9.47 %), adsorption (31.03 %), and reduction (59.50 %).

Magnetic MnFe2O4/ZnFe-LDH for Enhanced Phosphate and Cr (VI) Removal from Water

Huang Congxin,Tang Chaochun,Wu Qingqing,Zhu Qing

Due to the layered structure and recycling characteristics, magnetic MnFe 2 O 4 /ZnFe-LDH was prepared by co-precipitation. In this study, we intensively explored MnFe 2 O 4 /ZnFe-LDH for water purification compared with the ZnFe-LDH. The morphological and structural characteristics of the obtained products were systematically characterized. MnFe 2 O 4 /ZnFe-LDH exhibits the maximum adsorption capacity of 94.52 mg/g for phosphate and 49.03 mg/g for Cr (VI), respectively, which is superior to that of the ZnFe-LDH, indicating that the magnetic MnFe 2 O 4 effectively enhanced adsorption performance. Meanwhile, the mechanism of adsorption of phosphate and Cr (VI) was briefly studied, where the metal center ion in MnFe 2 O 4 /ZnFe-LDH and between layers of SO 4 2− serves as capture sites for phosphate and Cr (VI) removal. Furthermore, the MnFe 2 O 4 /ZnFe-LDH can be used for magnetic recycled and still maintained excellent removal efficiency (70%) for phosphate and Cr (VI) after five adsorption–desorption cycles. This work could open a new vista of designing magnetic novel adsorbents in environmental remediation.

Tailoring kinetics of Cr-chemisorption over La0.6Sr0.4Fe0.8Co0.2O3 cathode material through its porosity variation

Meigeng Gao,Elena Yu Konysheva,Jun Yang

The La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3 (LSCF) ceramics with the porosity of 20% (LSCF-20) and 50% (LSCF-50) were fabricated through temperature variation. Kinetics of the Cr-adsorption has been studied at 700 °C over 345 h under air. Different dominant mechanisms of Cr chemisorption over the ceramics with different porosities were identified. The Cr–substitution into the LSCF perovskite grains will dominate in the denser LSCF-20 ceramics, whereas the growth of SrCrO 4 crystals over the LSCF perovskite phase will occur preferably in the more porous LSCF-50 ceramics. The Cr penetrates into a more porous LSCF-50 ceramics up to 12–17 μm and the total Cr amount adsorbed after 345 h over the LSCF-50 ceramics is larger by about 10 times than over the denser LSCF-20 ceramics. The revealed remarkable differences could be associated with the increase in the surface area and with a higher volume of macro- and mesoporosity.

Enabling Low-Temperature Methanol Activation via Lattice Oxygen Induced Cu–O–Cr Catalysis

Zhao Sun,Shufan Yu,Sam Toan,Rufat Abiev,Maohong Fan,Zhiqiang Sun

Steam reforming of methanol is a promising approach to achieving hydrogen storage, transportation, and in situ supply. However, this technology is restricted by its high CO selectivity and catalyst deactivation. In this study, CuCr2O4-based catalytic oxygen carriers are tailored for lattice oxygen participating in low-temperature methanol reforming. We found that the low-temperature activation of methanol originated from Cu–O–Cr structure intensification and highly activated lattice oxygen induction. Specifically, methanol can be activated at temperatures as low as 160 °C, on the one hand, attributed to the reinforcement of the Cu–O–Cr structure and, on the other hand, owing to the highly reactive lattice oxygen from the CuO4 tetrahedron in the CuCr2O4 spinel. Combined with XAS and Raman results, the formation of the Cu–O–Cr structure is demonstrated. The hydrogen production rate with an applied CuCr2O4-based catalytic oxygen carrier is 53.2% higher than the control group without Cu–O–Cr formulation. Satisfactory cyclic stability is retained after the 50th lattice oxygen induction and supplement cycle, ascribing to the Cu–O–Cr structure that strongly intensifies Cu–Cr2O3 interactions. DFT results reveal that the process of CH3OH → CH3O* is the rate-determining step. Compared to Cu(111) and Cr2O3(110), the tailored Cu(111)/Cr2O3(110) surface with a Cu–O–Cr structure exhibits the lowest potential barrier during this process, promoting low-temperature methanol reforming.

Design and construction of SnIn4S8/Cd0.5Zn0.5S heterostructure photocatalyst for efficient Cr(VI) reduction

Meng Lan,Hanbing Jia,Xiaoli Dong,Nan Zheng,Xue Li,Yu Wang,Helezi Zhou

The development of highly competent and economical photocatalysts for competent erasure of heavy metal pollutants in water is of momentous import but still a significant challenge. Herein, 3D/0D SnIn 4 S 8 /Cd 0.5 Zn 0.5 S heterostructure photocatalyst was resoundingly fabricated through integrating Cd 0.5 Zn 0.5 S nanoparticles on the surface of SnIn 4 S 8 microsphere via a simple solvothermal method and applied to high efficiency photoreduction Cr(VI). The fabricated SnIn 4 S 8 /Cd 0.5 Zn 0.5 S with optimized composition ratio achieves the exceptional reduction Cr(VI) property and the photoreduction efficiency of 20 % SnIn 4 S 8 /Cd 0.5 Zn 0.5 S can reach 91.1 % within 30 min visible light illumination. The prominent photocatalytic efficiency comes from the intimate contact of heterostructure interface, which effectively expedites the separation and migration of carrier and inhibits the photocorrosion of photocatalyst. This work provides a promising photocatalyst for water environment remediation, and promotes the exploration of heterostructure photocatalyst for wastewater purification.

Novel nitrogen-doped KFeS2/C composites for the efficient removal of Cr(VI)

Qiaohong Su,Adnan Ali Khan,Zhi Su,Chen Tian,Xiaoqin Li,Jiahua Gu,Ting Zhang,Rashid Ahmad,Xintai Su,Zhang Lin

Adsorbents with excellent redox or adsorption properties are beneficial for the efficient removal of heavy metals. In this work, a novel nitrogen-doped KFeS2/C composite (NSC-1.3) was first prepared by a simple one-step pyrolysis method and used to effectively remove Cr(VI) from aqueous solutions. The kinetics and adsorption isotherms of Cr(VI) were in accordance with pseudo-second-order kinetic and Langmuir models, respectively. The maximum adsorption capacity of NSC-1.3 was 575.68 mg g−1 at 318 K and 326.8 mg g−1 at 298 K. The removal mechanism of Cr(VI) by NSC-1.3 was first discussed by X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) simulation. The XPS analysis showed that nitrogen or carbon functional groups provide abundant active sites for Cr(VI) adsorption, and Sn2− or S8 in NSC-1.3 reduces highly toxic Cr(VI) to less toxic Cr(III). The XPS analysis showed that the removal mechanism of Cr(VI) was through adsorption and redox reaction, but the dominant one was the redox reaction. DFT simulations showed that N atoms doping was feasible and thermodynamically stable. In addition, H2CrO4 makes stronger intermolecular hydrogen bonds and larger adsorption energies with the N-doped KFeS2 layer during the adsorption process, indicating that the N-doped system has a higher adsorption capacity for Cr(VI). This study confirms the importance of the adsorption and redox reaction mechanism of this new composite material, and has promising potential for the removal of highly toxic Cr(VI) from aqueous solutions.

Construction of hollow In2S3/CdIn2S4 heterostructures with high efficiency for Cr(VI) reduction

Cheng Cheng,Dongyun Chen,Najun Li,Hua Li,Qingfeng Xu,Jinhui He,Jianmei Lu

Hexavalent chromium (Cr(VI)) poses a serious threat to the environment and human health due to its high-toxicity and carcinogenicity. For efficient removal of Cr(VI), semiconductor photocatalytic reduction methods have been investigated, especially those using hollow structures. In this work, a hollow In2S3/CdIn2S4 composite photocatalyst was prepared via ion exchange for the reduction of Cr(VI). The microstructure, composition, optical properties, and elements of the In2S3/CdIn2S4 composites were characterized via scanning electron microscopy, X-ray diffraction, UV-vis diffuse reflectance spectroscopy, and X-ray photoelectron spectroscopy. Because of the molecular level heterojunction constructed through ion exchange and the hollow structure, the prepared photocatalyst demonstrated excellent catalytic properties for Cr(VI) reduction. Besides, a Cr(VI) aqueous solution (50 mg L−1) was reduced within 12 min. Importantly, the activity and structure of the photocatalyst were maintained after five cycling experiments, which demonstrates its advantageous stability. Finally, the photocatalytic mechanism is discussed in detail.

Morphology control synthesis of Cr-benzenedicarboxylate MOFs for the removal of methylene blue

Tian Zhao,Hexin Zhu,Wei Geng,Minmin Zou,Ming Dong,Jie Ying

Propionic acid could efficiently affect the formation of Cr-benzenedicarboxylate metal-organic frameworks (MOFs), giving rise to yielding products with various structures. Generally, nano-sized crystals of MIL-101(Cr) can be prepared with comparatively lower concentration of propionic acid (0.6 ​M), which possessed high porosity (S BET  ​= ​2720 ​m 2 /g). The hierarchically porous (HP) MIL-101(Cr) was obtained with medium concentration of propionic acid (1.2 ​M), and micro-rod like crystals of MIL-88B(Cr) was formed in high concentration of propionic acid (1.8 ​M). Compare to bulk MIL-101(Cr) and nano-sized MIL-101(Cr), HP-MIL-101(Cr) showed much higher uptake of methylene blue (119.1 ​mg/L) in aqueous. This approach can offer a facile and effective pathway to synthesize stable hierarchically porous Cr-benzenedicarboxylate MOF for the applications in pollutant treatment fields.